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B Y GEORGE EYAIS, LECTURER ON CROWN- AND BRIDGE-WORK IN THE BALTIMORE COLLEGE OP DENTAL SURGERY; MEMBER OP THE AMERICAN DENTAL ASSOCIATION, AND OF THE SOUTHERN DENTAL ASSOCIATION; HONORARY MEMBER OP THE MARY- LAND STATE DENTAL ASSOCIATION, ETC, Third Edition, Revised and Enlarged. WITH 631 ILLUSTRATIONS. PHILADELPHIA : THE S. S. WHITE DENTAL MFG. CO. 1893. 515 1893 ' ./4 Copyright, 1888, by Geoege Evans. Copyright, 1889, by Geokge Evans. Copyright, 1893, by Geokge Evans. To the Members of the First District Dental Society of the /State of New York, this Book is respectfully dedicated by The Author. PREFACE TO THE THIRD EDITION. Crown- and bridge-work has now received professional in- dorsement. A recognized and honorable position in dental prosthesis has been accorded to it. Its teaching has been added as a special branch to the curriculum of every dental college in the United States which is classed among those imparting a thoroughly practical and advanced education to its students. As the methods by which its results are achieved in dental practice become better understood, its great advantages are conceded. That crown- and bridge-work is being improved in methods of practical application, and that the sphere of its usefulness is widening, is evidenced by a comparison of the present edition of this work with those which have preceded it. The object of previous editions was, as stated in the first edition, to assist in obtaining a proper recognition of crown- and bridge-work, by placing before the dental profession a practical treatise on the subject which should explain in a liberal and im- partial manner the principles involved, and as well outline correct methods of practice. In preparing the present revised edition these objects have been kept plainly in view, and the author has endeavored also to better meet the need for a text-book for college and post-graduate study, as well as to enhance the value of the volume as a reference-book for the practitioner. George Evans. 133 W. 34th St., New York, January, 1893. vii PREFACE TO THE SECOND EDITION. In a field of practice so new as that of which this volume treats it is natural that changes and improvements in methods and systems should be evolved with unceasing rapidity. Although less than a year has elapsed since the publication of the first edition, the revision of the work for the introduction of new matter has become necessary to properly fulfill the requirements of a practical and comprehensive treatise. Professional interest in the subject of crown- and bridge-work continues unabated. Judging from the space its discussion occupies in the journals and the proceedings of societies, this branch of practice is gaining in favor. Many new ideas respect- ing it have reached the profession through each of the channels named. From these and from other available sources careful selection of methods and appliances possessing merit has been made which by incorporation in this second edition should enhance its value to the busy practitioner. The author entertains a grateful appreciation of the compli- mentary acknowledgments which have been accorded to his efforts and intentions, and hopes for an equally favorable estimate of his labors in connection with this edition. George Evans. New York, July, 1889. viii PREFACE TO THE FIRST EDITION. The aim of the author in preparing this treatise is to supply an admitted want in dental literature. Much that is new in dentistry and much more that is, by many practitioners at least, only imperfectly understood, is involved in crown- and bridge-work. Properly practiced it approaches a fine art; but misapprehension of the principles underlying it, lack of judgment in their application, and im- proper practice have conspired to prevent its general acceptation by the profession, and it has in consequence been only partially indorsed or even wholly condemned when a better understanding would have insured its hearty approval. Still, its possibilities are seen to be so great that at present no other branch of dentistry more engages the attention of practitioners, and in no other is a livelier interest or a greater desire for real information manifested. The subject is here presented almost wholly from the practical standpoint, in the belief that the utility and esthetic advantages of crown- and bridge-work may be thus more readily made apparent to the practical men in dentistry. To this end the various methods described are classified in systems, and their treatment is made as concise as their importance will permit. Due credit is given where the methods and descriptions of others are used. Acknowledgment is gratefully rendered to Drs. H. A. Parr, of New York .City, E. Parmly Brown, of Flushing, N. Y., and M. H. Fletcher, of Cincinnati, for personal assistance. George Evans. New York, August, 1888. ix CONTENTS. PAGE Introduction................................................................................... 1 Artificial Crown- and Bridge-Work............................................. 5 PART I. preparatory treatment op teeth and roots for crown-work. CHAPTER I. The Pulps of Teeth—Their Preservation or Devitalization—Pulp- Capping....................................................................................... 10 CHAPTER II. Devitalization of the Pulp......................................................... 16 CHAPTER III. Pulpless Teeth—Preparation of Root-Canals—Their Treatment, Disinfection, and Filling.......................................................... 21 CHAPTER IV. Chronic Alveolar Abscess............................................................. 28 CHAPTER V. Shaping Teeth and Roots for Crown-Work................................... 33 PART II. artificial crown-work. THE PORCELAIN SYSTEM. CHAPTER I. Porcelain Crowns.......................................................................... The Bonwill Crown....................................................................... 43 The How Crowns and Methods........................................................ 49 The Gates Crown.......................................................................... 56 The Foster Crown......................................................................... 57 The Howland Crown.................................................................... 57 The Logan, Brown, and New Richmond Crowns.............................. 58 Remarks on the Use of Porcelain Crowns........................................ 66 Xll CONTENTS. CHAPTER II. PAGE Porcelain Crown with Gold Collar Attachment......................... 68 CHAPTER III. The Weston Crown......................................................................... '" CHAPTER IV. Porcelain Crowns with Rubber or Vulcanite Attachment......... 76 the gold system. CHAPTER V. Porcelain and Gold Crown without a Collar.............................. 77 With a Partial Ferrule................................................................. 78 CHAPTER VI. Gold Collar Crowns...................................................................... 79 The Construction and Adaptation of Collars................................... 79 CHAPTER VII. Gold Collar Crowns with Porcelain Fronts................................. 85 Incisors and Cuspids.................................................................... 85 Bicuspids and Molars..................................................................... 88 CHAPTER VIII. All-Gold Collar Crowns for Bicuspids and Molars constructed in Sections................................................................................... 92 Incisors and Cuspids..................................................................... 100 CHAPTER IX. The Gold Seamless Cap Crown...................................................... 102 Incisors, Cuspids, and Bicuspids, with Porcelain Fronts..................... 102 All-Gold Seamless Bicuspids and Molars.......................................... 104 CHAPTER X. Gold Seamless Contour Crowns...................................................... 108 Adjustment of Seamless Contour Crowns.......................................... ill CHAPTER XI. Gold Crowns with Porcelain Fronts for Teeth with Living Pulps 119 Collar Crowns Hygienically Considered............................................ 124 CHAPTER XII. Special Forms of Gold Crowns with Porcelain Fronts................. 126 The Parr Crown ................................................................... 226 The Leech Crown.................................................................. 127 The Low Crown................................................................... 128 The Perry Crown................................................................. joq CONTENTS. xiii CHAPTER XIII. PAGE Crowning Fractured Teeth and Roots—Crowning Molar Roots decayed apart at Bifurcation—Crowning in Cases of Irregu- larity .......................................................................................... 132 Longitudinal Fracture of the Crown and Root................ .................. 132 Fracture of the Crown with Slanting Fracture of the Root.................. 133 Perforation of a Side Wall of a Root-canal or of the Dentine at the Bifurcation of the Roots............................................................. 134 Crowning Molar Roots decayed apart at the Bifurcation..................... 135 Dr. Farrar's Cantilever Crown.......................................................... 135 Methods of Crowning in Cases of Irregularity.................................. 136 CHAPTER XIV. Partial Crowns.............................................................................. 137 CHAPTER XV. Finishing and Polishing—Process of Cementation.......................... 145 Finishing and Polishing Crown-Work............................................. 145 Insertion and Cementation.............................................................. 145 Oxyphosphate of Zinc............................*..................................... 145 Gutta-Percha.............................................................................. 148 Amalgam................................................................................... 148 PART III. BRIDGE-WORK. CHAPTER I. Construction of Bridge-Work....................................... ................. 158 CHAPTER II. Special Processes and Appliances in Bridge-Work.......................... 171 CHAPTER III. Extension Bridges........................................................................... 178 CHAPTER IV. Bar Bridges.................................................................................... 182 CHAPTER V. Removable and Replaceable Porcelain Fronts............................... 187 CHAPTER VI. General Application of Crown- and Bridge-Work..................... 189 Extensive Applications of Crown- and Bridge-Work ........................ 193 CHAPTER VII. Repair of Crown- or Bridge-Work................................................ 202 XIV CONTENTS. CHAPTER VIII. PAGE The Hygienic Condition of the Mouth as affected by Bridge-Work 206 CHAPTER IX. Removable and Detachable Bridge-Work..................................... 208 Removable Incisor or Cuspid Crown................................................ 209 Removable Bicuspid and Molar Attachments.................................... 212 Connecting Bars......................................................................... 216 Construction of Removable Bridge-Work......................................... 217 CHAPTER X. Removable Plate Bridges................ ............................................. 225 CHAPTER XL Special Forms of Removable and Detachable Bridge-Work...... 238 Dr. Winder's Sectional Crown Method............................................ 238 Dr. Litch's Method...................................................................... 241 Dr. R. W. Starr's Methods............................................................. 243 Dr. Parr's Methods...................................................................... 248 Dr. Waters's Methods............................ ...................................... 255 CHAPTER XII. Removable Bar-Bridges................................................................. 260 CHAPTER XIII. The Low Bridge............................................................................ 266 CHAPTER XIV. Dr. Knapp's Methods................................................................. 270 CHAPTER XV. Dr. Melotte's Method............................................. 275 CHAPTER XVI. Partial Cap and Pin-Bridge Methods............................ 279 CHAPTER XVII. The Mandrel System..................................................... 287 Detachable Bridge-Work....................................... oqq CHAPTER XVIII. Porcelain Bridge-Work.......................................... „n(. Dr. Brown's Method............... ort_ ........................................... oOo CHAPTER XIX. Crown-and Bridge-Work combined with Operative Dentistry in Dental Prosthesis........................... .................................................... 315 CONTENTS. XV PART IV. MATERIALS AND PROCESSES USED IN CROWN- AND BRIDGE-WORK. CHAPTER I. PAGE Plate and Solders.......................................................................... 327 CHAPTER II. Porcelain Teeth............................................................................. 331 CHAPTER III. Molds and Dies........................................................................... 332 CHAPTER IV. Soldering........................................................................................ 335 CHAPTER V. Instruments and Appliances................. ...................................... 337 INTKODUCTION. Of the origin of the art of dentistry no one can speak with cer- tainty, as its early history is shrouded in the mists of antiquity; but dental operations are recorded in very remote times. References are made to the art in the writings of Hippocrates, in the fifth century b.c. Martial, the Latin poet, in the first century B.C., says that a Roman dentist " Cascellius is in the habit of fastening as well as extracting the teeth." To Lelius he says, "You are not ashamed to purchase teeth and hair;" and adds that " the toothless mouth of Egle was repaired with bone and ivory;" also, that "Galla, more refined, removed her artificial teeth during the night." Horace, in the same century, cites the case of the " sorceresses Canidia and Sagana running through the city and losing the one her false hair, the other her false teeth." Galen, the celebrated physician, in the second century a.d., also speaks of the art of dentistry as being then practiced. These early operations were limited to the extraction of offending teeth and the replacement of those which had been lost with substitutes which were retained in position by means of narrow bands or ligatures attaching them to the adjoining natural teeth, and without the use of plates. Crude as they were, they formed the first expression of the art of dentistry, a beneficent art from the beginning, in that it sought to restore pathological or accidental defects. Confined to the simplest operations, it existed for centuries, and then was apparently 2 l 2 INTRODUCTION. lost during the Dark Ages, to reappear when the more general diffusion of knowledge ushered in the modern era of science and invention. After its revival, dentistry, so much of it as was known, was in a measure a secret art, the practice of which even within the memory of men now living, and they not the oldest, was in- volved in mystery; but recent progress has lifted the veil, and dentistry, in the treatment of the teeth on correct, scientific, rational principles, has developed an art and a science which have given it honorable rank among the professions. In its two-fold evolution it has absorbed from every available source whatever would broaden its science or perfect its art. It calls to its aid anatomy, physiology, pathology, chemistry, thera- peutics, metallurgy, sculpture, and mechanics, with each of which it stands in closer or more remote relation; and the practitioners of dentistry who have become the most eminent and useful have been men of broad attainments and great versatility of talent. In the history of all progress, movements apparently of a more or less reactionary character are recorded. In the useful arts especially it is not uncommon to find a return to forms and methods formerly used but long since discarded and forgotten. So in dentistry we find methods of treatment and modes of practice once in vogue but long fallen into disuse, revived with improvements' and modifications that stamp them as prac- tically rediscoveries. These movements are not to be regarded as retrogressive, because the modifications which accompany the reintroduction of practical ideas and inventions stamp them as real advances and indicate clearly that the cycle of knowledge is ever widen- ing with experience. This volume demonstrates how modern dentistry has utilized the principles of some of the simplest original operations, and by " proving all things, holding fast that INTRODUCTION. 3 which is good," has attained its present honorable position in both its scientific and artistic departments. The history of dentistry of later years is, in brief, a recital of progress and improvement. The medical profession has officially recognized it as closely allied to medicine by inviting its rep- resentatives to take part in the International Medical Congresses on the footing of professional equality. Such is the position which dentistry has attained. Much of the progress which has made its present elevation possible must be credited to the dental profession of the United States, which has been justly termed the cradle of modern dentistry. Here the validity of the idea that scientific knowledge should form the basis of training for practice was first demonstrated by the successful establishment of dental schools; here the first journal for the interchange among dentists of thought and experience was founded; here the first association having for its object the uplifting and upholding of dentistry by the mutual helpfulness of its practitioners had its origin; here, in a word, dentistry was first divorced from mystery, here it first passed the narrow confines of a mere handicraft and earned for itself the right to be classed among the learned and liberal professions. ARTIFICIAL CROWN- AND BRIDGE-WORK. Modern artificial crown- and bridge-work belongs to the department of dentistry until recently termed " mechanical," but the judgment, skill, and scientific information required place it far above ordinary mechanical dentistry, which has sunk to a low estate since the introduction of vulcanite. To such an extent has vulcanite, by reason of its cheapness and ease of manipulation, superseded other materials demanding greater knowledge and skill in their manipulation, as to retard the higher development of prosthetic dentistry, and indeed to divest it, in the hands of those who depend upon vulcanite, of the dignity which should belong to dentistry as a profession. But modern crown- and bridge-work, properly understood and properly performed, takes high rank in dental art, and offers wide scope for versatility of talent and inventive genius. The varied and complicated cases presenting for treatment fre- quently suggest to the expert novel contrivances and methods of construction and application. Successful practice of crown- and bridge-work depends upon a thorough mastery of the under- lying principles, and expertness in the processes involved, gov- erned by sound judgment and perfect candor. The interests of the patient should be paramount to every other consideration, and after a careful examination he should be given an accurate statement of the applicability of the system to his case, in re- spect to usefulness, appearance, durability, and comfort, as compared with other processes and appliances in use. 5 6 ARTIFICIAL CROWN- AND BRIDGE-WORK. Surgical and mechanical operations of the most delicate nature are required. Nothing, indeed, in dentistry demands finer manipulation. A practical consideration of the subject will show that a knowledge of anatomy, pathology, and thera- peutics, and as well mechanical and artistic skill, are necessary to the correct treatment of cases and the proper performance of the operations indicated. Among the principal steps in an operation may be named, first, the preparatory treatment of the natural roots and teeth for the final process, involving the diag- nosis of present or probable lesions and the prescription of whatever remedial or prophylactic measures may be needful; second, in crown-work, the adaptation of the artificial crowns to the cervical portion of the natural roots and the contiguous membranes, and the restoration of the articulation and the ana- tomical contour; and, in bridge-work, the selection of suitable teeth or roots for foundation piers or abutments, and the choice and adaptation in constructive practice of the forms which will insure the highest degree of stability and best sustain the force of occlusion, thereby avoiding abnormal positions and condi- tions. The practice of crown- and bridge-work by dentists possessing the requisite attainments and governed by correct ethical princi- ples gives results which are gradually establishing its value, re- moving erroneous impressions, and insuring a wide professional and public indorsement of this important branch of prosthetic dentistry. Its extraordinary facilities for preserving and replac- ing teeth are gradually making for it the position in dental art which it merits. PAET I. PREPARATORY TREATMENT OF TEETH AND ROOTS FOR CROWN-WORK. PREPARATORY TREATMENT OF TEETH AND ROOTS FOR CROWN-WORK. Preparatory treatment of teeth and roots for crown-work includes, in addition to the shaping required to fit them for the reception of the crowns, the bringing about of the healthiest possible condition in the teeth and roots and the adjacent parts, as the cure of existing lesions, the removal of calculus where necessary, and the adoption of such measures as shall prevent the recurrence of old troubles or the inception of new. Notwithstanding all that advanced knowledge of therapeutical agents and skill in their use permit, there are many teeth and roots which cannot be rendered suitable for the successful appli- cation of crown- or bridge-work. Roots which are permeated and softened by decay, exposed or loosened from absorption of the gums and alveoli, or affected with irremediable disease of the investing membranes, should be thus classed. Cases in which abscess with necrosis has extensively impaired the walls of the alveoli are equally intractable. Experience shows that the results in this department of den- tistry depend largely upon diathesis or constitutional tendency and upon the attention given to the preservation of the health of the mouth; and these conditions should be carefully estimated in the selection of a system of treatment and the method of its application. 9 CHAPTER I. THE PULPS OF TEETH—THEIR PRESERVATION OR DEVITALI- ZATION—PULP-CAPPING. The preservation of the vitality of the pulps of the teeth is a matter of as much importance in connection with crown- and bridge-work as in any other class of operations, though the excision of natural crowns for the purpose of utilizing the roots as abutments for bridge-work is extensively practiced, and is defended on the theory that the vitality of the dentine is main- tained by the cementum after the extirpation of the pulp.1 Dr. C. F. "W. Bodecker, discussing the subject of the "Dis- tribution of Living Matter in Human Dentine," says,2— "1st. The dentinal canaliculi are excavations in the basis- substance of the dentine, each containing in its center a fiber of living matter. Besides the dentinal canaliculi, there exists an extremely delicate net-work within the basis-substance of the xDt. J. L. Williams says, "The life and vitality of the cementum remain in- tact and uninjured, and even the dentine may, and undoubtedly does, retain a certain amount of vitality, for something analogous to a healing process takes place at the ends of the broken fibrillae next to the pulp-chamber, and by one of those wonderful provisional conditions which we so often meet with in the economy of the animal kingdom nature reverses or changes the origin of nutri- tive supply, and the material for maintaining the continued vitality of the den- tine comes through the cementum." He further says, " Every practicing dentist has observed that a tooth which is removed from contact with the fluids of the mouth changes color. This change in color is largely the result of the evaporation of the water from the organic portion of the tooth. Now, if the apical foramen of such a tooth be closed, and the tooth be then placed in water, or preferably, glycerin and water, in a short time it will regain nearly its original color, and at the same time it will be found that it has increased in weight. This means, of course, that the entire tooth has absorbed from the surface a certain quantity of the fluid, and this fluid has pene- trated every part of the solid structure of the tooth. Will any one doubt, with these facts in view, that when the tooth is in position in the jaw, and surrounded by all *he delicate adjustments furnished by nature, there may be a circulation of nutrient fluids throughout the entire root after the removal of the pulp?" It is difficult to understand how a saturation can be compared to an infiltration controlled by vital circulation.—G. E. 2 Dental Cosmos, vol. xx, page 656. 10 Plate I. D Plate II. 4r,( i-ifi,tuK\4.^' 0 ■... x Xw.di.-. .i r. t. V.'ft From Specimens made by M. H. Fletcher, M. I)., Dentist Ci\f ivv-i-,., r\ ' '- l ,;nna ii, Uiuo. F. GUTEKUNST PRINT. THE PULPS OF TEETH. 11 dentine, into which innumerable offshoots of the dentinal fibers pass. Although we cannot trace the living matter throughout the whole net-work in the basis-substance, evidently owing to its delicacy, we are justified in assuming that not only the dentinal canaliculi, but the whole basis-substance of the dentine is also pierced by a delicate net-work of living matter. The living matter of the dentine is in direct union with that of the proto- plasmic bodies of the pulp, of the cementum, and of the enamel. " 2d. The cementum, as well as ordinary bone, is provided with lacunae and canaliculi. The lacunse contain nucleated protoplasmic bodies, and the canaliculi hold offshoots of the living matter of the protoplasm. The whole basis-substance of the cementum is traversed by a delicate net-work, which in all probability contains living matter, though this is traceable only in its thorn-like projections from the periphery of the proto- plasm and its larger offshoots. The living matter of the cementum is uninterruptedly connected with that of the periosteum, and continuous with that of the dentine, either through intervening 'protoplasmic bodies in the interzonal layer, or directly with the dentinal fibers." This distribution and relative connection of living matter as described refers to an existing state of perfect vitality of all the parts. When the pulp loses its vitality, an entirely different condition results. The tubuli are then deprived of vital circula- tion, except along the line of the outer portion of the dentine, where, in the interzonal layer, the fibrillse anastomose with the living matter of the cementum. The vitality supported by this anastomosis is almost entirely confined to this part, the nutrient supply being insufficient to assume the functions of the pulp and maintain circulation in the main body of the dentine. (See Plates I, II, III.)1 1 Platjc I.—Longitudinal section of the root of a superior bicuspid, at junction of dentine with cementum. 0, cementum; D, dentine; I, interzonal layer; L, lacunae of cementum. X 175. Plate II.—A field taken from Plate I in position marked A. L, lacunas of cementum ; C, canaliculi of dentine; I, interzonal layer. X 210. Plate III.—A field taken from Plate I in position marked B. L, L, L, lacunaa of cementum; I, interzonal layer; D, dentinal tubes and their nearest approach to the lacunae. X 210. A study of these plates demonstrates the limited nature of the anastomosis of the fibers of living matter of the dentine and cementum. 12 ARTIFICIAL CROWN- AND BRIDGE-WORK. Chemical analysis of the dentine shows that the organic matter, consisting principally of the fibrillse, exists in the pro- portion of nearly 28 per cent, to .72 per cent, of lime-salts. When the pulp has been removed, the devitalized fibrillse still remain, and are capable of generating septic gases which will exert an influence in producing irritation of the cementum and pericementum, no matter how thoroughly the root-canal has been filled and the foramen closed. An examination of the investing membranes of pulpless teeth generally shows the existence of; abnormal conditions, by which their firmness is to some extent impaired, their susceptibility to acute inflammation increased, and their reliability as foundations for crown- or bridge-work greatly lessened when compared with teeth which have living pulps. In crown-work, facilities are afforded for the preservation of pulps in the posterior teeth. Thus, in a case verging on expos- ure, only partial removal of the decay is usually necessary, as, when the operation is completed, the natural crown will be hermetically inclosed by the artificial one. In bridge-work, proper methods of practice permit the anterior teeth to be used as abutments without the extirpation of their pulps or the excision of their crowns. Extirpation is demanded for those pulps whose permanent preservation cannot be placed beyond doubt, as failure involves more serious consequences in crown- and bridge-work than in filling-operations. The lesions of the pulp which seem to re- quire its extirpation, according to the generally expressed opinion on the subject, are exposure with hypertrophy or rupture of the pulp-sac, congestion, and pulpitis which does not yield promptly 1 According to Berzelius and Bibra, dentine consists of Organic matter (tooth-cartilage) Fat..... Calcium phosphate and fluoride Magnesium phosphate Calcium carbonate Other salts .... 27.61 .40 66.72 1.18 3.36 .83 Age lessens the proportion of living matter and increases the percentage of lime-salts. THE PULPS OF TEETH. 13 to remedial treatment. Pulps actually exposed by decay are eeldom found in a normal condition otherwise, and they are only rarely proper or hopeful subjects for remedial treatment. Atrophy of the membrana ebon's, or investing membrane, which comprises the layer of odontoblasts, usually exists at the part exposed, and, as any subsequent calcification must depend on the activity of the odontoblasts, it is evident that the existence of the condition referred to affords a strong argument against the advisability of capping pulps in cases of extensive or even slight exposure. The difficulty of securing a condition of asepsis of the exposed and diseased parts so perfect as to assure them against the invasion of micro-organisms subsequent to capping is an additional argument against the operation. Pulps which are in a normal condition, still protected by a layer of even decomposed or partly decomposed dentine, usually admit of successful treatment. In such cases, the decayed dentine may be excavated from the side walls of the cavity, but that in the region of the pulp should be only superficially removed; in some cases, this portion may be allowed to remain undisturbed. Palp-Capping.—The operation of capping a pulp should in- clude, as a necessary precaution against subsequent irritation, the thorough disinfection of any remaining decomposed den- tine. An excellent method of securing disinfection is by first thoroughly washing the cavity several times with tepid water thrown gently from the large point of a syringe around the sides of the cavity; then, taking measures to prevent the entrance of saliva, wiping the cavity with absorbent cotton and passing over its surface a light current of hot air from a hot-air syringe. The heat should be sufficient to cause sonic: discomfort to the patient, but not enough to produce irritation of the pulp. The dried cavity is then immediately saturated with wood creasote1 previously warmed2 to the normal tempera- ture of the body by holding the pellet of cotton on which it is 'A refined pure wood creasote, such as is prepared for dental uses, is the best for this purpose. Carbolic acid, alone or in combination with oil of cloves, is preferably used by some operators. 2 Thermal shock to the pulp is as unwarranted from the application of cold creasote as if produced in any other manner. 14 ARTIFICIAL CROWN- AND BRIDGE-WORK. applied over the flame of a lamp for a moment. The creasote relieves any pain caused by the evaporation of moisture, and disinfects and sterilizes any decomposed matter in proximity to the pulp. The object of the application of the creasote having been accomplished, it may then be removed as far as possible. To this end the cavity should first be wiped with absorbent cotton, and hot air again introduced to evaporate the creasote sufficiently to give a dry appearance to the surface. This second application of hot air, owing to the effect of the creasote, will cause very little or no pain. This method, if practiced early in the preparation of the cavity, will be found to considerably obtund sensation, and, through the dryness secured, to materially facilitate the removal of the de- composed dentine. A reasonable amount of the decayed por- tion should be cut away, as it lessens the difficulty of proper disinfection. For excavating in the region of the pulp-chamber, spoon-shaped excavators should be used invariably. The disinfected dentine over the pulp is then capped with oxj'phosphate. For this purpose the cement should be mixed soft. The proper quantity is then applied to one side of the cavity and brought over against the bottom in such a way as not to inclose air between the cement and the surface, or cause the slightest pressure upon the pulp. This is an operation requiring careful and delicate manipulation. Properly performed, it is preferable, in most cases, to protecting the part with a plate or cap, either metallic or non-metallic, fitted to the bottom of the cavity to avoid pressure of the cement; or to the use of concave caps filled with the cement.; as, owing to the adhesive character of oxyphosphate of zinc, pressure from encompassed air is apt to occur frequently when the cap is adjusted in position. If there is any apprehension of acid reaction from the oxy- phosphate affecting the pulp, the bottom of the cavity can be first covered with a little dry oxide of zinc or chloro-gutta-percha, the chloroform being evaporated in the latter case with the hot- air syringe.1 The creasote by its presence and action on the sur- 1 Acidity of oxyphosphate cement arises from the use of too much acid in pro- portion to the oxide, from lack of thorough manipulation, or from unsuitable oxide of zinc. (See article on " Cementation.") THE PULPS OF TEETH. 15 face of the dentine forms the only really necessary barrier to acid reaction, if the oxyphosphate of zinc is suitably constituted, cor- rectly compounded, and properly used. Pulp-capping, when necessary, should precede any other oper- ation, and no subsequent procedure is admissible until the success of that operation is assured, the time allowed for this purpose being governed by the diagnosis of each case. A non-vital con- dition of the pulp in one root of a tooth contraindicates any at- tempt to preserve it in any of the other roots, in connection with crown- and bridge-work. The rubber-dam, when its use is prac- ticable, will be found a material aid in difficult pulp-capping operations. CHAPTER II. DEVITALIZATION OF THE PULP. In preparation for crown-work two methods of devitalization are practiced: the heroic,—instantaneous devitalization, or ex- tirpation,—and gradual devitalization by arsenical treatment. Instantaneous devitalization can be accomplished by first admin- istering to the patient sufficient nitrous oxide to produce partial anesthesia, then with a drill quickly opening into the pulp- chamber, and lacerating the pulp well up the canal with a probe or smooth broach. Instantly afterward a pellet of cotton, satu- rated with carbolic acid, is forced up the canal, and, if possible, left until the next day, when the pulp will be found in a coagu- lated mass that is easily removed entire. Devitalization of the pulp as just described is practicable only in teeth in normal condition. In acute inflammation, after lacer- ation of the pulp, warm water should be gently injected into the pulp-chamber, and sedative agents then applied. Subsequent treatment should be such as will complete the devitalization and extirpation of the pulp. In cases of actual exposure of the pulp, the rubber-dam can be applied, the exposed section obtunded with hydrochlorate of cocaine, either the moistened crystal or a very strong solution, and as soon as its action is manifested the pulp then injected with the solution and extirpated. Excision of the crown and instantaneous extir- 3 pation of the pulp is practiced by many as follows: Two parallel grooves are cut opposite to each other, through the enamel, deep into the den- tine, one on the labial portion of the tooth and the other on the palatal wall, close to the gum, with a rapidly revolving corundum or rubber and corundum disk (Fig. 1). Then 16 DEVITALIZATION OF THE PULP. 17 Fig. 2. Fig. 3. with excising forceps, the cutting-edges of which are inserted in these grooves, the crown is quickly severed from the root (Fig. 2). The pulp either adheres to the excised crown, leaving the canal empty, or remains in the root, fully exposed. In the latter case, a pointed piece of orange wood, previously cut to fit the canal, and saturated with carbolic acid, is quickly driven with a blow into the pulp toward the apex of the root (Fig. 3). When the wood is withdrawn, the pulp usually adheres to it; if not, the wood is instantly reinserted, cut off and drilled out with the pulp, using Gates-Glidden drills in the upper portion of the canal. In this operation, it is claimed, only trifling pain is experienced by the patient, as the pulp is paralyzed by shock in the excision of the crown, or by being forced upward toward the foramen and against the walls of the canal. The objections to this opera- tion are, that if the pulp is not successfully extracted entire with the wood the canal becomes filled with clotted blood, which is difficult to remove from the extreme end ; also that the root and socket are jarred by the for- ceps in excising the crown; but, expertly performed, it is advantageous in many cases, though it must be confined to pulps in normal condition. Devitalization with Arsenious Acid—The methods of devitalizing previously described are applicable principally to the pulps of incisors and cuspids. In the posterior teeth, which do not so well permit the heroic treatment, recourse is had to arsenious acid, notwithstanding the numerous objections to its use. Two theories as to the mode of its action in devitalizing are widely entertained: First, that by producing irritation of the pulp it causes its expansion, which stops circulation by strangulation at the foramen; the other is thrombosis.1 This theory of thrombosis accounts for the gradual devitaliza- LSee Dr. L. C. Ingersoll's " Dental Science, Questions and Answers," page 93. 3 18 ARTIFICIAL CROWN- AND BRIDGE-WORK. tion of the pulp toward the foramen, and is very likely the true explanation. Whatever the action of arsenic on the pulp may be, it always causes an infiltration of the tubuli of the dentine with certain constituents of the blood, probably the liquor sanguinis. The residue of the infiltration, after the devitalization of the pulp, remains in the tubuli, and increases the difficulty of producing an aseptic condition of the dentine. It is asserted that in some cases arsenic affects the vitality of the cementum, while after instantaneous extirpation of the pulp, when arsenic is not used, vitality is assured. Practical experience shows that usually instaut devitalization or extirpation is the most satisfactory in general and final re- sults. Arsenic, when used, should be applied directly to the pulp in the smallest quantity possible to effect its devitalization, and securely sealed in the cavity. In cases of non-exposure, requiring its application, a small opening into the pulp-chamber should be made. This can be accomplished with but little pain to the patient with a very small, sharp, spear-headed drill, rapidly revolved by the engine. The drill should be held steadily under gentle pressure at one point in the line of the intended exposure, until the pulp is slowly and gradually reached, and not suddenly punctured with the drill-point. The point of the drill should be occasionally removed and dipped in carbolic acid, or a saturated solution of cocaine in glycerin, during the operation. The use of arsenic, combined with agents which are non- coagulants of albumen, is recommended in preference to com- bining it with creasote or carbolic acid. Dr. Harlan's method is to apply an anodyne, such as wine of opium, for a minute or two, and then the following paste: R—Arsenious acid, gi; Muriate of cocaine, ^ii; Lanolin in quantity sufficient to make a stiff paste. The application should be kept in position no longer than is necessary to effect the devitalization of the pulp, twelve to forty- eight hours being sufficient for the purpose. The pulp is then punctured, a saturated solution of tannin in glycerin applied DEVITALIZATION OF THE PULP. 19 and securely sealed in the cavity, and the patient dismissed for several days. At the end of that time the pulp can, as a rule, be removed entire. The rubber-dam should be applied, the saliva entirely excluded, and absolute alcohol instead of water used in the treatment.1 When creasote or carbolic acid is used in com- bination with arsenic, the same method of subsequent treatment may be practiced. 1 See Dental Cosmos, vol. xxxiii, page 138. Plate IV. Sk CI & jjj^ ■f *li .©. ^0.

^ ^ ^* ^ ^ 0 / 1 20 CHAPTER III. PULPLESS TEETH—PREPARATION OF ROOT-CANALS—THEIR TREATMENT, DISINFECTION, AND FILLING. The treatment of pulpless teeth or roots consists in as thorough a performance as possible of the following operations: 1st. Removal of the contents of the canals. 2d. Disinfection of the root-canals and the dentine, and the establishment of permanent aseptic conditions by mummification of the contents of the tubuli. 3d. Closure of the apical foramen. 7Vii>htly necrosed state of the wall of the alveolus exists. Its use should CHRONIC AL VEOLAR ABSCESS. 31 however, be limited, and in subsequent external treatment through the fistula some of the other therapeutic agents should be employed, as the peroxide of hydrogen, sublimate solution (two)' or tne essential oils or carbolic acid, alone or combined with one of the preparations of iodine.1 Injections of sulphuric acid in the region of the mental fora- men should be made cautiously, and it should not be applied to an abscess bordering on the antrum until the operator is posi- tively assured that the abscess does not open into that cavity. Amputation of the Apex of a Root.—In long-neglected alveolar abscess, the pus-cavity occasionally involves the alveolus in such a way as to destroy a considerable portion of the pericementum of the end of the root. The cementum of that part is conse- quently devitalized, and the portion of the root affected becomes degenerated in structure, and saturated with septic matter. In this condition it acquires the character of a foreign substance, proves a constant source of irritation, and defies all efforts of the membranes to perfectly inclose or encyst it. In such cases, amputation of the portion of the root which is denuded of pericementum is the best course to pursue. An opening is made in the soft tissues over the affected part in the manner described on page 29, and gradually enlarged with C_ a tent of lint or cotton until the diseased territory is fully exposed (Fig. 11), when the devitalized end of the root and any necrosed bone in the territory are removed with a fissure-drill, and the end of the root smoothed. The root-canal is then closed with gutta-percha passed through from within, the surplus being trimmed off on the outside. Another way is to fill the canal solidly with gutta-percha previous to the amputation, so that when the end of the root is excised the stump will be left smoothly and snugly filled. Cocaine can be used in this operation. 1 For an extended consideration of this subject the reader is referred to Dr. J. N. Farrar's articles on "Sulphuric Acid v. Creasote in Treatment of Alveolar Abscess," commencing in Dental Cosmos, vol. xx, No. 7, and Dr. G. V. Black's article in the "American System of Dentistry," vol. i, page 929. Fig. 11. 32 ARTIFICIAL CROWN- AND BRIDGE-WORK The orifice of the cavity in the gum should be kept open until the cavity is filled by granulation. When the healing process is completed, crown-work can be proceeded with. The amputation of roots requires skill and experience, and had better be confined to the incisors. CHAPTER V. SHAPING TEETH AND ROOTS FOR CROWN-WORK. The principles governing the process of shaping the surface of a natural crown or root for any style of artificial crown with a collar attachment require that the cervical portion of the natural crown and root shall be given a form that has longitudinally parallel sides gauged to the line of the periphery of that part, and that any of the coronal section present below it shall be re- duced at least sufficiently in size to come within this line. Such a form is necessary to admit of a perfect adaptation of the collar. The coronal section of a natural crown to be prepared is usually first ground on the occluding surface with as large a corundum wheel as the case will conveniently admit (Fig. 12). Molars and bicuspids for all-gold crowns should have enough substance removed to make a small space between them and the antagonizing teeth. The approximal sides of the cervix should be reduced sufficiently to allow a free space between the gold collar when adjusted and the cervices of approximal natural teeth or artificial crowns. The approximal surfaces are removed straight from the cervical border to the occluding surface, using corundum or rubber and corundum disks (Fig. 13) and files, and last of all, as injury to the approximal teeth is then more easily avoided, the labial and palatal portions, for which small corun- dum points (Fig. 14) and wheels are best adapted. The corners are then rounded. The cervical portion, which includes the junction of the dentine and enamel, is trimmed so that the sides 4 33 34 ARTIFICIAL CROWN- AND BRIDGE-WORK as illustrated at A, Fig. 15, are level and parallel with the line of the root, and as deep as the collar is to be placed (Fig. 16). For this work, small corundum points, trimmers, and files can be used. Fig. 17 illustrates a drill, which in the ordinary hand- Fig 13. Fig. 14. piece or in the right-angle attachment will easily and quickly accomplish this. Fig. 18 illustrates another style, in the form of a triangular pyramid, which can be used as a scraper in a hand- socket, bracing the hand by resting the thumb on the adjoining teeth. The points should be tempered very hard. Files shaped as shown in Fig. 19 are useful in rounding angular portions. A smooth surface should be given the cervix. On approximal sides Fig 15 Fig. 16. Fig. 17. Fig 18. Fig. 19. Fig 20. and the curves to the other sides, medium coarse corundum tape and wheels can be used for this purpose. A root-trimmer or reducer devised by Dr. W. Storer How can be used in combination with or in place of the appliances before described. It is set in a cone-socket handle. The pin of the center shaft is inserted in the opening in the end of the root SHAPING TEETH AND ROOTS FOR CROWN-WORK. 35 and the scraper point rotated around the periphery underneath the gum margin (Fig. 20). The inward spring of the flat scraper shank causes the point to bear hard against the root, while following its outline closely. The root end is reduced without change of contour, while its taper is reversed, so that the greatest diameter is found at the portion acted on by the extreme end of the scraper point (A, Fig. 20). The milled nuts permit the scraper to be adjusted to different-sized roots. In pulpless teeth, the use of excising forceps should be avoided unless the parts admit of it without serious shock to the root. The best plan is to make a succession of holes with a spear- shaped drill across the portion to be removed, and then cut between the holes with a fissure-bur or corundum disk, which will permit of easy removal of the part (Fig. 21). Fig. 21. Fig. 22. Fig. 23. Fig. 24. Fig. 25. Fig. 26. In preparing incisors and cuspids for gold collar crowns with porcelain fronts, where the pulp is to be preserved, the labial surface and incisive edge should be ground down as much as possible without exposing the pulp or subjecting it to irritation; the palatal portion at an angle from the cervical border to the incisive edge, enough to level its prominences of contour and form a slight space between it and the antagonizing teeth (Fig. 22). Pulpless incisors and cuspids should be prepared by grinding the labial face to the gum margin, with the palatal portion slightly projecting and squared off to the inner line of the root-canal (see Fig. 23). Bicuspids which are to have porcelain fronts are given the same general form (Fig. 24). Bicuspids and molars with or without pulps, for all-gold crowns, 36 ARTIFICIAL CROWN- AND BRIDGE-WORK. should have as much of the natural crown left as possible, as it affords a more secure and more convenient attachment for the artificial crown than any other method (Figs. 25 and 26> It should be borne in mind, however, that unnecessarily cut- ting away the enamel and dentine of teeth with living pulps leaves them in an extremely sensitive condition, and is likely to result subsequently in some serious lesion of the pulp. Slight sensitiveness, such as may be readily caused in proper shaping, is relieved by drying the exposed dentine with hot air and apply- ing creasote or carbolic acid two or three times as required. For the porcelain system, roots are usually ground level with the margin of the gum. The palatal portion in some cases is left a trifle above the margin. The root-canal is shaped to the form of the post or pin to fit it tightly (see the articles on the Bonwill and Logan crowns). The occluding edges or surfaces of antago- nizing teeth should be removed sufficiently to allow ample space ■ for the artificial crowns or to favor them in occlusion. This is especially necessary where the occluding tooth, in the absence of an antagonist, protrudes beyond the proper line of occlusion. When the approximal teeth crowd against and overhang the cervix of a root, so that the space for the artificial crown at the occluding surface is less than at the prepared cervix,—measured from mesial to distal side,—they should be pressed away or a small portion of their interfering surfaces removed. Corun- dum or composition wheels or points should be kept wet and cool during all such operations in the mouth. A piece of sponge, held against the wheel with clamping pliers, answers the purpose admirably, and also protects the tongue and cheek from injury. Special Preparation of Badly Decayed Teeth or Roots.—The tem- porary exposure of the end of a root or of the cervical portion of a crown for the purpose of facilitating or simplifying a crowning operation, especially in the adaptation of a collar or band, is effected by inserting in the pulp-chamber or the root-canal a piece of gutta-percha large enough to admit of a portion being brought over against the investing membranes, to compress them for a day or more. When necessary to secure attachment for the gutta-percha, a plug of wood should be inserted temporarily in SHAPING TEETH AND ROOTS FOR CROWN-WORK. 37 the root, and the gutta-percha packed around it. Roots can thus be exposed to the border of the alveolar process if desired. In bicuspids and molars, when decay extends up on the cervix far- ther than will the edge of the artificial crown or the collar, the gums should be pressed up as de- scribed, the decay removed, retaining-pits made, and the cavity filled with amalgam shaped to the contour of the tooth (Fig. 27). In incisors and cuspids, when decay has destroyed a portion of the side of the root, a tight-fitting tube of a metal to which amalgam will readily adhere, and of such size as to admit the pin of the crown, can be inserted up the root-canal and the upper end cemented in with oxyphosphate and the lower with the amalgam forming the filling on the side of the root. In such a case, the pin should be tapered at the end, and inserted in the canal as deeply as possible beyond the Fig. 28. Fig. 29. Fig. 30. Fig. 31. u' I # ^ end of the tube, to gain additional strength by distributing the leverage along the whole line of the root. In setting a gold cap-crown on a badly broken-down tooth or root, a post of silver or iridio-platinum wire should be fitted to the root-canals (Figs. 28, 29, 30, and 31). The end can be bent or a piece of silver soldered to it. The post should then be l>arbed and the point first fastened in the root with a little oxy- phosphate or oxychloride of zinc, and the crown built down about two-thirds its length with a quick-setting amalgam, to be shaped when hard and then roughened to furnish a better attach- ment for the cement with which the crown is set. Screws may he used as posts to support the amalgam. As the artificial crown completely covers the amalgam, the existing prejudice against its use cannot apply to this method. PART II ARTIFICIAL CROWN-WORK. ARTIFICIAL CROWN-WORK. Artificial crown-work affords extensive facilities for restoring the crowns of natural teeth, and furnishes means of support for bridge-work. Two general systems are presented,—the porcelain and the gold. The porcelain system includes porcelain crowns with metallic attachments, with or without collars, and the gold systemjgold crowns with porcelain fronts. 41 THE PORCELAIN SYSTEM. CHAPTER I. PORCELAIN CROWNS. Porcelain crown-work is practiced by many dentists almost exclusively, excepting only the occasional insertion of a gold cap-crown on a posterior tooth. The reasons for this are, the intricate character of the construction of gold crowns, and the objection to crowns with bands or collars. The advocates of the porcelain system claim for it natural appearance, restoration of contour, strength, and cleanliness, together with simplicity of construction and easy adaptation and attachment to the root, to which the crown is hermetically sealed. Porcelain crowns are made in two general styles. In one the crown is attached to the root by a pivot, post, or screw, one end of which is cemented in the root and the other in the crown. Such are the Bonwill, Gates, Foster, How, and Howland crowns. In the other style, one end of the pivot, or post, is baked in the porcelain when the crown is made, and the other end cemented into the root when the crown is adjusted. The Logan, Brown, and new Richmond are of this class. Special advantages are claimed for each of these several forms of crowns. A general knowledge of the different methods is therefore essential to determine the adaptation of each to the requirements of a case. The preparatory treatment of the roots respecting the process of grinding, trimming, and shaping is nearly the same for all porcelain crowns. Exposing the end of the root, by pressing the 42 THE BONWILL CROWN. 43 gum away from it with gutta-percha preliminary to the opera- tion, will greatly assist the operator, by enabling him to avoid accidental laceration of the adjoining membranes, and the annoy- ance attending their bleeding, besides permitting him to care- fully study the adjustment and cementation of the crown. The obtaining of a close joint is much facilitated in all forms of por- celain crowns by passing a disk of black marking-paper over the post or pin which is to retain the crown, and placing the crown in position on the root. The points which prevent perfect adjustment are marked on both root and crown, either of which can be dressed off accordingly as seems most desirable. Crowns in which the post is cemented will first be described. THE BONWILL CROWN. This crown, being one of the first introduced in improved porcelain crown-work, has been very extensively used. The process of its adjustment and insertion is explained in a lengthy article by its inventor and advocate, Dr. W. G. A. Bonwill, from which the following is presented: " These all-porcelain crowns have three distinctive features: a concave or countersunk base; a triangular opening from the base to a point at or near the cutting-edge of the incisors, the base presenting to the labial surface (at its upper portion this groove is enlarged); a peripheral margin or border resting per- Fig. 32. Fig. 33. Fig. 34. Fig. 35. Fig. 30. Fig. 37. Fig. 38. Fig. 32.—Sectional view of an incisor crown, from me>ial side, showing the undercut at the point opening on palatal surface, the conical base, and the opening of the same to the retain- ing-grooves, with the exact relations. Fig. 33.—Palatal view of same tooth. « is the external opening for egress of alloy and for packing around the pin. The dotted lines show the recess or undercuts on the mesial and distal sides and near the point for retaining the crown, and its relation with the conical base. Fig. 34.—Grinding-surface view of a superior molar with the countersunk pin-holes on the buccal and paiatal sides. Fig. 35.—Same view of an inferior molar with the pin-holes on the mesial and distal sides. Figs. 36 and 37.—Sectional views of a molar and a bicuspid crown, showing the countersink? and their relations with the conical base. Fig. 38.—Sectional view of an incisor root, showing the retaining-cuts made by the wheel-bur shown in Fig. 45. 44 ARTIFICIAL CROWN- AND BRIDGE-WORK fectly flat on the root, the concavity of the base on the palatal side being at a much more acute angle than on the approximal sides. An anchorage is made in the incisors by a depression or undercut between the labial and palatal surfaces, opening on the latter. In the bicuspids and molars the retaining-pits are nearer the grinding-surface. " The concave base of the crown prevents the amalgam from escaping under the heavy pressure exerted to force it into posi- tion, and in impacting the amalgam and expressing the mercury. It allows of a dense body of material around the metallic pin, Fig. 39. Fig. 41. Fig. 42. Fig. 43 Fig. 44. Fig. 45. Fig. 39.—End view of a canal prepared for the improved combination-metal pin. Fig. 40.—End view of same canal as in Fig. 39, prepared for a triangular pin, showing how much more of the mesial and distal surfaces have been out away from it than in Fig. 39 for the improved pin. Fig. 41.—Sectional view of an incisor crown and root, with the improved pin in its relative position to each,1 with the depressions made by wheel-bur. Fig. 42.—Sectional view of a superior molar, with the large angular pin in palatal root and two square pins in the buccal roots, one being shorter and not passing through the crown. Fig. 43.—Block of a molar and bicuspid, showing the countersunk holes for pins in the molar, and the hole in the mesial side of the second bicuspid where a pin is alloyed in and set into a decayed cavity in the distal surface of the first bicuspid, being held upon the molar roots and attached to the bicuspid by the alloy. Fig. 44.—Side and end view of the largest-sue angular combination-metal pin with the stamped serrations.2 The square pins are without serrations and double-pointed, made of the same metal and of equal thickness throughout. Fig:. 45.—The smallest-sized wheel-bur for grooving the canals for anchoring the pin and alloy. xThe sectional views of the incisor and molar, giving the relative position of the" pins in the crowns and roots, should show pins of larger size. The pins as furnished should be filed down but little. It is not absolutely necessary that so many serrations should be made in the canals by the wheel-bur for retaining the amalgam and pin as are shown in the sectional view of the root of an incisor. While no serrations are shown in the roots of the molars, it is understood that all the canals must have the serrations. The square pins in the canals need no serra- tions. At the point where they occupy the countersink in the crowns, make two or three very slight cuts on the edges with a sharp file. The ends can be left blunt. ,2 These pins are now made without serrations. When amalgam is used for securing them, they become amalgamated and firmly united. THE BONWILL CROWN. 45 giving the equivalent of a pin the whole diameter of the base of the crown. It leaves no joint, the crown and root being continuous. The amalgam is so thoroughly hardened at once by impaction in the double concave of crown and root as to make a very firm operation. It prevents any possibility of the crown's twisting upon the pin and root. In the event of fracture of the crown, the convex surface of amalgam on the root makes the substitution of a new crown an easy operation. It enables the operator to fit the crown in much less time; it allows a proper position to be given to the pin, with less danger of frac- ture therefrom ; it permits of a larger quantity of amalgam in the crown, and is capable of bearing greater strain; it makes the permanent success of the operation probable, from the fact that it is absolutely jointless, and secures immediate solidity, even while the amalgam is semi-plastic. These crowns are capable of resisting the force of biting or mastication, because they are supported nearly to the cutting-edge or grinding-sur- face, the triangular opening from the concave base nearly to the cutting-edge allowing the pin to be imbedded in the labial face of the crown where there is the greatest amount of porcelain. " The amalgam to be used as the medium of union must set quickly and be very hard. Thus far I have found nothing better than the alloys I have specially prepared for this line of work, and, though they are costly, the superior results obtained by their use amply repay the cost. I use No. 1 generally. If mixed thick, it will set so quickly that the operator must work rapidly to prevent its being wasted. In incisor cases I use No. 3 at the gum line and make a close joint. " In preparing the canal, use first a small-sized, spear-shaped drill, carefully following the natural channel. Then follow with a larger one, taking care not to cut through the root near the apex. On the mesial and distal sides cut away but little, as there is where fractures are most liable to occur. The canal can be very tapering and yet hold the pin. There need be but very little space around the pin. By all means save all the walls of the root possible. The smallest-sized wheel-bur may be used to make an interrupted female thread at various points along the canal to hold the amalgam. 4(! ARTIFICIAL CROWN- AND BRIDGE-WORK. " If the patient exposes the gums much in speaking or smiling, the root may be cut down with the bur or corundum-wheel beyond the free edge to conceal the joint. With bicuspids and molars it is not necessary to go below the gum; a joint well made will not be observed, and the strength of the root will be preserved. If the root is decayed below the gum, after removing the softened parts, fill it with alloy., "It is not necessary that the face of the root should be flat; it may be either concave or convex, according to indications. " It is advantageous to take an impression and 'bite' of the root, and make a model and articulation in plaster. " The crown to be inserted should be inspected closely, as the retaining undercut in the incisors and the depressions in the bicuspids and molars may not be well defined. If not, the crowns are liable to work loose. If the base has been ground off in fitting, the edges should be beveled again to a fine margin with a corundum-point. The crown should be fitted to the root in the mouth, not to the plaster cast. The articulation should be clear, to avoid displacement. The pin should be as large as the previously prepared canal will admit. The pin must in every case be fitted, and in fitting it file only on the plain sides. Leave the end sharp, to offer the least resistance in passing through the amalgam. The end of the pin to be passed into the crown needs very little alteration. The crown being open on the palatal sur- face of the incisors, permits a blunt-pointed pin to go up to its place. The middle of the pin should not be interfered with if it can be avoided. It is well to cut the pin a little short for incisors, as it may not get pushed entirely up in the root through the amalgam. Small square pins are used in the bifurcated roots of bicuspids and in the buccal roots of molars. They can be sharpened at both ends, but the outer end will not require so much sharpening. The palatal roots of molars will generally take one of the largest thick pins, with one square pin in the largest and most accessible buccal root. Each canal should have a pin, if the canal can be reached and properly prepared to receive it, even though the pin has to be so short as not to pass through the hole in the crown. If it enters the countersunk base it will support the root. The lower molars will require two of the THE BONWILL CROWN. 47 largest-sized pins. As the support of the root is dependent upon the size of the pin and the depth to which it is inserted, single-rooted teeth should have the very largest thick pin. If the root is thin on the mesial and distal sides, the thin, angular pin is to be preferred. Ordinarily these large pins do not have to be bent. If necessary, it had better be done with a hammer, and before the mercury touches them. The pin should have free movement in both root and crown. Should it be discovered that the pin is too long after it has been packed in the root, it can be cut off with sharp forceps, pressing them up against the pin to prevent displacement. The pin can be sharpened subse- quently with the corundum-wheel. " To insure an amalgamation of the pin with the filling, brighten the surface of the former before inserting. " The roots, crown, and pins being in readiness and arranged on the table, so that no mistake may occur from getting the pin in the wrong position, and the appliances necessary for the opera- tion being at hand, the alloy preferred should be mixed a little thinner than if intended for a filling, especially where the root has a long canal. The shorter the canal, the thicker the amal- gam may be mixed. Mix only enough at one time for one root. Put enough amalgam in the canal to nearly fill it, but do not pack it; force a steel pin made for the purpose, of about the same size as the pin, to make way for the easier insertion of the latter. Then grasp the pin with suitable forceps, and carefully but steadily press it up to its destination. If you cannot suc- ceed in doing so, remove it, and again use the steel pin. When in place, use an instrument with a point small enough to pass between the pin and the root, and pack by tamping the amalgam around it. A piece of bibulous paper placed over the point of the instrument will assist materially in carrying the amalgam before it. Before the amalgam has become too hard, replace the crown to determine that the pin is in proper position; if not, it can be crowded to one side or the other with the tamping-tool. Should the pin be found to be rather long, it can be ground off with the corundum-wheel, holding it meanwhile with the forceps. No attempt should be made to bend the pin after it has been amalgamated, for fear of breaking it. If any amalgam has been 48 ARTIFICIAL CROWN- AND BRIDGE-WORK. left, and it is still plastic, it may be packed around the pin at the base of the root, using the bibulous paper as before directed. If not, mix again to complete the operation. Bank up the amal- gam on the root high enough to fill the base of the crown. The crown should now be tried on, and forced home with an adjuster adapted to the case, removing the surplus amalgam if too much, or adding if not enough. Remove and dry the crown, and fill up simply the undercut cavity near the cutting-edge if an incisor, or the depressions in the crowns of bicuspids or molars, allowing a very little to extend into the cervical base. Now force it home with the adjuster. It requires considerable force to set one of these crowns according to directions,—a force which cannot be applied with a mallet without danger of loosening or displacing the crown. Steady pressure with slight rotation will carry the crown into place, if the amalgam is not too hard or there is not too much of it. I would advise you not to attempt to set a crown without an adjuster or its equivalent. Free mercury will be squeezed out on the palatal surface, which should be wiped off. Now hold the crown in place with the fingers, with the bibulous paper under the tamping-instrument, and consolidate the amal- gam around the point of the pin in the crown, absorbing any free mercury which appears there. The excess of alloy at the joint must now be removed, care being taken to press the crown up while this is being done. The amalgam packed around the pin in the crown on the palatal side should be as stiff as may be to work readily. It is well to leave over some of the first mix- ing for holding the pin, and this will be about right for con- solidating about this point. " If in a bicuspid or molar crown the pin should come so far through as to interfere with articulation, it may be ground off with the corundum-wheel while the crown is firmly held. " The case can now be dismissed, with directions for the patient to return the next day, in order to make sure that the articula- tion is correct and to dress off the joint between the crown and root, which may be done with a small round-headed bur. " There are some cases in which the root cannot be filled with anything; if in a molar, the pulp-chamber can be relied upon to hold a headed pin or pins. When a tap-hole is required in the THE HOW CROWNS AND METHODS. 49 root it can be made low down and at an acute angle, and the amalgam packed around the root-canal above the tap. Fig. 48. " Should an artificial crown be broken, another F can easily be substituted, by burring off any excess of amalgam, and using fresh amalgam, mixed thin, to allow of ready adjustment. " Two crowns can be inserted on the root of one large molar with the assistance of the decayed approximal surface of an adjacent tooth (see Fig. 43)." THE HOW CROWNS AND METHODS. These crowns are the invention of Dr. W. Storer How. There are two styles,—four-pin crowns for incisors, cuspids, and bicuspids, and porcelain dovetail crowns for bicuspids and molars. Eaeh form embraces some novel features. Dr. How's methods, being general in application, are used in inserting other forms of crowns. The following are Dr. How's descriptions and illustrations of his methods and crowns : Fig. 46. Fig. 47. Fig. 50. Fig. 51. Fig. 52. Fig. 53. " The Four-l'in Crown.—The difficulties and uncertainties in mounting artificial tooth-crowns || on roots, by either old or new methods, led me to U a careful study of the problem, and resulted in a nearly simultaneous devising of several new forms of crowns and ap- pliances for setting them, as well as a perfected method of per- 6 MEDICAL LI NOV c 43 "CrON ;.. C 50 ARTIFICIAL CROWN- AND BRIDGE-WORK forming the operation of fixing a peculiar screw-post (Fig. 46) in a root,°and also a novel process of attaching the crown to the post. At present I will describe simply the four-pin crown (Fig. 47) and the successive steps to be taken in mounting it. " 1. When the root is in proper condition for mounting, measure the depth of the canal by means of the canal-plugger and its flexible gauge (Fig. 48), and fill the canal at and a short distance from the apex of the root, keeping the gauge at position to show the full length of the canal and also the distance to which it has been filled. Fig. 54. Fig. 55. Fig. 56. Fig. 58. " 2. Cut oft* the root-crown with excising forceps and a round file, down to the gum-margin, and with barrel-bur No. 241 cut the labial part of the root fairly under the gum without wound- ing it. " 3. Set gauge on a Gates drill (Fig. 49) to one-half the gauged depth of the canal, and drill to that depth. " 4. Set the twist-drill in its chuck (Fig. 50) to project the same length as the Gates drill, and drill the root to exactly that depth. " 5. Enlarge the mouth of the canal one-sixteenth of an inch deep all around to near the margin of the root, as shown in Fig. 51, using square-end fissure-bur No. 59, and then with oval, No. 94, undercut a groove lingually and at the sides. THE HOW CROWNS AND METHODS. 51 " 6. If the rubber-dam is to be used for a gold or plastic backing, put it now over the root with Hunter's root-clamp, also over the adjacent teeth, and thoroughly dry the canal. " 7. Set the tap in its chuck (Fig. 52) a trifle less in length than the drill, oil it, and carefully tap the root to the gauged depth. " 8. Insert the post in its chuck (Fig. 53) to the exact gauge of the tap, and turn the thumb-screw down hard on the end of the post, then screw the post into the root, release the thumb- screw, unscrew the chuck a half-turn, bend the post until the chuck stands in center line with the adjoining teeth, and unscrew the chuck from the post. " 9. Slit the rubber back from adjacent teeth, tucking the flaps out of the way, so that the occlusion may be tried, the post excised and ground off until the teeth close clear of the post. " 10. Try the crown on the post, and with disk F grind the rib between the neck-pins until the crown is labially flush with the root-margin, using the disk dry and cutting a little at a time until exactly flush. " 11. Take the crown and place the mandrel (Fig. 54) between the pins just as the post is to be, and with the pliers (Fig. 55) bend the pins carefully over the mandrel, cutting off the pins if too long to be pinched in on the mandrel at the sides, observing that the pin nearest the cutting-edge is first to be bent (Fig. 56), and the opposite pin bent below it on the mandrel, and so with the others (Fig. 57). "12. Slip the crown over the post, try occlusion, and with the post-chuck bend the post until the crown is properly aligned with the teeth, then with a stump corundum-wheel No. 3 grind the neck of the crown to a close labial fit with the root, fitting only the portion to be concealed by the gum, leaving narrow gaps at the sides to be filled by the backing between crown and root (Fig. 58). " 13. Grind cutting-edge for occlusion and relation to the other teeth, and be sure that the opposing tooth does not strike the crown, the post, or the pins. " 14. Fix the crown on the post by pinching the pins into the screw-threads in the post with the special pliers for that purpose. " 15. Finally, pack the backing of gold, or cement, or amal- 52 ARTIFICIAL CROWN- AND BRIDGE-WORK. gam, or Wood's metal,1 or—for temporary backing while treating abscess—gutta-percha, into all the crevices around the post and Fig. 59. Fig. 60. Fig. 61. behind and under the pins, and between the crown and the root; contour and finish thoroughly, so that no ledge or other imperfection can be found. "Fig. 59 shows in vertical mid-section an incisor crown mounted on a root; the blackened portions of the backing serving to define clearly the locking-hold of the backing on the screw-post, the crown-pins, and the root recess. " Fig. 60 shows in perspective a cuspid crown ready to be slipped over its post, and also a cuspid crown ready for its post in the bicuspid root, which has its lingual cusp remaining; and Fig. 61 shows these crowns on their posts awaiting the com- pleting or contour-backing. Fig. 62. Fig. 63. Fig. 64. i\ [\ 1,1 " When it is desired to contour the backing of a cuspid crown to form an inner cusp, or to adapt a cuspid or incisor crown for masticating uses, the pins may be twisted together over the man- drel, and again twisted tightly over the post as in Fig. 62; but 1 Wood's metal suggested by Prof. J. Taft. THE HOW CROWNS AND METHODS. 53 in some cases it may be better to bend the neck-pins, as in Fig. 63, instead of twisting them. In all cases the bent pins are to be pinched quite hard over the mandrel and post, so that the serrations of the pliers will roughen the pins to prevent their being pulled through the backing, which should also be carefully condensed around the pins and post. " When the root is much decayed, the bottom of the cone- shaped cavity may be drilled and tapped to the depth of a six- teenth of an inch, and the post, thus anchored, may be further secured by cement in the grooved walls of the cavity and around the post (Fig. 64). " The screw-posts are made of crown-metal, an alloy devised for the purpose in order to obtain a stiff post that will permit Fig. 65. Fig. 6H. Fig 67. Fio. 68. Fig. 69. the cutting of the peculiar and extremely accurate thread formed upon it, and which will not amalgamate or be otherwise affected by any backing-material that may be used. Of course platinum or platinum alloyed with iridium may be employed for posts, but the crown-metal is in every way superior. " There are some cases of a class which has hitherto presented difficulties that may now be easily overcome by grinding the post flat on the crown side after it has been set and bent in the root (Fig. 65), so as to be clear of the occluding tooth; and then the crown-pins may be bent over the reduced post, the crown fitted and ground to clear the opposing tooth (Fig. 66), and the hacking added in completion. 54 ARTIFICIAL CROWN- AND BRIDGE-WORK. "A similar case, in which the opposing tooth and a proper alignment require an oblique bending of the pins, is seen in Fig. 67, while the reverse arrangement of parts is shown in Fig. 68. The crown is thus seen to be adapted to a wide range of adjust- ments, because its point of contact with the root is at the labial portion of the neck, on which as on a hinge the crown may be swung out or in (Fig. 69, dotted lines), over an arc of at least sixty degrees, at any point of which it may be quickly and firmly fixed. The labio-cervical junction is made just under the gingi- val margin, and I usually interpose a thin layer of cement, amal- gam, or gutta-percha, or a narrow ribbon or several large blocks of soft gold; the joint always to be made carefully smooth, and hid from view under the free margins of the gums." The Porcelain Dovetail Tooth-Crown. — These crowns are de- signed for the roots of bicuspids and molars only, and the process of mounting them may be very briefly described. Fig. 70. Fig. 71. Fig. 72. Fig. 73. Fig. 74. Fig. 75. " Fig. 70 shows the roots of an inferior molar after the apical portions have been filled, the neck recessed, the canals drilled and tapped, and two How screw-posts firmly fixed therein, the ends of the posts having been pinched toward each other by means of a pair of pliers, so that they will go through the cen- tral opening in the crown (Fig. 71). This opening is of a dove- tail form, as shown in cross-section by Fig. 72, where the crown is seen in place over the posts on the root. It is thus made obvious that the crown may be easily put on and off the root in the process of fitting the crown-neck to the root-neck, and also that, for occlusion, the crown may be ground low on any or all sides without destroying the dovetail function of the central cavity. When the fitting is completed, and the crown cut so short as to be ^ of an inch distant from the occluding tooth, THE HOW CROWNS AND METHODS. 55 amalgam is packed into the neck recess, around the posts, and thinly over the cervical margin of the root, the crown put in place, and, with thumb pressure, firmly seated. Then test the occlusion, and complete the operation by packing amalgam into the crown opening, which will permit the forcing of the amalgam in all directions, to insure a firm base for the crown, and its secure dovetail attachment to the posts, as shown by Fig. 72. "The bicuspid crown (Figs. 73 and 74) is similarly mounted, as maybe seen in Fig. 75, cross-section; the same crown and root being shown in contour by Fig. 76. In some instances this bicuspid crown may, like the Foster crown, be secured by a headed screw, as shown in Fig. 77. The root having been drilled and tapped and recessed, and the crown properly fitted Fig. 76. Fig. 77. Fig. 78. Fig. 79. and articulated, the screw is put through the crown, amalgam packed in the crown-groove and around the screw, which is then inserted in the root, and the crown pressed hard into its place. The screw is then turned into the position shown in Fig. 77, thus compressing the amalgam or cement in both recess and groove, after which the screw-head ma}- be covered with amalgam, cement, or gold, as desired. "As a preferable mode, however, the screw-post may first be fixed in the root, the crown adjusted over the post, amalgam packed on the root and around the post, the crown seated firmly, more amalgam packed in the crown cavity around the post, and then a nut screwed on the post, as shown in Fig. 78. In all the sectional cuts cement, amalgam, or gutta-percha is to be under- stood as filling the cavities in the conjoined roots and crowns. " Fig. 79 shows in contour a dovetailed crown mounted on a superior molar root in the manner shown by Fig. 72. It is obvious that the crown of Fig. 72 might be ground quite down ARTIFICIAL CROWN- AND BRIDGE-WORK. to the post-ends, and yet be firmly held by the dovetail sides of the central cavity." THE GATES CROWN. The Gates crown has become identified with the Bonwill, owing to its similarity (Fig. 80). It is usually attached to the Fig. 80. j ooGQao root by a metallic screw manufactured for the purpose, such as is illustrated in Fig. 81, instead of the Bonwill pin.1 The screw is first inserted in the root and the amalgam packed around it. In nearly all roots, at a reasonable distance up the canal, a suitable place for fastening the end of the screw can be found. Too much force must not be applied in its insertion, as a root is easily split. In bicuspid and molar crowns nuts are used on the screws, which fit slots in the grinding-surface of the porcelain. They are screwed into the amalgam or cement, and covered with it in the process of cementation of the crown. When it is desirable or necessary to construct a screw for a special case, it should be made of iridio-platinum wire (as this alloy, being hard, will well maintain the edge of the thread). Gold is unsuitable, owing to the action upon it of the mercury in the amalgam, even though the amalgam is used " dry." In forming a screw a coarse-thread screw-plate should be used. The threads of most screws are cut too fine. 1 Dr. Gates originally used a double-end cone-shaped screw. The How screws (seepage 49) manufactured by The S. S. White Dental Manufacturing Company are applicable to these crowns. THE FOSTER AND HOW LAND CROWNS. 57 THE FOSTER CROWN. The Foster crown (Fig. 82), which in general form is similar to a crown introduced by Dr. H. Lawrence, of Philadelphia, in Fig. 82. Fig. 83 Fig. 84. rrl 1849, also resembles the Bonwill, but has less concavity at the base. The crown is attached to the root by a headed screw (Fig. 83) or a screw with a nut, instead of the Bonwill pin. The How screws and instruments (Fig. 84) are best adapted for use with these crowns. THE HOWLAND CROWN. This crown, which is similar in principle to one originally introduced by Dr. C. H. Alack, was devised by Dr. S. F. Howland. It is attached like the How dovetail crown, with screws that are first inserted in the root. It is used mostly on i • • t j i 4. Fig. 85. Fig. 86. Fig. 87. bicuspid and molar roots, and consists of a hollow porcelain crown, with a cavity in the crown suffi- ciently large to admit the screw or pins, and, when necessary, a small portion of the root (Fig. 85). The method of setting this crown, as described by Dr. How- land, is to shorten the root even with the gum with a stump file; fit the crown to the root; enlarge the root-canal so that a threaded pin of proper size will pass in easily, partially fill the canal with zinc phosphate, and press the pin to its place with pliers. The crown should then be filled with zinc phosphate and pressed to its place, care being taken to hold it in position until the cement sets (Fig. 86). If any operator distrusts the ability of zinc phosphate to make a perfect joint, a small quan- titvof silver amalgam or gutta-percha can be used to advantage. 58 ARTIFICIAL CROWN- AND BRIDGE-WORK This crown is strong, and during its test of several years none have broken so far as known. The mode of fastening is strong, and has the advantage of two pins when set on a bicuspid having two root-canals. It is simple, and when set—no metal being in sight—it is a perfect imitation of the natural tooth (Fig. 87). THE LOGAN, BROWN, AND NEW RICHMOND CROWNS. These crowns have their platinum posts or pins baked in the body of the porcelain. In the Logan crown the base is made Fig. 88. Fig. 89. Fig. 90. Fro 91. concave, to facilitate its adjustment to the end of the root, and to give the cement a more reliable form. The base of the Brown Fig. 92. Fig. 93. Fig. 94. Fig. 95. crown is convex, and that of the new Richmond Y-shaped, from mesial to distal side. The preparation of a root for each of these crowns is, in general, similar to that for the Bonwill crown. The root-canal THE LOGAN CRO WN. 59 is enlarged, and shaped so that the post, if possible, at least at its point, will fit tightly. Gutta-percha or oxyphosphate is used for cementing in preference to amalgam. Fig. 96. Fig. 97. Fig. 98. Fig. 99. The Logan Crown. — The Logan crown, now so extensively used, is the invention of Dr. M. L. Logan. The method of mounting is explained in all its details in the following article by Dr. W. S. How: "Fig. 88 shows a superior right central root, an end appear- ance of the same, and a Logan crown, front view. Fig. 89 ex- hibits, at a right angle to the plane of the first figure, the same Fig. 100. Fig. 101. Fig. 102. Fig. 103. Fig. 104. I root, its end, and the Logan crown, side view. In both I figures the root-canal is supposed to have been first drilled J to a gauged depth with an engine twist-drill, No. 154, and j then enlarged by means of a fissure-bur, No. 70, to the tapering form shown ; the walls being subsequently grooved with an oval bur, No. 90. The enlarged section, Fig. 90, shows the crown adjusted on the root by means of cement or gutta-percha, which surrounds the post and fills all the spaces in the root and crown. Fig. 91 shows the completed crown. Fig. 92 ex- 60 ARTIFICIAL CROWN- AND BRIDGE-WORK. hibits a bifurcated bicuspid root, its end appearance, and a Logan crown adjusted to the root. Fig. 93 illustrates the best manner of bending the post. Fig. 94 shows a split post, and its adaptation to a bifurcated bicuspid root is seen in Fig. 95. Figs. 90 and 97 exhibit the mode of mounting the Logan crown on a superior molar root, and Figs. 98 and 99 the same crown in its relations to an inferior molar root. " The preceding figures clearly present to the mind's eye of the expert dentist the essential features of the Logan crown and the method of mounting it. " The details are as follows: In every instance where a root is deemed ready to receive its filling, it should first be measured through its canal from the cervical opening to the apical foramen, and this may be accurately done with a gauge adjustable on a delicate canal-explorer (Fig. 100). The same device serves to measure the distance from the apex to which the canal should then be filled (Fig. 101). It also gauges the depth to which the drill may be carried. The proper degree of enlargement from the bottom of the drilled hole will, of course, depend on the observed size and character of the root. Every dentist should familiarize himself with generic tooth-forms, so that when the length of an Fig. 105. incisor, cuspid, or other tooth-root is * * known, he can so nearly determine its hidden outlines as to form with precision a corresponding enlarge- ment of the root-canal, such as is shown by the several cuts. For preparing the roots, the Ottolengui root-reamers (Fig. 105) and facers (Fig. 106) are very desirable instru- ments. The reamers are made in ;izes to correspond with the Logan pins. i root-reamer of the appropriate size, the root-canal is enlarged to fit the pin along its whole length, and so hold the crown firmly independently of the cement. AYith a root-facer a labial slope is given to the root-end, so that the crown neck shall fit under the edge of the gum. Fio\ 107 shows the method and its result, and the cross-section shows Fig. 106. three With THE LOGAN CROWN. gj how the cement incases the pin. The suitable preparation of the bifurcated roots of some bicuspids and of all the molars is a matter involving difficulties of an unusual character and requiring good judgment. The feasibility of splitting the post of a Logan crown to adapt it to the bifurcated root of a bicuspid is shown by Figs. 94 and 95. This example directs attention to the peculiar shape of the post, in which there is effected such a distribution of the metal that its greatest strength is in the line of the greatest stress that will in use be brought to bear on the crown, while the least metal is found at the point of the Fig. 107. least strain; the applied part of the post being in outline nearly correspondent to that of the root itself. The root-canal is like- wise conformably enlarged to receive the largest and stiffest post which the size and shape of the root will permit. " The fitting of a Logan crown to a root may be done with a wet stump-wheel in the engine hand-piece. A safe-side crown corundum-wheel (Fig. 108) can be used in the same manner. It also aftbrds the greatest facility for the slight touches required to abrade the thin cervical borders of the crown, which may by this means be done without encroachment on the post. " By the old method of adapting pivot-teeth to roots, the close fitting of the crown precluded the use of a plastic packing, 62 ARTIFICIAL CROWN- AND BRIDGE-WORK. because its thinness over the surface of the joint made the pack- ing liable to break loose under the shock and strain of use. The recess in the Logan crown obviates this defect by providing a receptacle for a considerable interior body of cement that will be deep enough to be self-sustaining internally, and yet allow the peripheral portions of the root and crown to approach each other so closely that, though only a film of packing remain, it will still be strong enough to insure the persistent tightness of the joint. This annular boss if formed of amalgam also adds strength in some cases to the mount. " When enough of the natural crown remains, it is well to leave standing some of the palatal portion, and cut the root under the gum-margin at only the labial part, as shown by Fig. 108. Fig. 109. Fig. 102. The safe-side crownwheel is especially useful in such cases (Fig. 109). Thus the labial joining of the root and crown will be concealed, and the other parts of the joint will be acces- sible for finishing and keeping clean (Fig. 103). The Logan crown may be ground until a large part shall have been removed for adaptation to the occluding tooth or teeth without seriously impairing its strength (Fig. 104). This crown also in such cases maintains the translucency which is one of its peculiar ex- cellences, owing to its solid porcelain body, and the absence of a metallic backing or an interior largely filled with cement or amalgam. " The distal buccal root of the natural superior molar is nearly always too small to receive a post of any useful diameter, and therefore the Logan superior molar crown has but two posts, THE BROWN CROWN. 63 which like those of the inferior molar crown are square, and thus may be easily barbed, as may also the ribbed posts of the crowns for the anterior tooth-roots. These posts are large enough in all the Logan crowns to answer in any given case, and can of course be easily reduced to suit thin or short roots. " Any of the cements or amalgams may be used in fixing these crowns, but good gutta-percha, softened at a low heat and quickly wrapped around the heated crown-post, which is at once seated in the root, forms the best mounting medium, and has the great advantage of permitting a readjustment, or, if need be, the ready removal of the crown by grasping it with a pair of hot pliers or forceps, and holding it until the gutta-percha is sufficiently softened." Tin Brown Crown.—Fig. 110 is a lateral view of a porcelain crown, with an iridio-platinum pin baked in position, invented by Dr. E. Parmly Brown. The pin has great strength at the neck of the tooth, where the strain is heaviest, and this strength is further increased by extending the porcelain up on to the pin. Fig. 110. Fig. 111. Fig. 112. Fig. 113. Fig. Ill is a front view of the same crown, showing by the dotted lines the shape of the pin and the position which it occu- pies in the crown. The pin is flattened laterally, affording a strong hold in the porcelain without bringing the pin too near the surface in thin teeth, while it also permits alteration of the palatal surface of the crown in a close " bite " without risk of weakening the body. Fig. 112 is a view of the bicuspid crown, in which a pin is provided for each root of two-rooted bicuspids. Fig. 113 is a view of a bicuspid crown with the two pins pressed together, forming a single pin of great strength for a tooth with only one root. 64 ARTIFICIAL CROWN- AND BRIDGE-WORK. The double pin in the bicuspids prevents the gradual loosen- ing of the crown by the rotary movement of the jaws in mastica- tion, which, acting on the two cusps, exerts such leverage as to sometimes turn and break down ordinary crowns where only one pin is used. The roots are ground concave to fit the crowns with corundum- points or a Willard countersink bur, and close joints are made well under the gum, the pins being set with oxyphosphate cement. The canal should be enlarged enough only to admit the pin, which should fit snugly throughout its entire length, the better to distribute the leverage exerted by the crown, and thus directly to increase the strength of the attachment. (For process of cementation, see article on " Insertion and Cementation.") The New Richmond Crown. —To illustrate and describe the method of mounting this crown, a superior left central incisor root will serve as a typical case, and its projecting end is to be shaped as seen in Figs. 114 and 115. This can be rapidly done Fig- 114. Fig. 115. Fig. 116. with a narrow safe-sided flat or square file, the angles of the slopes being such that the gum on the labial and palatal aspects will not interfere with nor be disturbed by this preliminary work, as the root-end is not, in this operation, to be cut quite down to the gum. An Ottolengui root-reamer No. 2 is then employed to bore out the root to receive the crown-post, which is of the same size and shape as the Logan crown-post for a central incisor. The sectional view (Fig. 116) shows the relation of the reamer to the root. The new Richmond crown (Fig. 117) is then tried on the root (Fig. 118), and its position relative to the adjacent THE NEW RICHMOND CROWN. 65 and occluding teeth noted. If the cutting-edge of the crown is to be brought out for alignment with its neighbors, the root can be drilled a little deeper, and the reamer pressed outward as it revolves to cut the labial wall of the cavity. The palatal root- slope must then be filed to make the V correspond to the changed inclination of the crown. Thus, by alternate trial and reaming and filing, the crown may be fitted to the root and adjusted in its relations until the post has a close, solid bearing against the labial and palatal walls of the enlarged pulp-chamber, and the crown-slopes are separated from the root-slopes by the thickness of a sheet of heavy writing- paper. This space can be accurately gauged, and the root-slopes conformed to the crown-slopes by warming the crown and put- F[Q. 117. Fig. 118. Fig. 119. Fig. 120. ting on its slopes a little gutta-percha, so that an impression of the root-end may be taken, and the root-slopes dressed with a file until the film of gutta-percha proves to be of equal thinness on both slopes. To permanently attach the crown, Dr. Richmond usually takes a thin, perforated disk of gutta-percha, pushes the post through it, warms the crown, presses it into place, and when cooled removes it, and with a sharp knife trims away the gutta-percha close to the crown-neck. He then warms the crown, puts a very little oxyphosphate cement on the post, and presses the crown home. Fig. 119 shows the completed crown. The obvious advantages of the device are the readiness with which the slopes of the root-end may be shaped with a file; the facility with which these slopes may be given any angle to set the crown out or in at the base or at the cutting-edge, or to give it a twist on its axis; the certainty that, once adjusted, the final 6 66 ARTIFICIAL CROWN- AND BRIDGE-WORK. setting will exactly reproduce the adjustment; the assurance that in use the crown will not be turned on its axis,—a most common cause of the loosening of artificial crowns; the firm- ness of its resistance to outward thrust in the act of biting. This is made apparent by Fig. 120, wherein it will be seen that in an outward movement the crown B would rock upon A as a pivot. The dotted line D shows how the crown-slope is resisted by the root-slope, which extends so far toward the incisive edge that a much firmer support is given to the crown than if the resistance should be, as it usually is, on the line of the gingival margin C. For roots that have become wasted below the gum-surface it is not suitable, except in such cases as are decayed under the labial or palatal gum-margin only, but have yet projecting the approximal portions of the crown (Fig. 121). Fig. 121. Fig. 122. Fig. 123. The sectional view (Fig. 122) and the perspective plan views (Fig. 123) illustrate the manner of mounting these crowns on this class of roots. The finished crown appears as in Fig. 123. The cases for which this crown seems specially adapted are such as have some considerable portion of the natural crown remaining. REMARKS ON THE USE OF PORCELAIN CROWNS. Porcelain crowns have some decided advantages. They are especially useful in many cases where an inexpensive or easily adjusted crown is required; or where some pathological con- dition limits the probable durability, or permanency, of any operation. In the insertion of porcelain crowns, the removal of the whole or a part of the natural crown, which could be util- ized to some extent as a foundation by other systems, has given REMARKS ON THE USE OF PORCELAIN CROWNS. 67 rise to various objections. If the natural crown is entirely cut away, the pin, or post, upon which almost the entire support of the artificial crown is thrown, acts like a lever in the root-canal, there being no band or brace to relieve the strain. With the whole force of mastication bearing directly upon these pulpless roots, whose disintegration is slowly but constantly progressing, the inevitable result can well be conjectured. Sooner or later they are fractured, and their usefulness as a foundation ended. Then, again, if porcelain crowns are attached with amalgam, the discoloration of the line of union with the root, if subse- quently exposed, is disfiguring. These tacts, and the lack of strength incident to some forms of construction, are the princi- pal objections urged against porcelain crowns as ordinarily inserted. CHAPTER II. PORCELAIN CROWN WITH GOLD COLLAR ATTACHMENT. A gold collar, either seamless or soldered, can be used advan- tageously in combination with many of the porcelain crowns. The root having been properly prepared, a collar is adjusted and adapted to it the same as for a gold collar crown (see page 79). The porcelain crown, the base of which should be fully as large as the end of the root, is then ground even with the cervical walls, and fitted into the collar, which should be trimmed and burnished to the form of the crown. Dr. Townsend's fusi- ble metal die, used in the following manner, facilitates the appli- cation of a collar to a Logan crown (Fig. 124). Enlarge the Fig. 124. root-canal to receive the Logan pin. Grind a Logan crown to fit, and articulate it. Construct / \ a band of No. 30 gold (or of No. 32 crown-metal, which is better) wide enough to project beyond the end of the root say -£% of an inch. Cut a wooden peg about an inch long and taper one end of it to the general size and shape of the pin in the Logan crown. Place the band on the root, insert the i. sock^l, Fusible Metal, peg in the canal, and fill up the band with Melotte's moldine or with stiff putty, pressing it closely about the peg. Remove all together and, holding the die over the flame of an alcohol lamp to melt the fusible metal, place them—the band, peg, and moldine, in the same relative positions they occupied in the root —on the die, with the pin in the socket, and press down until the moldine rests on the surface of the molten fusible metal. 68 PORCELAIN CROWN WITH GOLD COLLAR ATTACHMENT. 69 Chill; in cooling, the fusible metal takes a firm hold on the lower edge of the gold band, holding it securely in place during the remainder of the operation. Remove the peg and the Fig. 125. Fig. 126. Fig. 127. moldine, and with a wooden mallet drive the Logan crown into the band until the porcelain rests upon the fusible metal. Burnish the band smoothly about the crown. AVhen the gold is perfectly adjusted to the porcelain, melt the fusible metal to release the band and crown. If the work has been carefully done, the crown with its band will then be ready to be set, as the articulation and fit will not have been disturbed. Enough of the collar should be trimmed away at the labial por- tion to prevent too conspicuous exposure of the gold (Fig. 125). This collar combination is available in very difficult cases, as, Fig 128. Fig. 129. Fig. 130. for instance, when a root is decayed upon one side far beneath the gum, as seen in Fig. 126. Such an operation, when completed, would appear in vertical section like Fig. 127, and a view in perspective would resemble 70 ARTIFICIAL CROWN- AND BRIDGE-WORK Fig. 128. The collar ia also very useful wherever the root and crown are not made flush and smooth at every point, as, if prac- ticable, they should always be. Dr. E. C. Kirk, of Philadelphia, uses for bicuspids and molars a Foster crown in combination with a collar (Fig. 129). A collar is made, and, on being fitted to the root, is cut narrow on the labial side, and left wide on the lingual, so that it shall extend nearly to the cusp of the crown when finished (Fig. 130). (The seamless gold collars are well suited for application to this style of crown.) The crown selected should have a somewhat greater circum- ference at the base than the collar, so that when ground down somewhat conically on its lingual and approximal surfaces, it can be tightly adjusted to the collar. If a crown smaller than the collar is used, a tight joint 'cannot be made. The screw is fitted so that it shall hold the crown in proper relations with the root. The screw and crown are then removed, the parts dried, and the root-canal filled with a slow-setting oxyphosphate cement, mixed thin. The crown is then pressed into its position, the surplus cement flowing through the opening in the porcelain and filling up any interstices around or between the band, the root, and the crown. The screw is then driven into position, and when the cement is set perfectly hard the head of the screw or the nut on it is notched to form a retaining-pit, and the countersink of the crown filled with gold. Dr. C. S. W. Baldwin caps the root and attaches a Logan crown in the following manner: First, the root is shaped, the outer margin being beveled about the thickness of the gold used, to afford regular sides for close adaptation of the caps. Then an impression is taken and a die made in the gold seamless cap method. To strike up the cap, place No. 32 gauge gold plate on a cushion of lead, holding the die firmly on the gold where you wish to produce the cap, and strike until the required depth is secured before removing it. This drives the gold and die into the lead, forming a female die and a perfect-fitting cap at once, in less time than is occupied in describing the process. Trim the edges to fit the festoon of the gum, and drill a hole from the inner side for the pin, leav- PORCELAIN CROWN WITH GOLD COLLAR ATTACHMENT 71 ing the raggedness made by drilling to catch in the cement. Place the cap on the root and fit the porcelain crown accurately to -it in the desired occlusion and position. A Logan crown can, with little grinding, be made to do good service (Fig. 131). A crown having the H-shaped pin, but square on the edge, like some of the early patterns of Logan or Bonwill crowns, would reduce the time of setting and give best results. Having polished the edges of the cap, the crown may be conveniently adjusted as follows: Place oxyphosphate cement in the counter- sunk portion of the porcelain, and in the canal only enough cement, of creamy consistence, to fill it, as the pressure required to force out the surplus under the edges of the cap destroys Fig. 131. Fig. 132. Fig 133. Fig. 134 many nicely adjusted crowns, leaving bulging irritants instead of smooth supports. If proper attention has been given to fitting crown and root, all will come nicely to place, but in some cases of difficult adjustment it may be necessary to cement the crown to the cap before fastening the pin in the root (Fig. 132). In most cases the gold band will be invisible and below the free margin of the gum. Cases may occur where the anterior teeth are prominent, and it will be necessary to cut away the top of the cap in front, allowing the porcelain to come directly in contact with the root, the band going deeper than in ordi- nary cases, which prevents the appearance of gold (Fig. 133). Dr. Bonwill's plan is to cap the tooth with a platinum or gold cap having a slot, into which the pin passes as it is slipped on 72 ARTIFICIAL CROWN- AND BRIDGE-WORK the root (Fig. 134). The crown is then fastened on with amal- gam in the usual manner. Dr. S. S. Stowell suggests the following method of applying porcelain crowns, with or without a countersunk base in which a post can be cemented, forming what he calls the " Simplicity Crown": The end of the root is prepared in the usual manner and slightly countersunk. The porcelain crown (an ordinary pivot or a Perry-Howland crown) is then fitted in position, and the glazed surface of the base and cavity removed to secure better Fig. 135. ^ serted in the root in alignment with the cavity in the crown. After the screw-post is set, a groove is cut on the end of the root, around the post, with about a No. 0 engine-bur. This groove is filled with copper amalgam, the crown placed on the root, and the excess of amalgam pressed out The crown is then removed, filled with oxyphosphate cement, and pressed back in place. The excess of cement exudes on all sides, and carries with it any excess of the amalgam. The crown is held in position until the cement sets. Fig. 135 shows an incisor and a bicuspid made by this plan, when ready for adjust- ment; also, a sectional view of the completed incisor. CHAPTER III. THE WESTON CROWN. Dr. Henry Weston's method of crowning is described by him as follows: "This crown represents on its labial surface the ordinary plate tooth, the lingual or palatal surface being concaved in such a manner as to afford the largest amount of working room with- out impairing its strength at any point, The pins are so im- bedded in the thickest part of the crown that it is not liable to be weakened by grinding. Fig. 136 represents the crown. Fig. 136. Fig. 137. Fig. 138. Fig. 139. Fig. 140. Fig. 141. " The pin is made of hard platinum and iridium, and is spear- shaped and notched on both edges to give firmness to its anchor- age. The backing is of the same metal and strongly soldered to the pin. Fig. 137 represents the pin. " The preparation of the root for the reception of the crown consists in the removal of that part of the tooth which is to be replaced by the porcelain. Fig. 138 shows the root at this stage. " The canal must be sufficiently enlarged to allow space for packing gold or amalgam securely about the pin, and the sides reamed (Fig. 139). " The grinding of the crown to the root requires but little labor, and the fitting may be done directly on the natural root, or on a cast taken after the root has been prepared. This must 73 74 ARTIFICIAL CROWN- AND BRIDGE-WORK. always be done with the utmost neatness and precision. When fitting, the crown can be held in position by a cone of wax in- serted in the root. Next comes the adjustment of the pin to the root of the crown. After punching holes in the backing to receive the pins of the porcelain crown, bend the pin with small flat-nosed pliers, so that when in its proper position there shall be a uniform space around its entire surface. " Secure the tooth and pin together with a cement of resin and wax, invest in plaster and sand, and solder with fine gold solder. " It has been my practice of late years when preparing the root to leave just a line of enamel around its entire circumfer- ence, thus securing a joint clear of the free edge of the gum, especially when gold is used. If gold is to be used as the attachment, the rubber-dam is indispensable. When amalgam or cement is used, the rubber-dam may be dispensed with by those who prefer other methods of keeping out moisture. When gold is to be used, the root having been previously properly treated, and everything in readiness and the rubber-dam in place, put upon the point of the pin a pellet of phosphate or oxychlo- ride of zinc, the size of a No. 7 or No. 8 excavating bur; now press the pin and crown carefully to their exact position into and upon the root, and with a delicate but blunt-pointed instru- ment, thin enough to reach the end of the canal, pack the cement firmly about the pin. The object in using the cement is to secure the pin in its place during the first introduction of the gold. By using the hot-air syringe, the cement will harden in two minutes. Close the opening of the canal about the pin with a rope of bibulous paper, and attach the crown to the root and adjoining teeth on either side with soft wax; see that the joints are exact in every particular, as after the next step mistakes are not easily remedied. "Paint the joint from the labial side with cement mixed to the consistence of cream. Cover the labial surfaces extending over the cutting-edges of the porcelain crown and adjoining teeth to the thickness of three-eighths of an inch with carefully mixed impression plaster. When hardened, the plaster may be «ut from the cutting-edge of the crown, and the wax and the THE WESTON CROWN. 75 paper removed. Now paint the palatal sides of the joint with the cement mixed to a cream-like consistence, applied with flat- tened root-canal pluggers. Harden with hot air, and the case is ready for the gold. '• When filled and finished, the exposed dentine and enamel are all covered with cohesive gold and porcelain; the result will be a fac-simile of Figs. 140 and 141. " If preferred, the cement in the labial joint may be dispensed with, and the space between the crown and the root carefully filled with gold after the removal of the plaster, covering all of the exposed root and showing only a fine line of gold at the margin of the gum. " Where amalgam is used exclusively for the attachment, the greatest accuracy should be observed in the proper articulation of the crown before introducing or packing it and in removing carefully all excess, and the patient should be cautioned against biting on the crown until the following day." CHAPTER IV. PORCELAIN CROWNS WITH RUBBER OR VULCANITE ATTACHMENT. Fig. 142. Fig. 142 illustrates the formation of such a crown. The root, when prepared, extends at the palatal side a little below the line of the gum (A) at the point B. A plate tooth (C) is ground and fitted to the root. An iridio- platinum post is then fitted to the root, flattened slightly and bent at D, and riveted to the tooth. The proper alignments of the tooth and post to the root are then obtained, and they are invested and the post soldered and strengthened at the point D. The backing is then grooved and notched slightly, wax applied, the crown ad- justed to the root, and the wax shaped so as to form a foundation and overlapping edge at the palatal portion (E). The crown is then re- moved, invested in a flask, packed with rubber, and vulcanized. In trimming and finishing, the rubber is allowed to form a partial band or collar around the palatal portion of the root, where it will not show. It is then cemented on to the root with' oxyphosphate. The Weston crown and the four-pin How crowns have advan- tages over ordinary plate teeth in the construction of this style of work. 76 THE GOLD SYSTEM. CHAPTER V. PORCELAIN AND GOLD CROWN WITHOUT A COLLAR. The root of a cuspid will be taken as a typical case to illustrate the construction of this style of crown. The end of the root is prepared the same as for a porcelain crown (Fig. 143). The root-canal is then uniformly enlarged a reasonable distance up, with a drill which will tightly fit the opening. Into the canal, gauging its full diameter, is fitted a Fig. 143. Fig. 144. Fig. 145. Fig. 146. Fig. 147. piece of iridio-platinum wire, tapered off to a point, so that by introducing it far up the canal greater strength can be obtained, and the root rendered less liable to longitudinal fracture from pressure in a forward direction. A piece of platinum plate, a trifle larger than the end of the root, of about No. 30 U. S. standard gauge, with a hole punched in its center, is then slipped on the post, which it must fit tightly (Fig. 144). When the post is adjusted firmly in the canal, the platinum plate is pressed down on the root, and burnished into the orifice 77 78 ARTIFICIAL CROWN- AND BRIDGE-WORK. of the canal around the post. When the post is withdrawn from the root, the platinum will adhere to it, if fitted closely, with- out the use of wax. A particle of pure gold with borax is put in the joint, and melted in the flame of an alcohol lamp. Barely enough gold should be used to unite the parts. When soldered, the post and cap are again adjusted in the mouth and the cap malleted and burnished to the form of the end of the root, so that its edge will leave a mark on the platinum. The cap, on being removed, should be trimmed to this mark, and again bur- nished on the root (Fig. 145). Sometimes around the palatal portion of the root the platinum may be slightly burnished over the edge. The post is then cut off just above the platinum, and a plate tooth fitted, backed, and cemented with wax in position on the cap. The whole is then removed, invested, and soldered with gold at least twenty carats fine, which should be melted in at the base of the post, as at this point, when in use, the strain is very great. The post is then barbed, and the crown is cemented to the root with gutta-percha or oxyphosphate cement (Fig. 146). Dr. F. T. Van Woert, of Brooklyn, N. Y., in constructing crowns without collars, shapes the end of the root, and adapts the cap as shown in Fig. 147. The slant given to the palatal side aids the root to resist force in a forward direction. The advantages of a collar can in a great measure be given this form of crown by the addition of a metal flange, encircling , the palatal section of the root, as shown in Fig. 148. A piece of gold or platinum, similar A in shape to that shown at A, is formed and e^m fitted to the crown, fixed in position on the ^-^ crown with wax, and adjusted in the mouth, removed, invested, and soldered. After fin- ishing, the metal flange is burnished against the root before the crown is cemented. CHAPTER VI. GOLD COLLAR CROWNS. Tins style of gold crown includes those methods which consist in banding, capping, and hermetically inclosing with gold the end or the neck of a root, with or without any portion of a natural crown, for the purpose of securing stability to the arti- ficial crown, preventing fracture of the root and decay of the parts, thus permanently preserving them. This method pos- sesses much practical value as a preserver of tooth-structure and restorer of usefulness to the teeth, and affords excellent supports for bridge-work. Collar crowns, the use of which has become quite general, have been described by many writers in the past. Dr. Wm. IT. Dwinelle relates the application of the method to a crown with a porcelain front,1 and Drs. W. N. Morrison2 and J. B. Beersa tell of it in the construction of all-gold cap crowns.4 Collar crowns of which the part that essentially constitutes the cap is constructed in sections, will be first described. THE CONSTRUCTION AND ADAPTATION OF COLLARS. Careful study of the different forms of crowns and roots, and of the anatomical structure and relationship of the contiguous parts, is most essential for the perfect construction and adaptation of collars, bands, or ferrules, as they are variously designated. Many devices and methods in use facilitate this operation, but its skillful performance can only be attained by study and practice, as is proved by the easy and perfect manner in which it is done by experts in crown- and bridge-work, who use no appliances but pliers and shears guided by an intuitive percep- tion of the requirements of each case. 1 American Journal of Dental Science, April, 1855. 2 Missouri Dental Journal, May, 1869. 3 Circular to dental profession, 1873. * J. Patterson Clark, 1836. 79 80 ARTIFICIAL CROWN- AND BRIDGE-WORK. Fig. 149. Fig. 150 The collar is preferably made of coin gold, or of 22- to 23-carat gold plate. Pure gold plate lined with platinum is also used, and iridio-platinum plate in special cases. Gold plate of No. 32 to No. 34, or gold and platinum or iridio-platinum of No. 34 or No. 35, U. S. standard gauge, affords the requisite strength, together with easy adaptation to the form of the crown or root. The natural crown or root having previously been properly prepared (see page 33), a strip of the metal is cut of the length required, and generally from one-fourth to one-half of an inch in width* (Fig. 149). The end to form the underlap is beveled with a file. The strip is then bent with suitable pliers (Fig. 150) to the average form (Fig. 151), any special deviation from such average being noted (Fig. 152), and to the size of the cervical periphery of the root of the tooth to be crowned. It is then placed on the root and adapted as closely as possible to its form, with the upper edge of the metal pressing gently under the free edge of any portion of the gum it may meet. It is then removed and cut so as to allow the ends to lap over slightly. The adaptation to the root is then continued, during which process the metal should be heated and chilled in wrater after each trial, in order to maintain the shape given to it. At the last adjustment to the root, the lap-over is marked on the metal with a sharp-pointed instrument. The joint is made at this mark by placing there the least possible quantity of solder, or, better, fluxed solder filings, and holding the collar in the flame of an alcohol lamp or a blue gas flame. The collar is then slipped on the point of a small anvil, and the joint tapped down and trimmed level. The method by measurement is as follows: The root is encircled with a strip of thin sheet copper, previously annealed, one-sixteenth of an inch or less in width, and the copper fitted to the cervix. It is removed, and cut so there will be a slight THE CONSTRUCTION AND ADAPTATION OF COLLARS. 81 lap-over of the ends on the root, then again fitted to the root, and the position of the lap-over end marked on the copper. This little strip of copper, being soft and flexible, can be most accu- rately fitted to the root without inconvenience to Fig. 151. the patient, and when re- moved shows the exact length to cut the gold or (^~\^" ^/^\ platinum for the collar. ^-\V^ ^-"^-~n Upon a strip of the metal ^^ TL---^ to form the collar, from (^X Y^~^) one-quarter to one-half inch in width, is laid the copper pattern, and the exact length required for the collar is marked on the metal, which is. then ( Nj' z^^/ cut a trifle longer than the mark indicates (less than one-sixteenth of an inch), to allow for the under-lap. It is then bent and the ends brought together, the outer ^~Z-—\ r -^ end placed even or flush \ \ L / with the mark, and sol- \^^~, _f^\ dered as above described. \S/~\ C^-^ The collar is next bent to Cy \J the shape of the root, when ( j- \) it is ready to be adjusted. wC\ T\\) This method is simple ^ ^ n„A r,«n^t^nl ,.„A ^1 r,~ ~™ The palatal side of the superior molars, in many and practical, and also eco- cases £of the large oval form indioated by the outer HOmical, as it accurately line to the form of the first molar. The small spurs ir. .-, , n t . indicate the points generally found the most suitable defines the amount of plate t0 make the joint. required. When a mandrel is used in forming a collar, the size or shape is first taken by encircling the root with a piece of fine iron or copper wire, about No. 28 U. S. standard gauge, and twisting the ends together on the labial side. The wire is then 7 82 ARTIFICIAL CROWN- AND BRIDGE-WORK. pressed up on the root about as far as the upper edge of the collar is to go, and burnished to the sides (Figs. 153 and 154). The wire ring is then carefully removed, laid on a piece of air- chamber tin, a piece of flat iron put over it, and with a blow from a hammer on the iron the wire is driven into the tin (Fig. 155). The wire ring is removed from the tin, slipped on a mandrel1 that represents the form of the root to be crowned, and pressed down gently as far as it will go without stretching the wire (A, Fig. 156). The distance from the end of the mandrel to the Fig. 152. Fig. 153. Fig. 154. Fig. 155. Fig. 156. wire is then measured and marked on a strip of paper, and the wire removed. The gold to form the collar is then bent and shaped on the mandrel, with the edge which is to form the cervical portion (B) placed a little below the line of the wire (A), as shown by the measurement previously taken. The ends of the gold are beveled, slightly lapped, and the edge of the lap-over marked (C). The collar is then removed from the mandrel, and, the ends being held together with common tweezers, which are grasped by pliers, or better still, by a small hand-vise (Fig. 157), the extreme outer end of the joint is united by an atom of solder or fluxed solder filings with a blow-pipe. The points of the tweezers prevent the solder from flowing along the joint, the cervical portion of which is left open for the present. The collar is then shaped to the form given by the wire in the tin, after which it is ready for adjustment in the mouth. The unsoldered end of the joint 1 A description of mandrels will be found in the chapter on the " Mandrel System." THE CONSTRUCTION AND ADAPTATION OF COLLARS. 83 permits the collar to be easily and accurately adapted to the root, after which the solder can be flowed across the collar and the joint closed. When the collar has been formed, it is adjusted on the root and pressed or, by the aid of a piece of wood, one end of which is placed across the outer edges of the collar, tapped, up to the Fig. 157. Fig. 158. Fig. 159. Fig. 160. margin of the gum. A line parallel with the margin is marked with a sharp-pointed instrument on the collar (A, Figs. 158 and 159), which is then re- moved, trimmed to this mark, readjusted, and again marked (B), and the process continued until the collar fits proportionately under the margin of the gum. If, on adjusting, the collar is found a trifle too small, it is easily en- larged by tapping the gold with a riveting hammer on an anvil as shown in Fig. 160. If, on the contrary, the collar should prove to be too large in circum- ference, the difficulty can be remedied by slitting the gold partly across the side opposite the joint, lapping the edges slightly, and soldering. The edge is then burnished to the periphery of the g4 ARTIFICIAL CRO WN- AND BRIDGE- WORK. root. For this purpose a set of burnishers should be used espe- cially formed to suit the different positions and avoid irritation of the margin of the gum. Such a set is illustrated by Fig. 161. Fig. 161. The application of local anesthetics such as cocaine, carbolic acid, or a mixture of tincture of aconite-root and chloroform, will lessen the pain attending the operation. CHAPTER VII. GOLD COLLAR CROWNS WITH PORCELAIN FRONTS. INCISORS AND CUSPIDS. This style of crown for incisors and cuspids, as originally made by Dr. C. M. Richmond, and with which his name has become associated, consisted of a cap for the root, formed of a band of gold capped with platinum on which was soldered a tooth with a slot in the center between the pins. Through this slot and the center of the cap a screw passed which entered into a cylinder previously screwed and cemented into the root-canal. The form of gold collar crown in general use at present is, in principle, the same as what has been known in dentistry as a gold pivot tooth, with the addition of a gold collar for the root, and having the advantage of oxyphosphate for its cementation. These improvements, howrever, enhance its value as a crown, and materially change the process of its construction. In making an incisor or cuspid crown of this style, the collar, having been formed, is trimmed even with the surface of the end of the root. With the collar in position on the root, a corundum-wheel is passed over the labial edge, along the margin of the gum, to level the gold with the root and render it invisible when the crown is finished. The side of the wheel used should revolve toward the root, and when necessary be reversed for that purpose, so as to turn the feather-edge of the metal of the collar over the end of the root. The work will then present the appearance shown in Fig. 162. The cap is made by adapting the surface of a very thin piece of platinum plate to the outer edge of the collar, and uniting them with solder in the flame of a lamp (Fig. 163). The quan- tity of solder used must be very small, and it should be placed on the platinum outside of the collar, as otherwise it will flow over the inside of the collar and interfere with the fit of the cap. 85 86 ARTIFICIAL CROWN- AND BRIDGE-WORK. The process is facilitated by first merely attaching the platinum, with the solder, to the edge of the collar, then readapting, and finishing the soldering. The platinum is then trimmed to the collar, and the cap adjusted on the root. The labial section of the surface of the cap is then burnished to the end of the root (A, Fig. 162). The root-canal having been slightly enlarged, a pin of round iridio-platinum wire, No. 16 or 17, U. S. standard gauge,—filed a little smaller for laterals or other roots which require it,—is slightly tapered at the point, fitted to an aperture made in the cap, and to the canal (B). The pin is then cut off even with the cap, removed, and temporarily laid aside. A hollow wire, the open space in the center of which is very small, has been introduced for use in crown-work by Dr. J. G. Morey. The advantage it confers is the comparatively easy manner in which it can be drilled out of the canal if for any Fig. 162. Fig. 163. Fig. 164. Fig. 165. reason it becomes necessary to remove the crown, as the drill will follow the fine opening in the center of the wire. A plain-plate cross-pin tooth, suitable in form and color, is ground and fitted in position on the cap. The labio-cervical edge of the porcelain (A, Fig. 164) should be flush with the edge of the collar, and meet the margin of the gum. It should be cut out at the base (B) so as to form a slight space just over the end of the pin. The tooth is then backed with very thin pure gold, gold lined with platinum, or pure platinum foil. Platinum gives a faint blue shade, and gold, or gold lined with platinum, if the gold side is toward the porcelain, a slight yellow shade. The backing should extend as far as possible under and between the tooth and the cap, as the solder will flow in and fill the space, 5730 GOLD COLLAR CROWNS WITH PORCELAIN FRONTS. thus giving strength and continuity of structure. The backing, if bent over the incisive edge (C) at an obtuse angle, will protect the porcelain in occlusion. A narrow strip of fine gold placed transversely across at that point previous to investing, and united in the soldering of the backing, will answer the same purpose. If the platinum backing used is of the nature of foil, it is advisable to rivet a small piece of gold plate over if on the back of the tooth, to insure against melting the platinum off the por- celain with the gold solder, which may occur if a' pointed flame is used. The tooth, when backed, is secured in position on the cap with a compound of wax and resin, and the whole adjusted in the mouth, then removed, and the pin, which has been laid Fig. 166. Fig. 167. Fig. 168. aside, warmed and placed in position by passing the end from the inside of the cap through the hole into the wax attaching the porcelain crown. Another adjustment in the mouth is then made to determine the exact line for the pin, and the case is ready for investment. After the fitting of the pin to the root and root-canal, as has been described when the cap was formed, some prefer to solder it to the cap, for which purpose it should be adjusted in position and cemented with wax, then removed, invested, and soldered (Fig. 165). At this stage of the work, if desired, an impression can be taken in a small impression cup (Fig. 166) with either plaster or modelling composition. The cap should be removed in position in the impression. To aid this, a piece of gutta-percha can be put on the end of the pin projecting from the cap. An articulation of the lower teeth should also be obtained. When 88 ARTIFICIAL CROWN- AND BRIDGE-WORK. the model is made, the pin is cut off even with the cap, and the porcelain tooth fitted as already described. Calcined marble-dust and plaster, in the proportion of two parts of marble-dust to one of plaster, to which is added a pinch of sulphate of potassium to quicken the setting, makes what is considered to be the most suitable investing material for crown- work. The crown, when invested, should be left exposed at the sides, as illustrated in Fig. 167. The investment should be first heated over a Bunsen burner, and then removed to a char- coal soldering-block. Gold solder cut in small pieces is then placed in and over the aperture between the porcelain front and the cap. By uniformly heating the investment, especially under- neath, with a large flame from a gas blow-pipe, mostly pointed in the direction A, the solder is melted and flowed between the porcelain and cap. More solder should be added, and melted in this manner until the space between cap and porcelain is filled in; but if an excess is used, it is apt to bulge or flow out over the collar. Additional solder is then placed on the backing and cap, and with a small pointed flame melted and flowed over these parts. Only sufficient gold should be used to insure restoration of contour. When soldered, after having been placed in acid and thoroughly divested of borax, the crown is ready for the finishing and polishing process. Fig. 168 represents the com- pleted crown. BICUSPIDS AND MOLARS. Bicuspids crowned by this method will have greater strength if a portion of the palatal section of the natural crown is reserved (Fig. 24), and the band or collar made deep enough to cover it. The end of the root is capped after the manner of the typical central already described, one or two pins being used in the canals as required. A porcelain cuspid tooth, or a bicuspid front, is then ground, backed, and adjusted on the cap to repre- sent the labial aspect, and secured with wax. The front and cap are then removed, invested, and soldered, after which they are adjusted in the mouth, and the occluding edge of the por- celain is ground clear of the antagonizing teeth (A, Fig. 169). With a die of suitable size representing the occluding sur- face of a bicuspid, as illustrated in Fig. 170, a thin piece of pure GOLD COLLAR CROWNS WITH PORCELAIN FRONTS. gold plate is swaged (Fig. 171) and the cusps filled in with 18- or 20-carat gold plate. The cap is then trimmed (Fig. 172), ground, and fitted to the occluding edge of the porcelain front (Fig. 173) in proper position as regards occlusion, and the wax attaching it is shaped to the contour of the crown (A). A piece of pure gold plate (B), not over 34 or 35 U. S. standard gauge, is then Fig. 169. Fig. 170. Fig. 171. Fig. 173. Fig. 174. adjusted on each side of the crown, which is invested (Fig. 174). The long ends of the two side-pieces of gold plate are designed to retain them in position, as the investing material should be removed from the portion inclosing the sides of the crown (A). Mica—isinglass—is recommended for this purpose, and is prefer- able to metal. In the process of soldering, the solder is placed in the aperture at B, and the flame of the blow-pipe being Fig. 175. Fig. 176. Fig. 177. Fig. 178. directed on the exposed sides of the gold at A, the solder is flowed into every part, forming perfect continuity of structure of the metallic portion of the crown. If this aperture at A is left open without the gold or mica, and the solder is first flowed in the interstices as described in soldering an incisor crown, the remaining solder necessary to contour the part can be added, if the pointed flame is used and not applied to the other portions of the crown and investment. In finishing, the surplus gold is » 90 ARTIFICIAL CROWN- AND BRIDGE-WORK. trimmed to the contour of a bicuspid tooth. Fig. 175 represents the finished crown. The method described produces a perfect and artistically formed crown, but simpler and quicker methods are practiced. One of these is to build up the palatal cusp with several pieces of gold plate, which have been previously melted into the form of small balls and flattened out on an anvil. These, laid in posi- tion and united with solder, are shaped in finishing to represent the palatal cusp (Fig. 176). The porcelain front should be backed so that the solder can be flowed over its occluding edge. Another method is to extend the palatal part of the collar down as shown in Fig. 177, and then fill in the space with solder. In finishing, the gold is trimmed to the form of the crown. In this and in the method just previously described, the porcelain front can be soldered and the palatal cusp formed in the one investment. The method of construction of molar crowns with porcelain fronts is similar to that for bicuspids (Fig. 178). Dr. StowelVs Method.—A porcelain crown can be soldered on the cap, according to Dr. S. S. Stowell's method,as follows:1 " The tooth used may be a Logan or an E. Parmly Brown crown or an ordinary countersunk tooth, but in most cases the Logan crown is preferable. The pin is first cut off, then the tooth is ground to fit on the cap, the porcelain and the stump of the pin Fig. 181. Fig. 182. Fig. 183. being reduced alike evenly and smoothly; after which the stump of the pin is ground with a small wheel below the surface of the porcelain (Fig. 179). The tooth is then invested (Fig. 180) and pure gold fused on to the platinum pin, and while in a fluid state it is with a wax spatula < spatted' down flat (Fig. 181). 1 Dental Cosmos, vol. xxix, page 641. Fig. 179. Fig. 180. GOLD COLLAR CROWNS WITH PORCELAIN FRONTS. %\ The gold is then filed or ground down even with the porcelain, and at the palatal border the tooth is ground to bevel back until the gold is reached (Fig. 182). The tooth is then secured in place on the cap with wax cement (Fig. 183), the case invested, and heated until the wax has melted and burned out. A small clipping of thin platinum plate is crowded into the opening (Fig. 184) caused by the grinding of the bevel on the crown. The clipping of platinum serves as a lead for the solder, which fol- lows it down into the countersunk cap, around the ends of the Fig. 184. Fig. 185. Fig. 186. Fig. 187. Fig. 188. dowels, and finally attaches itself to the pure gold already at- tached to the stump of the platinum pin. Fig. 185 represents the completed crown. A sectional view of a like crown (Fig. 186) also shows the organization in detail. A porcelain crown can be used to represent any of the teeth in the same manner. See Figs. 187 and 188." CHAPTER VIII. ALL-GOLD COLLAR CROWNS FOR BICUSPIDS AND MOLARS CONSTRUCTED IN SECTIONS. The root and crown having been properly prepared, the collar is formed and adjusted as described at page 80, and the edge toward the antagonizing teeth trimmed, to fully clear them in occlusion. The collar is then slightly expanded toward the occluding surface to effect contour. A close knuckling can be insured by seizing the collar and the approximal tooth in the manner shown in Fig. 189. The crown is removed, filled with Fig. 189. Fig. 190. plaster, and adjusted in position. Fig. 190 represents a typical case. The antagonizing teeth, having been covered with a piece of tin foil, are then occluded until the plaster sets. The collar is then removed. The surface of the plaster inside the collar will give the impression of the natural root or crown, and the outside that of the antagonizing teeth. The latter furnishes an outline of the grinding-surface of the crown. The plaster is then trimmed and shaped to represent the cusps and fissures of the natural tooth, enough of the surface being removed to allow for the thickness of the plate that forms the cap. Readjustment in the mouth will show the accuracy of the occlusion. 92 ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. 93 A small tube of copper, a trifle larger in circumference than the crown under construction, is filled with Melotte's "moldine," and the surface rubbed with soapstone. An impression of Fig. 191. Fig. 192. the lower portion of the form of the crown A to the line B, Fig. 191, is then made in the mold- ine, and a strip of paper wound around the tube, extending about an inch above the edge. Fusible alloy is then melted and poured into the mold, thus forming a die. An indentation is made with a punch in a block of lead, into which the die, when cold, is hammered slightly beyond the impression of the od^e of the collar. By this method a die and a counter-die (Fig. 192) can, with practice, be completed in five minutes. With this die the cap is then struck up on the lead from a flat piece of plate and fitted to the collar. A little of the surface of the plaster in the collar may have to be removed, if, on trial in the mouth, the cap is found a little flush. The crown, with the Fig. 193. Fig. 194 The frame of this clamp is formed of iron wire, and the support for the crown of plaster, asbestos, and marble-dust. plaster still inside the collar, is fixed in a soldering-clamp con- structed in one of the forms shown in Figs. 193 and 194, which holds the parts together and permits the flame to reach all points. No more solder should be used than the contour requires, as an excess necessitates additional labor in finishing. A, Fusible die. B, Counter-die. C, Plate to form the cud. 94 ARTIFICIAL CROWN- AND BRIDGE-WORK. Another method, if the crown is not to be contoured with the aid of the solder, is, when the cap is struck up, to melt solder into the cusps, and then adjust the cap in position on the collar, for which purpose some of the plaster underneath the cap must be removed. A jet of flame from the blow-pipe is then thrown upon it in such a way as to cause the solder to flow down on the edge of the collar and fill the seam from the inside. The objection to this method is that, when a large portion of the natural crown is inclosed by the gold, the solder will occasionally alter the inside form of the fitted cap, thereby interfering with its adjust- ment, which is a defect troublesome to correct, Still another method is to adjust the collar in the mouth, and, with a small piece of wax or impression-compound pressed upon it, to take an impression and " bite," in which the collar will be imbedded and removed. With this a model and articu- lation are made and the form of the cap shaped in wax. An impression of the cap is then made, either in moldine in a soft Fig. 196. Fig. 197. L-A state in a tube, or in plaster, and a die cast. The cap is stamped on this die, then adapted to the collar by the model, and the crown finished. This method, which was first made known by Dr. N. W. Kingsley, is adopted when it is preferable to construct the crown between the visits of the patient. In utilizing a tooth as an abutment in bridge-work when all or nearly all of the occluding surface of the natural crown is ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. 95 present, a practical method of construction is to mark the out- line of the natural crown on the inner surface of the collar; then remove the collar and trim so as to leave a border of about one-sixteenth of an inch outside the mark. This border is then thinned with a corundum-wheel, and slit as seen in Fig. 195. The collar is next adjusted on the crown, and the slit border bent over to the form of the occluding surface, to which it is burnished. A piece of pure gold plate, about No. 34 gauge, is 96 ARTIFICIAL CROWN- AND BRIDGE-WORK. then placed on the occluding surface of the tooth and adapted to it and to the collar. The gold may be first struck in the form of a cap by laying it on a block of lead and hammering into it a die corresponding to the surface of the tooth to be crowned (Fig. 196). The antagonizing teeth are then occluded on the gold, which is thereby pressed to form to articulate with the occluding surfaces. Enough of the occluding surface of the tooth crowned should always be removed to allow for the thick- ness of the gold covering its surface. The collar and cap are next removed and soldered. This is done by resting the collar on the cap, which is held by a pair of tweezers, or by clamping Fig. 199. the cap and collar together and placing the solder in small pieces around the collar outside the cap, at A, Fig. 197, and soldering by holding in a blue gas flame. Only sufficient solder should be used to join and fill the seams, so that it will not interfere with adjustment on the natural crown. The methods described insure a perfect occlusion of the crown with the antagonizing teeth. In the absence of antagonizing teeth, or when the general form of the grinding-surface permits it, the cap can be struck up with a die similar to the one shown in H ig. 196. The cusps are then filled in, and the edges of the inner surface of the cap ground level on the side of a corundum- whee . The entire circumference of the edge of the collar is also leveled, and the cap adjusted, clamped, and soldered. If ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. 97 Fig. 200. the cusps of the cap are filled in with solder, it will flow down and join the collar on the inside; if with gold plate, the cap and collar must be joined with solder either on the inside or outside. Metallic caps, or forms of the occluding surfaces of teeth for use in constructing crowns, are quickly made with the die-plate shown in Fig. 198,1 " in which are four groups of intaglio dies representing, with distinctive correctness, the peculiar cusps of the upper and lower right and left bicuspids and molars. The hubs A, B (Fig. 199) are of the sizes shown, and are made of an alloy composed of tin one part, lead four parts, melted together. The mold C should be warmed, the metal alloy poured in every hole, and the over- flow wiped off just before the metal stiffens : this will make the butts of the hubs smooth and flat. After a minute or two the mold may be reversed, the hubs shaken out, and the casting process continued until a considerable number of hubs shall have been made. In Fig. 200 a molar hub is shown in place on Fig. 201. a piece of No. 32 gold plate, which lies over the upper right first molar die. A succession of blows on the hub with a four-pound smooth-face hammer will drive the plate into the die, and, at the same time, spread the hub metal from the die center to its circum- ference, in such a manner that the plate will be perfectly struck 1 Dental ( osmos, vol. xxix, page 482. 8 98 ARTIFICIAL CROWN- AND BRIDGE-WORK up with the least possible risk of being cracked. The flattened hub is seen in Fig. 201, which also shows at D the obverse of the struck-up hub, and at E the cameo of the struck-up plate, having every cusp and depression sharply defined. The counter- die plate (Fig. 198) is made of a very hard cast metal, which will 3 \ admit of the striking up of many crown plates by the means described, if the crown plates be not too thick and stiff. Of course they should be annealed before they are placed over the die. ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. 99 " In careful hands the die-plate should give clear cusp defini- tions after years of use. The counter-die plate is in some re- spects similar to a stereotype plate for printing, and the struck impressions on two strips of thin plate will therefore appear as in Fig. 202, wherein their regular order is noticeable, as seen from the cameo surface of the struck plates. " The peculiar action of the hub in forming first the center of the crown plate, and spreading from the center outward, as the hub is shortened under the hammer, until the die is overspread by the plate and hub, with the result shown in Fig. 201, is an essential feature of this process for obtaining easily and quickly the superior styles of coronal cameos shown. If a cusp or fissure should chance to crack in hubbing, a small piece of plate may be struck up over the fissure, and then soldered to the original cap." The methods which have been described for the construction of all-gold bicuspid and molar crowns are those generally adopted in practice. Of others, Dr. J. J. R, Patrick's method1 consists of first forming a very narrow collar and telescoping it with a seamless cap of the form of the crown, and soldering along the line of the cap to the collar. Dr. E. P. Brown's method is to make or select a metallic die for the crown to be formed; then place a piece of pure gold plate, about No. 31 gauge, on the flat surface of a block of lead, and gradually stamp the die downward into the gold to about half the depth of the intended crown. The gold is then re- moved, and each side of the unswaged portion slit and adapted to the form of the die, the full length of the-crown, which is then adjusted in the mouth, the edges of the gold trimmed to the proper form, and the slits soldered. Dr. M. Rynear's crown is of the same general character and is constructed in the same manner as Dr. Brown's, except that a seamless cap is used to form the crown, instead of the flat piece of plate used by Dr. Brown. Dr. T. Fillebrown's method of constructing a bicuspid or ij)r. Patrick's crown-work methods and the principles upon which they are based are set forth in a paper published in the Dental Cosmos for October, 1888, page 706. 100 ARTIFICIAL CROWN- AND BRIDGE-WORK. molar all-gold crown when the sides of the natural tooth have not, for some reason, been reduced in dimensions to that of the cervix, is to first form and fit a full-sized collar of thin pure gold, then adapt and solder over it a second and narrower collar of Fig. 203. thin 22-carat gold plate, extending only from the oc- cluding surface about half the distance to the gum- margin. The cap for occluding surface is then added in the usual manner. When the finished crown is cemented in position, and while the cement is yet quite soft, a burnisher is passed around the neck of the crown, and the pure gold forming that part, as represented by A, Fig. 203, is brought close against the neck of the natural tooth. This method of forming a gold crown can be advantageously practiced in cases of bridge-work. All-Gold Crowns for the Incisors and Cuspids.—When the teeth are short and the incisive edges flat or abraded, and the all-gold crown required is to correspond in form or be only a little longer, the gold collar, after being fitted to the tooth, is slit on the palatal or lingual side, and bent and burnished to it. The collar is then removed and the seams soldered together. This is best done by holding the collar in a Bunsen gas flame, with the solder placed in position in very small pieces, and only suf- ficient in quantity to join the seams. The collar is next ad- justed to the tooth, and the gold at the incisive edge trimmed even. A flat, thick piece of gold plate or clasp-material is sol- dered across the incisive edge to form and inclose that portion of the crown. When the crown required is of the normal form, the collar when properly fitted should be removed at the palatal section, Fig. 204. as shown in Fig. 204. The edge of the gold is then a chamfered, and bent and burnished over the incisive edge and sides, close to the natural tooth. To this open section is next adapted a flat piece of gold plate, the collar is removed, and the parts are soldered together. Fluxed solder filings can be melted in the interior of the incisive edge to increase its thickness. A fusible metal die of the natural tooth is a material aid in the construction of this stvle of crown. ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. 1Q1 Fig. 205 represents a case of abrasion of the lower teeth, to which all-gold crowns have been applied, as shown in Fig. 206. In such cases, owing to the aggression of the occluding teeth, Fig. 205. Fig. 206. the cap forming the occluding surface should be constructed of heavy gold and platinum plate. An artificial plate replaces the upper teeth. CHAPTER IX. THE GOLD SEAMLESS CAP CROWN. This method consists in the use of a gold seamless cap for the construction of the required root cap or crown. Fig. 207. Fig. 208. INCISORS, CUSPIDS, AND BICUSPIDS, WITH PORCELAIN FRONTS. Incisor, cuspid, and bicuspid crowns with porcelain fronts are constructed by this method as follows: The natural crown is ground down to within about one-eighth of an inch of the gum at the palatal wall, or enough to clear the antagonizing teeth when occluded, and slanting from the posterior edge of the pulp-chamber to the cervico-labial edge of the gum and slightly under its margin if it is desirable to conceal the joining of the crown with the root. The sides are shaped the same as for a collar crown (Fig. 207). A die of the end of the root is then made. For this purpose an impression of the part is taken with gutta-percha on the end of a piece of wood trimmed to the proper size, or by placing some plaster of Paris with a little sulphate of potassium, mixed to the consistence of a paste, in a tube formed of a strip of copper about one and one-half inches in length and three-eighths of an inch in diameter, cut out on the sides to the depth of half an inch, with the flange for the palatal side shortened1 (Fig. 208). The impression thus taken will be confined almost entirely to the end of the root to be capped. When gutta-percha is used, it is cooled and dried perfectly. A^strip of paper is tied around the wood 1 See article on « Molds and DiesTwhichdescTibes how to make a tube without soldering. 102 THE GOLD SEAMLESS CAP CROWN. 103 or tube, and a die cast with the fusible metal. The cooling is hastened by immersion in a glass of water. When cool, the die is removed from the mold, and the metal is trimmed, with file and chisel, a little deeper than the gum has permitted the im- pression of the root to be taken, and without altering the form of the end of the root (Fig. 209). A counter-die is then made by punching a hole in the surface of a block of pure lead, and with a few blows of a hammer driving the die into it. A cap of gold can be formed by placing a piece of gold plate (preferably pure, No. 32 U. S. standard gauge) of suitable size upon a block of lead, and with an oval-shaped punch one-fourth of an inch in diameter gradually driving it into the lead until the gold Fig. 209. Fig. 210. Fig. 212. has assumed the shape of a cap about a quarter-inch in depth (A, Fig. 209). The gold should be withdrawn from under the punch and annealed several times during the process. Caps can also be made with a stamping-press such as was introduced by Dr. J. J. R. Patrick, of Belleville, 111. (See page 110.) The cap is then annealed and swaged on the die to the form of the end of the root (B, Fig. 209). The palatal portion of the cap should be allowed to go well up under the free edge of the gum, and at the cervico-labial edge it can be, if preferred, cut out to the edge of the root. In the process of adjustment, the edges which 6^ under the gum should be marked and trimmed as 104 ARTIFICIAL CROWN- AND BRIDGE-WORK. directed in describing the construction of a collar crown, and then burnished close to the sides of the root and into the orifice of the root-canal, forming a perfect-fitting seamless cap (Fig. 210). An iridio-platinum pin is then fitted in the root-canal and soldered to the cap (Fig. 211), or afterward adjusted as in the construction of the gold collar crown with porcelain front (page 86), with which operation the remainder of the process ot construction is identical. Fig. 212 represents the completed crown. The advantages of this style of crown are, simplicity, as the formation of a collar is avoided, and strength, as a large portion of the natural crown can be left at the palatal side. This affords a stronger and more reliable foundation than can be obtained at any other point, as the direction of the force in mastication is forward at an angle with the line of the root, and although the gold of the cap, where it encircles the root at the cervico-labial edge, is entirely removed, the crown is still held securely. In a paper on the subject of preserving and utilizing this part of the tooth, Dr. W. F. Litch, of Philadelphia, describes a crowning operation,1 in which he constructed the cap of platinum by slitting a piece of the plate in a number of places, adapting it to the form of the end of the root, and then soldering the whole together This operation is not, however, so easily or so satisfactorily performed as the method above described, in which platinum, if desired, can be used instead of gold, and the soldering done with 22- or 24-carat gold. In some respects pure platinum is prefer- able to gold in capping roots, as it is less likely to be affected by the secretions of the mouth. ALL-GOLD SEAMLESS BICUSPIDS AND MOLARS. All-gold seamless crowns for bicuspids and molars that will accurately fit the natural crown and root, and occlude properly with the antagonizing teeth, are easily and quickly formed, if sufficient of the natural crown remains to admit of temporary restoration of its contour with gutta-percha or any other suitable Pjashc^matenahjfi^^ of ^ 1 Dental Cosmos, vol. xxv, No. 9, page 449 ~~ THE GOLD SEAMLESS CAP CROWN. 105 restored tooth is taken in plaster or gutta-percha in a tube, as explained on page 102, and a die then formed of fusible alloy; or a plaster model can be made from an impression of the tooth taken in wax, and a mold obtained from the model with moldine. The preparation and shaping of the natural crown to receive the artificial crown can then be proceeded with. Where the natural crown is very badly decayed or broken down and the method just described is not practicable, the portion of the natural crown or root remaining should be shaped and prepared to receive an artificial crown. Then the form of the cervix is ascertained with a wire as described on page 81, and an impres- sion of the parts taken in wax, and the wire form, the twisted ends having been shortened, is carefully adjusted on the wax at the cervical line. The plaster model, when made, will show the Fig. 213. Fig. 214. wire slightly imbedded in the plaster. The plaster should be trimmed to the inner edge of the wire, as that represents the exact form of the root (Fig. 213). Another method is to encircle and adapt to the form of the root a strip of annealed copper, No. 35 standard gauge, about one-eighth of an inch wide, and mark the end of the overlap. The copper is then removed, the ends joined with an atom of solder, and the copper adjusted on the root. An impression is next taken with plaster, in which the copper band is removed in position. A model made from this impression, after the copper is removed, presents the exact form of the root. From a " bite " taken in wax a plaster articulation is then made to the model. A hole is then drilled in the center of the form of the root on the model to be crowned. In this hole, and over 106 ARTIFICIAL CROWN- AND BRIDGE-WORK the end of the root, a ball of soft plaster, slightly colored with carmine, is placed, and the teeth of the articulation, covered with tin foil, closed on it. This, on separation, gives the outline of the form of the grin ding-surface for the crown. The sides of the plaster are then trimmed to the form of the crown, and the whole carved in detail (Fig. 214). As the crown will always stamp larger in circumference than the die, in proportion to the thickness of the gold used, an allowance must be made by trimming off a proportionate amount of the surface of the model; otherwise the outer surface of the crown will be larger than is desired. When the plaster model for the crown is made, it is separated from the rest of the model at the dotted line seen in Fig. 214, and trimmed in the form shown by the cast A, Fig. 215. From this model the die is made in a tube with Fig. 215. Fio. 216. Fig. 217. Fig. 218. moldine and fusible metal as described at page 102. The cast should always be lengthened at the neck, so that the crown when constructed shall have a surplus in depth of gold to allow for any trimming or shaping ot the collar that may be required. The counter-die (B, Fig. 215) is made by punching a hole in a block of lead and hammering the die into it, The crown, which is usually formed of pure gold, or gold slightly alloyed, or gold lined with very thin platinum from No. 30 to No. 32 gauge, is then made-by first stamping a piece of plate (see page 108) in the form of a cap of gold (A, Fig. 216). This cap is then placed on the cast, and with the aid of the counter-die (B, Fig. 215) swaged to the form of the crown B, Fig. 216. A piece of kid leather should be used to cover and protect the gold from the lead, and facilitate its removal from THE GOLD SEAMLESS CAP CROWN. 107 the counter-die. An allowance for the thickness of the leather must be first made, by driving it, without the gold on the cast, into the counter-die to enlarge it. If this is not done, the gold is li.ible to be torn in the swaging. Dr. C. B. Parker's method of stamping the piece of gold plate is to form two dies of the required crown,—the first with a cone-shaped neck up to the grin ding-surface (Fig. 217), and th j second straight on the sides (Fig. 218). The gold is stamped up on the first die, giving the grinding-surface, but leaving the sides flaring, and then on the second to straighten the sides. Cuspid crowns from which a portion of the gold on the labial aspect is to be removed, or which are to be used entire as a support for bridge-work, can usually be advantageously formed Fig. 219. with a seamless cap (Fig. 219). The necks of these crowms can be contracted in fitting in a contracting plate, or slit, lapped, and soldered, should the case so require. (For details of process of adjustment and insertion, see " Adjustment of Seamless Contour Crowns," page 111.) CHAPTER X. GOLD SEAMLESS CONTOUR CROWNS.1 The artistic requirement of all-gold crown-work is, that it shall reproduce the anatomical contour of the natural teeth. This is usually accomplished by melting solder on the collar and then trimming it to the form of the crown. A preferable method is to shape the metal forming the sides of the crown by swaging. This is easily done in a crown formed in sections, but a special process is required in the construction of seamless crowns. A contour crown can be made by placing a seamless cap on a sectional die or mandrel of the shape of the tooth, first swaging Fig. 220. Fig. 221. Fig. 222. m- the grinding-surface on the mandrel and then stamping down- ward on the straight sides of the crown with a cap fitted to the shank part of the mandrel. But such a process, like many others, is too complicated to be of any use to the dental prac- titioner. The sectional mold method here presented is simple, practical, and general in its application. To describe and illustrate the process, we will take one of the most difficult crowns to construct,—a superior molar (Fig. 1 Gold crowns of this form are now made and sold as the " Evans Gold Crowns." The Evans gold non-fusible crown is lined with platinum on the interior of the oc- cluding surface and part of the sides, to prevent melting the gold in soldering. 108 GOLD SEAMLESS CONTOUR CROWNS. 109 220). A natural tooth, or one made of plaster, is used as a model. From this a sectional mold is made, as illustrated in Figs. 221 and 222, in Babbitt's metal, zinc, or fusible alloy. Into the mold a cap of gold (Fig. 223) 23 to 24 carats fine, 30 to 32 gauge, *is adjusted, fitting tightly the orifice of the closed mold. The mold is placed in a vise, the cap expanded to the general form of the mold by hammering into it a mass of cotton, and then swaged more in detail to the form, and with a wood point or a burnisher revolved by the dental engine burnished into every part of the mold (Fig. 224). To facilitate the process, the mold should be frequently opened, and the gold annealed. Fig. 225 represents the completed crown. These results can be secured by other styles of molds: Fig. 224 illus- trates one, but the principle is the same. Fig. '-'24. Fig. 225. Another method is to form a fusible-metal die of the tooth to be crowned, and, after having stamped the grinding-surface of the crown, to reverse and swage the sides close to the die; the crown is then relieved of the core (die) by heating to the melting point of the fusible metal and pouring it out. For practical use, a variety of molds is required, made from natural teeth of different sizes and average forms to serve in corresponding cases. The crowns can be contracted at the neck more than their size and contour call for, so that the gold will act as a tight-fitting band which will expand to the form of the root as the crown is pressed up in the process of adjustment. Caps of metal can be made in different sizes and kept on hand for use in this and other styles of crown-work by means of a machine (Fig. 226), which in principle is such as is used by ARTIFICIAL CROWN- AND BRIDGE-WORK jewelers for forming cap-shaped pieces of gold, and in factories for making copper cartridges. The gold plate, cut into circular Fig. 226. The form of stamping machine introduced by Dr. J. J. R. Patrick. pieces, is pressed through a steel die-plate, with punches gauged to the holes; at each punch a small portion of the gold is turned Fig. 227. Fig. 228. e B 0 0 © © ©@ over, thus preventing its lapping or creasing (Fig. 227). Repeated annealing of the metal is very necessary in this process. Methods of Contouring Crowns constructed in Sec- tions.—In constructing a crown in sections, the collar can be first formed on a mandrel, then placed in a mold, and burnished GOLD SEAMLESS CONTOUR CROWNS. m to the shape of the sides. The process of its adjustment to the neck of the root is then continued in the usual manner. Another method is to stamp or burnish up the collar on a die representing the upper sections of a tooth, designated as the middle and cervical third (Fig. 228). After contouring the collar, the cap is adjusted and soldered on. With a metallic stamping plate (see page 95) these caps are quickly made. ADJUSTMENT OF SEAMLESS CONTOUR CROWNS. A superior molar—one of the most difficult teeth to operate on—will serve as a typical case to illustrate this process. The crown or root is first shaped and if necessary built down with amalgam, straight, or tapering slightly on its sides toward the occluding surface, as described at page 35. Hon- to Select a Suitable Crown.—The width of the crown re- quired from the anterior to the posterior sides of the occluding surface is first obtained by measurement with a piece of card- board or thin copper plate, as shown at A, Fig. 229. The measurement can be taken direct from the mouth, or more con- veniently from a small plaster cast made from a correct impression of the prepared crown or root and the two approximal teeth. This measurement can also be taken by means of tweezers with a set-screw (Fig. 230.) With this meas- urement as a guide, the proper-sized occluding surface is readily found by comparison with the dimensions of the various crowns as shown on the printed chart of the crowns (C, Figs. 231 and 232). ' Fig 230. Fig. 229. Tweezers with set-screw to use as calipers. The size of the neck can be calculated by the eye, or by taking the dimensions with a piece of fine wire (Fig. 235), pressing the wire on the surface of a piece of sheet wax, and then comparing with the impression the necks of the gold crowns. 112 ARTIFICIAL CROWN- AND BRIDGE-WORK. In making a selection, it should be borne in mind that the cervix of the gold crown should preferably be smaller than larger, as it can always be easily expanded, while its contraction is difficult. It is not essential that the curve of the collar shall correspond with that of the tooth, as the gold will readily take the proper shape as the crown is adjusted. Method, of Adjusting the Crown.—1. Anneal the crown selected, and slip it over the end of the natural crown or root and gently press or work it upward—the gold of the collar will expand to the form of the root in the operation—until the edge meets the margin of the gum (A, Fig. 233). 2. Mark a line (B) on the gold parallel with the margin of the gum. 3. Remove and trim to this line (A, Fig. 236). If necessary, repeat the marking and trimming until the edge meets the gum evenly. 4. Bevel the edge of the gold, readjust the crown and press it up until the edge of the collar passes under the margin of the gum,vand, if the occlusion is correct, burnish the gold to the cervix. To Expand the Collar and Croivn.—If the collar of the crown needs enlargement, it is easily and most properly accomplished GOLD SEAMLESS CONTOUR CROWNS. 113 with crown expanders (shown in miniature form in Fig. 237), the points of which should be introduced at first just within the edge of the neck, and the gold spread sufficiently to allow it to fit over the end of the natural crown or root, the process of ex- Fig. 235. Fig. 236. Fig. 237. Fig. 238. pansion being gradually continued as the crown is brought into position. By proceeding in this manner too great expansion is avoided. If the entire crown needs enlargement, it is best done by soft- ening a mass of gutta-percha of about the same size as the crown upon the closed ends of a pair of expanding or clamp forceps, which are heated for the purpose. The forceps points with the gutta-percha are then introduced inside the collar of the crown, which should be moistened to prevent adhesion. The gutta- percha is next withdrawn, hardened in cold water, and cut through the center between the points of the for- ceps. This makes practically an ex- panding sectional mandrel with which the crown can be enlarged according to the position in winch the forceps were introduced (Fig. 238). To expand the crown without enlarging the neck, trim off the gutta-percha on the forceps at the neck. The naked points of an ordinary clamp forceps can sometimes be used to advantage to expand a portion of the coronal section of the crown. To Alter a Side.— The contour of one or both sides can be de- pressed and the crown thus narrowed by introducing the points of a crown expander or some tool that will fit loosely inside the crown, 9 114 ARTIFICIAL CROWN- AND BRIDGE-WORK. then steadying the crown with the fingers, as shown in Fig. 239, and tapping the sides to be reduced with the flat end of a rivet- ing hammer. This is necessary when the contour or the side of a crown presses on an adjoining tooth, and the crown is thus prevented from coming in proper position. To Alter the Shape of a Portion of the Collar or Side of a Crown.— Slip the crown over the point of an anvil, or the end of a pair of expanders, or a small round-handled instrument held in a vise, and then tap the part to be altered with the flat end of a riveting hammer to the form desired. To Alter the Occluding Surface.—Before the crown is pressed up to its apparently proper position, the occlusion should be ex- amined, and calculations carefully made to obviate any defects Fig. 239. Fig. 240. of articulation, which can be readily corrected at this stage Im- proper manipulation of the crown. Any necessary change in the form of the occluding surface can be made with the crown in position on the tooth, by means of an instrument tapped by the mallet; or by removing the crown, placing it over the closed points of an expander, and tapping and burnishing the part; or by holding the crown between the thumb and forefinger with the edge 0f the collar resting on the side of the next finger, which when necessary can be protected with a napkin, and then tapping the gold with the point of a riveting hammer (Fig 240) The occluding of the antagonizing teeth on the crown by the patient will assist and complete the process of articulation. To Contract the A^.-Slightly bend in the edge of the gold at the neck with narrow-beaked pliers, and holding the crown GOLD SEAMLESS CONTOUR CROWNS. 115 evenly and firmly between the fingers, as shown in Fig. 241 burnish the sides of the neck section inward around the entire circumference of the crown. To Considerably Contract a Crown.—Slit the gold longitudinally at the palatal or lingual side its full length to the grinding-sur- face, bevel off the edge to lap under, con- tract the crown, readjust to the tooth, Fig. 241. remove, place the smallest quantity of dampened fluxed solder filings in the seam on the inside of the crown only, and solder by holding in an alcohol flame. Then proceed with the further adjust- ment of the crown. The outside line of the seam can be stoned off and polished after the crown has been fitted, and additionally soldered to strengthen the sides or grinding-surface. Strengthening Seamless Gold Contour Crowns.—Additional strength and stiffness can be given to seamless gold crowns, when desired, in several ways. The liability of melting the gold which forms the sides of the crown in the operation has, with some, been the principal objection to their use. This, however, can be avoided. When the crown has been properly adjusted, dampen the inner surface with a piece of wet cotton on the point of an in- strument; place in the interior a quantity of fluxed solder filings (solder filings mixed with Parr's flux or pulverized vitrified borax); place the finger over the open end of the crown, invert, and shake well. A portion of the solder filings will adhere evenly all over the wet surface. The surplus is allowed to drop out by removing the finger. Then gradually and uniformly heat the crown by holding it with tweezers in an alcohol flame (not gas) until the solder fuses, when it will flow evenly over the surface of the gold without materially altering the general form. The crown should be held in such a position that a full view of the interior is presented and the melting of the solder rendered visible, which will occur at a red heat. An extra quantity of the solder filings can be placed in the 116 ARTIFICIAL CROWN- AND BRIDGE-WQRK interior of the cusps with a spoon-shaped excavator to additionally fill or strengthen them if found necessary. When a Bun sen gas flame is used instead of an alcohol flame, the grinding-surface and sides of the crown should be first coated with whiting. This is easily done hj dipping the crown into a cream-like mixture of whiting just before inserting it in the flame. The moisture in the whiting should be first slowly evaporated by heating up gradually. Great care must be exercised in the use of a gas flame to avoid melting the crown. The crown should be watched, and instantly removed as soon as the solder fuses and flows. If too much solder has been applied at any point, it can be trimmed and smoothed with corundum melted on to an old engine bur-point. Always boil the crown in acid to remove the flux. The removal of flux from the inner surface of the crown is absolutely necessary if you intend to use it in bridge-work, as solder will have to be melted on the outside. To repair a hole melted in any kind of a gold crown, place a piece of soft wax in the aperture on the outside of the crown, adapt on the inside close against the gold a piece of platinum foil, somewhat larger than the aperture, so that it will adhere to the wax. Fill the interior of the crown with investing material, and flow a little solder over the surface of the platinum and gold on the outside of the crown. Fig 242 ^°^ seamless crowns can also be strength- ened or filled with solder, or even 18- or 20- carat gold plate, by investing the outside sur- face in plaster and marble-dust (Fig. 242), and then with a small flame of the carbo-oxyhy- drogen blow-pipe, not over one-half an inch in length, introduced inside of the crown, melt and flow the solder or gold plate over any portion or even all of the surface of the gold. The crown, if formed of gold with a thin lining of platinum, can be soldered by either method with little danger of being melted. Supporting the Crown.—In crowning teeth with living pulps there is sufficient of the natural crown present to afford a secure GOLD SEAMLESS CONTOUR CROWNS. 117 foundation and attachment for the artificial crown, as is also the case with many teeth that are pulpless; but in badly broken- down crowns, or where only the root is present, a metallic pin or post should be inserted in the root, and the part built down with amalgam to a form which \vill afford FlQ- 243- secure support and attachment to the artificial crown, and facilitate its adjustment. (See "■ Special Prepa- ration of Badly Decayed Teeth or Roots," page 36.) In many cases the required support for the crown can be secured by means of a screw (Fig. 243). A How screw or a post of silver wire is inserted in the root-canal A (see page 49). Amalgam is then packed in the lower section of the artificial crown, C, to the line B, and into the amalgam the screw is pressed. Amalgam which has been put in a piece of chamois and the mer- cury pressed out with a pair of pliers until it is in the condition termed " dry" will adhere to the gold without affecting it. The amalgam is first placed in the crown slightly in excess of the amount required, and the crown adjusted, removed, and the surplus scraped out. This process is continued until the screw or the crown section of the natural tooth forms an indentation in the amalgam, which it will fit when the crown is cemented on. The vent for the escape of air and surplus cement—which should always be put in perfect-fitting crowns and afterward filled with ffold or amalgam—should be in the line of the indentation in the amalgam, with which it must connect (D). (For process of cementation, see article on "Insertion and Cementation.") These crowns can be inserted in an easy and inexpensive man- ner by filling in the lower section of the crown with amalgam instead of gold, and allowing the head of the screw or the nat- ural crown to indent the amalgam as above described, and then cementing on the crown with oxyphosphate in the usual manner. In a case so inserted, with no antagonizing teeth, the result is the fame as though the inside of the occluding surface of the crown was filled with gold; but if antagonizing teeth are present, the gold of the crown is apt to wear through in places and expose the amalgam. ARTIFICIAL CROWN-AND BRIDGE-WORK. To Securely Attach a Crown.—If the tooth is short, and the occlusion of a character requiring the reduction of the collar to such a degree as to suggest insecurity when the crown is cemented, a barbed or headed pin, which will anchor in the natural crown or root, should be soldered in the center of the gold crown, as shown in Fig. 244. This is done by passing the pin through a hole drilled in the occluding surface of the crown, which is then adjusted in the mouth, removed, invested, and the pin soldered from the outside. If the pin is tapered and fitted tightly to the hole (Fig. 245), the soldering can be accomplished without investing, by holding the crown and pin with solder in position in an alcohol flame. To Alter a Gold Crown to the Exact Form of any Corresponding Natural One.—In a case having nearly all the natural teeth present, in which the occluding surface and sides differ in shape Fig. 244. Fig. 245. Fig. 246. from the form of the gold crown, to such an extent as to inter- fere with its adjustment, a die of the natural crown should be made of fusible metal (Melotte's Fusible Alloy,—see article on " Molds and Dies"), and with it the interior of the gold crown should be altered in shape sufficiently to receive the natural crown, by resting the occluding surface of the gold crown on a folded napkin and gently tapping the die into it. Fig. 246 represents the typical molar crown cemented in position. The advantages of seamless contour crowns are, that they represent perfectly the tooth in its anatomical contour, present a uniform surface of pure gold, which preserves its color without tarnishing, and are quickly and easily adjusted. Their defects are inability to meet the requirements of abnormally-shaped roots and anomalous articulations. CHAPTER XI. GOLD CROWNS WITH PORCELAIN FRONTS FOR TEETH WITH LIVING PULPS—COLLAR CROWNS HYGIENICALLY CON- SIDERED. In the anterior teeth, in case of atrophy or erosion, or where decay has destroyed the approximal sides of a tooth in such a manner that crowning is considered the most desirable operation to perform, the pulp is frequently found unexposed and in a normal condition. The importance of its preservation in such a case is unquestionable. The methods which have been commonly used to form a crown under such conditions are in many respects defective and objectionable, notwithstanding the advantages their indorsers claim for them. In the first place, all crowns of platinum or iridio-platinum with body baked on the labial aspect of the metal have a dead and unnatural appearance, and from those on which films of porcelain representing teeth are baked the porcelain frequently chips off, and both styles usually protrude beyond the line of the adjoining teeth. The methods here presented are intended to overcome these objections and to produce more satisfactory results. The descrip- tive details of the crowning of a central incisor will serve to illustrate one of the methods. A model is first made represent- ing the tooth in a perfect form. This can be done either by shaping the natural tooth in the mouth with oxyphosphate or gutta-percha, taking an impression of it in wax or moldine, and forming a model in plaster or fusible alloy, or by taking a natural tooth and shaping it to correspond, or, if the operator is an expert, carving one from a piece of plaster. Two casts, one of the coronal form of the tooth (Fig. 247), 119 120 ARTIFICIAL CROWN- AND BRIDGE-WORK. and the other of only the palatal and approximal portions (Fig. 248), are made, using the moldine in tubes with fusible metal. This will consume only a few minutes. A piece of gold and platinum crown plate, No. 34 IT. S. standard gauge, about the length and circumference of the tooth, is then struck up on the palato-approximal cast, from which it receives the palatal and approximal aspects of the tooth (Fig. 249). It is then transferred to the coronal cast, which is previously trimmed the thickness of the gold plate upon the approximal surfaces, and worked down to the exact form of the tooth on the anterior portion. The metal, which is then the exact form of the tooth on all sides, is cut even at the incisive edge, the seam down the front Fig. 247. Fig. 248. Fig. 249. Fig. 250. Fig. 251. Fig. 252. beveled, lapped, and marked, then slightly opened, and the gold slipped off the die. Guided by the mark, the gold is then pressed back to the form assumed on the die, and fitted to the natural crown, which should have been previously trimmed and shaped as described on page 35 (Fig. 22), and the joint on the labial side soldered (Fig. 250). Into the incisive edge, which is open, a narrow strip of gold, about one-sixteenth of an inch in width and thick enough to fill the space, is fitted and soldered. This strengthens the whole crown, and forms a protecting edge for the porcelain front. We have now a gold contour crown, an exact imitation of the tooth under treatment. The crown is then filled with plaster, and the labial portion ground and filed away, leaving the upper part to form the band, and the lower the incisive edge, as represented in Fig. 251. A porcelain tooth of the proper shade and form is then ground A�4A GOLD CROWNS WITH PORCELAIN FRONTS. J21 down—in which operation the pins are obliterated—to a thin porcelain front, thickest at the incisive edge, and fitted to the space made by cutting away the labial face of the gold crown. The porcelain is then removed and a piece of platinum foil adapted to its back, and turned just barely over the edges, the upper and lower of which should be slightly tapered off, as shown in Fig. 252. The platinum can be made to fit closely to the porcelain by rubbing the edges on a piece of cloth or chamois, on a flat surface. The porcelain front is then adjusted on the crown and cemented on one side with wax, and the crown invested in plaster and marble-dust, so that the seam along the edge of the platinum and gold is exposed on the cemented side and at one end as shown in Fig. 253. When the investment has set, the wax is removed, and small pieces of gold solder or fluxed gold solder filings, 20-carat fine, are packed in and over the seam, in quantity sufficient to make a perfect joint when finished. The investment is then heated uniformly and the seam soldered. Care must be taken not to flow the solder upon the porcelain, or to use more borax than is absolutely necessary, as otherwise the porcelain will be fractured. When the investment is cold, the crown is removed, again invested, and the remainder of the seam soldered, or the invest- ment can be immediately removed from the other side, and the soldering completed; though this latter plan is attended with some risk to the porcelain. After the crown has gone through the finishing process, any excess of porcelain on the inside of the crown is ground away in a few minutes with a small piece of corundum melted on an old oval-shaped bur. The cavity in the crown is, meanwhile, kept filled with water (Fig. 254). 122 ARTIFICIAL CROWN- AND BRIDGE-WORK. In adjusting the crown, the natural tooth can be smeared with a paste made of rouge and sweet oil, which will easily indicate any point obstructing its perfect adaptation. When fitted, the crown is attached with oxyphosphate cement. Fig. 255 shows the completed crown. In making this style of inlaid crown, Dr. J. B. Littig depresses the labial aspect of the gold crown as much as possible, and grinds and properly fits over it a porcelain front. The porcelain is then removed and a narrow strip of gold soldered around the line of the porcelain which will just receive its edges. In this setting of gold the porcelain is inlaid by cementing it with oxy- phosphate and burnishing the edges of the gold over on the edge of the porcelain. Bicuspids and molars can be made in either of the methods described by using a contour crown of gold lined with platinum (see chapter on Gold Seamless Contour Crowns), and, after its ad- justment, filling in the crown with plaster, and then cutting away the labial portion and replacing it with porcelain (Fig. 256). Facing or Enameling with Glass Filling-Material.—A gold crown such as has been above described is made for the case, or a suit- able seamless gold crown obtained or made. The crown is fitted to the tooth in the mouth, the sides properly stiffened, and the cusps or incisive edge strengthened with fluxed solder filings, and the crown boiled in acid. It is then adjusted in the mouth, the portion of the labial section which is exposed is out- lined on the surface of the gold with a pointed instrument, and the crown is removed. The area of the marked labial section is then ground quite thin with corundum wheels and points, and with a spear-pointed drill perforated in a number of places Fig. 257. (see Fig- 257)' Tne crown is next adjusted in the mouth, and the thinned labial section depressed with a burnisher inward or against the natural crown, if one is present, for the purpose of obtaining space for the inlay, and the crown removed. Some glass filling-material of the proper shade is mixed with water to the consistence of paste, ami with a spatula a small portion of it is spread over the labial surface of the gold, the surplus moisture removed by gentle pressure with a napkin, and dry particles of the material GOLD CROWNS WITH PORCELAIN FRONTS. 123 around the section to be inlaid or enameled removed with a dry camel's-hair brush. The enameling-material is then fused. This is best and most easily performed in the following manner: A very small muffle is made of thin platinum, in size and form similar to that shown in Fig. 258. The depres- sion in the base is to hold the crown in position, and prevent its moving during the baking of the enamel. The seams of the muffle are united with the smallest possible quantity of pure gold. The inner surface of the base is given a thin coating of whiting, the moisture evaporated, and the crown placed in position, with the enamel part upward. The sides of the depressed platinum can be bent and altered to suit different-sized crowns. The whiting prevents the possibility of adhesion of the crown to the platinum by the fusing of either the gold or enamel. The muffle is then placed on a charcoal soldering-block, in which an indentation has been made to accom- modate the depressed base of the muffle, and gradually heated up with a gas blow-pipe, by blowing the flame against the closed end of the muffle to a light red heat, which will fuse the enamel. The crown is then removed, sufficient enamel-material is added to give proper form to the part, and the fusing repeated. The surface of the enamel is then ground level and smooth with a dry corundum-point, the edges finished with sand-paper disks, and the dust removed with an air-syringe. All pits and inequal- ities are then filled in with enamel, and the surface coated by the aid of a brush with some enamel-material mixed quite thin. A little is also placed inside the crown at the grinding-surface, to clinch the inlay at that point. In the last fusing the heat is carried to a higher point than before, the open end of the muffle being turned toward the operator, so that the degree of heat received by the crown can be observed. This method gives a smooth, dense inlay of enamel. Any particles that may extend beyond the gold on the interior sur- face of the crown may be removed as described under the pre- vious method. Crownint/ in Cases of Abrasion.—In a case of extensive abrasion of the incisive edges of the anterior teeth, with pulp living 124 ARTIFICIAL CROWN- AND BRIDGE-WORK. though considerably calcified in the coronal section, crown-work to restore the length and form of the teeth is best performed by removing a portion of the labial aspect of the natural crown and then forming the artificial crown similar to a gold collar crown without the pin. An accurately adapted collar, cemented with oxyphosphate, will usually hold the crown se- Fig. 259. curely. Fig. 259 gives an outline of the construc- tion of such a crown. If a case should suggest the necessity of a pin, a short one can be so inserted as not to endanger the pulp. COLLAR CROWNS HYGIENICALLY CONSIDERED. The principal argument against ferruled or col- lared crowns is that they are productive of irritation to the peridental membrane, ultimately causing its absorption and the exposure of the collar. This would be theoretically and practically true of a rough or porous substance encircling the root, or of an imperfectly and unskill- fully adjusted or cemented ferrule or collar which would by its presence hold a position analogous to a calcareous deposit, but no such comparison can be fairly made with a perfectly fitted collar, forming at its edge a smooth and imperceptible union with the sides of the root, and presenting a uniform and benign surface to the investing membrane. In case of perfectly adapted collars, when any irritation of the membrane exists, it will be found to result from such causes as usually produce it when the natural crowns are present, namely, dental concretions. A tarnished and unclean condition of the surface of the gold of the collar will produce irritation of the membranes, which is a matter independent of the collar itself, and easily remedied by cleansing and polishing the surface. Where an acid condition of the secretions of the mouth exists, a collar of platinum or iridium, or one of gold and platinum crown-metal, presenting the platinum surface, is suggested in, preference to gold, as these metals will not be affected, but will constantly present an untarnished surface. When evidences of a tendency to pyorrhea alveolaris exist, a collar adjusted to support bridge-work should be extended well COLLAR CROWNS HYGIENICALLY CONSIDERED. 125 under the gum-margin, or the edge of the collar kept consider- ably above it. Where pyorrhea alveolaris is present, a collar of fine gold, properly fitted and extended to the line of the peri- cementum, has often a tendency to retard the disease, as calcareous deposits do not adhere to the smooth surface of the gold so readily as to the dentine. CHAPTER XII. SPECIAL FORMS OF GOLD CROWNS WITH PORCELAIN FRONTS. THE PARR CROWN. This crown, which in form of construction possesses special points of merit, is largely used by Dr. H. A. Parr. The root is prepared, banded, and capped without a pin, the same as for a gold collar crown (A, Fig. 260). A hole is made in the cap, and a post fitted in the canal. A piece of gold plate, fully the size of the cap on the root, is adjusted on the post above the cap by making a hole in the gold in which the post will fit tightly. The gold plate is then adapted to the cap on the Fig. 260. Fig. 261. Fig. 262. root, and burnished into any open space around the post, \ forming an outside cap; the pin and the outer cap are then removed and soldered together and adjusted on the inner cap, and the edge of the outer cap trimmed even with it (B). The porcelain tooth to form the crown, C, is fitted and attached to the outer cap, which, when finished, is cemented in position as shown in Fig. 261. The advantage of this form of crown is that the root is securely and permanently capped independently of the crown, which can be removed without disturbing the cap on the root. 126 THE LEECH CROWN. 127 Dr. Parr, in using this style of crown in bridge-work, constructs the outer cap with a band which half encircles the inner cap, and tapers off from the palatal to the labial section, as illustrated in Fig. 262. The cap on the root is cemented with oxyphos- phate, and the post and outer cap with gutta-percha. THE LEECH CROWN. Dr. Leech's crown is thus described by Dr. J. E. Dexter:1 "A method devised by Dr. H. K. Leech, of Philadelphia, shown in Fig. 263, and described in the Dental Cosmos for April, 1879, is as follows : The root is drilled out to a depth of about three-eighths of an inch in diameter of about No. 16, standard (American) wire gauge, the bottom of the hole being flared or enlarged, and the canal above filled with gutta-percha. A gold tube is made to fit the hole accurately and project sufficiently for convenience of handling, and is sol- dered through a hole in a gold base struck to the root, projecting through the plate some distance. A plate tooth is fitted to the root and plate and soldered to the latter, gold being flowed onto the plate and backing and around the projecting tube to form the palatal contour, and the tube cut off flush with the latter. We now have a plate tooth, gold backed, with a tube-pivot, the orifice of which opens on the palatal aspect of our tooth. The root-end of the tube is now slit per- pendicularly in three or four places, for about two-thirds of its length, a thin sheet of warmed gutta-percha is placed on the base of the crown around the tube, and the whole is pushed securely to place. Xow pack gold or tin into the tube, condensing the bottom portions so that the slit end will spread and tightly fill the flared end of the hole in the root, and the operation is complete." A collar crown fastened with a tube-pivot as described can be used to advantage in detachable bridge-work, as the tube if filled with tin foil will admit of the crown being easily detached. 1 Dental Cosmos, May, 1883. 128 ARTIFICIAL CROWN- AND BRIDGE-WORK. THE LOW CROWN. In the method for crowning pulpless roots of Dr. J. E. Low, of Chicago, the root-canal is reamed out with an instrument which at the same time shapes the end of the root, or a portion of it, to receive a combined post and cap, which the inventor Fig. 264. calls a " step-plug," from its peculiar form. There are seven sizes of the cutting instruments (Fig. 264), and corresponding exactly with them seven sizes of the step-plugs. These step- plugs are not unlike a minute cone-pulley set in a saucer-shaped cap upon the bottom of which is a stout boss. They are made of platinum and nickel. As these last fit the prepared root accurately, it is claimed that they Fig. 265. Fig. 266. Fig. 267. afford a secure foundation for the )V\ n\ M artificial crown and also prevent / \ /k| ^L longitudinal fracture of the root. ,i jy] ™ To describe and illustrate the pro- \ MA liP cess, the root of a central incisor (Fig. 265) is selected. The end of the root is first ground level with the palatal margin of the gum. A cutting instrument of suitable size is then selected, with which the root is shaped as shown in Fig. 266. The end of the root is removed enough to permit the palatal edge of the cap of the step- plug (Fig. 267), which is then adjusted, to pass just below the THE LOW CROWN. 129 margin of the gum. Fig. 268 shows the step-plug in position, and ready for the adjustment of the porcelain front (Fig. 269) and the construction of the crown, which is completed as in methods previously described. The porcelain front when adapted should meet the labial margin of the gum, the labial surface of the end of the root being trimmed (with the cap in position) with a corundum-wheel when necessary to permit it. When the porcelain front is to be adjusted in the mouth, the backing should be warmed, a small quantity of resin and wax cemented upon it, the tooth placed in position in the mouth, and the con- vex surface of the step-plug cap carefully imbedded in the wax. The wax and the porcelain front should next be carefully removed Fig. 268. Fig 270. Fig. 271. Fig 273. Fig. 275. and then the step-plug, using pliers for the last. The step-plug is then placed in the wax impression, to which it is fixed with a heated spatula, and invested for soldering. Fig. 270 shows the completed crown ready for final adjustment, and Fig. 271 gives a sectional view of it in position. In crowning bicuspid roots, one step-plug in the palatal side of the root (Fig. 272) is usually sufficient, the remaining exposed surface of the root-end being covered by adapting thin platinum plate over it and onto the surface of the cap before adjusting the porcelain front (Figs. 273 and 274). Figs. 275 and 276 show the completed bicuspid crown before and after the final adjust- ment. Molar roots are capped similarly, using two step-plugs. The plugs are useful in building up badly decayed roots to support and retain all-gold crowns. 10 130 ARTIFICIAL CROWN- AND BRIDGE-WORK. Fig. 277. THE PERRY CROWN. Dr. Safford G. Perry, of Xew York, employs a porcelain crown in combination with a capped root. A bicuspid will be taken as a typical case to illustrate Dr. Perry's method. The end of the root, by trimming the edge, is given the tapering form shown at A, Fig. 277. The collar (B) is made very narrow. A cap is fitted on the collar, and a post or posts fitted in the roots and through the cap. The entire cap is made of platinum soldered with pure gold. Enough of the post is allowed to extend beyond the cap to attach and firmly retain the porcelain crown (C). One or two holes to serve as vents are drilled through the top of the cap, and it is set in place with oxyphosphate, the excess escaping through the holes. The holes are then reamed out and filled with gold, and the edge of the collar, under the gum, is burnished to the root. The porcelain crown used is similar in principle to the Howland crown, but differs in the details of its formation. The base is given a curve approximating that of the line of the margin of the gum, with the palatal portion projecting slightly above it, to include a little of the cervix. The cavity in the porcelain is given a size, form, and position which will receive the posts extending from the cap without impairing the strength of the crown-walls. Thus they Q) v.afcj are made round in the incisors and cuspids (A, Fig. 278), oval in the bicuspids (A, Fig. 279), and following the curve of the line of the posts in the molars.1 Fig. 278. Fig 279 1 The form of porcelain crown described is also used by Dr. Perry without capping the root, similarly to the Howland crown. In ,such cases he usually protects the end of the loot either with a surface of condensed gold foil anchored in a reamed cavity formed around the post in the root-canal, or with a very thin disk of gutta-percha. The disk with the aid of heat or chloroform is made to form a line of union between the root and crown. In both methods oxyphos- phate is used in the cavity which receives the post to attach the crown. THE PERRY CROWN. 131 A suitable, crown (C, Fig. 277) having been selected, it is ground and fitted in proper position on the cap. This operation is facili- tated by perforating a disk of marking-paper with the posts and adjusting it on the cap. Then, as the crown is placed on the cap and pressed against it, points which prevent perfect adjustment are marked on the porcelain. By this means a close joint is easily secured. The edge of the porcelain should be fitted under the free margin of the gum, especially at the cervico-palatal part. The porcelain crown is next set over the projecting pins, and cemented to the cap with oxyphosphate. The advantage of this method is, that the root being slightly tapered, the collar can be made to fit absolutely, while the excess of oxyphosphate is gotten rid of through the vent-holes, instead of being squeezed out around the edge of the collar. The edge of the collar being made to a knife-edge, can be properly burnished before the crown is placed, so that it will not irritate the gum or make a shelf. The crown covers the cap, and can usually be ground and fitted so as to entirely hide any exposed portion of the collar, the junction of which with the cap should be trimmed and then rounded with a burnisher, to give a form which will better meet the interior of the porcelain cap or crown. Fig. 279 shows the finished crown. Fig. 278 gives a sectional view of a central incisor. The porcelain can be replaced at any time in case of fracture without disturbing the cap on the root. The easy repair thus afforded, the simplicity of construction, and the artistic result, are the special features of this form of crown. CHAPTER XIII. CROWNING FRACTURED TEETH AND ROOTS—CROWNING MOLAR ROOTS DECAYED APART AT BIFURCATION—CROWN- ING IN CASES OF IRREGULARITY. The crowning of fractured teeth and roots is a process that requires skill and delicate treatment. Its practicability depends on the nature of the fracture, the previous health of the parts, and the length of time that has elapsed since the occurrence of the injury. LONGITUDINAL FRACTURE OF THE CROWN AND ROOT. By this is meant a fracture extending lengthwise through the crown or what remains of it, and down the root or roots. Foreign substances having been removed from within and around the parts, the crevice of the fracture is syringed thoroughly with a solution of carbolic acid and tepid water. The fractured parts of th e root are th en draw n together with waxed floss silk, passed at least twice around the tooth, and tied, the ends being passed through twice in forming the knot. The pulp-chamber is then prepared, and dovetail slots drilled across the parts (Fig. 280). If it is suspected that in the preparation any particles of dentine have invaded the crevice of the fracture, the ligature must be removed, the parts again syringed, and the ligature readjusted. Aromatic sulphuric acid followed by water can be recommended for the final injec- tions. The upper parts of the root-canals are then filled with gutta-percha, and the main body of the cavity and the slots with a hard, quick-setting amalgam. A collar crown should always be used in these cases. If the form to be used has a post, a short, small tube of gold or platinum should be set in the amalgam in proper position to receive it. At the next visit of the patient 132 CROWNING FRACTURED TEETH AND ROOTS. the ligature is removed and the parts carefully prepared for crowning. The circumference of the root is first measured with a wire, a tight-fitting collar constructed, and the crown then completed in the usual manner. The crown may be favored by leaving a slight space between its occluding surface and the antagonizing tooth. The great drawback in these cases is that the patient generally fails to present himself immediately for treatment, and foreign substances work into the fracture, causing inflammation, which is difficult to control. Often subsequent to treatment a septic condition of the fracture supervenes, the irritation caused thereby and the exudations from the fracture becoming so annoying that extraction is the only alternative. Teeth fractured as above described are rarely found with living pulps. FRACTURE OF THE CROWN WITH SLANTING FRACTURE OF THE ROOT. Fractures of this kind are common, especially in bicuspids, where large fillings are inserted extending from the anterior to the posterior approximal walls, leaving the separated buccal and palatal cusps to bear the brunt of mastication. In such cases the fracture seldom extends beyond the edge of the alveolar process. The fractured part having been carefully Fig. 281. Fig. 282. removed, a dovetail slot is made in the crown or root, into which gutta-percha is inserted for a day and the membrane of the gum pressed back, so as to fully expose the surface of the fracture. The form of the root is then in a measure restored with amalgam, which, when hard, is polished (Figs. 281 and 282). 134 ARTIFICIAL CROWN- AND BRIDGE-WORK. The root is then crowned, the mode of operation being the same as in any other case. PERFORATION OF A SIDE-WALL OF A ROOT-CANAL OR OF THE DENTINE AT THE BIFURCATION OF THE ROOTS. Extensive perforation by decay in these locations below the line of the edge of the alveolar process seldom admits of suc- cessful treatment. When the decay is of limited extent, and a very slight perforation has been produced by its thorough removal or by the improper or careless use of a bur, cicatricial tissue may be induced to form over the part by creating and maintaining a sterilized condition, and then sealing the cavity. The method of procedure is as follows: Inject the canals with peroxide of hydrogen, then bathe with alcohol, dry with hot air, and fill the canals closely, but not tightly, with cotton saturated with oil of cloves, and seal the cavity with gutta-percha. Renew the dressing at intervals, preventing the entrance of saliva until the exudation of serum ceases at the perforation and a film of cicatricial tissue has been formed. Dry the canal thoroughly, and fit closely over the perforation a small, flat piece of gutta-percha, warmed and applied with a gentle pressure, sufficient only to produce adhesion without forcing the gutta-percha through. Previously painting the adjacent walls with thin chloro-gutta- percha will cause the gutta-percha to adhere readily. The filling of the canal can then be carefully completed. If this method proves unsuccessful and inflammation ensues, the position of the perforation should be carefully calculated, and an artificial fistula should be formed on a direct line with it through the gum and alveolar process (see Fig. 283). Carbolic acid may be used as de- scribed at page 29, to obtund the tissue. The necessary perforation through the alveolar process should be small in diameter, and should be made with a drill. Injections should be made through the fistula, and the perforation sealed with gutta-percha similarly to the closing of a foramen in cases of alveolar abscess. CROWNING MOLAR ROOTS. 135 CROWNING MOLAR ROOTS DECAYED APART AT THE BIFURCATION. DR. FARRAR'S CANTILEVER CROWN. Figs. 285 and .286 represent Dr. J. N\ Farrar's cantilever crowns. He describes them as follows: Fig. 285 illustrates a sectional view of three teeth, and an amputated first bicuspid root preserved by a screw, showing the application of the canti- lever crown T P, set upon the decayed second bicuspid and Fig. 285. Fig. 286. made to project over to bridge the space formed by the loss of the first bicuspid, and resting in contact with the cuspid so as to connect the broken line of masticating surfaces and prevent tilting forward of the second bicuspid. The abscessed root here shown was extracted.1 Fig. 286 illustrates the appearance of two molars, the posterior half of one of which is destroyed, showing also the application of two thimble-crowns, which are con- structed so as to form a cantilever bridge over the chasm by locking midway in such a manner as to prevent tilting or sliding of surfaces, and at the same time be easily cleansed by a quill or thread. 1 Dental Cosmos, vol. xxvi, No. 3. 136 ARTIFICIAL CROWN- AND BRIDGE-WORK. METHODS OF CROWNING IN CASES OF IRREGULARITY. Fig. 287. Fig-. 287 shows a method of treat- ing a case of irregularity without de- stroying the vitality of the pulp. The tooth at B, which stood inside the line of the lower teeth when the mouth was closed, was trimmed, shaped, and capped. To this cap was attached the tooth at A, with an oval-shaped piece of gold that cleared the lower teeth in occlusion. The cap was then cemented to the natural crown. Fig. 288 represents a case of irregularity treated by Dr. Bon- will, who says in his description of it,— " This shows a case of irregularity which was beyond correc- tion, on account of the poor character of the teeth, their position in the palatal arch, and the age of the patient. In such cases I Fig. 288. do not hesitate to cut off the crown, destroy the pulp, and insert an artificial crown. The crown is brought in the circle and con- nected with the root by a strip of heavy gold plate. The plate is attached to the root with a post or a screw with a nut." CHAPTER XIV. PARTIAL CROWNS. Gold.—Partial crowns of gold for the protection of plastic fillings in large cavities and for the restoration of contour are often desirable when, for any reason, a solid metallic filling cannot well be inserted. The cavity having been properly excavated, its orifice is trimmed as uniformly straight or circular as its position and character will allow, and the edge of the enamel beveled off, tapering toward the center. In the preparation ot cavities in the grinding-surface, trimming and cutting away the enamel should be confined to that surface. In approximal cavities which reach the grinding-surface, it is advisable to extend them in that surface and bring the gold over and anchor it there, so as to afford greater security against its displacement in mastication. Where de- cay extends close to the margin of the gum, if the tooth is trimmed away so that the gold will extend just under its free edge, a recurrence of decay at that point will be avoided. The bicuspid shown in Fig. 289 will serve as a typical case to illustrate the constructive details. The cavity having been properly prepared, a die of the tooth in its original form is then secured. For this purpose the mold is made by taking an impression of the tooth with wax, making a plaster model, and then restoring the contour and forming from it the mold in gutta-percha or moldine; or the shape of the natural tooth may be restored with wax or gutta-percha and the mold made directly from it in plaster. The die and counter- die having been formed (see article on " Molds and Dies"), a piece of pure gold, No. 28 to 30 standard gauge, the exact thick- ness being governed by the size and nature of the cavity, is struck up to the form and size of the part to be capped. The gold is 137 138 ARTIFICIAL CROWN- AND BRIDGE-WORK. Fig. 290. Fig. 291. then adjusted to the cavity, to the margin of which the edges are trimmed and burnished to fit close and flush. In the case of large cavities including apart or the whole of the approximal surface, a model of the tooth and the empty cavity from an im- pression taken in wax will sometimes facilitate and guide the pre- liminary trimming and shaping of the gold. Two headed pins fixed on the inside of the cap (Fig. 290) are usually sufficient to secure it, but others can be added if the con- ditions of the case seem to require it. In com- pound cavities, including one side and the grind- ing-surface, one pin at least should be fixed in the latter portion. Where the grinding and both approximal surfaces are included, a wire should be extended from one side to the other (Fig. 291), but the brace should not touch the bottom of the cavity. In pulpless teeth the pin from the upper part of the cap should extend up the canal, giving great stability in such cases (Fig. 292). In soldering the pins or loops when inserted in holes drilled in the gold, a little solder can be flowed over the adjacent parts if deemed necessary to stiffen and strengthen them. Oxyphosphate is, as a rule, the best to be used in connection with these caps, as it forms a solid and unyielding foundation, and, when properly protected from the fluids of the mouth by a care- fully adjusted cap, is very durable. The cement should be first inserted in the cavity, and then a small quantity placed around the pins of the cap, which should be immediately adjusted accurately in position. When gutta-percha is used, it is heated and applied m the same manner to cavity and cap. The cap is then heated, pressed into position, and held there until the gutta-percha hardens. This can be hastened by the application of cold water from a syringe. The surplus of gutta-percha is then removed, and the edges of the gold burnished. These caps applied to teeth with living pulps show durability Fig. 292. PARTIAL CROWNS. 139 of a commendable character. The advantage they possess over pieces of porcelain is found in the close joint that can be made with the edge of the enamel by burnishing the gold against it. Dr. H. A. Parr, in this style of work, adapts No. 60 platinum foil to the form of the inner walls of the cavity and just over its edges by the aid of burnishers and cotton twisted on the end of an instrument, assisted by frequent annealing of the platinum. The matrix thus formed is then filled with wax, chilled, and removed from the cavity and invested, after which fine gold or 22-carat solder is melted into it. The removal of the matrix from the cavity can be facilitated by the insertion in the wax of a pin or a short piece of wax, which is grasped with tweezers. The plug of gold thus formed is properly trimmed and polished, and cemented in the cavity of the tooth. When completed, it has the appearance of a gold filling. If necessary, the cavity can be previously partly filled with amalgam or shaped with it, to give a better form to permit the removal of the shell of plat- inum foil. Plugs so made can occasionally be utilized as an anchorage for bridge-work. Dr.W. B. Ames, of Chicago, makes solid gold tips for abraded pulpless teeth in the following manner for cases' in which he prefers not to insert fillings : An opening is made through the occluding surface of the crown into the root-canal. A flat post, wide enough to fit closely in the pulp-chamber across its greatest diameter, thus tending to prevent any rotary motion of the gold tip, is then formed. A very thin piece of pure gold plate, say No. 35 American gauge, is adapted and burnished, with hand- burnishers and Herbst's revolving agate points, into all the irregularities of the abraded sur- face, and into the orifice of the pulp-chamber. The gold is then trimmed flush and even to the edges, and burnished just over them. An opening is next made in the gold cap, and through it the post is inserted in position. A strip of thin gold plate or platinum foil is next adapted around the tooth, well over and above the edge of the gold cap, and trimmed to the length desired for the tip. With the gold cap and post placed accurately in position, the cavity formed by the / 140 ARTIFICIAL CROWN- AND BRIDGE-WORK. Fig. 294. strip of plate or foil encircling the tooth is filled with wax cement, and cap, post, and plate or foil removed and invested to the lower edge of the latter (see Fig. 293). The investment is then heated, and 20-carat gold plate or 20- or 22-carat solder melted into the matrix formed by the plate or foil over the cap. The surplus gold is then trimmed to the edge of the abraded surface of the tooth and to the desired form for the tip. When finished, the o-old tip is cemented in position with a thin mixture of oxy- phosphate. Fig. 294 gives a sectional view of a central incisor tipped in this manner. In cases of living pulps, two or three small pins, as the case may suggest, are used in holes doubled on each side of the pulp, in the manner shown in Figs. 300 and 301. If the gold tip required is short, the ends of the pins extending above the cap will hold and maintain enough solder in posi- tion to give material for proper contouring, without enveloping it with a matrix of platinum or gold foil as previously described. Porcelain and Gold.—The partial restoration with porcelain and gold of an incisor crown such as is shown in Fig. 295 is often desir- able. The edges of the crown to form the joining with the porce- lain are trimmed straight and level, and then polished. A shallow groove is generally formed to advantage at A, Fig. 296. A very Fig. 295. Fig. 296. Fig. 297. C-' to thin piece of platinum is then adapted to the crown as shown atB, Fig. 297. The pin C is fitted to the root-canal, passing through the platinum. The post and cap of platinum are then attached with wax, removed, invested, and soldered with pure gold. A little of the gold at the same time is flowed over the cap. The cap and post are then adjusted to the crown, and the cap is PARTIAL CROWNS. 141 trimmed level and burnished closely against the surface of the portion to be restored and into the groove at A, Fig. 296. At this stage of the work, to facilitate the subsequent operations, an impression can be taken which will remove in it the cap, and from this a model can be made. A cross-pin porcelain tooth is then ground down to a size and shape that will properly restore the part and form an accurate joint with the labial edge of the natural crown. The porcelain is then backed, cemented to the cap, removed, and soldered with 20-carat solder. The partial crown when properly finished is cemented in position with oxyphosphate. In a case such as is represented in Fig. 298 the cap is shaped to the surface of the dentine and enamel at A and over its palatal edge, and the backing on the porcelain is extended out over the palatal edge of the enamel at B. The two sections of the platinum are united in the soldering. Fig. 298. Fig. 299. Fig. 300. Fig. 299 illustrates a fractured central incisor in which the pulp was not exposed, restored with porcelain by Dr. J. Bond Littig, of New York. The cap to the fractured part was fastened by three small pins as shown in Fig. 300, which illus- trates the details of the construction. " Where the piece broken off is so narrow that the porcelain tooth cannot be ground to fit in the ordinary way, without cut- ting out the pins," Dr. Littig describes his method as follows: "First cut a groove in the end of the broken tooth, making slio-ht undercuts. The pins of a suitable porcelain tooth are bent outward, and the ends flattened. The porcelain is then ground 142 ARTIFICIAL CROWN- AND BRIDGE-WORK. away from both ends, until it is made as narrow as the natural tooth is thick or nearly so. The piece is fitted to the end of the tooth by placing the pins in the groove. If the joint is not good, grind away from either tooth or porcelain until it is perfect. Then set the piece with zinc phosphate, and after it has become hard, grind the tip to shape in the mouth, and polish with moose- hide disk and pumice-stone. Fig. 301 illustrates the second Fig. 301. Fig. 302. method; the ground porcelain tip, prepared crown, and restored tooth being shown separately." Dr. Littig's third method is to first cap the fractured part with platinum, allowing the ends of the pins, which are soldered with pure gold, to project below the cap. English porcelain body the desired form for the tip is then baked on the cap. The porcelain by this method is secured to the platinum forming the cap, by the platinum pins embodied in it. Figs. 302, 303, and 304 show how Dr. W. F. Litch's pin-and- plate process may be utilized for the attachment of porcelain tips for broken or decayed incisors, when the appearance of gold fillings is obnoxious to the patient. A represents the por- Fig. 304. Fig. 305. Fig. 306. celain tips; B, the space to be filled by them; C and D, the open. ings for retaining-pins; F and G, openings in the base-plates (E) for the pins. Fig. 304 shows the appliance with pins attached. Figs. 305 and 306 illustrate a case in which the contour of a PARTIAL CROWNS. 143 single incisor tooth was restored in this manner. Fig. 305 shows the palatal aspect of the tooth, in which the openings for two retaining-pins were drilled, the openings being made quite small. in Fig. 306 is seen the porcelain tip attached to the plate and ready for mounting. The two retaining-pins will be observed soldered to the plate. In this case the cervical margin of the natural tooth was made level to afford a secure resting-place for the porcelain tip. Dr. C. II. Land, of Detroit, employs porcelain partial crown- work in cases of the character here described. He first forms a dovetail cavity in the central portion of the section to be tipped or contoured, and then adapts, aided by frequent annealing, a piece of platinum foil (No. 60 Fig. 307. U. S. gauge) to the cavity and surface of the part, by means of burnishers, and a pellet of cotton twisted on the end of an instrument. The platinum is then removed, and on its sur- face porcelain body is placed, and baked in the muffle of a furnace. (Dr. Land's Midget Furnace, Fig. 307, is the most suitable for the purpose, as each baking of the porcelain can be performed in about ten min- utes.) After the first baking, the thin platinum, which is usually warped by the shrinkage of the porcelain body in the baking, is corrected by readjustment to the tooth, in doing which the porcelain is usually fractured. The interstices and fractures in the porcelain are then filled, the part properly shaped with body, and the porcelain rebaked, and again adjusted and fitted in position. The platinum is next trimmed free of the edge with a corundum-wheel, and the porcelain shaped accurately to the 144 ARTIFICIAL CROWN- AND BRIDGE-WORK. form desired. Any imperfections existing are again filled with body, and the final baking given. Dr. Land claims that in such cases porcelain, if fitted to the irregularities of the cavity, will be securely retained when cemented with oxyphosphate. An additional attachment is obtained by placing a piece of iridio-platinum wire across the retaining cavity of the tooth, with the ends caught or bent against the sides, and then forming a dovetailed groove across the base of the porcelain tip, which will receive the wire. When a porcelain tip is desired without the platinum base, after the final baking, the platinum is removed by tearing it off the por- celain. When this is the intention, the platinum should not pre- viously be trimmed close, but should be left extending around Fig 308. and slightly beyond the edge of the porcelain. Fig. 308 illus- trates a case of atrophy,1 in which the tips of the central incisors were contoured with porcelain by Dr. Land. The right central shows the porcelain in position, and the left the porcelain tip ready to be adjusted. 1 This operation was performed by Dr. Land at the meeting of the First District Dental Society of the State of New York, in January, 1889. CHAPTER XV. FINISHING AND POLISHING—PROCESS OF CEMENTATION. FINISHING AND POLISHING CROWN-WORK. The finishing should be done with small corundum-wheels and points, first coarse, then fine, on the dental engine, which, for this part of the work, is preferable to files or the lathe. In the final finishing use leather polishing-wheels with fine pumice on the engine, or felt wheels on the lathe; and, in the polishing, a brush wheel, with whiting and rouge on the lathe. The gold should first be properly shaped, which includes trimming the collar off to a fine edge where it fits under the gum, so that the seam of union with the root will be impercep- tible. The gold that has been placed on the incisive edge of the incisor and cuspid crowns should be trimmed away, so that although it will protect the porcelain, very little if any gold will be seen when the crown is in position in the mouth. INSERTION AND CEMENTATION. In the insertion and cementation of all crown- and bridge-work, the object to be effected is the same in principle, that is, to form with an insoluble material a solid, substantial, and impervious union between the natural tooth or root presented and the arti- ficial crown. OXYPHOSPHATE OF ZINC. As a cement for this purpose, the plastic oxyphosphate of zinc is generally preferred, and it is in many respects one of the most suitable that has been found. Exact scientific proportions of the chemical substances of which the cement is composed are essential in its preparation. The oxide of zinc should have been calcined at a high heat, and then ground to a very fine powder. It should possess the property 11 145 146 ARTIFICIAL CROWN- AND BRIDGE-WORK. of being uniformly dense and hard clear through the center, when set, after being mixed thin and formed in a mass. The setting of the best preparations of pure oxyphosphate of zinc is materially affected by temperature. Thus, a cement which is slow-setting at 40° F. is apt to be quite quick-setting at 80° F. In some of the preparations of cement, an effort is made to remedy this variation by adulterating with various sub- stances, but this tends to increase the solubility of the compound. A standard preparation of cement, answering the requirements previously outlined, should be used in crown- and bridge-work. For all styles of crowns with collars, and for bridge-work de- pending on crowns of similar construction, the cement should be mixed thin; but for crowns without a ferrule or collar it can be moderately thick. For mixing the cement, a piece of plate- glass about five inches long and three inches wide as a slab, and a small spatula, are suitable. The surface of the slab must be per- fectly clean. The acid and powTder should first be separately placed on the glass, the amount of powder being fully equal to the requirements of the acid. A portion of the powder should be drawn over and mixed with the acid, and then more of the powder added, a little at a time, until a suitable consistence is reached, when the surplus powder should be instantly thrown off the slab, and the mixing, which must be rapid and thorough, con- tinued; the consistence should be that of thick cream. It is not a good plan to mix cement excessively thin, and then wait until it becomes thickened by the process of setting to a consistence suitable for use, as the resulting compound is unnecessarily acid, the overplus of acidity being proportioned to the excess of acid used over the quantity required. If the slab is placed on a towel which has been saturated with ice-water, the cold will retard the setting, which is quite an advantage in many cases. In this respect the side of a square bottle filled with ice-water and well corked is preferable to a slab. The parts to be crowned should be previously syringed with water, then protected by a napkin, bathed with alcoholl applied 1 Alcohol used in this manner not only aids in drying the parts, but act8 as a styptic on any lacerated portion of the gingival margin. INSERTION AND CEMENTATION. 147 on cotton with tweezers, and wiped with bibulous paper. Each cap or crown, which should have been thoroughly dried, is first filled with enough cement to insure a slight surplus. A small portion is then put in each root-canal or hollow part of a natural crown present, and the artificial crown or bridge immediately adjusted in position. In many cases it is best to quickly remove the napkin and close the mouth to insure the occlusion of the teeth, and then open the mouth and replace the napkin. The crown or bridge should be held under a slight pressure until the cement has set. For this purpose a piece of wood notched on the end or an adjuster (Fig. 309) can be used. With bicuspids Fig. 309. or molar crowns, however, it is better in most cases to occlude the teeth, and keep them in position until the cement sets. Under these circumstances the saliva can reach only the surplus portion of the cement, and cannot interfere with that under the cap or crown. One or two thicknesses of tin foil, placed over the crown as the teeth are occluded, will slightly favor the length. When the cement has set perfectly hard, the surplus around the edges should be removed. In collar or shell crowns the edges of the gold of the collar or shell should be given a final burnishing. Wet floss silk or dental fiber, charged with pumice, should be passed between and around the teeth to remove every particle of the superfluous cement, and finally the parts should be syringed with tepid water. The patient should be requested to call in a few days, so that an examination may be made to see if any particles of the cement were overlooked. Cleansing gently at this time facilitates the healing of the gum around the collar or neck. Care in these little details tends to prevent that inflamed appearance and reces- sion of the gum often seen around crowns, and also insures a satisfactory result to the patient and commendation to the dentist. Previous to insertion the posts of crowns should be slightly ARTIFICIAL CROWN- AND BRIDGE-WORK barbed. In all-gold cap-crowns a vent for the escape of air and surplus cement is made in the form of a small hole usually in the deepest fissure of the grinding-surface by some, but is generally considered unnecessary. When the cement has hardened, the hole must in all cases be closed with a gold or amalgam filling. GUTTA-PERCHA. When gutta-percha is used for cementing, the cavity in the root and crown having been moistened with chloroform and then dried and heated by a hot-air syringe, a portion of the gutta- percha is inserted and caused to adhere to the sides. The post and the crown are then heated, the proper quantity of the gutta- percha attached, and the crown inserted. When the gutta-percha is cold, the surplus is removed with a sharp instrument, and the edges smoothed by drawing back and forth against them some twisted fibers of cotton saturated with chloroform. Sometimes the post can be fastened with oxyphosphate and the end of the root and artificial crown joined with gutta-percha. In such a case the crown should be heated and the gutta-percha, rolled down very thin, placed on the edges to be united in the form of a perforated disk. The crown is then pressed to position in the oxyphosphate placed in the root. The order of the use of these materials can be reversed where it may be desirable at some future time to easily remove the crown. Bridge-work can be conveniently attached temporarily with gutta-percha. In this event a quantity barely sufficient to fasten the caps should be used. Gutta-percha does not possess sufficient rigidity for general use in bridge-work. AMALGAM. Amalgam is used to some extent to support and retain porcelain crowns. Its use in connection with the Bonwill crown is given on page 47. Where it is desirable to use amalgam Dr. Kirk gives copper amalgam the preference to other kinds for attachments of the Logan crown on weak or badly decayed roots. The following is Dr. Kirk's method for the adjustment of Logan and similar classes of crowns, which he has found extremely satisfactory in cases where there has been much loss of root- INSERTION AND CEMENTATION. 149 structure through the action of caries in the pulp-canal, resulting in a large funnel-shaped opening with more or less weakened root-walls. The canal is prepared by removing the softened structure, filling the apex, and making suitable undercuts or roughnesses along its walls, and then filled flush with its orifice with a good grade of copper amalgam softened to a plastic, buttery condition. The apical end of the crown pin is sharpened to a point or hatchet edge as may be most expedient, and placed against the amalgam surface in the root-opening, and the crown at once driven to place in close contact with the root by holding against its morsal (occluding) surface a suitable point mounted in the Bonwill mechanical mallet. For this purpose, the blow of the mallet should be considerably increased in intensity beyond that ordi- narily used for filling-operations. The point used in the mallet for driving the crown home is best improvised from a porte polisher armed with a hickory point, the use of which avoids chipping the porcelain. All excess of copper amalgam is by this means driven out between the surfaces of contact of the crown and root in precisely the same manner as occurs in the use of oxyphosphate. An excess should be used in order to be sure of filling all interstices. This method, involving the use of copper amalgam, is advocated only in the class of cases de- scribed, for which it possesses the advantage of giving complete support to the root, because of the great strength and insolubility of the material employed. Other amalgams experimented with for this purpose have not been so satisfactory, because of their lack of plasticity, and of the flowing quality which characterizes the copper amalgam when subjected to the rapid vibratory per- cussive force of the mechanical mallet blow. PART III. BRIDGE-WORK. BRIDGE-WORK. The artificial replacement of the loss of a portion of the teeth by bridging the vacant spaces with substitutes, supported in posi- tion by means of their attachment to adjoining or intervening natural teeth, is, as we have seen in the introduction, of antique origin, having been practiced long before plates came into use. Fig. 310. FlG. 311 Originally, the application and mechanical construction of such dentures was of a most primitive character; and as the attachments were simply ligatures or clasps of gold, the teeth were more ornamental than useful. Figs. 310, 311, and 312 illustrate the antique methods.1 Fig. 310 is an illustration of a specimen of ancient Phoenician dentistry. Fig. 311 is that of one in the Etruscan age, dating about five hundred years B.C. Fig. 312 gives a view of the same denture inverted. Dentures constructed on the bridging plan by various methods have been occasionally employed from the earliest days of modern 'See Independent Practitioner, vols, vi andvii, " Evidences of Prehistoric Den- tistry," by J. G. Van Marter, D.D.S., Rome, Italy. Figs. 310, 311, 312are copies of the illustrations of the specimens, the first of which is represented as being in the museum of the Louvre, Paris, France, and the second in the Corneto Museum, Corneto, Italy. 153 154 ARTIFICIAL CROWN- AND BRIDGE-WORK. dentistry, though until recent years the system has not obtained general recognition nor been extensively practiced. Dental literature presents bridging operations as described by J. B. Gariot in 1805, C. F. Delabarre in 1820, Dr. S. S. Fitch in 1829, William Imrie in 1834, J. Paterson Clark in 1836, and Dr. W. H. Dwindle in 1856. Figs. 313 and 314 are copies of illustra- tions in Dr. Fitch's work, published in New York in 1829, and Fig. 315 one from a translation of F. Maury's work in 1843. In 1871 the bridging process or bridge principle was again brought to notice by a patent applied for in England by Dr. B. J. Bing, of Paris, for an improved means of supporting and Fig. 313. Fig. 314. securing a bridge by anchoring with cement or fillings clasps or bars extending from it into holes formed in the adjoining teeth (Fig. 316). The system was also practiced in operations by the late Dr. M. H. Webb, and is described in his " Notes on Opera- tive Dentistry." The facilities afforded by the artificial crown-work now in vogue for supporting and securing bridge dentures have caused a revival of the system in an improved form, termed " Bridge- Work," in which artificial crowns cemented to natural teeth or BRIDGE- WORK. 155 roots are employed as abutments to support artificial teeth which span or bridge the spaces between them. These bridges are so devised, in the best methods, that while supplying the patient with the means of masticating his food the cleanliness of the denture is also provided for. Ordinarily, bridge-work is immovably cemented in position. The claims set up in its favor are as follows: First. The perfect replacement of lost teeth by artificial ones, and without the use of a plate. Second. The absence of any mechanical contrivance to inter- fere with the tongue in articulation. Third. The natural teeth are not abraded by the presence of clasps, the functions of the sense of taste are more perfectly performed, and a healthy condition of the tissues preserved, because the gums and palate are not covered over with a plate. Fourth. The solidity and immovability of the denture at all times, both in speech and mastication. Fifth. The weight of the denture and the strain of mastica- tion are proportionately distributed on the natural teeth, which are better suited to sustain them than the contiguous alveolar surfaces. Sixth. Its special adaptation to the replacement of single teeth, or of a small number, where bridge-work is usually superior to any other device. Seventh. While all operations performed for the restoration of lost teeth, like other remedial operations, are temporary rather than permanent in their results, bridge-work as regards per- manency takes equal rank with any other operative procedure. The following, on the other hand, are the objections raised against bridge-work: First. It fails to restore the contour of the soft tissues above the bridge, as artificial gums cannot properly be used in this style of work. 156 ARTIFICIAL CROWN- AND BRIDGE-WORK. Second. The slots beveled under the artificial teeth, called self-cleansing spaces, fill with particles of food. Third. The speech of the wearer is often affected by these self-cleansing slots under the front teeth. Fourth. The teeth employed as abutments are usually irre- parably destroyed by the process of crowning. Fifth. If an extensive bridge is made of gold, being im- movable, it is impossible to keep it perfectly clean, as the metal will gradually tarnish in parts out of reach of the brush, and will gather offensive matter on its surface and in its interstices. Sixth. In cases where it becomes necessary to temporarily remove the bridge for the purpose of repair, or because of dis- ease in the teeth which support it, the operation is difficult and the bridge is usually injured so as to unfit it for reinsertion. Seventh. The teeth which support the bridge are required to bear more force and pressure than nature intended,—where the piece is large many times more,—and, the bridge being perma- nently attached, at no time can any rest be given the abutments or the contiguous parts by its temporary removal. Thus in a piece of bridge-work of fourteen teeth supported by caps or crowns on four natural ones, each one of the natural teeth may have to bear more than three times the strain in supporting the weight of the denture and the force of mastication, that was intended. The ultimate result is evident to any one who is experienced in dental practice; and unless the anatomical conditions are most favorable, the usefulness and durability of such work is decidedly limited in character, considering the time, trouble, and great expense attending it. Such are the objections which have been put forth against bridge-work; and yet, whatever may be urged against it, its advantages have won from a majority of the profession, includ- ing many accepted authorities, an enthusiastic, almost a sen- sational, indorsement; some practitioners even going so far as BRIDGE- WORK. 157 to proclaim it the only true method for the insertion of artificial teeth. Judged impartially, bridge-work has many advantages when practiced by experts who properly construct and apply it. Without doubt it has been abused. Bridges have been inserted where the support was insufficient, or the construction was wrong in principle or faulty from lack of skill. More than this: bridge- work has been passing through the experimental period, when failures are apt to appear more prominently than successes. The chronicles of dental literature, however, in this respect offer only a repetition of the historical difficulties that attend all new departures in the arts. CHAPTER I. CONSTRUCTION OF BRIDGE-WORK. To the skilled mechanical dentist, well versed in metal- and crown-work, bridge-work does not present extreme difficulty. The foundations or abutments—that is, the teeth or roots on which the bridge will rest—are first to be considered, due respect being paid to the mechanical principles controlling the leverage and the force of occlusion in mastication. The amount of strain that can be borne by the different teeth, individually and collect- ively, according to their position and condition of health, should be carefully calculated. As a rule, the force exerted upon the incisors in occlusion will be directed outward on the upper, and inward on the lower teeth, and its tendency when they support a bridge will be to gradually push them out of line in each direc- tion. When the incisors are replaced by a bridge, the tendency of the force of occlusion is toward a similar result. On the bicuspids and molars the force is direct. The rules which govern the number and position of the teeth or roots that are required as foundations for bridges in practice, are as follows: One central root will support two centrals, and if spurs or bars from the sides of the bridge rest upon or are anchored in the adjoining teeth, a lateral in addition. Two central roots will support the four incisors, spurs or bars resting on or anchored in the cuspids to be used additionally, if the case requires them. The cuspid roots, alone, or with the aid of a central root, will support the six anterior teeth. One molar or bicuspid on one side, and a bicuspid or molar on the other, with one or two roots in an intermediate position, will support a bridge between them. One right and one left molar, with the assistance of the two cuspids, will support a bridge comprising the entire arch. A bridge on one side of the mouth can be supported by two 158 CONSTRUCTION OF BRIDGE-WORK. 159 or three teeth or roots on that side. The cuspids always afford the most reliable support. In general, the application of these principles will cover the subject of foundations, the operator being governed by the exact condition of individual cases. In a bridge of the six anterior teeth on the two cuspids, when the articulation of the antago- nizing teeth is close and deep, the strain should be relieved by an additional attachment of the bridge to the teeth posterior to the ouspids. Fig. 317. The preparation of teeth or roots to support a bridge is the same as for ordinary crowns, except that the trimming of the sides and the drilling of the root-canals of the various anchorages should be, as far as possible, in parallel lines, so that the collars and posts of the crowns shall move readily to their places in the adjustment of the finished bridge. Teeth or roots which are to be supplied with all-gold cap-crowns are crowned by some one of the methods already described. Those on which porcelain fronts are to be used are merely capped, the posts being soldered and allowed to project a short distance beyond the caps. The case represented in Fig. 317 will be used to illustrate the construction of a piece of bridge-work in all its details. The abutments, or supports, consist of the right second molar capped with an all-gold crown, constructed in sections by first forming 160 ARTIFICIAL CROWN- AND BRIDGE-WORK. the collar and then soldering on the cap (see page 92), the two cuspid roots capped for collar crowns with porcelain fronts (see page 85), and the left first molar, which will afford anchorage tot bar on that side of the bridge (Fig. 318). A slot, dovetail in form, is usually cut well into the body, but not to an extent that will endanger the pulp of the last-named crown (Fig. 319). If the tooth is not decayed, it can be first opened up with a rubber and corundum disk. The shaping of the slot is best accomplished with fissure-burs. With the crowns and caps in position, an impression and articulation of the case are then Fig. 318. Fl«- 319, taken with plaster1 slightly colored with carmine. The plaster is mixed moderately thick and, with the aid of a spoon, placed around in the mouth on the crowns, caps, and parts to be included in the bridge, and the antagonizing teeth occluded tightly and so held until the plaster sets. The mouth is then opened and the plaster carefully removed, the pieces being adjusted together should it break. The crowns and caps (the latter held more firmly by the protruding ends of the pins) are removed in it. The plaster is then varnished, and, on the side containing the crowns, a model is run, composed of equal parts 1 Impression compound is used to some extent for this purpose instead of plaster, but in the author's opinion cannot be recommended as suitable. 4590555091��940� CONSTRUCTION OF BRIDGE-WORK. \Q\ of calcined marble-dust and plaster, to which is added a little sulphate of potassium,—less than the proportion of salt generally used,—which causes the mixture to set hard quickly. When the model has set, it is mounted with plaster on an articulator, and the other side of the colored plaster impression giving the articulation is run with plaster and the opposite section of the articulator adjusted, all at the same time. When the impres- sion plaster is removed (an operation which is greatly facilitated by its having been colored with carmine), a correct model and articulation of the case will be found, with the crowns and caps in exact position as in the mouth (Fig. 320). Fig. 320. Another method is to first take the impression in an impression- tray, and then the articulation in wax, and make a model and articulation from them in the usual manner. Dr. Melotte's method is to place a piece of impression com- pound in the space between the crowns to be occupied by a bridge, and occlude the teeth. The compound is then chilled, removed, trimmed, and readjusted until it accurately fits the space, when it is placed in position and an impression is taken with plaster. When the impression is removed, iron pins to act as dowels are placed in the portions representing the natural teeth, and then several pieces of fusible metal, by a few puffs of flame from the blow-pipe, are melted in around the pins. The rest of the impression is then run with plaster and marble-dust 12 162 ARTIFICIAL CROWN- AND BRIDGE-WORK. in the usual manner. This forms a plaster model on which the natural teeth are represented in metal. These metal teeth are to be removed before investing in soldering the bridge. An impression of the occluding teeth is taken in plaster, and the entire impression run with fusible metal. When the plaster impression is removed from the model of the bridge, the piece of impression compound between the crowns is to be left in position, and the metallic model of the occluding teeth fitted in position, guided by the indentations of the occluding teeth in the compound, and the case mounted on an articulator. The principal object of this method is to avoid fracture of forms of natural teeth, both in removal from impressions and in the con- struction of the bridge-work. The pins protruding from the caps on the model are next cut off short. Teeth are selected,—ordinary cross-pin plate teeth for the incisors and cuspids, and partial teeth, representing the front section of the tooth and styled porcelain facings, which were specially designed for crown- and bridge-work, for the bicuspids and molars (Fig. 321). Cuspids are sometimes used to form the fronts for bicuspids. The teeth are ground and fitted to the model and articulation, so that the labial upper edge of the teeth shall press lightly on the gum. Those which are intended to form the fronts of the caps on the cuspid roots should be ad- justed in the ordinary manner for single crowns. To determine the proper positions of the teeth for producing the best appearance, they can be adjusted in the mouth on wax, without the gold crowns or caps of the supports. The correct position of the teeth on the model having been obtained, investing material, composed of one part plaster to two of cal- cined marble-dust, is placed on the outside of the model on the labial aspect of the teeth, merely sufficient in quantity to hold them in position, thus forming a matrix, or, the matrix can be 95 CONSTRUCTION OF BRIDGE-WORK. 163 formed of plaster and entirely removed before investing for sol- dering. The wax is then removed, exposing the palatal portion, and permitting their form and position to be studied (Fig. 322). The porcelain teeth or fronts, with the exception of fronts for the roots capped, are then removed from their investment, and the base ground from a line on the palatal side below the pins, straight to the labio-cervical edge (A and B, Fig. 322). This is to Fig. 322. A, central incisor, and B, bicuspid, ready for metallic backing. C, is a central backed. D. D, D. porcelain fronts as they appear on insertion after the process of backing, capping, and soldering. form the self-cleansing spaces. The incisors are then backed, using either very thin platinum or pure gold (0). The backings are allowed to extend just over the incisive edge as a protection to it, and, if preferred, down on the curve of the self-cleansing space. A more desirable result is secured if the backing extends only to the edge of the self-cleansing space, and the porcelain is pol- ished, as its surface is superior in cleanliness to that of gold. If the platinum backing used is so exceedingly thin as to be of the nature of foil, it is advisable to rivet a small piece of gold plate over it on the back of the tooth, to insure against melting the 164 ARTIFICIAL CROWN- AND BRIDGE-WORK platinum off the porcelain with the gold, which is apt to occur if a pointed flame is directed against it. The cuspids are backed in the manner described for collar crowns. The bicuspid and molar porcelain fronts, their tips being ground off (A, Fig. 323), are lined in a similar manner. A cap of pure gold or gold lined with platinum, representing the grinding-surface of each tooth, is struck up as described and illustrated in the construction of gold crowns (see page 96), and the concave portion filled by melting in scraps of 20-carat gold plate. The surface is then ground smooth (B), and closely fitted to the tip of the porcelain front to form the occluding surface Fig. 323. Fig. 324. HP1P-B in accordance with the articulation of the lower teeth, and the space filled in with wax. This metallic occluding surface is to protect the porcelain. Triangular pieces of very thin gold plate, platinum foil, or mica (C), cut and fitted to the sides, over which they should extend slightly, will retain the gold in position when melted, but seldom are necessary. The tooth is next invested, leaving the back open, presenting the form of a pocket (Fig. 324). Fig. 325. Another method of constructing bicuspid and molar dummies is to fit the cap to the labial edge of the porcelain front, back the porcelain with thin platinum, extending the backing over and between the porcelain and cap, and then filling in the space with gold in soldering, as shown at A, in Fig. 325. The bar intended to be anchored in the slot cut in the molar on the left side is made of iridio-plat- inum wire, about No. 15 U. S. standard gauge, with the end shaped as shown in Fig. 326, and fastened with wax to the tooth and cap, and adjusted in the mouth to obtain accuracy of position before soldering. CONSTRUCTION OF BRIDGE-WORK. 165 The advisability of constructing bridge-work with what are termed self-cleansing spaces is not favorably accepted of late by many practitioners. Instead, the following method is adopted : Porcelain fronts thicker in the line from the labial to palatal side than those most commonly used are selected. The base or cervical section of the porcelain is ground and fitted to the alveolar ridge very accurately. The fronts are then waxed in position, and with a fine-pointed lead-pencil a line is drawn accurately around the base of each porcelain front on the model. The fronts are then removed, and with a suitable scraper the plaster under, and only under, the base of each is removed uni- formly the thickness of cardboard. The porcelains are then fitted back in position with the bases in the indentations. The work is then proceeded with in the usual manner. When the bridge is finished and inserted, the base of each porcelain will equally indent the gum to the depth the plaster was removed, Fig. 327. Fig. 328. and will also exclude particles of food and present a much more agreeable appearance for the patient. The shape a bicuspid dummy would assume, constructed as described, is shown in Fig. 325.1 The teeth forming the bridge between the crowns are called " dummies." In the construction of dummies it is well to favor the occluding surface by shaping it a trifle narrower from labial to palatal side than the corresponding natural tooth was. All the porcelain teeth or fronts can be invested at the same time, including the incisors and porcelain fronts to the cuspid crowns, as shown in Fig. 327. In the soldering, if the backing is done with platinum, and the occluding surface of the bicuspids 1 The author, at present, in his own practice constructs his work in this manner. 166 ARTIFICIAL CROWN- AND BRIDGE-WORK. and molars made with gold lined with platinum, 20-carat gold plate may be melted into the pockets formed by the cap and side pieces to fill out to the line at A, Fig. 328, and flowed over the backings of the incisors and cuspid fronts in sufficient quan- tity to shape them as shown at B, Fig. 329. When the backing and occluding surfaces are made of gold plate, 20-carat solder and small pieces or filings of gold plate should be used instead. After the soldering and removal of the borax with acid, the metal of each tooth is then, when it is easily done, very carefully trimmed and shaped with corundum-wheels and points. The teeth are next placed in their relative positions on the model as shown at D, D, D, Fig. 322, and attached to one another Fig. 329. Fig. 330. with wax in exactly the relation and only where they are to be united with the gold solder. The model is then detached from the articulator, trimmed down as much as possible in size, and additional investing material, composed of two parts marble- dust and one of plaster, or one part plaster, one marble-dust, and one common white sand, applied until all of the bridge is covered except the space along the backings and crowns where they are to be united in the soldering. To prevent fracture during the process of soldering, which might readily occur from contraction in so large an investment, an iron wire or a narrow horse-shoe shaped strip of sheet iron should be placed in the investment so as to encircle the teeth and crowns about one- CONSTRUCTION OF BRIDGE-WORK. 167 fourth of an inch from their exterior surface (Fig. 330). In anv spaces between the backings pieces of gold or platinum plate or wire, about one-eighth of an inch long, are placed lengthwise, and the joints well soldered. When the backings have been soldered with gold plate, 20-carat solder may be used. If the backings were done with 20-carat solder, an easy-flowing 18-carat solder should be used. The soldering is best done with a gas blow-pipe on a piece of charcoal with a concave depression. When the bridge is removed for finishing, the joints of the backings and crowns are finished with corundum-wheels and points and leather polishing-wheels on the engine, and the entire bridge finely polished with whiting carried by a brush-wheel on the lathe. Any little pits that may exist can be filled in with gold foil. The bridge is then ready for insertion (Fig. 331). If the constructive details have been properly performed as described, a finished piece of bridge-work is the result. In constructing bridge-work many prefer, after the porcelain fronts are backed and the caps forming the occluding surfaces of the bicuspids and molars are properly adjusted on the model, to invest and do the entire sol- dering at once. When this plan is followed, pieces of gold wire should be laid lengthwise in the slots under the gold caps of the porcelain fronts, and the parts filled in and all the sections of the bridge joined together in the soldering. By this method there is less liability of frac- turing the porcelain fronts, but warping is more apt to occur, and the finishing of the bridge is not so easily or so perfectly done. In large pieces of work warping may be avoided, whichever method of soldering is adopted, by first removing, in proper position, the "dummies," and soldering those of each span together. The spans are then replaced in the matrix and soldered to the abutments. 168 ARTIFICIAL CROWN- AND BRIDGE-WORK Adjustment and Attachment.—The bridge when finished is ad- justed in the mouth, every point carefully examined, and any alterations required are then made. Should the edges of the collars of any of the crowns catch, so as to prevent their being Fig. 332. Fig. 333. placed in position, a small quantity of articulating paste should be applied and the point found and trimmed off. If extensive warping has occurred in the soldering, the bridge must be sawed apart in one or two places, adjusted in the mouth, and removed in an impression-tray, using only sufficient investing material (equal parts of plaster and mar- ble-dust with the usual quantity of sulphate of potassium) to cover the points of the teeth and crowns (Fig. 332). The inner surface of the tray should be oiled. The bridge and the in- vesting material are then removed together from the impression-tray, and more investing material is added to complete the investment. The cut parts of the bridge are then soldered together. When the adjustment of the bridge is accomplished, it can at first be temporarily inserted for a day or two, if desired, which CONSTRUCTION OF BRIDGE-WORK. 169 permits it to settle accurately in position. Burnishing the col- lars will usually secure it for this purpose; if not, it can be attached with a little gutta-percha placed in each cap. For its permanent attachment the pins or posts of the crowns are barbed, and the teeth and roots to which crowns have been fitted are then treated the same as single crowns, and the bridge cemented on with oxyphosphate cement (see page 144). The end of the bar is anchored in the slot by either a gold or an amalgam filling. Fig. 333 represents the bridge in position. Fig. 334. The Construction of Small Pieces of Bridge-work is much simplified by the following method : Crowns are first made for the teeth or roots that form the abutments and temporarily placed in position. The teeth —"dummies"—which form the span, having been ground and backed, are adjusted and cemented with resin and wax in proper position between the crowns. The crowns and dummies are then removed together, in an impression-tray filled with investing material. The inside of the tray should be previ- ously oiled or coated with a film of wax with a serrated surface. The impression-tray is then heated, and the investment with the crowns and dummies removed; more investing material is then mixed, and the exposed parts of the crowns and teeth covered. The investment, when set, is then cut away sufficiently to expose 170 ARTIFICIAL CROWN- AND BRIDGE-WORK. the parts that are to be filled in and united together in the pro- cess of soldering. Figs. 334, 335, represent cases of bridge-work constructed in this manner. Fig. 335. In a bridge of two teeth, often a preferable method is to pro- perly adjust crown and dummy tooth cemented with wax in the mouth, carefully remove them in position, then invest and solder. CHAPTER II. SPECtAL PROCESSES AND APPLIANCES IN BRIDGE-WORE. Fig. 336. Fig. 337. Shoulders on Anterior Crowns or Artificial Teetii are sometimes desirable, especially on the superior cuspids at the point of occlusion with the lower teeth. A shoulder can be made by melting gold plate into the form of a small ball or globule, then flattening it out and soldering it against the backing. Another method is to attach with wax transversely across the backing in proper position a strip of gold plate as shown in Fig. 336, and then flow in gold to the line A, by spe- cially investing or in the soldering of the bridge. The strip of gold should be left extending a little on both sides of the backing so that the investment will retain it in position, or the gold instead can be extended over the incisive edge. Solid Gold Crowns.—In a close articulation, when the patient prefers strength to appearance, the bicuspids and molars may be made of solid gold. They are constructed by stamping up the cap (A, Fig. 337) representing the grinding-surface (see page 94), adjusting and cementing to this with wax a piece of plate cut and shaped to form the front and sides (B), the whole being then invested and filled in with gold solder, or, if pure gold and platinum has been used in the sections of the crown, with 18- or 20-carat plate. Seamless contour crowns can be used for the purpose as follows : The proper crowns having been selected, the gold is trimmed and the crowns adjusted in position on the model. A matrix of plaster is then placed on the labial side, which permits exposure of the palatal portion, the crown removed, and cut 171 172 ARTIFICIAL CROWN- AND BRIDGE-WORK. away to the form required. They are then removed, invested, and filled in with scraps of gold plate and solder. A bar-bridge can be made with these seamless crowns by passing an iridio-platinum wire through the crowns before filling in (Fig. 338). A Solid Gold Crown for a Pulpless Molar, supporting the end of a bar as shown in Fig. 339, is constructed as follows: The natural crown is ground down, banded, capped, and pivoted as in Fig. 340. The gold forming the top of the cap is made per- fectly flat and left projecting a little at the sides. A contoured Fig. 338. Fig. 339. Fig. 340. ficiently to represent the absent coronal section \ / \ / / of the tooth, and with a corundum-disk the orifice v Vvf of the anchorage cavity is formed. A shell of thin platinum of the size and shape of the anchorage cavity is then inserted and cemented with wax on the inside of the crown. The crown is then invested and filled with 18-carat gold solder, which should be cut into small pieces, and be placed successively in the crown Fig. 341. and melted by maintaining a uniform heat with the large flame of a blow-pipe. The base of the crown is next ground level and accurately fitted to the cap and articulated to the antagonizing SPECIAL PROCESSES AND APPLIANCES IN BRIDGE-WORK. 173 teeth. It is then clamped in position to the cap, the pivots of which are protected with investing material (Fig. 341), and soldered, making a perfect joint. This is an easy method of constructing an otherwise difficult form of crown. Fig. 342 illustrates a bridge supported by a bar-anchorage in a solid gold crown on the roots of a molar, and a shell crown on a cuspid. Fig. 342. Fig. 343. Fig. 344. Fig. 345. Connecting Bands or Bars for Bridges, which obviate the removal of crowns of intervening natural teeth between the sections of a projected bridge, are formed by passing a heavy band of oval- shaped gold or iridio-platinum wire around the intervening teeth, close to but not touching them, and resting lightly on the gums. 174 ARTIFICIAL CROWN- AND BRIDGE-WORK. The application of this device was first illustrated by Dr. J. L. Williams, Figs. 343, 344, and 345. Intervening Roots between the abutments of a projected bridge Fig. 346. Fig. 347. should not be extracted, but whenever practicable they should SPECIAL PROCESSES AND APPLIANCES IN BRIDGE-WORK. 175 be treated, filled, and trimmed level with the gum, as they can usually be made to afford some support for the bridge, which may rest upon them. Figs. 346 and 347 represent a case in which the root of the cuspid on the right side has been so treated and utilized. Shell Anchorage or Crown.—A shell crown or anchorage for a cuspid to support bridge-work is preferablv used instead of a gold collar crown with porcelain front, where the insertion of such a form of crown involves the excision of a natural crown with a living pulp. A convenient method of construction is the following: Shape the natural crown parallel on the sides. Construct and adapt to the cervix, and slightly under the gum-mar- Fig. 348. Fig. 349. gin of the natural crown, a gold p*-- collar wide enough to extend a little below the incisive edge. Remove a portion of the gold from the incisive labial section, and slit the palatal surface on both sides of its center, as represented in Figs. 348 and 349. The part at A is bent back, and the parts at B, B beveled, bent in on the crown, and burnished close to its surface. The piece A is next brought down in position, and adapted to the crown and over the parts B, B. The collar has now assumed the form of a gold crown having an open face and seams. The seams are next united by placing, melting, and flowing solder into each of them, a little at a time, by holding the crown with tweezers in a Bunsen gas-flame. The seams will hold and retain solder sufficient to join and fill them without its flowing over the adjacent parts, unless there is an excess of heat or solder. When the soldering is completed, the crown is adjusted, a line showing the exact portion of the labial aspect to be exposed marked on the gold, the crown removed, its edges trimmed to the mark, and the soldered parts smoothed with corundum-wheels and points on the engine. Another method for the construction of a shell crown prefer- ably practiced by some is: Fit a gold collar around the natural crown, and remove the gold at the labial aspect as shown at a, 176 ARTIFICIAL CROWN- AND BRIDGE-WORK. Fig. 350. In the vacancy between the collar and tooth at the palatal side, fit and burnish a piece of pure gold or thin platinum, which will cover the exposed surface of the tooth at that part, and fill in the space between the collar and piece of plate with Fig. 350. wax cement, d, Fig. 350, shows the form generally of the piece of plate before it is fitted in the collar. Remove the collar, invest, and flow'solder into the space between the piece of plate and collar, and remove the surplus gold of the collar extending above the crowm; b and c show the finished shell crown. A Seamless Shell Anchorage is formed as follows: From an impression of a natural crown taken in plaster, gutta-percha, or moldine, a die in fusible metal is formed, and from it a counter- die in lead is made. (See " Gold Seamless Cap Crown.") On the die a crown is stamped from a seamless cap of gold (Fig. 351). This crown is then fitted on the natural tooth, the labial aspect Fig. 351. Fia. 352. of which is exposed by the removal of the section of gold cover- ing it in either of the forms shown in Fig. 352. A shell for a cuspid can be made from a gold collar as well as a cap. The shell formed in either manner is then filled with investing material, and strengthened by flowing 20-carat solder over the^surface. SPECIAL PROCESSES AND APPLIANCES IN BRIDGE-WORK. 177 This process for cuspids has decided advantages for the easy formation of a perfect-fitting crown or shell for bridge-work. Fig. 353 shows the forms usually given shell crowns for bicuspids. When the gold is removed at the labio-cervical part, Fig. 353. Fig. 354. the crown should be additionally secured by a pin introduced and soldered at the point A. Fig. 354 illustrates a bridge in which the lower incisors are supported by shell crowns on the cuspids. In cases where this form of crown is expected to sustain a great strain, the gold at the cervico-labial section should be re- inforced by the addition of a strip soldered across it and extend- ing around on the sides. Fig. 355 represents the restoration of the inferior bicuspids and molar on the right side, by a bridge with a shell crown on Fig. 355. the cuspid and an all-gold crown on the second molar as abut- ments. Before cementation of the gold crown the surface of the enamel should be cleaned with pulverized pumice, wet with aromatic sulphuric acid, to secure a better adhesion of the cement. 13 CHAPTER III. EXTENSION BRIDGES. This term is applied to bridges which are chiefly supported by one abutment. In relation to the anterior teeth, it consists in attaching a dummy to an artificial crown, to replace an adjoining absent tooth. A bridge of this style replacing two or three of the posterior teeth is formed by using two of the teeth Fig. 356. Fig. 358. Fig. 357. Fig. 359. anterior to it as one abutment, with a saddle for the other. A saddle is an oval-shaped piece of*gold, of the form of the gum and a little larger than the base of the tooth, placed under the posterior tooth of the bridge. Figs. 356 and 357 represent an extension bridge. A crown on the cuspid, an all-gold crown on the bicuspid, and a saddle, are the abutments. In constructing this bridge, the teeth form- ing the abutments were first crowned. The crowns were then adjusted in position, and an impression and articulation taken in 178 EXTENSION BRIDGES. 179 plaster, in which the crowns were removed. From this impres- sion a model was made of plaster and marble-dust, and an articulation in plain plaster. With the crowns in position on the Fig. 360. Fig. 362. Fig. 361. Fig. 363. Fig. 364. model as in the mouth, the bridge was then constructed by the methods described on page 162. The part of the model on which the saddle rested was marked, and enough of the surface of the plaster removed to cause the saddle to press tightly against the soft tissues when the bridge should be completed and inserted in the mouth. A shell crown on a cuspid can be used as an abutment in this style of bridge, instead of ex- cising the natural crown and mounting an arti- ficial crown on the root for the purpose (Figs. 358, 359). Figs. 360 and 361, 362 and 363, represent small extension bridges of frequent construction, the former to repair losses in the anterior portion of the mouth, the latter to replace posterior teeth. Fig. 364 shows a pin shell crown which can be made to support a porcelain front represent- ing a cuspid or bicuspid. Figs. 365, 366, and 367 represent an extension bridge con- structed by Dr. II. A. Parr. The anterior abutment consists of 180 ARTIFICIAL CROWN- AND BRIDGE-WORK. the six front teeth, which were all crowned and joined together, the pulps being preserved in the incisors. A saddle on each side forms the posterior abutments. Fig. 365. Fig. 366. Fig. 367. A Spur Support consists of a flange formed at the end of an extension bridge, affording support by resting on the palatal wall of either an incisor or a cuspid, or in the sulcus between the cusps of a bicuspid or molar, as shown in Fig. 368. Fig. 369 illustrates a case with a spur resting against a cuspid. In the case represented in Figs. 370 and 371 the spur rests in an inden- tation in an amalgam filling in the molar. This form is termed a cantilever bridge. In extension bridge-work, the portion which constitutes the bridge exerts on the abutments, in resisting the force of occlusion, an action like that of a lever. The ratio of the force exerted is EXTENSION BRIDGES. 181 proportioned to the length of the bridge or lever from the abut- ment or fulcrum. This principle must receive consideration in the employment of this form of bridge. A flange or spur support, if attainable, should as a rule be applied. More than Fig. 368. FIG 369 one tooth should not be extended from an abutment without ample alveolar support besides. When two approximal crowns support an extension bridge tooth or dummy, the force is counterbalanced by the resistance of the farthest anchorage crown from the bridge, the pressure on which is in a direct line Fig. 370. Fig. 371. from the socket, the approximal crown acting as a fulcrum, the force on which is upward in the line of the root. The occluding surfaces of the bridge teeth should be made unusually narrow from labial to palatal side, to offer less occluding surface to those antagonizing. CHAPTER IV. BAR BRIDGES. This style of bridge receives its name from the fact that the teeth or dummies forming it are supported by bars anchored in the natural teeth on either side by means of fillings. Failure to appreciate its limitations and faults of construction are re- sponsible for disappointments in its use which have militated against its more common application. In the first place, its successful employment is confined to the insertion of one, or at most two teeth. An attempt to support more than two teeth by this method will almost certainly result in failure. The most glaring fault of construction is insufficient anchorage for the bars. If the anchorage tooth is alive, the bar should ex- tend in a suitably shaped cavity two-thirds or three-fourths the width of its palatal or occluding surface, according as it is an incisor or cuspid, or a bicuspid or molar, and be thoroughly se- cured by the filling-material. Thus an- chored, the bar is capable of supporting the bridge and resisting the leverage exerted on it in occlusion and mastication, which it can- not reliably do when simply anchored in a shallow filling inserted in the side of a tooth,—an incorrect method too often practiced. In a pulpless tooth the bar should be bent and inserted into the root-canal, as shown in Fig. 372. In the incisors and cuspids the anchorage cavities or slots are formed in the palatal portion of the teeth, extending from the approximal surface contiguous to the space to be bridged, two- thirds to three-fourths the width of the tooth, and usually about one-third of its length from the gingival margin (Fig. 373), direct access into the cavities being afforded through the palatal 182 BAR BRIDGES. 183 KAsi^.-^^g^: wall. The slots or cavities having been formed, a model of the case is made. Should the cavities to receive the bar be imper- fectly represented on the model, they should be trimmed and shaped to correspond to those in the mouth. The exact align- ment of the porcelain tooth in the mouth having been deter- mined with the aid of wax, it should be adjusted on the model and secured in position by a matrix of plaster. The base of the tooth should rest firmly on the gum, to accomplish which a small portion of the plaster should be removed from underneath the tooth on the model. The bar is best constructed of iridio- platinum wire, 14 to 16 gauge. The wire can be extended in one piece en- tirely across the bridge from one anchor- age to the other by bending, or by removing a portion of its bulk back of the porcelain tooth; or the bar can be cut and made in two sections, if the position of the anchorage cavities so suggests. The ends of the bar should be flattened with a hammer, annealed, and shaped as shown at A, Fig. 373. The remainder of the section of the bar which is to rest in the cavity is best filed on the sides, so as to give it a somewhat triangular form, the broad base of which is toward the bottom of the cavity. This form favors the ready impaction of the filling-material which is to secure the bar. The porcelain tooth having been backed, the bar, whether in one piece or two sections, is attached to it with wax cement, then removed from the model and soldered. Enough gold should be added to properly contour the tooth and securely connect the bar. Anchoring the Bar.—Gold and amalgam are the only filling- materials suited for securing bars. Amalgam is objectionable only when the position of the cavity renders it visible. Under such circumstances, however, the exposed portion can be cut awav when set, and covered with gold. Fastening one end of 184 ARTIFICIAL CROWN- AND BRIDGE-WORK. the bar temporarily with oxyphosphate, while the other is being secured, will sometimes facilitate the operation of anchoring with amalgam. When the anchorage tooth is pulpless, the end of the bar which extends into the canal should be cemented first. Fre- quently when bicuspids and molars containing large cavities of decay are used for anchorages, it is advantageous to first insert the anchorage fillings, and then drill out sufficiently to admit the bar, which can then be secured with additional filling-material. When gold is the filling-material used, the rubber-dam, which must be thin, is first adjusted on the natural teeth, and the bridge then pressed to position over it. In anchoring with gold, the best way is to first fill such portions of the cavities as are inac- cessible when the bars are in position, how far to proceed being determined by occasionally trying in the piece as the gold is inserted. The bridge is then pressed to place, and held firmly while the ends of the bars are secured by condensing around them a few pellets of foil, after which the gold is carefully im- pacted around the bar, the filling of one of the cavities being carried to completion before going on with the other. In the preparation of the cavities, their sides should be given an undercut form with strong edges. When only sufficient tooth-structure has been removed at the approximal portion to just admit the bar, it is a doubtful expedient to attempt to fill the narrow seam around it with gold. In such cases, this por- tion of the filling is better made with amalgam, which is inserted at the sides and along the floor of the cavity before the bridge is fixed in position. Then, beginning at the interior end of the cavity, gold can be inserted and gradually condensed toward the amalgam, with which it will unite when brought in contact. Any surplus of amalgam can be removed subsequently when it has set. Amalgam placed around the bar as here described is seldom visible from the labial side, and the quantity required is insufficient to materially discolor the tooth. In Bicuspid and Molar Bar Bridges the bar should be carried well across the occluding surface, and the end bent and imbedded in the line of the sulcus toward the side opposite to that from which the bar enters, as shown in Fig. 374. Forming the end of the bar in this way affords the greatest security, when it is properly BAR BRIDGES. 185 anchored with the filling-material, by preventing any rotatory movement, or any loosening of the bar by force applied in a forward direction. The principles involved and the Fig. 374. method described for shaping and securing the ends of bars apply equally well to cases where one end of the bridge is supported by a bar and the other by an artificial crown, as has been previously illustrated. An Extension Bar Bridge.—In this form of bridge the artificial (dummy) tooth is supported by a bar anchored in a natural tooth at one end only. At the other end of the bridge the bar is either made in the form of a spur to rest against the adjoining natural tooth, or it is not extended beyond the dummy. In the case represented in Fig. 375, an upper cuspid, the patient, a lady, declined to have the bicuspid capped or crowned in any way for the purpose of sup- porting the cuspid. The posterior approximal side of the bicuspid at the time contained a large filling. This filling was removed, and a cavity of proper shape to receive a bar was extended forward from it between the cusps to the anterior side. A suitable bar for the cavity was formed to support the cuspid in the manner illustrated at A and B. The angular form (C) given the bar rendered it, when anchored with the filling-material, very secure, and fully capable of supporting the cuspid. The filling-material, which was gold, occupied most of the space of the occluding surface between the cusps. The oc- cluding tooth was trimmed off proportionately. A spur ex- tended from the anterior side of the artificial tooth resting on the lateral incisor. The occlusion was favorable to the insertion of the bridge tooth in the form presented, and it has been com- fortably and satisfactorily worn, now at the date of writing four years. " When recently examined it showed no change, except that the force of occlusion on the cuspid had slightly bent the Fig. 375. 186 ARTIFICIAL CROWN- AND BRIDGE-WORK. bar and caused the tooth to assume a deeper position in the jaw than at the time it was inserted, though this was only to the extent of the absorption of gum-tissue under the bridge. In some instances the bar of a bridge of this kind can be extended across the occluding surfaces of two teeth, and additional sup- port thus obtained. Cast Fillings, as described on page 139, can be used in some instances to support the end of a bar. In such a case, a short piece of wire to form the bar is inserted in position in the wax in the matrix of platinum before it is removed from the cavity, and soldered in it. The attachment of the bridge is then made to the bar. Bar bridge-work affords advantages for artificial restoration, in many cases where a single tooth has been lost, not presented by other methods. Its practical success depends chiefly upon the character of its supports and the skillfulness with which it is anchored. CHAPTER V. REMOVABLE AND REPLACEABLE PORCELAIN FRONTS. In those forms of crown- and bridge-work in which porcelain fronts are used there is some liability of fracturing the fronts, either in the soldering processes connected with its construction, or subsequently, after the insertion of the piece in the mouth, by the patient in mastication. The replacing of a porcelain front after the work has been permanently fixed in position is fre- quently attended with great difficulty, and the result is often unsatisfactory or doubtful regarding its permanency. The desire to obviate such difficulties has prompted the introduction of vari- ous methods of construction in which the porcelain fronts are removed from their positions previous to the soldering processes, and afterward adjusted so as to be easily replaceable by means of duplicates in case of fracture when the work is being worn in the mouth. These methods applied to a bar bridge afford access to the cavities of anchorage. A modification of Dr. I. F. Wardwell's method, which is simple in construction and application in comparison with most forms in use, is as follows: A thick, narrow piece of 18-carat gold plate, at least No. 18 standard gauge, is soldered to the tooth, and its two sides undercut with a very thin separating file (Figs. 376, 377). A very thin piece of platinum, covering the entire back of the tooth, is burnished against it, well into the undercut sides, the platinum being annealed several times during the operation. The platinum is held in a flame while a small quantity of pure gold is flowed over the outer surface and then refitted to the back of the tooth, to which it is again burnished. This operation is repeated until the platinum and gold form a moderately light backing which fits perfectly. The platinum sur- face is then covered with investing material, and on the other side 18- or 20-carat gold plate flowed until a suitable thickness is obtained. When trimmed into proper shape and attached to the 187 188 ARTIFICIAL CROWN- AND BRIDGE-WORK bar, this forms a substantial backing or socket (Fig. 378), in which,. when the bar is anchored, the porcelain tooth can be fastened with a little oxyphosphate cement or gutta-percha (Fig. 379).1 Fig. 376. Fig. 377. Fig. 378. Fig. 379. Fig. 380. Any ordinary porcelain front to a bicuspid or molar dummy can be made on the removable or replaceable plan, by backing the porcelain in the usual manner with gold or platinum plate without bending the pins, adjusting the gold cap in position, at- taching cap, and backing with wax cement, then, removing the porcelain front (Fig. 380), investing and sol- dering the cap and backing together. The backing must be made thick with solder, the holes in it deepened with a drill, and the pins of the porcelain front serrated and fitted therein. After the final soldering, the porcelain fronts are cemented in position with oxyphosphate. Dr. Low has invented for use in crown- or bridge-work a ready-made metallic socket or shell, into which fits a correspond- ing porcelain front, which can be replaced in case of fracture. Fig. 381. Fig. 382. Fig. 383. Fig. 384. Fig. 385. Fig. 381 shows a socket shell; Fig. 382 the same with por- celain in position; Fig. 383 a socket for incisors and cuspids, and Figs. 384 and 385 the same with porcelain in position. *Dr. F. T. Van Woert has introduced a pliers with combination points which simplify the construction of a socket of this form and the replacement of the- porcelain front in case of its fracture by the patient. CHAPTER VI. GENERAL APPLICATION OF CROWN- AND BRIDGE-WORK. The construction and general application of bridge-work, as ^explained in the foregoing chapters, are additionally illustrated in the following typical cases : Fig. 386. Fig. 388. Figs. 386, 387, 388 represent the artificial restoration of the four "superior incisors on the two central roots. Spurs might be additionally formed on the laterals to rest on the cuspids. When approximal crowns, as in this case, are united to support bridge- work, a free space should be preserved at the neck between their respective collars to admit the gum septum. r 189 190 ARTIFICIAL CROWN- AND BRIDGE-WORK. Figs. 389, 390, 391 show a bridge of the incisors supported by two collar crowns on cuspid roots. Shell crowns can also be used for this purpose, according to the preference of the operator. Fig. 389. Fig. 390. Fig. 391. Figs. 392, 393 illustrate a method of replacing a superior lat- eral. The lateral is formed with a base of gold or platinum resting closely on the gum. A gold cap crown on the first bi- cuspid supports the lateral in position by means of an iridio- platinum bar. GENERAL APPLICATION OF CROWN- AND BRIDGE-WORK. 191 Figs. 394, 395 represent a case in which two centrals are sup- ported in position by bars extending from gold crowns on the right and left first bicuspids. Fig. 392. Fig. 393. Fio-s. 396, 397 show bridge-work supported by cuspid and molar crowns. If the cuspid contains a living pulp, the natural 192 ARTIFICIAL CROWN- AND BRIDGE-WORK. crown should be preserved, and a shell crown used in preference to the form illustrated. Figs. 398, 399 illustrate a case of bridge-work similar to the one preceding it, extended to the central incisor. Such a piece Fig. 397. of bridge-work is insured against misfit from warping in sol- dering during its construction by forming it in sections. The central and lateral sections can be made separate from the rest, Fig. 398. Fig. 399. EXTENSIVE APPLICATIONS OF CROWN- AND BRIDGE-WORK. 193 Fig. 400. placement of one or two inferior incisors. The labial section of the shell crowns which form the support for the artificial tooth should be removed only sufficient to avoid any consider- ble exposure of the gold in the movement of the lips. Fig. 401 explains and illus- trates a method of restoring an incisor and supporting the ad- joining loosened teeth with suc- cessive cemented collars of gold, in cases of pyorrhea alveolaris. Fig. 402 represents a case fre- quently presented, suitable for bridge-work. The inclination Fig. 402. of the teeth toward each other suggests the construction of the bridge in the form illustrated. The molar is capped entirely, the bicuspid on the occluding surface, with the gold extend- ing down on the contour of the natural crown (A) only. A pin inserted in the cap fitting a hole drilled in the sulcus of the occluding surface will secure this cap in position. This method is very suitable to a case where the crown of the bicuspid is long and the root slightly exposed. Molars under similar circum- stances can be capped for bridge-work in like manner. EXTENSIVE APPLICATIONS OF CROWN- AND BRIDGE-WORK. The following illustrations of bridge-work by Dr. H. A. Parr show extreme cases in the way of large operations in which the system has been applied. Figs. 403, 404, 405, and 406 represent a case in which the roots^of the'two superior centrals, a partially decayed right first molar, and a badly decayed, pulpless left first molar were all that remained of the upper natural teeth. On the two central roots were mounted 'collar crowns, and on the two molars all-gold 14 ARTIFICIAL CROWN- AND BRIDGE-WORK. cap crowns. These four crowns, acting as abutments for the bridge denture, bore between them, proportionately on each Fig. 403 Fig. 404. Fig. 405. EXTENSIVE APPLICATIONS OF CROWN- AND BRIDGE-WORK. Fig. 406. 195 Fig 407. 196 ARTIFICIAL CROWN- AND BRIDGE-WORK. side, the force and leverage of occlusion. The contour of the arch in the region of the cuspids was restored by a skillful and artistic placing of the artificial teeth, which are prominent and long. Figs. 407, 408, 409, and 410 represent a case in which two large and firm superior cuspid roots, and a right pulpless molar, with a saddle—an invention of Dr. Parr's—on the leftside sup- port a large bridge. Fig. 409. Fig. 410. In the bridge-work illustrated in Figs. 411, 412, and 413, crowns on a second bicuspid, a pulpless molar, and the roots of a cuspid and lateral constitute the abutments. Figs. 414 and 415 illustrate an extensive case of artificial replacement by crowning and bridging operations. Fig. 414 represents the case as presented for treatment. The few remaining superior and inferior natural teeth had no corre- sponding antagonists, which caused the interlocking and abnor- mal condition in regard to occlusion shown. The superior right bicuspid, the left central, and the left cuspid were crowned, the bicuspid being shortened and the cuspid lengthened in the EXIENSIVE APPLICATIONS OF CROWN- AND BRIDGE-WORK. 197 Fig. 411. Fig. 412. Fig. 413. 473756 198 ARTIFICIAL CROWN- AND BRIDGE-WORK. operation. The intervening lateral root between the central and cuspid, having been treated and filled, was allowed to remain. With the three crowns to serve as abutments the intervening spaces were bridged with artificial teeth, the exten- Fig. 414. sion on the left side being supported by a saddle. The spaces between the inferior cuspids and molars on both sides were bridged, the bicuspid on the left supporting the bridge, instead of the cuspid, as on the right; the left cuspid was crowned and the incisive edges of the incisors trimmed even. EXTENSIVE APPLICATIONS OF CROWN- AND BRIDGE-WORK. 199 Fig. 415 illustrates the case finished, and shows the complete artificial restoration of the parts. In the case illustrated by Figs. 416 and 417, two superior mo- lars and a second bicuspid on the right, and a first bicuspid and Fig. 416. a saddle under the " dummy" representing the first molar on the left side, form the abutments. Prior to the insertion of the bridge-work, the patient had worn artificial teeth on a plate. Fig. 417. Figs. 418 and 419 represent a case in which crown- and bridge- work has been extensively applied. The occluding surfaces of the teeth were affected with abrasion. Gold crowns with porce- lain fronts which presented laterally the form illustrated were mounted on the incisors and cuspids, the pulps of which were 200 ARTIFICIAL CROWN-AND BRIDGE-WORK. Fig. 418. Fig. 419. EXTENSIVE APPLICATIONS OF CROWN-AND BRIDGE-WORK. 201 preserved. The posterior teeth were crowned with all-gold crowns. The missing teeth, except those on the inferior left side, were artificially restored with bridge-work. The application of cemented bridge-work of the extensive character illustrated in some of these cases is seldom practiced now. Removable plate bridges, which offer the additional ad- vantage of alveolar support, are used in preference. Cemented bridge-work in sections is still used, and extended around the arch, where the abutments are numerous and offer suitable sup- ports. CHAPTER VII. REPAIR OF CROWN- OR BRIDGE-WORK. The fracture of a porcelain front to a permanently attached bridge is an annoying incident for both patient and dentist. It is usually attributable to failure to properly protect the incisive edge or occluding surface of the porcelain with metal, a precau- tion rendered necessary by the rigid character of the resistance offered the antagonizing teeth through the abutments. In most cases the porcelain can be replaced without the removal of the bridge, but the attachment is not usually so reliable as in the original piece. The following is the method commonly adopted with incisors or cuspids: The surface of the backing to the porcelain is trimmed level, the platinum pins drilled out, and the holes slightly countersunk on the palatal side. A tooth similar to the one frac- tured, with long pins, is ground and fitted to the backing. If a suitable long-pin tooth is not pro- curable, the short pins of an or- dinary tooth can be lengthened by bending a piece of platinum wire in the form of a semicircle, and soldering its ends to the ends of the pins with pure gold. The wire is then cut in the center, and the lengthened pins trimmed as required. The pins are then riveted on the palatal side into the countersunk holes of the backing. The riveting is best done with punch forceps having a large punch, the por- celain front being protected by a piece of lead placed against the labial aspect (Fig. 420). The heads of the pins should then be 202 \ REPAIR OF CROWN- OR BRIDGE-WORK. 203 burnished smooth with a revolving burnisher. In case of the fracture of the porcelain front of a bicuspid crown or dummy, a corresponding front is selected with very long pins, and ground to fit. Holes are drilled in the gold, in proper positions, to re- ceive the pins their full, length. The pins are then roughened a little with a sharp instrument, and pins and front are cemented to the gold. Should the holes extend through the gold at the palatal side, the cement and the ends of the pins should be covered with gold foil or amalgam. If any gold is present to protect the occluding edge of the porcelain, it should be bur- nished against the surface. Another method to replace a porcelain front is the following: Back the porcelain front around the pins with platinum foil, bend the pins down together on the platinum, andhammerthem flat. Invest and flow a little gold plate over the pins and platinum, and file the metal down close to the porcelain. Drill a hole in a strong part of the backing on the bridge at a central point, square the hole, and fit to it a piece of square platinum wire. Attach the end of the wire to the backing of the porcelain front with an atom of wax cement, and while warm insert the wire through the hole in the backing on the bridge, and adjust the porcelain front in correct position. Chill, and remove front and wire. Invest, and solder wire to backing on porcelain front with 18-carat gold solder, and then remove all metal from back of porcelain, except what is necessary to secure the end of the wire to the pins. Countersink the gold backing on bridge sufficient to permit the front to come in position. Slit the end of the wire, cement the porcelain front in position to the back- ing, and bend the ends outward into two slightly grooved places on the backing. Fill the slit in the wire with gold, and smooth the surface.1 Dr. R. W. Starr's method differs from the preceding, in that he uses round instead of square wire, cuts the pins of the por- celain front off short, making corresponding depressions in the backing on the bridge to receive them and prevent rotation, and solders the end of the wire to retain the front between the pins. 1 Dr. W. W. Williamson's method. 204 ARTIFICIAL CROWN- AND BRIDGE-WORK. He then cuts a screw thread on the wire, and secures it in the backing with a nut on the palatal side screwed into a depression reamed to receive it. Figs. 421, 422, 423, and 424 illustrate this method. Fig. 421. Fig. 422. Fig. 423. Fig. 424. Bridge-work can be made with replaceable porcelain fronts which can be easily substituted in case of fracture. A descrip- tion of their application will be found at page 188. If the character of the breakage is such as will not permit its repair in the mouth, the bridge must be removed for the pur- pose and then reinserted. Under such circumstances the advan- tages of bridge-work in a detachable form are most evident. The results following the repair of single crowns in the mouth will seldom repay the labor attending it. Removal of Cemented Crowns and. Bridges.—When it becomes necessary to remove an artificial crown, whether inserted singly or as a support for a bridge, incisors or cuspids are detached by grinding the gold or porcelain away at the palatal section over the post, which when exposed is severed, and the attachment of the.cement broken up. The collar can also be slit and bent aside if found necessary. In an all-gold cap crown on a posterior tooth a hole drilled in the grinding-surface will give access to the cement, a sufficient quantity of which can then be removed to loosen the attachment; or, the collar can be divided and pried up from the root by first making a groove with a small rubber and corundum disk, and then cutting the gold with a sharp in- strument. With care and patience in the operation, the crowns will not usually be injured beyond repair. When gutta-percha is the cement that has been used, a hot instrument can be placed against the metallic part of the crown, or the crown seized with the beaks of heated forceps, the gutta- percha thereby softened, and the crown removed. A hole or slit in a gold collar or crown is repaired easily by REPAIR OF CROWN- OR BRIDGE-WORK. 205 first placing a piece of soft wax in the hole or slit on the outside of the gold, adapting a piece of platinum foil larger than the aperture on the inside close against the gold, and fixing it to the wax. The interior of the crown is next filled with investing material, and solder flowed over the platinum and gold on the outside of the collar or crown. The crown should be heated slowly, to allow the plaster to dry out before the soldering is begun. CHAPTER VIII. THE HYGIENIC CONDITION OF THE MOUTH AS AFFECTED BY BRIDGE-WORK. The probable future condition of a mouth in which a piece of bridge-work is permanently fixed is a matter of the deepest interest to both patient and operator. There is no valid reason why an artificial structure in the mouth should be more hurtful than that which is natural, provided that correct conditions are observed in its construction and proper measures are taken for their maintenance. The natural teeth demand care on the part of their owners, and all forms of artificial dentures require attention to secure their cleanliness and thus preserve the health of the adjacent tissues. What will result from the wearing of a permanently fixed bridge is almost wholly dependent, in the first place, on the proper application of principles and correct formation in every detail of construction of both crowns and bridge-work; and in the second place, upon the maintenance of cleanliness. Neglect of a single requirement will so far detract from the usefulness of the work, and may influence the final result disastrously. Firm, properly selected abutments will not redeem incorrect conception or faulty construction ; neither will the best construc- tion remedy that which is wrong in principle or application. Self-cleansing spaces, if improperly formed, have exactly the contrary effect from what is intended, by becoming receptacles for particles of food debris, instead of preventing their accumu- lation. Inaccessible spaces or interstices, which are always apt to cause uncleanliness, should be avoided. Continuity of structure of the several parts is also essential to fully insure perfect hygienic conditions. The health of a mouth containing a piece of bridge-work 206 THE HYGIENIC CONDITION OF THE MOUTH. 207 constructed under these precautions can be readily maintained. For this purpose a suitably formed brush and a dentifrice are necessary. Floss silk can be passed through apertures around the necks of crowns, in places out of reach of the brush, and drawn along the gum under the bridge by the aid of a slightly curved blunt-pointed needle, to remove accumulations of debris otherwise inaccessible. A solution of a detergent and disin- fectant mouth lotion in water, injected with a dental syringe, can be used advantageously to wash out such places and maintain a healthy condition of the gums. In addition to these measures, the crown and bridge should be thoroughly cleansed by the dentist at regular intervals. So cared for, a permanently fixed bridge will not militate against the absolute wholesomeness of the mouth; but it can hardly be expected that the insertion of bridge-work will insure a state of the mouth which for cleanliness will be superior to the presence of the natural teeth. Neglect on the part of the patient to perform such duties as are necessary to preserve the natural teeth in a healthy state will have about the same effect on an artificial denture. The attention required to be given to bridge- work is not greater than is commensurate with the advantages which it confers on the wearer. CHAPTER IX. REMOVABLE AND DETACHABLE BRIDGE-WORK. The evident advantages of bridge-work have stimulated the inventive genius of dental mechanists to improve the methods and forms of its construction and to extend its application. With these objects in view, some bridges have been made so as to be easily detachable by the dentist, and others removable by the patients themselves. The construction of bridge-work in either of these forms overcomes the chief objections to the system. Large bridges are much more easily made in a detachable or removable form than are the smaller pieces, which present some of the best features of the permanently attached methods. In all kinds of removable bridge-work a prime requisite is that the posts and collars, or other form of attachment used, shall be so constructed that the piece shall move evenly on or off the supporting roots or crowns in adjustment and removal. To secure this, the post-cavities and the gold crowns should be so shaped that the lines of the cavities and of the sides of the gold crowns shall be as nearly as possible parallel to one another. To facilitate this, a post of wood or metal may be first accu- rately but loosely inserted in any root-canal intended to receive a post, and left protruding a quarter of an inch, and an impres- sion taken. On the model made from this impression the post will be found placed as in the mouth. The position and shape of the natural teeth or roots can be thus studied, and their plas- ter forms trimmed as a guide. Gutta-percha or impression compound, fitted to the model and removed with the posts in position in it, can then be used to guide the operator and gauge the preparation of teeth or roots in the mouth. Posts, or the tubes inclosing them, should be placed as nearly as possible in 208 REMOVABLE INCISOR OR CUSPID CROWN. 209 the lines of the root-canals to avoid weakening the side or sides of the root. When a molar leans forward, the removal of a portion of the anterior approximal side usually restores its perpendicularity sufficiently, as does the cutting away of the posterior side of a bicuspid which inclines backward. The methods and forms of attachments most commonly used in the different styles of removable bridge dentures are very similar. A preliminary description of these and of their con- structive details is therefore first in order. REMOVABLE INCISOR OR CUSPID CROWN. A removable gold crown with a porcelain front is frequently used in connection with removable bridge-work where incisors or cuspids form abutments. The cap and tube crown is the style (Fig. 425) preferably applied. It consists of a cap for the end of the root with a tube attached ex- 4. A- +u + i a +\. Fig. 425. Fig. 426. tending up the root-canal, and on the cap the crown with a post fitted tightly to the tube is adjusted. To the crown so formed (Fig. 426) the bridge is joined in the usual manner. The end of the post can be formed with a slit which will permit this portion to be slightly expanded, making what is termed a spring-post. The con- structive details of this crown are as fol- lows : The root is first prepared and capped the same as for a collar crown. The collar can be formed of gold and the cap sectionof platinum, No. 32 gauge (A, Fig. 427). A substantial piece of gold and platinum wire, from No. 16 to No. 18 gauge (the number being regulated by the size of the root), is slit for about one-eighth of an inch to form a spring-post. This is easily done by placing the wire in a vise and steadily cutting it downward from one end through the center to the required depth with a saw-edged strip of very thin steel (Fig. 428). This takes only a few minutes, and is preferable to the method some- times adopted of partially joining two pieces of half-round wire. 16 210 ARTIFICIAL CROWN- AND BRIDGE-WORK. The wire is then tapped together at the slit, burnished smooth and rounded just at the end (B, Fig. 427). The tube for this post is formed by once encircling the post with a piece of iridio- platinum plate, No. 34 gauge, the edge of which is beveled and cut to meet the plate even and close (C). The post is then withdrawn, and the seam is touched along its length with the smallest possible quantity of borax. The proper way to use borax in fine work is to grind it, mixed with water, on a slab, to a cream-like consistence, and apply on the point of a camel's- hair brush. A very small piece of pure gold is placed in the seam, and the tube is held in a Bunsen flame. When a suffi- cient degree of heat is reached, the gold will flow along the seam and form a joint without obstructing the inside passage FIG. 427. Fig. 428. Fig. 429. for the post. The post is then inserted, and the tube trimmed (D), and gauged in a gauge-plate. With a drill just the size of the tube the root-canal is enlarged so that the tube will fit tightly (Fig. 429). This plan prevents weakening of the root by too great enlargement of the canal. A hole the size of the tube is made through the cap, and cap and tube are then adjusted, waxed together, and, the post being withdrawn, they are removed, invested, with the investing material inserted in the tube, and soldered. The second or outer cap is then constructed for the root-cap, of a piece of platinum about No. 34 gauge. It is per- forated in the center, and the post fitted in proper position. At the palatal and approximal sides, if desirable, the platinum can be slit and bent over the edge of the root-cap to form an inner par- tial band or flange, or a half band can be formed of a piece of REMOVABLE INCISOR OR CUSPID CROWN. 211 plate, the open space at the labial side being filled with the por- celain tooth. The outer cap and the post, having been cemented with wax, are removed and soldered together. As the point of the post may have to be filed, it is well to place it so that the line of the slit shall cross the tooth from mesial to distal side. On this outer cap the porcelain front is fitted and soldered. The end of the tube is closed with a little gutta-percha, and the root- cap cemented on the root with oxyphosphate and the crown placed on it, which helps to bring the root-cap to its place and insure the intended position of the crown. When necessary, the split post can be tightened in the tube by slightly springing it open. Fig. 426 represents the finished crown. The incisive edge of the porcelain does not necessarily require to be protected with metal as in fixed bridge-work. Fig. 430 illustrates a removable cuspid crown which can be used in removable bridge-work. It is constructed as follows: The end of the root is first capped, and a post attached fitting the root-canal. A porcelain cross-pin tooth, the pins of which are set well apart, is then ground and adjusted in position, cemented with wax to the cap, and both removed. Enough plaster to form a matrix is placed on the labial aspect of the porcelain and collar to hold them in relative position when the wax is removed. A flat post is then formed on the root-cap, extending from the palatal edge for- ward between the pins of the tooth, the porcelain of which, between the pins, should be slightly cut out to receive it. To this is soldered the piece A, which is to act as a spring. The post is formed of gold plate No. 18 gauge, and the spring of clasp or spring gold No. 26. The post is soldered to the cap from the opposite side to the spring by investing without the tooth. The tooth is then lined with very thin platinum, and with the aid of the matrix is adjusted in position on the cap, and a thin piece of platinum plate is slit at the edges and adapted over the post, cap, and edge of the collar, with its inner edge meet- ing the backing of the tooth. The platinum plate is then cemented with wax to the backing on the tooth, removed 212 ARTIFICIAL CROWN- AND BRIDGE-WORK. with it from the cap and post, and invested, the slot for the post being carefully filled with the investing material. Twenty- carat gold solder is then flowed over the plate and backing so as to consolidate the parts in one piece. This crown when finished will fit on to the cap and post, the spring of which can be bent to securely7 retain it. The line of the post on the cap as it fits in the slot in the crown should be such as will favor the insertion and removal of the bridge.1 In the form shown in Fig. 431, which is a sectional viewT, a square or round iridio-platinum wire is used as a post on the cap instead of the form above described. The post having been soldered to the cap, a thin piece of plat- inum is first perforated and fitted over the top of ig. 431. ^e cap^ next a tube of platinum over the post and /T\ between the pins of the porcelain. The porcelain /£?:: \ front is then lined with platinum foil, and cemented ii with wax to the tube and the platinum at the base, |j and removed and soldered together. Where one /^pf^\ end °f a bridge is securely attached to a molar, the ' ; ; ' ^ form of crown here described is ample support for the other end. REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. Bicuspids and molars, especially the latter, in all cases where possible, are the teeth selected and most depended on to support all forms of removable bridge-work. Removable Partial Cap and Collar.—This is a form of attach- ment made to fit over a natural tooth, or more frequently a gold crown. The sides of the natural tooth have to be first trimmed as nearly as possible straight or parallel to the sides of any other supporting crown or line of attachment. If the tooth is to be first capped, a straight-sided gold crown is made and fitted. The gold crown is then removed, a strip of damp paper wound around it, and fusible metal melted and poured in crown and paper tube. This forms a die of the crown, with a shank as seen in Fig. 432. When the natural tooth is not crowned with gold, a die of the lT>v. Parr's method. REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. 213 tooth is made in a manner similar to that described on page 105, and in chapter on Molds and Dies. The crown is then en- circled with a strip of pure gold about 30 gauge, one part of which will extend above the rest in the form shown in Fig. 433. The sections of the gold at A, A are to reach from the edge of the neck of the crown to or slightly above the occluding sur- face. The gold is fitted evenly, but not tightly, around the Fig. 432. Fig. 433. \ B / A A crown, the ends being placed at the side opposite to that where the collar will be joined to the bridge if the space permits. The collar is then removed and the ends soldered together (Fig. 434). The collar is readjusted on the crown, and the part at B, Figs. 434 and 436, bent down over the occluding surface, so that it nearly meets the collar section A. On the outside of the collar a slightly narrower strip of gold clasp plate, No. 30 (Fig. 435), Fig. 435. Fig. 436. Fig. 437. Fm. 438. is next adjusted in the position shown by the lines C, Fig. 435, then removed and the ends, which are best placed at the point C Fi-s. 435 and 436, soldered together. It is readjusted on the gold collar, removed with it, and soldered to it. The collar can be invested for this purpose, but the work is more easily done bv holding the collar in a Bunsen flame and placing small pieces of solder in position in the seam. Only enough solder should ARTIFICIAL CROWN- AND BRIDGE-WORK. be used to unite the parts, any surplus being carefully avoided. Painting the inner surface of the collar with whiting will pre- vent the solder flowing there. The collar section of the removable cap is then trimmed smooth. The cap section at B can be adjusted and soldered to the collar now, or preferably after the cap has been united to the bridge, and its relative position on the gold crown accurately determined. Fig. 437 shows the gold crown and the finished removable par- tial gold cap over it. The gold crown is freed from the fusible metal by dropping it with the die into a ladle containing a quantity of melted fusible metal. The portion within the crown will melt in with that in the ladle and leave the crown, which should then be removed and immersed in nitric acid to remove any traces of the fusible metal still adhering to the gold. Flanged Collar Attachment—Fig. 438 shows another form of removable partial cap. In this the entire edge of the collar is bent over on the occluding surface of the crown, and thereby supported in position. In the construction the edge of the pure gold collar should be shaped to form the flange. Spur Collar Support.—Fig. 439 illustrates a form in which a straight-sided removable collar is maintained in position by a lug or spur on the side of a gold crown. Removable Partial Cap and Clasp Attachment.—In this form a partial cap in combination with an elastic gold clasp, encircling only a portion of the crown, is used instead of a collar. Its application is principally confined to a cuspid or bicuspid tooth or artificial crown. The attachment is best constructed on a metallic die, either of the natural tooth or of the artificial crown mounted on a model. In the case of a cuspid a piece of pure gold, No. 31 gauge, is adapted to the palatal surface and partly over on the approximal side, in the form shown at A, Fig. 440. In some cases it may be extended to the incisive edge. A gold clasp of at least 24 gauge is fitted over the gold partial cap in the position shown in Fig. 441, the cap being beveled to an imperceptible edge on the sides at the points where the clasp passes forward, to assure perfect adaptation. Cap and clasp are next cemented REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. 215 with wax, then removed and joined at the approximal sides with a very small quantity of solder. The attachment is then ready to be connected to the bridge denture, which should be done by soldering the clasp portion only at the point B, Fig. 441. This method allows the soft gold of the cap portion to be again adapted to suit any position the clasp may assume in the final adjustment of the denture in the mouth. The bridge and clasp should then be again invested, and solder flowed over and be- tween the cap and clasp. A Bicuspid or Molar Partial Cap and Clasp Attachment.—Fig. 442 illustrates the form the attachment just described usually assumes in cases of bicuspid and molars. The dotted line marks the boundary of the partial pure gold cap. The con- struction follows similar lines to those laid down in the case of Fig. 439. Fig. 440. Fig. 441. Fig. 442. a cuspid. If preferable, the cap section can be burnished down against the crown; and if necessary, it can be slit, and solder can be flowed over it at the final adjustment of the bridge. This form of attachment is especially useful in cases where a natural tooth tips out of line so as to render it difficult to entirely en- circle it with a continuous band. Pure gold has been given the preference to thin platinum in the construction of these partial caps, for the reason that the form and the position of the former are less liable to be altered in soldering, an advantage which is relatively more important than the non-fusible quality of the platinum. The forms of attachments described for removable bridge- work are those most generally applied in practice. The methods for their construction, which as given are the results of practical experience, may in some respects differ from those followed by 216 ARTIFICIAL CROWN- AND BRIDGE-WORK. others. In application, as will be shown, they enable the operator to avoid difficulties often encountered in obtaining a proper adjustment of removable bridges on the abutments and alveolar border. Special forms of attachments not in general use will be described in the succeeding chapters, in their applica- tion to practical cases. Their use in combination with the forms already explained may at times prove advantageous. Connecting Bars.—Connections between the different sections of a removable bridge are formed in the following manner: A plaster impression of the case or the part to be spanned is taken in plaster, and a cast made by pouring into it fusible metal which melts at a point less than or not over two hundred degrees (see chapter on Molds and Dies). The cast must correctly represent the lingual or palatal surfaces of the teeth. Upon this cast a strip of pure gold, No. 30 gauge, about one-quarter of an inch in width and of the proper length for the required connecting-bar, is bur- nished over the palatal or lingual surface of the teeth intervening between sections of the bridge or attachment to be connected. Wax is placed on the surface of the gold, and the gold is removed and invested. The wax is next removed, and a piece of gold clasp plate, a trifle narrower than the strip of pure gold, is bent and shaped to fit over its surface. Twenty-carat solder is then flowed over the gold in quantity sufficient to join the parts, level the surface, and make a rigid bar capable of resisting such force in use as would tend to destroy its shape in the slightest degree. When the bar is formed on the metallic cast it can be trans- ferred to the plaster model, and then, or in the subsequent con- struction of the work, connected to the attachments; or the bar can be adjusted in the mouth, cemented with wax or ligatured on the teeth, the attachments placed in position, and the bar and attachments removed in their relative positions in a plaster im- pression. On the model made from this impression they will be found the same as in the mouth. The construction of the bridge can then be continued. Fig. 443 represents a bar of this character to span the lower front teeth and connect attachments on the cuspid and bicuspid. For the Upper Front Teeth.—Where a bar narrower than the one described is required, the strip of pure gold should be cut REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. 217 proportionately, and pieces of half-round iridio-platinum or gold clasp wire used to form and stiffen the bar, instead of gold clasp plate. Construction of Removable Bridge-Work.—In removable, as well as other styles of bridge-work, the method of procedure is en- tirely governed by the conditions presented in each case. There- Fig. 443. fore directions given regarding bridge-work embracing certain teeth and attachments in one instance may vary considerably from what is required for the same teeth in another; conse- quently the process of construction can only be outlined in somewhat general terms. A case frequently presented, involving the loss of a portion of the lower teeth, as shown in Fig. 444, will be taken to illus- FiG. 444. trate the method generally adopted for the construction of re- movable bridge-work. The molar is shaped to receive a gold crown. The anterior approximal side is trimmed parallel with the line of the posterior side of the cuspid. Removing a little of the enamel on the distal side of the cuspid will assist the operation and straighten 218 ARTIFICIAL CROWN- AND BRIDGE-WORK. that part of the tooth. A straight-sided gold crown is made for the molar. A plaster impression is then taken, which will remove the gold molar crown in position, and a cast is made as follows: The form of the cuspid and interior of the gold crown are first filled with fusible metal, and the remainder of the im- pression with pure plaster, as described in chapter on Molds and Dies. The bite is taken in wax, and an articulating model made. A removable partial cap is made for the molar, and a partial cap and clasp attachment for the cuspid. Dummies are then fitted and soldered together, placed in position, and joined to the attachments with wax cement. The bridge is then removed from the model, invested, and soldered together. Connection with the attachment is only to be made at the collar section. The gold crown and fusible metal are then separated from the model and the fusible metal removed from the crown in the manner described on page 214. The molar crown and the bridge are then fitted to the mouth. The crown is next cemented on the molar and the bridge im- mediately adjusted over it, pressed into position, and allowed to remain until the cement has set. The partial cap section of the attachments is burnished down on the bicuspid and the gold crown on the molar, while the bridge is kept firmly pressed against the gums. The bridge is then removed, invested, and the partial cap sections made rigid by flowing gold solder over them. The final trimming, finishing, and polishing of the bridge is then performed, and it is ready for insertion. The procedure in the case described can be varied by making the entire model of fusible metal, or by placing a little wax in the interior of the grinding-surface of the gold crown, making a plaster model, removing the gold crown and filling it with fusible metal, making the attachment and replacing the gold crown on the model. The cuspid attachment can be formed on a fusible metal cast of the tooth. The methods of construction as above given may be still further varied by first forming the gold crown and attachments, fitting them in position in the mouth, taking a plaster impres- sion which will remove them in position, and then making a REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. 219 model of plaster and calcined marble-dust. On this the dum- mies can be fitted and soldered to the attachments. The gold crown is to be removed from the model after the position of the attachment on it is secured by the investing material. Removable bridge-work is best constructed with the bases of the dummy teeth pressing firmly on the tissue of the gum. If the collar of the molar attachment should prove difficult to remove when first inserted, it should be slit at the posterior section, slightly expanded, and reunited with solder, when the eap sections of the attachments are stiffened in the final process of soldering. A small piece of gold plate can be inserted in the aperture of the collar to aid the gold to unite the ends. In Fig. 445 are illustrated the two forms of removable bridge- Fig. 445. work that could be constructed for the same case. In the one a clasp attachment is placed on the natural cuspid, in the other the natural crown is excised and a removable cuspid crown con- structed. In the construction of either style, a gold crown is made for the molar, with a removable gold partial cap and collar attachment. A removable partial cap and clasp attachment is made for the cuspid, or, if the natural crown is excised, a re- movable cuspid crown, and the cap and tube section cemented in position on the root. The crown or crowns and attachments are adjusted in position in the mouth. If the cuspid attachment is used, and it seems liable to become misplaced, it can be liga- tured to the natural crown. An impression and bite are then taken in plaster, and when removed from the mouth the crowns 220 ARTIFICIAL CROWN- AND BRIDGE-WORK. and attachments are to be replaced in position in the impression, and a model of plaster and calcined marble-dust made, and also an articulating model in plaster. The lateral and bicuspid and molar dummy teeth are next fitted in proper position on the model. A piece of pure gold is adapted against the lateral, and burnished over the palato-approximal side of the central to form the flange. The case is then invested, the gold crown slipped out of the attachment, the place it occupied is filled with ad- ditional investing material, and the parts are all soldered to- gether. The construction can be varied by first making the bridge from the molar to the cuspid, and then adding the lateral and flange. When, finished, a suitable quantity of cement is placed in the gold crown, the crown is fitted on the molar, the bridge adjusted in position, and the teeth occluded and so allowed to remain until the cement sets. Fig. 446. The denture illustrated in Fig. 446, a case of Dr. A. S. Rich- mond's, was made to restore a loss of teeth which is frequently met with, but one not suitable for the insertion of cemented bridge-work. The application of a removable denture combin- ing bridge- and plate-work is a method possessing advantages over those ordinarily practiced. In brief, the constructive details are: A connecting bar is formed as described on page 216. In the case in hand, when the pure gold to form the connecting bar was adapted to the cast, it was extended around and over the cuspid and bicuspid. Gold clasps were then adapted over this, and the soldering done at the same time as the bar. The bar and clasp attachments were inserted in the mouth, an im- pression taken in plaster, and a model made with the attach- REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. 221 ments and bar on it in position. Metal casts were also made of the parts at A, A, Fig. 447, and two gold plates struck up. The teeth were then arranged in position, the bicuspids resting on the gums and the molars on the two plates or saddles, and the denture completed as shown in the illustration. Fig. 447. Removable bridge-work offers peculiar advantages for arti- ficial replacement of lower incisors in cases similar to that illustrated in Fig. 448. A portion of the contour of the ap- proximal sides of the right cuspid is removed. Shell caps for Fig. 448. the rio-ht and left cuspids are then formed of crown gold, reaching nearly to the margin of the gum. The caps are en- circled with a narrow strip of stiff gold plate or clasp metal about No 35 gauge, which is soldered to the caps as described on pao-e 213 in the construction of molar partial caps. The 222 ARTIFICIAL CROWN- AND BRIDGE-WORK. caps are next adjusted in the mouth, and an impression and bite taken in plaster and the caps removed in it. A model of half plaster and marble-dust and an articulation in plaster are then made. Porcelain incisor teeth with straight pins are fitted in position, backed, and a broad bar extending from the lingual-approximal side of the gold cap on the left cuspid around to the mesial side of the lateral is formed of a strip of pure gold, adapted to the parts, overlaid, and soldered to a slightly narrower strip of gold clasp plate. The different portions are then cemented together with wax, invested on the model, and properly united with solder. When finished and inserted in the mouth, it constitutes a denture that can be worn Fig. 449. without inconvenience by the patient, and removed daily and cleansed, which last especially is a great advantage, as in a case like this the teeth replaced have usually been lost by pyorrhea alveolaris and those remaining are affected by the same trouble. The natural teeth, if loose, are in a measure steadied and sup- ported by the appliance. In some cases, especially if the teeth tip, one or both of the attachments on the cuspids can be made of thick clasp metal in the form of a clasp attachment, as des- cribed on page 214. In the case represented in Fig. 449, gold crowns with remov- able partial cap and collar attachments are made for the molar and bicuspid, and removable crowns with flanges of the metal on the palatal sides for the centrals and cuspid. The right central REMOVABLE BICUSPID AND MOLAR ATTACHMENTS. 223 is capped and the crown fitted over it without a post, as the posts in the other two crowns afford ample security. After the crowns are made, the root-caps are cemented on each root. The central crowns are cemented together with wax, Fig. 450. adjusted in position, covered with a small quantity of investing material, removed, more investing material added, and the crowns soldered together. The centrals and the cuspid are then adjusted in the mouth, a lateral is backed, fitted, and waxed between them in position, Fig. 451. the whole .removed in investing material, and the process of investing and soldering proceeded with to join the parts as before described. This bridge of four teeth is fitted to the mouth, and the points of the posts trimmed on the side and in 224 ARTIFICIAL CROWN- AND BRIDGE-WORK. the direction which will best favor their entrance into the tubes in each root, so that the bridge will readily slip into position. The dummy bicuspids and molar on the right side between the cuspid and molar are then added by first taking an impression and bite of that section, and then proceeding with the construc- tion as described in previous cases. The section of the bridge with the extension on the left side is next added in a similar manner by taking an impression of the part while the portion of the bridge already constructed is in position, removing bridge and impression together, and making a model. A piece of pure gold is shaped to the model by successive burnishing and an- nealing, to form a base for the molar. The one molar will exert as much leverage on the abutment of the bridge in mastication as can safely be borne. Fig. 450 shows the bridge completed, and Fig. 451 the piece in position. CHAPTER X. REMOVABLE PLATE BRIDGES. In this style of bridge a plate is used to span the space and support the artificial teeth between the abutments. An essential requisite of this class of dentures is that the plate portion shall rest closely and firmly on the alveolar border, and at the same time receive support from the abutments. Attachments similar to those used in connection with removable bridge-work are also applicable to removable plate bridges. The methods to be given describing their application will differ in some respects, which will be advantageous in a practical way. Fig. 452. Fig. 453. The case shown in Fig. 452 will be taken to describe the con- structive details of a denture of this class. In the root of the central a tube is inserted, attached to a cap on the end of the root. Over this cap is placed an outer cap which has a split spring pivot or post fitting the tube. A narrow plate between the teeth connects the outer cap to a clasp attachment which fits around and rests upon the cuspid. 16 225 226 ARTIFICIAL CROWN- AND BRIDGE-WORK. The cuspid, which because of its conical form is one of the most difficult teeth in the mouth to clasp, is trimmed sufficiently to partially square its approximal sides, and the palatal portion is notched slightly (A, Fig. 453), to form a shoulder for the clasp to rest upon. This notch can be safely made, as the enamel is very dense at the point indicated. A gold plate is swaged to fill the space between the central root and the cuspid as shown in Fig. 452. The cap and pivot are adjusted on the central root, and the plate is then fitted in the mouth, pressed tightly in position against the gum, and retained there with a little wax, which is cemented to the plate and pressed against the cuspid and side of the cap. An im- pression of the parts and an articulation are then taken in plaster. The cap, pivot, and plate being removed in the im- pression, they will be presented on the model made from it in exactly the same position as in the mouth. A second or outer cap is then fitted over the root-cap, the band being made very narrow at the approximal and palatal sides, and open at the labial side, as the porcelain tooth to be attached will serve in its stead (B). The pin is then soldered fast in the outer cap, and a clasp of clasp gold (C), No. 23 to No. 24 gauge, is formed to extend well around the posterior approximal portion of the cuspid. The outer cap having been placed in position on the inner one, the plate extending from the central to the cuspid is cemented to it and to the clasp with wax, removed, invested, and the parts REMOVABLE PLATE BRIDGES. 227 soldered together. Aided by the plaster articulation, teeth are ground and fitted on the model, backed, attached to the plate with wax, and inserted in the mouth. Platinum foil is then burnished to the form of the notch on the cuspid, the clasp fitted over it and attached with wax, removed with the plate, and soldered to it simultaneously with the teeth. When the piece is finished and fitted in the mouth, the inner cap—the end of the tube having been closed with gutta-percha —is first cemented on the central root. A very small quantity of oxyphosphate is used, and while it is yet soft the plate is adjusted in position, and allowed to remain there until the cement has set. The split pivot is sprung open a little and forced to place. With the aid of the clasp around the cuspid it will be found to perfectly secure the plate. Figs. 454 and 455 Fig. 455. show the bridge finished and in position. If the plate forming the bridge is tightly adjusted against the soft tissues, and removed in that position in the impression taken with the caps, it will always be found to fit in a similar manner when the bridge is finished. Should the clasp cause decay or abrasion of the cuspid, the tooth can be excavated to a slight depth under the clasp, and filled with gold. This is best done by making a few retaining- pits, filling them with a hand-plugger, and then inserting the main body of the gold in the ordinary manner, the Herbst method being useful in condensing the foil. Such a filling inserted at any time will prevent injury from a clasp. A denture of this style can be made to pass intervening teeth. 'in the artificial replacement of the lower teeth in a case such as is illustrated in Fig. 456, a plate bridge possesses many advan- tages In the construction of such a denture, the teeth are first properly shaped. Gold crowns (Fig. 457), with sides as nearly 228 ARTIFICIAL CROWN- AND BRIDGE-WORK. as possible parallel the one with the other, are then made and fitted to the bicuspid and molar. This operation is frequently fa- cilitated by shaping the external surface of the crown with metal. On the crowns, at the buccal sides, a narrow shoulder (A) is con- structed to sustain the collars and bridge in position. In some Fig. 456. cases this shoulder is placed on the approximal side to better advantage. The crowns are then adjusted in the mouth, a small quantity of wax being applied inside of the crowns when neces- sary to retain them in correct position. A piece of plate is next Fig. 457. swaged and fitted between the crowns and attached with wax as described in the previous case. An impression and articulation of that part of the mouth are then taken with plaster and the crowns and plate removed in it. On the model made from this impression the crowns and plate will appear in position. Collars REMOVABLE PLATE BRIDGES. 229 reaching from the cervical to the occluding edge are fitted to these crowns. The. collars, though fitting accurately, should move easily over the crowns, as they can be readily tightened when the case is finished. If a collar is troublesome to adjust and remove, cut the side opposite to that attached to the plate, and spring it open a little. After fitting the teeth it can be again united when they are being soldered. This collar and shoulder form a support in some respects preferable to a partial or an entire double cap, being less difficult to keep clean. A collar is more easily con- structed, and also permits the position of the bridge to be altered by the removal of a little of the shoulder or of the upper edge of the collar, and is a secure but less rigid attachment than is provided by other methods. Fig. 458. The collars and plate are next cemented with wax, removed, invested, and strongly soldered together (B, B, Fig. 457). The artificial teeth are fitted in proper position on the plate by the aid of a plaster articulation, attached with wax, and, if preferred, the piece may be adjusted in the mouth without the gold crowns. The bridge is then invested and finished. The attachment of the artificial teeth to a plate of this kind can be of either gold or rubber. Whichever is adopted, the first bicuspid is best supported by being soldered to the collar. If iridio-platinum is used in the construction instead of gold plate, and the soldering done with pure gold, porcelain body can be used. When ready to be inserted, the crowns are adjusted with cement, and then the bridge, which is left in position until the cement sets. By burnishing the collars they can be made to clasp the crowns as firmly as desired. Fig. 458 shows the denture in position. 62603454�72951�7�30246483�8777��30 230 ARTIFICIAL CROWN- AND BRIDGE-WORK. Figs. 459 and 460 represent an upper removable plate bridge. In its construction the cuspid roots were first capped, tubed, and pivoted, and the molars crowned with shoulders formed on the buccal sides. The plate intended to connect the abutments was then adjusted in position as has been described. An impression was next taken and a model and articulation made. The cuspids Fig. 459. were then double-capped and collars formed on the molar crowns. The double caps, pivots, collars, and plate were next soldered together. The artificial teeth were attached with vulcanite, the gum section being formed with pink. In order to avoid any warping, which might readily occur in the construction of so large a denture as this, the plate may at first be swaged up, as Fig. 460. in ordinary artificial dentures, to cover the whole of the hard palate. A shallow groove can be made around the palatal sur- faces of the teeth, and after the final soldering the plate can be cut along the line of this groove, the portion covering the palate being removed. The groove will insure a close fit for the palatal edge of the plate. REMOVABLE PLATE BRIDGES. 231 In the case represented in Fig. 461 the natural teeth were very short. The posterior approximal side of the molar was Fig. 461. decayed to such an extent that the pulp ,v» nearly ^'^ considerable irritation of the inverting gum-t,ssue had been �1657313�3 232 ARTIFICIAL CROWN- AND BRIDGE-WORK. caused by the clasp of a plate worn by the patient working upward against it. The patient declined to have a plate made which would extend across the palate. The lateral was hardly strong enough to support a permanent bridge. The molar was capped, and a removable appliance constructed with a band which slipped over the cap and rested, on a shoulder on the mesial side to form the posterior abutment. The lateral was notched and clasped for the anterior support. Figs. 462 and 463 are two views of the appliance in position. Fig. 464. Fig. 465. Fig. 464 represents a case in which the bicuspids and a molar are replaced, and also a central, on an extension of the plate, the cuspid being partly encircled by a clasp with a shoulder resting on the palatal section of the tooth. Fig. 465 shows the denture in position. Fig. 466 represents a case in which a bridge-plate was in- serted without crowning either of the abutments. The clasp of a plate which had been worn for some years had worked upward and abraded the distal section of the cuspid to such an extent as to expose a large portion of the root and superinduce decay. REMOVABLE PLATE BRIDGES. 233 The cavity was filled with gold, and the gingival border, by treatment, brought nearly to its normal position on the tooth. A plate bridge, such as is represented in Figs. 467 and 468, was then constructed. Clasps, with flanges resting on little shoulders formed at A, A, Fig. 466, support and retain it. A flange such as was used in this case is best made subsequent to the con- struction of the plate and clasps, by burnishing a piece of platinum foil in the mouth to the form of the shoulder and the side of the tooth upon which it is to rest, adjusting the clasp over Fig. 467. Fig. 469. it, and cementing with wax, then removing, investing, and soldering. Wherever the platinum is placed, the solder will flow and fill all the space between it and the clasp. This gives the clasp the exact form of the tooth. Fio-. 469 shows the denture finished and in position. If the teeth& are dense in structure, an attachment of metal held in proper position against the lower portion of a crown will be worn a long while before it causes injury to the parts. * illing, or crowning, if necessary, can subsequently be resorted to Bv a correct application of the methods just explained and 234 ARTIFICIAL CROWN- AND BRIDGE-WORK. illustrated, a piece of removable bridge-work of this style can be devised for many cases. Dr. J. L. Davenport describes the methods he adopted in the application of plate bridges to the following case: " The patient was a gentleman about fifty-five years of age. The upper jaw contained the six front teeth, the three molars on the right side, and the first bicuspid on the left. The lower jaw contained all but the left central incisor, the second bicuspid, the three molars on the right side, and the first and third molars of the left. "In consequence of this lack of occluding back teeth, mastica- tion had been performed solely by the front teeth, causing attri- Fig. 470. tion so great on the upper ones as to entirely obliterate their crowns, while the lower ones suffered but little loss, as will be seen by reference to Fig. 470. " The patient had managed for a long time to masticate, though imperfectly, upon these stumps, but latterly could eat scarcely anything but soups and soft foods. " The restoration of the lower teeth being completed to the extent of about one-eighth of an inch on an average, to make them of uniform height, my attention was directed to the upper incisors and cuspids, nearly all of which I found with dead pulps, and some of them in a condition of active abscess. " The two superior cuspid roots were dressed down nearly to the gum, and fitted with 22-carat gold cap crowns. After these REMOVABLE PLATE BRIDGES. 235 had been placed in position, a hole was drilled through each cap of a size suited to that of the pulp-canal, and a tube of iridium and platinum was adjusted in the root and cap and waxed in position. The cap and tube were then taken off and soldered, great care being taken to have the tubes enter both roots per- fectly parallel. These were permanently secured in the roots with gutta-percha, and to prevent the caps being pulled off the top of each tube was slit down a trifle, and after insertion was bent back into the gutta-percha with a warm instrument. "The incisor roots having been dressed down even with the gum and filled, a plaster cast was taken and a narrow 20-carat gold plate was swaged to fit over the ends of the incisors and the capped cuspids, making it a little broader where it had to rest on the gum back of the first left bicuspid root. A hole in the plate was then made to expose the root of the first left bicuspid. This was fitted with a bifurcated iridio-platinum pin, having notched sides, and a hammered head upon its lower end, which came down below the root about three-eighths of an inch. "A thin iridio-platinum band was then made to encircle the root, passing just under the gum and being slightly longer than the headed pin. This band was perforated with two rows of holes, from without inward, giving the inner surface a rough- ness similar to that of a nutmeg-grater. The band and pin were then made secure to the root with a non-shrinkable copper amalgam. "Fig. 471 shows the upper jaw ready for the plate. "Afterthe amalgam had become hard and the end and sides had been polished, a gold crown was fitted over all just up to the margin of the gum, and in close contact with the end of the band and amalgam. This crown was loose enough to admit of its sliding on and off, though with just enough friction to hold it in place when at rest. This gold crown was then placed in posi- tion, the plate also inserted, and hard wax used to firmly join the two in the mouth. They were then removed and soldered. " Gold pins were then placed through holes drilled in the plate into the tubed cuspids; then soldered to the plate, the pins being of a size to fit the tubes accurately. The plate was also provided with a wide clasp encircling the first molar on the right. 236 ARTIFICIAL CROWN- AND BRIDGE-WORK. " The plate was then provided with a gold bar about one-eighth of an inch wide, occluding perfectly with the lower teeth, and plain teeth soldered in place, hiding the bar, and just meeting the gum in front of the incisor roots. The plate rested squarely against the capped cuspids, each of which showed a narrow band Fig. 471. of gold when the plate was in position. As finally completed (see Fig. 472), this was the most perfectly fitting piece I ever inserted, requiring great care in its removal, and yet by a little practice the gentleman was able to remove and replace it quite Fig. 472. easily. It was also as firm as any permanent bridge could have been, though it had no support on the left side back of the first bicuspid. " The lower jaw was supplied with a double 20-carat gold plate, having a wide clasp on the first right bicuspid, which,' after being REMOVABLE PLATE BRIDGES. 237 built up, presented a cone-shaped top, about which the clasp fitted so as to rest firmly upon the end of the tooth, thus pre- venting injury to the gums during mastication. "The only other peculiarity was that the second left inferior molar, being abnormally short, though well formed and standing Fig. 473. straight upright, was fitted with a wide clasp, extending almost one-eighth of an inch about the tooth, and a piece of gold plate with gold cusps was soldered into this clasp, covering the molar crown and occluding with the molar on the upper plate (see Fio\ 473). This not only prevented the plate from being bitten Fig. 474. down unpleasantly on the gums during mastication but enabled me to use a shorter molar upon the upper than I otherwise could have done, and allowed better the anteroposterior and lateral movements of the jaws. "Fig. 474 shows the case as completed. CHAPTER XL SPECIAL FORMS OF DETACHABLE AND REMOVABLE BRIDGE-WORK. A description of special forms and methods of constructing detachable and removable bridge-work is given in the following articles, as practiced by the introducers or as adopted in general practice. DR. WINDER'S SECTIONAL CROWN METHOD. This method, an invention of Dr. R. B. Winder's, presents the novel feature of constructing the crowns and forming the abutments in sections, the bridge being attached to the detach- able section. Fig. 475. Fig. 475 illustrates a case of bridge-work made in this manner. The collar section of the artificial crown is capped and cemented on the natural crown or root, the gold forming the occluding portion of the crown, when the bridge is adjusted in position, being secured to it with a screw. The screw may be made to enter the body of the crown as in Fig. 476, or it may be soldered to the cap on the collar, passing through the occluding section of the crown, and being secured by nuts on the screws (Fig. 477). When incisor or cuspid roots form the abutments, Dr. Winder first forms a cap for the end of the root, to which a tube is attached extending up the root-canal, as illustrated on page 209, 238 DETACHABLE AND REMOVABLE BRIDGE-WORK. 239 Fig. 425. On this cap is mounted the crown (B), the post of which fits the tube tightly. To the crown so formed (Fig. 426) the bridge is joined in the usual manner. In constructing a bridge of this style, the crowns forming the abutments having first been made, are removed from the mouth in a plaster impression and articulation, from which a model Fig. 476. is made, showing the crowns in position. Each section of the bridge between the crowns is then constructed, and the crowns adjusted in the mouth. The bridges are next inserted in posi- tion, and cemented with resin and wax to the detachable sections of the crowns. The whole is then removed in investing material, in an impression-cup, or by placing the investing material in ft Fig. 477. position on the bridge. After being removed from the mouth more investing material is added and the bridge and crown sec- tions soldered together. Only the detachable sections of the crowns should be in the investment at the time of soldering. The incisive edges can be protected and the occluding surfaces of the porcelain capped with gold as in permanently attached 240 ARTIFICIAL CROWN- AND BRIDGE-WORK. bridge-work, or they can be formed of the porcelain, which latter lessens the labor of construction, as the bridge is easily detached from the abutments for the purpose of repair. When the occluding surfaces of bicuspids or molars forming the bridge are to be capped with gold, the collar sections alone are first made and removed in the impression. The caps for the crowns and the bridge teeth are then formed of one continuous piece of gold plate. This is made by laying the strip of gold on a piece of lead and stamping along its length with suitable dies representing the occluding surfaces of the different teeth. The gold is then properly fitted to the collar sections on the model,- conforming to the occlusion of the antagonizing teeth. The cusps are filled with solder, and the porcelain fronts, backed with plat- inum plate, leaving the pins straight, are fitted in position to the gold forming the caps and the backings, and cemented with wax. The porcelain fronts are next removed, without removing the backings, which are invested and soldered to the caps. When this is completed, the holes in the backings are deepened with a drill, and the pins of the porcelain fronts, having first been slightly serrated, are cemented in position with oxyphosphate. When the bridge is finished the root and collar section of each- crown is first cemented on in position in the mouth; the surface of the detachable section of the crown approximating the section fastened to the bridge is then heated and its surface covered with a mere film of gutta-percha. The bridge is then adjusted in position and secured by the screws or nuts. The gutta-percha prevents the secretions invading the interstices between the sections of the crown. Fig. 478 illustrates another method, devised by Dr. W. R. Spencer, of constructing the sections of the crowns in this style of bridge-work. The part A slides in the groove B. The dovetail flange A is made of a thick piece of plate, fitted to the groove B, and riveted to a piece of platinum adapted transversely across the cap and then soldered to the removable section of the crown. Fig. 479 shows the sections of the crown in position. A decided advantage possessed by this method of bridge-work DETACHABLE AND REMOVABLE BRIDGE-WORK. 241 over others is the facility it affords in practice for the ready utilization of irregular teeth as abutments, no matter how much they converge or diverge, or lean in or out of the line of the arch. DR. LITCH'S METHOD. Dr. Litch's method of constructing detach- able bridge-work consists in forming a shell an- chorage over posts permanently fixed in cuspid roots, and anchoring the ends of the bridge with bars in slots formed in natural or artificial crowns. Figs. 480,481, and 482 illustrate a bridge similar to the one illus- trated in Fig. 331 (pagel67) with this style of attachment applied. Fig. 480. Fig. 481. 242 ARTIFICIAL CROWN- AND BRIDGE-WORK. backed, attached with resin and wax, and removed with the cap. The cap is next invested in plaster to the edge of the collar, and a little plaster placed on the labial aspect of the porcelain front in the form of a matrix, so as to allow the porcelain to be Fig. 482. Fig. 483. removed and replaced. A piece of heavy iridio-platinum plate (E), No. 16 U. S. standard gauge, is then shaped into the form of a half-ring, with the ends of the plate against the backing of the porcelain front, and of sufficient size to rest on the flanged edge of the cap when completed. On the outside of this half-ring is fitted and soldered a thin strip of gold (F) of No. 28 IT. S. standard gauge, which will cover the half-ring and extend beyond its cervical margin, slightly overlapping the flange of the collar (G). This forms a brace or edge on the anchorage cap as it rests on the root-cap. The half-ring is then fitted to the tooth, at- tached with wax, and removed with the tooth out of the plaster matrix from the root-cap, invested, and securely soldered on the inside to the backing of the tooth. The tooth and half-ring are then adjusted to the root-cap, over the post of which the ring must slide easily (Fig. 484). To this ring the bridge is soldered the same as to a crown. When the bridge is inserted, the cap for the root, with the post, is first cemented on with oxyphosphate. After the cement has DETACHABLE AND REMOVABLE BRIDGE-WORK. 243 set, the anchorage ring is filled with more cement and pressed into position upon the cap over the anchorage post. The surface of the cement (H, Fig. 483) can be protected by a metallic filling. This form of attachment permits the bridge to be easily re- moved by affording access to the cement around the pin. The bar ends of the bridge are anchored in the crowns with gold or amalgam fillings, which likewise are not difficult to remove. The anchorage cavity for a bar in a gold molar crown for use over a tooth with a living pulp is best made by cutting out the gold to the form of the slot required, and inserting in its place a piece of platinum of the shape of the walls of the anchorage cavity. The crown is then filled with investing material, and the metal forming the anchorage cavity soldered to the crown at the edges of the cavity. DR. R. W. STARR'S METHODS. Dr. R. Walter Starr gives the following descriptions of his methods in detachable bridge-work: " The case of Mr. W. presented difficulties of an unusual character, as may be seen by inspecting the illustration (Fig. 485), which renders detailed description unnecessary. " It will be observed that the molars and the left second bicuspid overhang to a degree that would make the taking of an accurate impression by ordinary methods well-nigh impossible. After a careful study of the case, it was decided that two separate pieces of detachable bridge-work should be attempted, and, as an essential preliminary step, the overhanging sides of the molars and bicuspids were ground with engine corundum-wheels and points until those sides were made much less inclined, when plaster impressions were taken, first of one half, and then of the other half, of the jaw. Gold cap crowns were closely fitted over the molars, left second bicuspid, right first bicuspid, and cuspid stump. Gold crowns were made to telescope over all the caps, which were then, by means of oxyphosphate cement, fixed firmly on the teeth. Suitable plate teeth were selected, fitted, backed, and hard-waxed in place between the telescoping crowns. After hardening the wax with cold water from a tooth- svrino-e, the pieces were carefully removed, invested, and sol- dered The two completed bridges were easily replaced on or 244 ARTIFICIAL CRO WN- AND BRIDGE- WORK. Fig. 486. DETACHABLE AND REMOVABLE BRIDGE-WORK. 245 removed from the supporting capped teeth, and their appearance when detached is correctly shown by the illustration, Fig. 480, which also shows the capped teeth and stumps. The figure like- wise shows the results of the novel method employed in crown- ing the incisors. Gold collars were fitted tight on the necks of the incisor stumps, and the new-style porcelain caps adjusted in the collars, and set in the oxyphosphate cement which had been packed into the collars; thus at the same time fastening the collars on the stumps and the caps in the collars, as shown completed in Figs. 486 and 487. Fig. 487. "Fig. 487 illustrates the finished crowns and bridges, which latter were secured in position by placing a small piece of gutta- percha in each of the telescoping cap crowns, which were then warmed and carefully pressed in.place—the gutta-percha filling only the spaces between the flat tops of the caps of the natural teeth and cusped caps of the bridges. "Whenever, for repair or for any other purpose, it shall be- come desirable to remove one of the bridges, that may readily be done by applying a hot instrument or hot air to the caps to soften the gutta-percha sufficiently to permit the telescoping bridge to be taken off. 246 ARTIFICIAL CROWN- AND BRIDGE-WORK. "A full upper vulcanite denture was made to replace the old one, which, by improper occlusion, had thrown the full force of mastication on the anterior teeth of the lower jaw, and produced the destructive action that resulted in the deplorable loss of tooth-substance shown in Fig. 485."1 The next case also presented unusual difficulties. " The forward overhang of the inferior right second molar was so excessive that an impression could hardly be taken, until with corundum-wheels and points the sides of the tooth had been made parallel, or rather slightly tapering to form a truncated cone, with the neck Fig. 488. Fig. 489. as a base. The molar was alive and sound, but the crown was gone from the pulpless cuspid, which I suitably shaped by means of my root-trimmers (Fig. 488). " An impression was then taken, the cast from which is illus- trated by Fig. 489. A seamless gold collar was, by means of a slightly tapering mandrel, made to exactly fit the tapered natural molar, the lower edge of the collar cut to conform to the gin- gival margin ; a cap piece of gold plate soldered to the top edge of the collar, and a hole drilled through the center of the com- pleted cap (A). Care was taken to so fit and proportion the cap that it would require finally pretty hard driving to send it home 1 Dental Cosmos, vol. xxviii, No. 1, page 17. DETACHABLE AND REMOVABLE BRIDGE-WORK. 247 on the tooth; but first there was fitted to the cap a telescoping seamless collar, on which was soldered a gold plate, with cusps, to form a molar crown as shown. The molar was then thoroughly dried, slightly painted with Agate cement, and the cap, A, driven hard down with a flat pine stick held upon it and struck with a mallet; the hole in the cap enabling me to see when the cap was quite down. The cuspid was then likewise fitted with a seam- less gold collar, the top edge of which was given a roof-shape, as seen above the root in Fig. 489. A piece of gold received a corresponding roof-shape, had a short section of gold tubing soldered into it, and was trimmed to the outline of the collar, beside which, B, its form is seen, and to which it was subse- quently soldered, after suitable investment to keep the parts in Fig. 490. proper place. The root-canal had been previously prepared to receive the tube, which, with its roofed cap, was with stick and mallet driven hard down over the root. A piece of gold wire exactly fitting the tube had a roof-shaped piece of properly perforated gold plate slipped over it into position on the root; became fixed in such relation by a drop of melted hard wax; was removed, invested, soldered, and finished in such shape that, excepting the hollowness, it looked like the tube and cap B. " The relations of the occluding teeth had, of course, been determined by an articulating model, and by means of it a series of seamless gold collars and cusp-crowns were adjusted on a thin platinum plate fitted on the cast between the cuspid and second molar and the collars soldered to the plate after investment. * 248 ARTIFICIAL CROWN- AND BRIDGE-WORK. The truss thus formed received an appropriate finish by the rounding and smoothing of its basal borders. A plain plate cuspid was backed with gold plate and fitted on the roof-plate,to which, after determining its proper occlusion, it was secured by hard wax; removed, invested, and soldered. It was then put into the tube on the root; the telescoping cap put over the molar; the truss put in position in the mouth, and the whole covered with plaster and marble-dust, contained in a suitable sectional impression-tray, wdiich enabled me to hold the mass steadily in place until the mixture was sufficiently hard to bring away cap and truss and roof-plate all in proper position. A second mixture of plaster and marble-dust, and a suitable trimming of the first mixture after all was hard, sufficed for the soldering process that resulted in the denture which, when finished, appeared as shown detached at C, Fig. 489, and mounted on the cast in Fig. 490. It went firmly to place in the mouth, and yet was removable in the possible event of accident to the denture, or for readjustment of the cusp-crowns, which latter could easily be done by warming the piece sufficiently to soften the gutta-percha, replacing the denture on its anchorages, and directing the proper closure of the occluding teeth." DR. PARR'S METHODS. Detachable.—Fig. 491 illustrates a method of this style. The teeth forming the abutments lean toward each other posteriorly and anteriorly over the space to be bridged, as shown on the Fig. 491. original model, Fig. 492. The bridge is supported by two shoulders on the abutment crowns, which slide into grooves in the dummies (Fig. 493). These supporting shoulders and slots are made by shaping two pieces of platinum plate to the form DETACHABLE AND REMOVABLE BRIDGE-WORK. 249 shown in Fig. 494, so that one shall telescope the other. The inner one is then invested on the outside surface and filled in with gold plate. The outer piece is then filled inside with investing material, and gold plate is flowed over the outer surface. The shoulders are first soldered to the crowns, and afterward the slots are adjusted to them and soldered in position in the bridge. Fig. 492. Fig. 493. V CD Fig. 494. Fig. 495. Fig. 495 shows a bridge constructed with the attachment described at one end and a double cap attachment at the other.1 Removable Bridge.—In this style the crowns forming the abut- ments are permanently cemented in position, each section of the bridge between them being removable. The case illustrated in Fig 496 will serve as a type to give the constructive details. The cuspid and molar crowns are first formed in the usual man- ner. A model from an impression is then made on which the crowns will appear in the^ame position as in the mouth^gold ~i Case o7DiTc7L.~Alexander, described page 27, Dental Cosmos, vol. xxxiii. 5 250 ARTIFICIAL CROWN- AND BRIDGE-WORK. and platinum bar (A, Fig. 497) is then formed between the cuspid and molar. The end for the cuspid is rounded, and that for the molar flattened. This last may be done by hammering the wire flat or by soldering a piece of clasp plate transversely to it. The two ends of the bar are then fitted in sockets of platinum (B, B). The ends of the bar should be bent and the platinum sockets placed in such a position against the sides of Ftg. 496. the crowns that the bar can be easily adjusted and removed. The sockets are next soldered to the sides of the cuspid and molar crowns (A, A, Fig. 496), for which purpose the sockets and crowns should be removed and invested. The sockets are held in position when the wax is melted out by pieces of iron wire, one end of which, covered with a portion of the investing material, is inserted in the socket, the other end being imbedded in the investment. If preferred, the slot on the side of the Fig. 497. Bi | B molar crown can be made with a piece of platinum adapted over the flat piece of gold forming the end of the bar, and then sol- dering the platinum to the side of the crown, the platinum being stiffened by flowing the solder over it. At this point the crowns and bar may be adjusted in the mouth, as well as on the model, to insure accuracy. A piece of thin platinum or gold is then perforated and slipped over the ends of the bar, which is DETACHABLE AND REMOVABLE BRIDGE-WORK. 251 placed in position on the crowns, and the platinum or gold adapted to the form of the attachments, and to the immediately adjacent surfaces of the crowns. These shell forms are made to assure to the ends of the bridge a perfect fit by giving them the shape of the crowns and the attachments on the crowns. To this bar the teeth constituting the bridge are fitted in their respective positions and soldered. Bending either end of the bar slightly (B, B, Fig. 496) or sawing a slit in the cuspid end of it (Fig. 428), affords the means of holding the bridge firmly in position, although it may be removed and reinserted at the option of its wearer. Fig. 498 shows the inserted bridge. Fig. 499 shows another method of forming a socket attach- ment. In the figure, the socket section of the attachment is seen projecting from the side of the molar crown. The other Fig. 498. Fig. 499. section consists of a cap having a spring flange. The flange enters the socket, which the cap incloses on the top and sides. The spring is made by bending open a little the part of the flange marked A. This form of attachment is constructed as follows: To make the spring flange, two pieces of clasp or spring gold plate about No. 23 TJ. S. standard gauge, one of them one-half and the other one-fourth of an inch long and from one-eighth to one-quarter of an inch wide, the exact dimensions being governed by the case in hand, are laid together, so that one end of the short piece is nearer one end of the larger piece than the other. The edge of the short piece nearest the end of the longer one is then soldered to it with a hard-flowing solder, the two being held during the operation in a blue gas flame with tweezers, and the end is trimmed square. A little whiting placed between the other edges will prevent the solder from flowing between or joining the pieces there. The 252 ARTIFICIAL CROWN- AND BRIDGE-WORK. short piece of plate is to form the spring, and is left unconnected at one end for that purpose (A, Fig. 500). To Form the Socket.—The spring flange is first enveloped once around with a thin piece of platinum, a little deeper than the socket is required. The platinum is then enveloped with one thickness of coin gold plate, No. 32 U. S. standard gauge, about the depth the socket is to be, leaving a ledge of the platinum projecting. The plati- num and gold are next removed and soldered, by holding them in a flame and using very little solder, of a hard- flowing variety, which is placed upon the ledge. The sides and ends of the socket are then filed level and the socket given a square form (B). To Form the Cap.—The spring flange having been inserted in the socket, two pieces of the spring gold plate of the same length as the socket are adjusted along its sides, the pieces being cut a little wider than the depth of the socket, so that when adjusted they shall project slightly above it. A piece of thin platinum plate is then adapted to the end of the flange, to the socket, and to the pieces of spring plate, first being perforated to allow the projecting ends of the latter to pass through it. The spring plates and the flange plate are then cemented to the platinum plate with wax, removed from the socket, invested, and soldered (C). The sockets must be so placed on the crowns that the springs at the ends of the bridge shall enter them on parallel lines. Their proper relative positions to secure this movement are readily determined by attaching the tops of the spring flanges (either temporarily or permanently) to the ends of a piece of wire of the length of the space to be bridged, which will permit the necessary adjustment. The sockets are then soldered onto the crowns. When the bridge teeth or dummies adjoining the sockets have been fitted in position, they are withdrawn with the caps and spring flanges, and soldered to the bar, in the manner described DETACHABLE AND REMOVABLE BRIDGE-WORK. 253 at page 250. The gold caps forming the occluding surfaces of the bridge tooth1, can usually be fitted over the cap. When the socket is attached lengthwise from labial to palatal side to a gold Fig. 501. Fig. 502. Fig. 503. A, Fig. 496, the spring metal plate of the flange is Dii the side t~" In a bridge of this sty crown as at best placed on the side toward the crown. -^-yle of the anterior teeth only,—where the 254 ARTIFICIAL CROWN- AND BRIDGE-WORK. abutments form the extremities of the piece,—the ends should be attached to the mesial sides of the crowns forming the sup- Fig. 504. ports; but when it also carries teeth posterior to the abutment,. and the sections of the bridge are united together, the attach- Fig. 505. Fig. 506. Fig. 507. ment should be made on the distal side, the bar supporting the anterior teeth resting in a slot formed on the palatal side of the abutment (Fig. 501). A shell crown on a cuspid can be utilized as a support for this form of attachment. DETACHABLE AND REMOVABLE BRIDGE-WORK. The attachment described can also be used in combination with removable plate bridges. Fig. 502 shows the cast of a lower jaw in which only the left second molar, left cuspid, and right first bicuspid remained. The molar and bicuspid were fitted with gold cap crowns, and spring socket attachments (Dr. Parr's form) were soldered in proper positions on the crowns, as illustrated. The completed denture in position supported by the attachments is seen in Fig. 503. The under side is shown in Fig. 504. Fig. 505 represents the articulated cast of a case in which a similar form of attachment and a clasp were used. This is illustrated in Fig. 506, which needs no description. Fig. 507 shows the denture in place. It was constructed of vulcanite, and made for and placed in the mouth of a patient exhibited at a clinic of the Odontological Society of Pennsyl- vania, at Philadelphia, in December, 1888.1 DR. WATERS'S METHODS.2 Dr. T. S. Waters explains the advantages of his removable plate bridge-work as follows: "In the system I present the denture is retained securely and steadily in the mouth, yet is readily removed and replaced at pleasure by the wearer. The pressure and strain are distributed properly over all the struc- tures and tissues available for the purpose, and the roots and crowns to which the denture is attached are so prepared that there is no place for the lodgment and retention of food, and when the denture is removed, both it and the mouth can be thoroughly cleansed. Should the roots or other tissues be attacked by disease, thus requiring treatment, or should repairs to the mechanism become necessary, the removable bridge-work offers facilities for those purposes not to be found in permanent dentures." Dr. Waters thus describes the formation, combination, and application of his devices to cases of removable plate bridge- work: " My devices are three in number, each of which maybe used 1 Dental Cosmos, March, 1889. 2 International Dental Journal, April, 1889, p. 197 256 ARTIFICIAL CROWN- AND BRIDGE-WORK. alone, or two of them or all three may be combined and applied in the same case, as the position, character, and relation of the teeth and roots remaining in the mouth may seem to indicate. Fig. 508. " The first is a gold crown fitted to and sliding on a cap attached permanently to the root or natural crown. This cap is made high and has on one side a longitudinal groove. The gold Fig. 609. crown has soldered on the inside a spring catch, which works in the groove on the cap, and holds the crown firmly in its place. The character of the device is seen in application to the case Fig. 510. represented in Fig. 508. Fig. 509 shows the denture in position. Fig. 510 gives the lingual aspect. It will be readily seen that under proper circumstances two or more roots or teeth may be DETACHABLE AND REMOVABLE BRIDGE-WORK. 257 fitted with this device, the gold crown may be soldered to and made a part of the denture, making the whole a piece of bridge- work capable of being removed, cleaned, and replaced at will. The spring catch regulates the firmness of retention.1 " The next device is the box cap and split post; the box cap being fitted permanently to the root, and the split post being Fig. 511. Fig. 513. soldered to the plate bearing the teeth. The box cap is the usual cap, with a box or tube soldered to it and extending into the root, the cap end of the tube being open. The split post is so secured to thedeuture as to slide snugly into this tube the firm ness of retention being regulatedjby press.ng the split slightly 1 Dr. Waters has pa tented this invention and donated it to the profession. 18 258 ARTIFICIAL CROWN- AND BRIDGE-WORK. open when necessary. This device, like the first, may, under proper circumstances, be used by itself in any case, as shown in application in Figs. 511, 512, and 513, in which the whole denture Fig. 514. is supported by box caps and split posts adjusted to the roots of the six anterior teeth. " The third device consists in soldering to the side of the gold DETACHABLE AND REMOVABLE BRIDGE-WORK. 259 crown covering the natural tooth a split pin or post, which is inserted into the open tube attached to the denture. " As before remarked, these devices may be used singly or in combination in any one case. In one of the dentures illustrated the box cap and split post alone are used; in another, the cap, gold crown, and spring catch are used; in the case illustrated in Figs. 514, 515, and 516 the three are applied, in which the entire denture is attached to and retained by two cuspids, a bicuspid, and a molar. In all this, great care must of course be taken in the preparation of the roots and natural crowns, to protect them against the action of destructive agents." CHAPTER XII. REMOVABLE BAR-BRIDGES. In removable bar bridge-wTork the bar is permanently attached to the abutments, and spans the space between them independent of the bridge. The bridge portion proper of the denture, con- sisting of the artificial teeth (dummies), is formed with a slot, or a countersunk base, into which the bar slides as the bridge is placed in position. Fig. 517. In the case represented in Fig. 517, one end of the bar is attached to the gold molar crown and the other end anchored in the cuspid with a gold filling. The bridge section fits over the bar as illustrated. The process of construction given by Dr. J. G. Morey is as follows: The molar is capped with gold. A flat bar of iridio-platinum, about No. 12 gauge and one-eighth of an inch wide,—the width being regulated by the needs of the case in hand,—is fitted to the space. One end of the bar is fitted in the anchorage cavity in the cuspid, and the other end to the gold molar crown. A slot is then cut in the bar, beveled slightly toward the gum (Fig. 517). A piece of gold clasp plate, about No. 28 gauge, the width of the slot, is cut and shaped in the form of a clamp to fit over both sides of the bar and in the slot. The end of the bar is then soldered to the gold crown. The bar must be placed far enough toward the palatal side to leave space for the artificial teeth. 260 REMOVABLE BAR-BRIDGES. 261 Porcelain teeth are next fitted in place, backed with thin plat- inum, cemented with wax to the clamp-shaped piece of gold and removed from the bar. Teeth and gold clamp are then in- vested and soldered together. In investing, one end of a narrow strip of sheet iron is inserted in the slot of the gold clamp, and the other end extended into the body of the investment, to hold and steady the gold clamp in position, while the gold solder is flowed between it and the porcelain tooth after the wax is removed. When finished, the point of the gold clamp is to be bent a little inward to secure and fasten the bridge section when slid into position on the bar. Firmness is also obtained by the slightly beveled form given to the slot in the bar. Fig" 518 Fig. 518. Fig. 519. C_ gives a sectional side view of the bridge-tooth and bar. Fig. 519 represents the bar and bridge section in position.1 Dr. Morey's method of constructing a double bar-bridge with a removable molar or dummy is as follows : The bar is formed as seen in Fig. 520. " A countersunk molar is ground and shaped as seen at A and B, Fig. 521. To the base of the molar and up in the slot is shaped and fitted the shell C, made of a very thin piece of gold and platinum crown-metal by 1A description of a removable bar-bridge, as given by Dr. J. G. Morey, was presented in the first and second editions of this work. A more extended de- scription of bridge-work on this principle is given in the present edition, as many members of the profession seem to favor the various methods it involves. In England the method is designated the " Gartrell Bridge," having been intro- duced there by Dr. Gartrell, an American dentist, formerly of New York, now practicing at Penzance, England. The models of a case similar to the one illustrated in Figs. 517 and 519 were exhibited at the Ninth International Medical Congress at Washington and presented by Dr. Morey to the author in 1887, and are still in his possession ; but as the method did not favorably impress him at the time, further description of it than has heretofore been given was withheld.—G. E. 262 ARTIFICIAL CROWN- AND BRIDGE-WORK. first stamping it on a fusible metal die of the base and then adapting it to the part. A thin piece of clasp-metal (D) is then formed to fit over the bar and in proper position into the slot of the shell (C, Fig. 520), to which it is soldered by investing and soldering on the inside of the shell. The shell is then cemented with oxyphosphate onto the base of the molar as seen at A and B, Fig. 520, and is secured to the bar by springing together the edge of the metal at D, Fig. 521. Fig. 522 illustrates the tooth in position. A variation in the method of construction of removable bar- bridges involving the principle above demonstrated is given by Dr. G. L. Curtis in the following case, illustrated in Fig. 523. The bicuspid and molars are capped with gold, and models made. In the construction of the dummies, the caps and backing at first are merely joined together with solder only sufficient to prevent movement of the caps. The sockets like A, Fig. 524, which are made of thin gold, are then placed in position and held by means of fluxed wax, and the entire piece again incased as before, so that the ends of the sockets project beyond the cusp-surface of the bridge and are imbedded in the plaster, which holds them in position. The wax is melted out and the sockets soldered into place. After cooling, the projecting parts of the sockets REMOVABLE BAR-BRIDGES. 263 are cut away until the bridge fits perfectly between the crowns, and the soldered surface is ground away to the proper fullness, and the whole piece rendered quite smooth or ready for polishing (C, Fig. 523). Arms like B, Fig. 524, are now placed into the sockets and cut off until a perfect adjustment with the crown is obtained. It will be found that the arms are considerably wider Fig. 523. Fig. 524. A" \ ^\ + Fig. 526. than the sockets are deep, allowing them to project one-sixteenth of an inch or more. Secure the bridge in position by a drop of wax at the junction of the porcelain surface and the cast, then varnish the palatal surface of the cast and pour soft plaster and marble-dust over this surface until it is on a level with the masticating surface, and allow it to harden. Then carefully 264 ARTIFICIAL CROWN- AND BRIDGE-WORK. remove the bridge and replace the arms in position as marked in the plaster, and retain them by means of additional plaster, or by steel springs, and solder them to the crowns, first placing in the joint sufficient fluxed wax so that in the process of sol- dering the arms will be perfectly united to the crown, which requires a very small quantity of solder. The case is now ready to finish. Fig. 527. If the adjustment of arm and socket is perfect, the structure will be found to fit so snugly that it is only with considerable effort that the bridge can be removed. With everything in readiness for cementing, the crowns are quickly forced into position, the bridge carried to place, and the cement allowed to harden. Should there be necessary in the articulation any alteration REMOVABLE BAR-BRIDGES. 265 that cannot be met by grinding off the cusps of the antagonizing teeth, the bridge can readily be removed without disturbing the crowns. The arm B, Fig. 524, is made of a strip of clasp-metal, No. 16 gauge in thickness, and of any desired width or length. The strip is placed in a slot like E, Fig. 525, and the projecting end hammered to form a solid head as shown. A longer or shorter arm may be formed in the slot F, wherein the adjustable limit, G, may be set to limit the length of the arm while the hammered head is being formed. A piece of 20-carat gold plate, or pref- erably clasp-metal No. 33 gauge, is cut to the size and shape of Fig. 526, and by means of a former, K, Fig. 525, is forced into a suitable slot. The place of the former K is then taken by the arm B, Fig. 524, and the part H, Fig. 525, bent and delicately hammered over the head of the arm. The socket so formed is then removed, soldered from the outside, and finished as at A, to exactly fit the arm B, Fig. 524. Figs. 527 and 528 illustrate a case by Dr. Parr, in which a removable bar-bridge plate was applied. CHAPTER XIII. THE LOW BRIDGE. Dr. J. E. Low is the reputed inventor of bridge-work formed with self-cleansing spaces and supported by means of cemented collars or collar crowns.1 The following is Dr. Low's method of using his step-plug crown (see page 128) in conjunction with all-gold cap crowns in bridge-work. Fig. 529 shows a case with the prepared molar crowns and cuspid roots. The bridge constructed according to this method is seen in Fig. 530, and adjusted in position in Fig. 531. Figs. 532, 533, and 534 illustrate a case of four incisors supported by two step-plug crowns on the cuspids. Dr. Low gives the following instructions relating to the con- struction of shell crowns or anchorages on cuspids, to support a bridge of the four incisors in a case such as is shown in Fig. 535 : " I first measure the tooth with strips of tin, and make the gold bands and cut out the outside lower portion of the band before 1 The construction of bridge-work supported by collars or any form of collar crowns cemented on teeth or roots, according to a judicial decision, is not at present free to public use. The two claims which reserve the use of these methods to the inventor as specified in the letters patent granted, are as follows: " What I now claim as new is : 1. The herein-described method of inserting and supporting artificial teeth, which consists in attaching said artificial teeth to continuous bands fitted and cemented to the adjoining permanent teeth, whereby said artificial teeth are supported by said permanent teeth without dependence upon the gum beneath. " 2. An artificial tooth cut away at the back, so as not to present any contact with the gum except along its front lower edge, and supported by rigid attach- ment to one or more adjoining permanent teeth, substantially as and for the purpose set forth." A denture between two or more teeth or roots, supported by such means as bars extending from it anchored into teeth or caps or crowns which do not encircle the teeth or roots, with the artificial teeth resting on or pressing into the gums and not formed with what are termed and described as self-cleansing spaces, and removable bridge-work, are not, in the opinion of experts, included in the mean- ing or specifications of this patent.—G. E. 266 THE LOW BRIDGE. 267 beginning to fit. In fitting, as the band is being driven down, cut away any of the band that touches the gum before all touches; never drive the band under the gum, as inflammation will prob- Fig. 529. ably follow. I mention this, as I have seen many attempts to get rid of the bands by driving up under the gums and cutting them out on the front, until they are too narrow for strength. The bands should be heavy and strong, and the patient should under- ARTIFICIAL CROWN- AND BRIDGE-WORK. stand that if he expects to get rid of the annoyance of the plate he must sacrifice his dislike to showing gold. After driving the bands up close to the margin of the gums, as the cuspid teeth are very tapering, the bands will have to be taken in at the Fig. 532. bottom. To do this I slit the band about a third of its length up, then place it on the tooth again, lap it over to bring it to a close fit, and then take it off and solder. Continue taking it in wherever it does not perfectly fit the tooth, and after a good fit Fig. 533. Fig. 534. is obtained proceed with the construction of the bridge by taking an impression and articulation. " In adjusting the bridge when finished, first try it on to see that it fits and that the articulation is all right. Fig. 536 shows the case ready for adjustment. Next dry the teeth upon which the bands are going, and then mix your cement. This should THE LOW BRIDGE. 269 be mixed to about the consistence of thick cream. It must be neither too thick nor too thin, or the adhesion will not be stron- enough to hold. Cover your teeth with cement, and then the Fig. 535. inside of the bands. Place these on the teeth and carefully mallet up into position. For this purpose I use a steel instru- ment with a crease or groove in the end. The teeth must be kept dry after the case is in position until the cement is well set. Fig. 536. Fig. 537. After this is done bevel the edges of the bands and burnish close to the teeth, and if properly done they will resemble gold fillings. In Fig. 537 we have the case completed. I always impress upon my patients the necessity of having the case reset immedi- ately should it become loose, and advise them to have their cases examined at least once a year." CHAPTER XIV. DR. KNAPP'S METHODS. Dr. J. Rollo Knapp has introduced some novel methods in crown- and bridge-work, for effecting artistic results and con- tinuity of structure. In crown-work, Dr. Knapp invests for soldering so that the parts to be united and filled form a miniature mold. Into this mold, at a high heat, with a pointed flame from his blow-pipe, he flows solder, which fills the interstices, joins the parts, and assumes the form of the mold. The following is a brief descrip- tion of his methods: Fig. 538. Fig. 539. In constructing a gold collar crown with porcelain front, for an incisor or cuspid, 22-carat The S. S. White Dental Mfg. Co.'s collar gold, No. 28 standard gauge, is used for the collar, which is formed by adapting the gold to the root by the aid of pliers. The cap to the band is then made of pure gold, No. 34 gauge, and a gold pin soldered in position for the root-canal. A plate tooth is then ground in proper position, backed with pure gold, and fastened to the cap with wax. On being removed from the mouth after proper adjustment, the side and incisive portions of the wax, including the edges of the backing and contiguous portions of the cap, are completely enveloped with pieces of pure gold No. 34 gauge (Figs. 538 and 539). The crown is then invested so that when the wax is removed the backing on the tooth with the gold on the sides shall form a small mold or pocket (Figs. 540 270 DR. KNAPP'S METHODS. 271 and 541). When the investment is heated, the flame of his blow-pipe is played over its surface until the mass is aglow, when the point of the flame is thrown into the mold by rapid thrusts until the solder melts like wax and fills every part of the mold with liquid gold. This gives an excess of gold which affords ample facilities for contouring in the process of finishing (Figs. 542 and 543). Fig. 540. Fig. 541. Fig. 542. Fig. 543. In constructing a bicuspid crown with porcelain face, the natural tooth is ground down to the gingival edge and capped similar to a cuspid. A bicuspid porcelain front is then ground and fitted in position (Fig. 544), and the remaining portion of the crown is shaped in wax to the form required. A die of the grinding-surface is then made in metal, a cap stamped in pure Fig. 544. Fig. 545. Fig. 546. Fig. 547. Fig. 548. Fig. 549. gold, No. 34 U. S. standard gauge (Fig. 545), and the cusps filled with 20-carat gold solder. This cap is next trimmed (Fig. 546) so as to fit when placed in proper position against the end of the porcelain cusp, for which purpose sufficient wax must be removed. The approximal surfaces are enveloped and the palatal portion of the collar protected with pieces of pure gold, No. 34 standard gauge, which are slit to facilitate their adjust- 272 ARTIFICIAL CROWN- AND BRIDGE-WORK ment (Fig. 547). This leaves the palatal portion open when the crown is invested and the wax removed, which last should be done with hot water. Fig. 548 shows the invested crown ready for soldering, in which operation the parts are filled in and joined with 20-carat gold solder. The result when finished is a solid gold crown with a porcelain front (Fig. 549). All-gold bicuspid and molar crowns are formed by Dr. Knapp in a similar manner, but as porcelain fronts are not used in these cases, the thin gold plate is placed entirely around the labial aspect of the wax model. In crown-work, after the cap has been made, an impression is generally taken and a plaster Fig. 550. Fig. 551. model and articulation made to facilitate the subsequent con- struction. Dr. Knapp's method of constructing bridge-work is similar to that in general use except in the investing and the soldering to- gether of the parts, the latter being done with the blow-pipe in a manner similar to that above described. Figs. 550 and 551 illustrate specimens. Dr. Knapp's compound blow-pipe (Fig. 552) consists of a miniature blow-pipe in which the ordinary illuminating gas (carburetted hydrogen or coal gas) flame is combined with a current of nitrous oxide from a cylinder of the condensed gas. The combination of these gases in combustion forms essentially DR. KNAPP'S METHODS. 273 a carbo-oxyhydrogen flame.1 By means of a yoke and set- screw, the valve of the cylinder is connected with the tubes and valves of the blow-pipe, so that the proportions of the mixture Fig. 552. 1 The ordinary compound oxyhydrogen blow-pipe flame is produced by 2 volumes of hydrogen; 1 volume of oxygen. Carburetted hydrogen consists of 2 volumes of hydrogen ; 1 volume of carbon. And nitrous oxide of 2 volumes of hydrogen; 1 volume of oxygen. Consequently Knapp's blow-pipe flame is produced by a mechanical mixture of 2 volumes of hydrogen ; 1 volume of oxygen ; 1 volume of carbon. 19 274 ARTIFICIAL CROWN- AND BRIDGE-WORK. of nitrous oxide and the illuminating gases are under perfect control. The flame-jet can be diminished to half an inch in length, and at that size will melt a small piece of gold plate. Where illuminating gas is not available, an apparatus termed a carburetter can be used, which supplies the deficiency in a simple manner by vaporizing naphtha. This blow-pipe is useful for many purposes in the laboratory of the present time, especially in forming solid gold backings to dummies for bridge-work, strengthening seamless gold crowns, and forming solid gold crowns. Dr. Knapp has exhibited to the profession some very fine specimens of crown- and bridge-work, and presented much that is novel and interesting, as well as encouraging to the artistic element of prosthetic dentistry. The real value of processes or methods, however, depends on their practicability. Therefore, in contemplating that which is novel and beautiful in connection with dental art, we must be governed by this fact in estimating its value. Judged from this standpoint, Dr. Knapp's special methods, while admitting of the highest artistic results, embrace some processes which, on account of their intricacy, are not likely to be generally adopted in practice. CHAPTE R XY. DR. MELOTTE'S METHOD. Dr. G. W. Melotte describes the construction of a bridge supported by a gold crown, and a shell or partial gold crown, and the use of his invention, "moldine," in connection with fusible metal in crown- and bridge-work, as follows:1 "Fig. 553 illustrates a case for the supply of a lateral and a bicuspid. In this instance the cuspid could be cut off, and the root collared and capped in combination with a pin entering the enlarged root-canal; but as there may be grounds for objection to cutting off sound teeth, I ob- viate the necessity by cutting a shoulder on the lingual portion of the cuspid, and suitably shaping its sides to permit a close fitting of the collar just under the free margin of the gum. A narrow strip of pure pattern tin, bent tight around the tooth-neck, and cut through with a knife at the lap on the labial surface, will serve as a measure for the length of a strip of 22-carat gold plate, No. 29 thick, and as wide as the length of the distal side of the cuspid. The ends of the gold are then squared, and with round-nosed pliers brought evenly together, to be held in flush contact by the soldering- clamp as shown in Fig. 554. The soldered collar, with its joint side inward, is then adjusted on the tooth as accurately as pos- sible, giving slight blows with a mallet until the collar touches the gum, when it should be marked to indicate the necessary trimming to conform it to the gum contour. After it has been thus trimmed, the edges beveled, the labial part swelled with contouring pliers, and the lingual part cut down to about one- tenth of an inch in width, the collar is again driven on, and will 1 Dental Cosmos, vol. xxviii, No. 12, page 745. 275 276 ARTIFICIAL CROWN- AND BRIDGE-WORK. appear as seen in Fig. 553. A stump corundum-wheel is then used to grind a shoulder on the lingual surface of the tooth, grinding also the edges of the collar flush with the shoulder. The collar is again removed, and a piece of thin platinum plate, about No. 32, sufficient to cover the lingual surface of the tooth, is caught on the lingual edge of the collar by the least bit of solder, and all put in place on the cuspid (Fig. 555). The platinum should now be burnished on to the shoulder, and over the tooth and collar to the extent shown by the lines in Fig. 555. Fig. 554. After trimming to those lines, and careful replacement and bur- nishing on the tooth, the collar and half-cap are removed, filled with wet plaster and marble-dust, and the platinum soldered to the gold. It is then placed on the tooth, burnished into all the inequalities of the tooth, very carefully removed, invested, and Fig. 555. Fig. 556. Fig. 557. enough solder flowed over the platinum to cover and give it strength. Fig. 556 shows it complete on the cuspid. " I have feared that a detailed statement would imply a long and tedious process, but I have often made such collars in less than an hour, and in any case time must be made subservient to exactness of fit and adaptation to the end in view. " In the preparation for fitting a collar on the first molar (Fig. 553), I should have wedged or otherwise separated it from the second molar, so that a piece of sheet brass might be put in place, as shown by Fig. 557, and an impression taken in plaster, DR. MELOTTE'S METHOD. 277 which if allowed to get hard would bring away the metal. If not, it could be replaced in the plaster. Melted fusible metal, when near the cooling-point, is then poured into the impression, and when cold will allow the safe removal of both the plaster and the metal strip. On this metal model a collar can be formed that will accurately fit the molar, as seen in Fig. 553. If the molar has no antagonist, a cap may at once be struck up on the model; but if there be an antagonist the cusps of the natural molar should be removed by grinding at points where the occluding tooth will admit of sufficient thickness of the gold cap. An exact copy of the ground cusps can then be made in less than five minutes, by the use of moldine with its acces- sories, and the process is as follows: Make the tooth perfectly dry. Put the collar on it. Nearly fill the cup with moldine, and coat it with soapstone powder. Press the compound on the tooth and collar firmly to about one-fourth the depth of the tooth. Carefully remove the cup; trim off any overhanging material, and place the rubber ring over the cup to about one- half the depth of the ring. Melt the fusible metal and pour it as cool as it will run from the iron ladle. As soon as the metal is hard, remove it with the ring, taking care not to impair the impression, which can be used again if the die is found imperfect or gets injured in use. Place the die and ring in cold water, to remain until quite cooled. While the die is wet and held over a basin of water, pour into the ring fusible metal which has been stirred until it begins to granulate, and quickly immerse all in the water. The die and counter-die should separate readily by tapping them with a hammer, but if they stick others can be quickly made from the same impression by the same method, using more care. With this die and its counter-die, a piece of No. 29 or 30 gold plate is swaged to fit perfectly the cusps and collar, which, when removed, can be held to its place on the cap by the soldering-clamp, using spring pressure enough merely to hold them together for careful soldering with the pointed flame so as not to unsolder the collar. The seamless collars are excel- lent when care is used in selecting the proper size, as directed on the diagram (see page 290). " The caps being in place on the cuspid and molar, an impres- 278 ARTIFICIAL CROWN- AND BRIDGE-WORK. sion is taken with plaster; the caps accurately set in the impres- sion, and hard wax melted with a hot spatula around the edges of the caps. The impression is then thoroughly coated with sandarac varnish, after which it is dipped for a moment in water, and filled with a wet mixture of one part marble-dust with two parts of plaster; using great care to perfectly fill the caps and molds of the teeth. Wait until this mixture has become quite hard; remove the cup, and with a suitable knife chip off the plaster without marring the cast: secure a good articulating Fig. 558. impression and transfer it to the cast to obtain an exact repro- duction of the relative occlusions of all the teeth involved. With such an articulation in hand, and with the means already described for swaging gold or platinum plate to fit the cusps and articulating surfaces of either the natural or artificial teeth, it should be within the capacity of any competent dentist to com- plete a suitable bridge; although there are practical points that can only be imparted by clinical instruction and actual demon- stration in the mouth. Such a bridge is shown in position by Fig. 558." CHAPTER XVI. PARTIAL CAP AND PIN-BRIDGE METHODS. Dr. W. F. Litch's processes in this style of work have for special cases many decided advantages, and are thus described by him:* "Fig. 559 represents a typical case, in which a lateral incisor (crown and root) has been lost, the cuspid and front incisor, fully vitalized, and without approximal carious cavities, remaining in position. " To Make a Pin and Plate Bridge. — 1. Take in plaster an accurate impression of the cuspid and incisor and the interspace. From this obtain a plaster model of the parts. Fig. 559. "2. Make from pure gold, rolled to the thinness of No. 26, standard gauge, base-plates, to be carefully adjusted to the palato- approximal surfaces of the cuspid and incisor. These can be made by swaging on dies and counter-dies obtained from the model, but more conveniently by bending the gold into shape upon the plaster model and pressing and burnishing it into perfect adaptation upon the natural teeth. "3. Select a plain plate porcelain tooth of suitable length, shape, and shade, and wide enough to fit easily into the inter- space. Let the neck of the tooth rest lightly upon the gum. i Dental Cosmos, »ol. xxviii, No. 3. 279 280 ARTIFICIAL CROWN- AND BRIDGE-WORK. " 4. With pure gold or platinum make a backing for the por- celain tooth. " 5. Place the tooth thus prepared and the base-plates already made upon the cast, and accurately adjust the approximal edges of the base-plates to the backing of the porcelain tooth in situ upon the cast. "6. When this adjustment is made, cement together the base- plates and backing with a brittle, resinous cement (resin, two parts; wax, one part; or sealing-wax will answer), and before the cement has fully hardened remove from the cast to position in the mouth, perfecting the final adjustment there. By this method much greater accuracy of adaptation is obtained, as the lines of length, width, and contour are too fine to be repro- duced with absolute fidelity in a plaster model. In this part of the process too much care cannot be taken to have each piece of the appliance fitted with absolute accuracy to the surface for which it is designed. When this has been accomplished, throw upon the yet more or less plastic cement a stream of ice-cold water from an office syringe; this renders the cement perfectly brittle and incapable of bending. This done, immediately remove from the mouth and invest in a mixture of equal parts of marble-dust and plaster of Paris. "7. After the investment has firmly set, solder the base- plates to the backing, and the backing to the platinum pins of the porcelain tooth, using as a solder 20-carat gold. Thus joined, the appliance will present the appearance shown in Fig. 563,—A representing the base-plate for the cuspid; B, the base- plate for the incisor; C, the porcelain tooth with its platinum backing; D, the points of union between the base-plates and backing. At these points the greatest strength is required, and it is important that here a large amount of the solder should be placed. The porcelain tooth being usually thinner than the natural teeth, there is nearly always an angle or depression at the points indicated, in which the thickness of the gold can be considerably increased without interfering with occlusion. " 8. For the purpose of attaching the denture as thus far con- structed, drill a small cylindrical opening through the palatal surface of the enamel of the cuspid and incisor respectively. PARTIAL CAP AND PIN-BRIDGE METHODS. 281 These openings should usually be placed about as indicated in Fig. 562, at C, D. Sometimes, owing to a close occlusion or to Fig. 560. Fig 561. the contour of the tooth, it is desirable that they should be located a trifle nearer the neck of the tooth. Each opening should be Fig. 562. well undercut, but must not encroach upon the dentine far enough to endanger the pulp. In size the openings need not be larger than will admit a platinum pin-head, in diameter cor- responding to No. 13, standard gauge, with a shank of No. 18, standard gauge. Into each of these openings must be fitted a platinum pin of the size indicated. The head of each pin must be made thin and perfectly flat both upon its upper and under surfaces.1____________________.______ " i Practical experience in the use of attachments of this form shows that two pins in one, if not in each of the caps, are necessary.—G. E. 282 ARTIFICIAL CROWN- AND BRIDGE-WORK. " 9. In each of the base-plates make an opening correspond- ing in position to those in the natural teeth. Pass through these openings and cement in them the free ends of the platinum pins. While the cement is yet plastic, place the denture in position in the mouth, carefully pressing the pin-heads into the openings made for them, and burnishing the base-plates into perfect contact with the palatal surfaces of the teeth; chill the cement, remove and invest as before, and with 20-carat gold solder the pins to the base-plates, flowing upon them and the backing as much of the solder as may be necessary to give them the desired thickness and rigidity; the amount admissible largely depend- ing upon the nature of the occlusion; a central thickness of about No. 21, standard gauge, being all that is really requisite for strength, while the edges can be made much thinner. "Fig. 560 represents the appliance without the pin. A is the porcelain tooth and backing; E, the base-plates; C and F, the openings for the pins. " Fig. 561 represents the appliance completed with the pins in position. " Fig. 562 represents the natural teeth and interspace B, with openings for retaining-pins, C, D. " Fig. 563, already described, represents the appearance pre- sented when the bridge is cemented in position. " To Attach the Bridge.—To attach the bridge the best attain- able oxyphosphate cement should be used. It is desirable that it should set slowly. Thoroughly dry the teeth and denture; mix the cement to as thick a consistence as is compatible with per- fect plasticity. A thick, viscid, semi-fluid mass is what is re- quired. With suitable instruments, swiftly but carefully place the cement around the head and shank of each platinum pin, and also in the openings in the natural teeth. This care is necessary in order to exclude all air-bubbles and thoroughly engage the pin-heads in the cement. They furnish ample retaining surface, but none to spare. In packing the cement around the pins, the under surface of the base-plates should at the same time be covered. " The above details being perfected, the denture is at once carried to position, and with broad-pointed, serrated instruments PARTIAL CAP AND PIN-BRIDGE METHODS. 283 pressed firmly into place, the excess of cement, if of the proper consistence, freely oozing at all margins. " Application to Pulpless Teeth.—In the above description the vitality of the pulps of the cuspid and incisor has been assumed; but, as can readily be understood, the pin and plate bridge can be even more easily and securely placed when one or both pulps are devitalized, for the reason that, the pulp-chamber being empty, the pin-holes in that tooth can be made as much larger and deeper as may be deemed desirable, the size of the pin being, of course, correspondingly increased. In a devitalized tooth, too, the base-plates can be sunk into the palatal surface when they interfere with occlusions, as sometimes happens when the antagonism of the lower teeth is very close and the overlap is considerable. " Ordinarily, howTever, such interference is inconsiderable, and the difficulty can always be overcome either in devitalized teeth by the expedient just suggested, or by carrying the base-plates as far away from the cutting-edge as practicable, at the same time making them at the point of contact as thin as is consistent with strength; finally, if necessary, removing a slight portion of the cutting-edge of the occluding lower tooth. . . . " As a rule the writer has confined the use of this form of bridge to cases in which only a single incisor is missing, but he has successfully attached a front and lateral incisor to a cuspid and the remaining; front incisor. Where an unusual strain is to be expected the retaining-pins and pin-holes should when practicable be made correspondingly large, or two smaller pins maybe anchored in one tooth, which latter plan gives very great resisting power. " Pin and Plate Attachments to Bicuspids.—Although chiefly applicable to the incisors, the pin and plate attachment may be successfully combined with crown- or bar-bridges for molars and bicuspids. " Fig. 564 represents a practical case in which the upper third molar and the first bicuspid (both without antagonizing teeth) were utilized for the attachment of a bridge made of gold crowns with porcelain facings, to supply the loss of the interven- ing teeth. 284 ARTIFICIAL CROWN- AND BRIDGE-WORK. " Fig. 565 represents the case as prepared for the bridge. A, the inner cusp of the bicuspid cut down to allow the placing of Fig. 564. a sufficiently thick crown-plate; B, a cylindrical undercut open- ing between the cusps for a retaining-pin; C, the third molary Fig. 565. D--_ made uniform in size from neck to grinding-surface, the latter also being considerably retrenched; D, the crown-plate of a Fig. 566. partial cap, made of pure gold, soldered with 20-carat gold, and so constructed as to cover every portion of the tooth except its PARTIAL CAP AND PIN-BRIDGE METHODS. 285 buccal surface, the free edge passing up under the gum ; E, a retaining-pin adapted to the opening B; F, the gold cap for the molar. "Fig. 566 represents the bridge anchored in position with oxyphosphate cement. " In the above case it will be observed that there is a con- Fig. 567. siderable space between the bicuspid and cuspid. This made it readily practicable to give so considerable a thickness to the mesial wall of the partial cap as to hold it securely against the side of the tooth. Had the space been less, contact with the cuspid would have afforded the desired security. " Fig. 567 represents another case in which a bridge was at- Fig. 568. tached by a bar, partial cap, and retaining-pin. A is an upper second bicuspid (without antagonist); B, its inner cusp, cut down; C, opening for retaining-pin; D, second molar, with slot for bar; E, cuspid; F represents the partial facing; G, the retaining-pin; H, a molar crown of gold, with porcelain front; I, a platinum bar attached to the crown (H) and made to fit into 99999994 286 ARTIFICIAL CROWN- AND BRIDGE-WORK. a slot (at D); J, a plain plate cuspid, heavily backed and strongly soldered to the partial cap, but left without attachment to or contact with the cuspid. " Fig. 568 shows the bridge anchored in position. " This case, after two years of wear, is still in perfect condition and doing good service. As it was possible to keep the gold attach- ments, backings, etc., out of sight, the appearance presented is very natural. " The absence of antagonizing teeth for the bicuspids in each of these cases was a favorable condition, as a considerable thick- ness could be given to the crown-plate without any interference with occlusion. When the conditions are not so favorable, cutting down the inner cusp to the required extent and sinking the opening for the retaining-pin to the necessary depth are pro- cesses certainly to be, as a rule, preferred to the entire removal of the crown for the purpose of ferruling the root for the mount- ing of a crown of gold and porcelain,—a procedure, however, not by any means to be indiscriminately denounced, for in many cases it is in the highest degree advisable. " There is this fact to be considered in regard to the use of the partial caps here figured,—that many patients can be induced to consent to their employment who would refuse to submit to more radical measures, and thus, even when the latter would be advisable, the former may be employed as a compromise, or even as a temporary expedient. Having once tested the advantage of a well-fitting bridge, the wearer is much more likely to consent to whatever measures are necessary to give it security and per- manence." CHAPTER XVII. THE MANDREL SYSTEM. In all styles of collar crowns the shaping and adapting of the collar is usually found by many dentists to be the most difficult part in their construction. To facilitate its performance the " Mandrel System" was introduced by The S. S. White Dental Manufacturing Co. The following is a revised description taken from an article on the subject:1 " An examination of a large number of human teeth shows that, no matter how great differences may exist in the apparent shapes of the crowns of individual teeth of a given class, there is a remarkable uniformity in the configuration of their necks. That is, the necks of upper cuspids, for instance, were found to have a fixed type, from which the variations were very slight as to shape, though there appeared to be no exact standard of size. So of the other classes, with the single exception of the superior molars, in which two distinct forms were found, the first being those in which the buccal roots were wider than the palatal; the second, those in which the reverse condition was found, the single palatal root being wider at its junction with the crown than the two buccal roots. The occurrence of roots of the second class being rather exceptional, the first class was accepted as the type. " The configuration of the necks of all the teeth having been determined, a set of mandrels for shaping collars to fit them was devised. The set (Fig. 569) consists of seven mandrels, six of which are double end. Their shapes are modeled upon the general typal forms of the necks of the teeth which they repre- sent, and they are made tapering to provide for all required variations in size. The illustrations are about two-thirds actual ^-Dental Cosmos, vol. xxviii, No. 8. 287 Right Inferior Central, Lateral, xsss Cuspid, and First Bicuspid. Left. Bifurcated Bicuspid. Superior Lateral and Inferior Second Bicuspid. 91 THE MANDREL SYSTEM. 289 size, the longest instruments being nine inches in length. The cross-sections show the shapes and proportionate sizes at the greatest and least diameters. The long taper permits the most minutely accurate adjustment of the collars. " No. 1 is a double-end mandrel, for superior molars, right and left; No. 2 is a single mandrel, for superior bicuspids, right and left; No. 3 is double-end, for superior cuspids, right and left; No. 4, double-end, for superior centrals, right and left; No. 5, double-end, for inferior molars, right and left; No. 6, double-end, for the inferior centrals, laterals, cuspids, and first bicuspids, right and left; No. 7, double-end, one end for the superior lateral incisors, the other for those bicuspids in which a bifurcation of the roots, or a tendency in that direction, extends across the neck to the crown in the form of a depression on one or both approx- imal surfaces. The foregoing scheme comprehends all the teeth of the permanent set except the second inferior bicuspids. The necks of these approximate those of the superior central incisors so closely in shape that it was deemed inexpedient to make a separate mandrel, as the No. 4 mandrel will serve for both. " The collars or bands are made seamless, of No. 30 (Ameri- can gauge) gold plate, 22 carats fine. Fifteen sizes, each of three widths (TV, T2o> and T ni this case continuous-gum teeth are ^^^^X^ bent over the bar on the plate and soldered to it with pure gold. When one end of the bridge is supported by an all-gold crown onT tooth with a living pulp, the end of the bar „ passed into 308 ARTIFICIAL CROWN- AND BRIDGE-WORK. the grinding-surface, or flattened and bent against the side of the gold crown and soldered to it. This is done by investing in asbestos and plaster and carefully heating up the porcelain before using the blow-pipe. Insertion.—When the bridge is supported by crowns alone, the posts are barbed and the bridge is then cemented on, the same as any other. If one end is supported by a porcelain crown and the other by a bar, the filling on the bar end is inserted up to the position the bar is to occupy before fastening the post of the crown end, which is then cemented and the filling of the bar end com- pleted. (See "Bar Bridges.") Fig. 594. Fig. 595. Fig. 596. 12 3 12 3 Fig. 597. In Fig. 594, No. 1 is a third molar, pulp alive, with large filling; No. 2 is a porcelain bridge; No. 3 is a first molar, pulp dead, with a metal bar entering the pulp-chamber. In Fig. 595, No. 1 is a second molar, pulp alive, with a crown filling of gold or amalgam retaining the bar; No. 2 is a porce- lain bridge; No. 3 is a gold crown with bar passing through one side of the crown into the root. Fig. 596 is a view of a central incisor bridged onto two teeth whose pulps have been lost. Fig. 597 is a view of an extension bridge consisting of a right central and left lateral, supported by a left central tooth or crown as the case may be. The bar can be anchored in a filling in the natural crown or attached to the artificial one. Nos. 1 and 3 PORCELAIN BRIDGE- WORK. 309 are teeth on a porcelain bridge; No. 2 the natural tooth or arti- ficial crown on which the bridge is saddled. Figs. 598, 599, and 600 represent a bridge of eleven teeth inserted by Dr. Brown on two cuspid roots, a pulpless molar Fig. 598. on the left side which was capped with a gold crown, through the side of which the bar was passed and anchored in the root, Fig. 599. Fig. 600. and a molar on the right side into which the other end of the bar was anchored in a gold filling. Fig. 601 represents a bicuspid bar-bridge anchored in the molar and first bicuspid. The side cut shows the construction. This ARTIFICIAL CROWN- AND BRIDGE-WORK. operation was performed by Dr. Brown for Dr. Wm. Crenshaw, at the anniversary clinic of the First District Dental Society of the State of New York, in January, 1887. Fig. 601. Fig. 602 * represents an extension bridge in which the support consists of a crown and bar combined. Fig. 603 represents an extension bar-bridge. The filling in the second bicuspid, which extended from the mesial to the distal side, had been inserted some time previously. Enough of the gold was removed from the mesial section of the filling to Fig. 602. - Fig. 603. admit the bar, which was then securely anchored and the filling restored to its original form. The operation was performed by Dr. Brown for Dr. F. P. Hamlet. The antagonizing teeth in the act of occlusion favor the artificial tooth forming the bridge. iCase of Dr. F. P. Hamlet. PORCELAIN BRIDGE- WORK. 311 In porcelain bridge-work, should a case require it, artificial gum in a moderate amount can be formed above the teeth of the bridge, to restore the contour of the parts. Figs. 604 and Fig. 604. Fig. 605. Fig. 606. c 4r\,\a nVmracter A, Fig. 606, shows the ^rt runt-"?- ^ ^ ^ insertion. �73943 312 ARTIFICIAL CROWN- AND BRIDGE-WORK Fig. 607 represents a case restored by Dr. Brown's method by Dr. M. L. Rhein. To remedy the abnormal character of the occlusion, the lower anterior teeth and the right upper cuspid Fig. 607. Fig. 608. Fig. 609. were trimmed to the dotted line seen in the figure. To replace the missing teeth porcelain bridge-work was then constructed. The lateral and central roots, and the right cuspid and the molar, Fig. 610. constituted the abutments. On the central and lateral roots were mounted caps with collars. A platinum crown was then PORCELAIN BRIDGE-WORK. 313 made for the cuspid (Fig. 608), and to this crown was attached the bar, which was extended to its anchorages in the molar crown and the lateral and central roots, the caps on the ends of which the posts pierced. Owing to the large quantity of porce- lain body to be used in forming the artificial gum, a strip of platinum plate was extended above the bar to stiffen its pro- jecting ends and prevent warpage in baking. The artificial teeth were then articulated to meet the incisive edges of the in- ferior natural teeth, and thus in a measure overcome the deformity Fig. 611. caused by the abnormal occlusion. In doing this the labial aspect of the cuspid was covered by the artificial teeth. Porce- lain gum was then formed above the teeth in sufficient quantity to restore the contour of the parts. It was brought to a feather edge and pressed hard against all the tissues to insure a hygienic condition Fig. 609 shows the finished bridge. In Fig. 610 the bridge is seen in position. The artistic result and improved appearance effected are at once apparent. The mechanical con- struction of the piece was intrusted to Dr. C. L. Andrews. 314 ARTIFICIAL CROWN- AND BRIDGE-WORK. Figs. 611 and 612 represent an upper and lower case of por- celain bridge-work, inserted by Dr. Wm. Crenshaw, in which several roots and teeth were used to form the necessary abut- ments. The upper section anteriorly receives the combined support of several roots as illustrated in Fig. 611. The bar on the left side is made flat and hooked on the end, affording a secure means of anchorage. A gold crown forms the support on the right. The lower section is firmly supported on the right side by passing the bar through the cuspid and inserting the end in the pulpless bicuspid as illustrated in Fig. 612. The pulpless bicuspid on the left constitutes the other abutment. Fig. 612. Dr. Brown's system and method of bridge-work compares with other forms of bridge-work as continuous-gum work com- pares with other forms of plate-work. In cleanliness, through the unalterable character and continuity of its surface and the incorruptibility of the material, it has advantages as a denture. The ultimate value of this method, however, as a means of replacing lost members of the dental arch, depends, like others, on its proper, correct, and skillful application to cases where the occlusion and other conditions are suitable for it. CHAPTER XIX. CROWN- AND BRIDGE-WORK COMBINED WITH OPERATIVE DENTISTRY IN DENTAL PROSTHESIS. The combination of operations on the natural teeth with crown- and bridge-work affords extraordinary advantages in dental prosthesis. The results which can be accomplished commend the plan strongly to the experienced practitioner. A few cases are adduced in illustration. Fig. 613. A case which was interesting, owing to the conditions pre- sented and the various operations connected with it, is illustrated in Fio\ 613. Fig. 614 shows the methods and operations prac- ticed, and Fig. 615 the case completed. The upper front teeth show the effects of abrasion on the in- cisive edges and occluding surfaces. The bicuspids and molars were affected with pyorrhea alveolaris. The four incisors and the left cuspid were pulpless, and alveolar abscess existed at the roots of three of the incisors. The abscesses and root-canals were properly treated. Gold collar crowns with porcelain fronts, havino- flat incisive edges which entirely protected the porcelain ° 315 316 ARTIFICIAL CROWN- AND BRIDGE-WORK. fronts and slightly opened the bite, were made for the incisors and left cuspid (Fig. 614). The bicuspids and molars were placed in as hygienic a condition as possible by treatment. On the left side a dummy bicuspid with a bar which fitted in a slot formed to receive it in the occluding surface of the second bicuspid Fig. 615. was attached to the cuspid crown. When the cuspid crown with the dummy bicuspid was cemented in position, the bar was OPERATIVE DENTISTRY WITH CROWN- AND BRIDGE-WORK. 317 anchored in the slot in the second bicuspid with amalgam. The cuspid root being very firm, stability was thus imparted to the natural bicuspid, which was quite loose because of absorption of its socket. On the right side the second bicuspid was entirely capped with a gold seamless crown. On the anterior side of this gold crown an artificial tooth was attached as a dummy first bicuspid, with a bar extending from its anterior side and fitted into a slot formed in the incisive surface of the natural cuspid crown. From the posterior side of the second bicuspid gold crown a bar was extended backward into the side of the molar. When the gold crown was cemented in position on the second bicuspid, the anterior bar was firmly anchored in the cuspid with a gold filling, which also lengthened the incisive edge, and the posterior bar was fixed in the molar with amalgam. The reasons for this form of construction are : The second bicuspid was very loose in its socket, and the molar, though comparatively more stable, was also similarly affected. The attachment of the bar in the cuspid supported the dummy bicuspid and steadied the second bicuspid, and the extension of the posterior bar into the molar likewise afforded additional support to the bicuspid. The pulp of the molar being exposed, was devitalized, removed, and the canal properly filled. Fig. 615 shows the completed case.1 The lower teeth, in comparison with the upper, were but slightly abraded. The cuspids and one of the incisors were tipped with gold. The molars on the left side were absent, so that bridge-work on the upper jaw on that side between the bicuspid and molar would have been to no purpose. In the case presented in Fig. 616 the operative procedures were confined to the upper jaw, the lower teeth of the patient being in good condition. The bicuspids and the first and second molars of both sides of the upper jaw had been lost many years before, and the incisors and cuspids showed the effects of extensive 1 Recently, during the~presence of inpatient in my office, these operations were examined by members of the profession, and pronounced apparently in as perfect condition as when completed four years ago. The treatment of the teeth affected with pvorrhea and the support imparted to them by then-attachment to the other firm teeth and to each other had apparently checked the disease, and the affected teeth appeared to be more secure in the.r sockets than before the insertion of the bridge-work and crowns. 318 ARTIFICIAL CROWN- AND BRIDGE-WORK. abrasion. The occlusion was sustained and the principal part of mastication performed by the incisors, as the third molars had been forced backward and antagonized only very slightly on one side. The patient, a gentleman, had had a plate inserted, to the pres- ence of which he had vainly endeavored to accustom his mouth. The abrasion of the incisors and cuspids was of the rapidly pro- Fig. 616. gressive character. These teeth were contoured with gold foil to the form shown in Fig. 618, and a wire post was inserted in the right lateral, wdiich was pulpless. At the occluding section of each filling, the layer of gold, after being packed with the plugger, was additionally condensed and hardened with a Herbst agate- point burnisher to enable it to better resist the aggressive force of the lower teeth. The third molars were capped and length- ened with gold crowns, the lines of their sides being made parallel, to admit of a proper adjustment of the supporting collars for a removable plate bridge, by adding gold on their external surfaces. The plate bridge was employed because of the space between the abutments, which suggested the idea of utilizing the alveolus to assist in supporting it. A narrow shoulder was formed on each crown to support the collars. The attachments to the cuspids rested by means of a little shoulder on the occlud- OPERATIVE DENTISTRY WITH CROWN- AND BRIDGE- WORK. 319 ing portions of the fillings inserted. Fig. 617 shows the com- pleted denture, and Fig. 618 an anterior view of the same.1 In the case illustrated in Fig. 619, the patient, a lady, had previously worn a plate, the clasp of which had entirely abraded the sides and cervix of the right cuspid of enamel, and caused recession of the margin of the investing gum. The decay which Fig. 618. followed the abrasion extended in a circleground the tooth. As he patient objected to crowns of any ktnd being appted •♦i -f tl,P rnsDids, the decay was removed and the edges ot tt cl^^eTalaining fo/n, Agoh^^sthenintro- 1 Case operated on in 1888. 320 ARTIFICIAL CROWN- AND BRIDGE-WORK. duced in three sections, two of which embraced the approximal and palatal sides, while the third surrounded the labial wall, joining the other two sections at that point, the three thus com- pletely encircling the tooth with gold. A portion of the filling Fig. 619. was brought over the edges of the cavity to better shape the tooth for the attachment to be applied and also to protect the sides from future injury. When this operation was completed, the tooth presented very much the appearance of having had a close-fitting shell crown applied. Gold fillings were introduced Fig. 620. in the palatal and approximal surfaces of the left cuspid, to pro- tect it from the attachment. Gold crowns were placed upon the molars, one of which, the left, was pulpless. The appearance of the teeth after these operations is shown in Fig. 620. OPERATIVE DENTISTRY WITH CROWN- AND BRIDGE-WORK. 321 A plate bridge (Fig. 621) was then constructed, the attachments for which were collars on the molars, and half-collars or clasps on the cuspids. The former rested on shoulders formed on the gold crowns, and the latter on the palatal curves of the cuspids.1 Fig 621. Fig. 622 illustrates a case as presented for treatment to Dr. H. A. Parr. The loss of the posterior teeth of the lower jaw and the abrasion of the anterior teeth had resulted in the abnormal occlusion shown. The incisive edges of the lower teeth were lengthened with gold contour fillings. Gold collar crowns with porcelain fronts were placed on the upper anterior teeth, to lengthen them sufficiently to restore the occlusion. The upper molars, which were all more or less decayed and broken Fig. 622. down, were restored in form with gold crowns. The space representing the loss of the left bicuspid was filled with a bridge tooth having a porcelain front, attached to the approximal gold crown. In the lower jaw a partial set was inser^Pon^ach_s^de 1 Case operated on in 1889. 22 322 ARTIFICIAL CROWN- AND BRIDGE-WORK to substitute the lost posterior teeth. Fig. 623 shows the appear- ance of the case when completed. The following case is a marked illustration of extensive con- tour filling combined with gold and porcelain crown-work. The operations were performed by Dr. E. P. Brown, with the excep- Fig. 623. tion of the porcelain inlays, which were inserted by Dr. C. H. Land. Fig. 624 represents the case before treatment. The teeth show the effects of erosion, abrasion, and decay. The upper teeth at the incisive and palatal portion were contoured with rolled gold, Xo. 60, condensed with the Bonwill electric mallet. A porcelain crown was placed on the root of the left cuspid, and a gold crown on the first left bicuspid. The eroded, decayed, and abraded portions of the other bicuspids were contoured with gold. The treatment of the lower teeth consisted in contouring with gold the abraded occluding surfaces of the right first and second bicuspids and left first bicuspid. The left second bicuspid and two right molars were crowned with gold. The cervical decay which affected the inferior right lateral, cuspid, and first bicuspid and left cuspid was removed and inlaid with sections of porcelain colored with gum enamel at the line of the gum- margin by Dr. Land. Fig. 625 shows the superior arch from the palatal aspect when completed. Fig. 626 is a labial or front view of the several operations.1 xThe patient, Dr. W. I. Thayer, exhibited these operations, nearly completed, at the clinic of the First District Dental Society of New York, February, 1889. OPERATIVE DENTISTRY WITH CROWN- AND BRIDGE-WORK. 323 Fig. 624. Fig. 625. Fig. 626. 4 PAET IY. MATERIALS AND PROCESSES USED IN CROWN- AND BRIDGE-WORK. CHAPTER I. PLATE AND SOLDERS. Plate.—In the construction of crown- and bridge-work, gold, platinum, or iridio-platinum is used in the following forms and grades in carat, as suits the requirement of the case and the preference of the dentist: Gold plate, 24 carats, from No. 30 to No. 34 TJ. S. standard gauge,1 for constructing the collars and caps to collars of crowns and seamless crowns, and for backing porcelain fronts. Gold plate, slightly alloyed,—about 23 carats fine,—in crown- work, if less flexibility of the metal is required. Gold plate, 22 carats, No. 31 to No. 32 standard gauge, in constructing collars for crowns with porcelain fronts and all-gold crowns made in sections. Gold plate, 20 carats, in construction of bridge-work. Gold for constructing collars should be of as high a carat as possible, to better resist the action of acids. A large proportion of copper as an alloy is objectionable, owing to its tendency to cause tarnishing of the collar where an acid condition of the saliva exists. For this reason, United States gold coin, contain- ing 10 per cent, copper, so much used for collars, is not quite suitable. It is also too stiff, and collars made of it are not readily burnished to fit at the edges. Dr. J. J. R. Patrick's formula, which is equal parts of coin and pure gold, affords a plate which is decidedly preferable, inasmuch as the proportion of copper is reduced to 5 per cent. Gold plate, 24 carats, with a very thin lining of platinum or iridio-platinum plate, can be used in any of the processes con- nected with crown- and bridge-work, and is especially recom- mended to the inexperienced, for the reason that the melting of a part of a crown h^the^oldenng process is^preventedjyjtsjse. "TThTunited StateTstandard is the~on7y^aug7referred to in the original descriptive matter of this treatise. ^ 328 ARTIFICIAL CROWN- AND BRIDGE-WORK It is formed by placing together an annealed gold plate and a plat- inum plate (the gold about No. 20 gauge and the platinum No. 30)and passing them through a rolling-mill, in which process the plates are welded and reduced to the desired thickness. Platinum and iridio-platinum plate is used for forming crowns for use in connection with porcelain bridge-work. Iridio-plat- inum plate for forming small collars need not be over No. 35 gauge. At this thickness it can be easily adapted to the cervix of the tooth. Pure platinum rolled very thin is used for forming caps to collars, backing teeth, and for various purposes connected with this class of operations. Iridio-platinum wire is used for pivots, pins, or posts, being more rigid than pure platinum. A wire of gold and platinum alloy is used on account of its elasticity for split or spring pivots or posts in removable bridge-work. Solders.—Gold solder, 22 carats fine, is used for crown-work; 20 carats for crown- and bridge-work. 18 carats is used for crown- and bridge-work, but this is con- sidered by some too low a carat. 14 carats for strengthening seamless crowns; used only in crowning operations. Successive grades of solder from hard to easy flowing can be used in the regular soldering of crown- and bridge-work; gold plate or a hard-flowing solder for the first, a medium-flowing sol- der for the next, and an easy-flowing one for the finish. This avoids melting or flowing of the gold at any point previously soldered. Any grade of solder can be made according to the following formula: Zine, \\ grs.; Pure gold, Silver solder, in quantity sufficient to make up the 22$ remaining parts in weight. The quantity of silver solder used will regulate the grade in carat of the solder. Thus: Zinc, \r\ grs. ; Pure gold, 20 grs. ; Silver solder, 3 grs., will, by the burning out of a portion of the zinc in the process, make a solder about 20 carats fine. PLATE AND SOLDERS. 329 By lessening the proportion of zinc from 1£ grains to 1 grain, the proportion of silver solder being kept the same, the solder will become harder-flowing and a little finer. Dr. W. II. Dorrance recommends the following formula as an alloy for the formation of different grades of gold solders, the proportion of the alloy used determining the melting-point and fineness in carat of the solder: 1 part pure silver; 2 parts pure zinc : 3 parts pure copper. The silver and copper are first melted together in a crucible lined with borax, and the zinc added quickly in small pieces, stirring the mass meantime with a pipe-clay stem. It is then, on the fumes of the zinc passing off, immediately poured into an ingot-mold or into a large wooden pail filled with water; 4 grains of this alloy melted with 20 grains of pure gold will result in a solder fully 20 carats fine. As a solder for crown- and bridge-work constructed of 22- carat gold plate, Dr. Litch's formula is as follows: Gold coin (ten dollars), 258 grs.; Spelter (or brazier's solder), 24 grs.; Silver coin, 24 grs. This is a proportion of about 26 grains of pure copper and 232 grains of pure gold to the remaining 48 grains of the alloy, and makes a good solder a little over 18 carats fine. Dr. C. M. Richmond originally used American gold coin for forming gold crowns, rolling it out in the form of plate. The scraps he formed into solder by melting and adding one-fifth of their weight of fine brass wire cut in small pieces, using plenty of borax. Dr. Low's formula for solder in bridge-work is : 1 dwt. coin gold ; 2 grs. copper; 4 grs. silver. This makes a solder about 19 carats 330 ARTIFICIAL CROWN- AND BRIDGE-WORK The following formula1 gives a 20-carat solder which is specially . recommended for crown- and bridge-work: American gold coin (21.6 carats fine), $10 piece, 268 grs.; Spelter solder, 20.64 grs. Fluxed Solder. Filings.—Fluxed gold solder filings are made by filing with a clean, flat plate file a thick piece of solder held in a vise. The filings are allowed to fall in a box or on a sheet of paper placed to receive them. A magnet should be passed through the filings to remove any minute particles of steel. To five parts of the filings so made is added and well mixed with them one part of the prepared flux or finely pulverized vitrified borax. Solder prepared in this way is useful for strength- ening crowns, and also in fine soldering operations, as the parti- cles of the solder take the heat separately and fuse much more quickly than when the solder is cut in pieces. The flow of the solder is also more easily limited. 1 American System of Dentistry, vol. iii, p. 849. CHAPTER II. PORCELAIN TEETH. The qualities specially requisite in the body of porcelain teeth for use in crown- and bridge-work are density, strength, and the ability to withstand unaltered in form or shade any degree of heat to which they may necessarily be subjected. In these respects the porcelain teeth of our best American manufacture seem to excel, besides affording the most artistic imitation of the natural teeth in form and shade. They are also distinguished by the practical location of the pins. In some crowning operations, where to imitate the conforma- tion of a natural crown considerable alteration of the labial surface of a porcelain front is required, teeth of English manu- facture may be used, as the texture of the porcelain admits of a fine polish being given to a ground surface. Teeth are sometimes fractured in the process of soldering, caused by the contraction of the backing when adapted over the edges of the porcelain in a curve instead of at a right or slightly obtuse angle, or by melting solder on some point of the porcelain which is unprotected by a backing of metal. The solder, or the borax, as it cools, contracting on the porcelain, or a very thin edge of the metal covering it, will usually cause a fracture. The porcelain tooth has yet to be made that will, as a rule, endure such extreme treatment without breaking. 331 CHAPTER III. MOLDS AND DIBS. Metallic models of fusible metal can be easily and quickly formed for use in crown- and bridge-work. The melted alloy can be poured into a plaster, moldine, or gutta-percha impression taken in a tube or impression-tray. When a tube is used, a strip of paper should be wound around it to lengthen the die. The following fusible alloys of tin are suitable for the purpose : PROPORTIONS OF METALS. MELTING POINT OF THE ALLOY. Tin. Lead. Bismuth. Fahr. 12 2 236° 5 3 3 202° 3 5 8 197° Dr. G. W. Melotte, of Ithaca, N. Y., to whom is accorded the credit of introducing the use of fusible metal and the compound called " moldine" into crown- and bridge-work, gives the propor- tions of his alloy in parts as— Tin, 5; Lead, 3; Bismuth, 8. Dr. Melotte's moldine, a preparation compounded of potter's clay and glycerin (to which, when needed to soften it, more glycerin can be added), is very useful in molding. HOW TO QUICKLY MAKE A TUBE AND FUSIBLE METAL DIE. Take a thin strip of copper plate, at least 35 gauge, anneal, and bend it around the tooth in the mouth or its form on the plaster model. Both ends of the copper at the part lapped are next cut, as shown at A, Fig. 627, and turned over tight and close in the manner seen at B. This fastens both ends of the copper, which when trimmed off at C, forms a tube. In this tube, with a little impression compound, gutta-percha, or moldine, take an impres- sion of the natural crown either in the mouth or from the plaster model by trimming around the tooth or by separating it from 332 MOLDS AND DIES. 333 the rest of the model. Encircle the tube with a strip of paper. Hold the paper and tube with a clamp. Melt and pour the fusible metal moderately cool, and immerse tube and metal in water. This gives a die with a long narrow shank, which may require to be trimmed at the neck with a file. When impression compound or gutta-percha is used, cool and then dry the surface with an air syringe before pouring the fusible metal. A counter-die to a small cast or die of fusible metal is made by indenting a block of lead with a punch, and then driving the cast or die into it. Its use in crown- work is described on pages 93, 102, and 106, and by Dr. Melotte on page 276. The following method of forming a metallic model of a prepared root or crown is given by Dr. W. C. Barrett, of Buffalo, N. Y., who accords Dr. H. A. Baker, of Boston, the credit of being the originator of it: " Copper is rolled down quite thin, and a band three-fourths of an inch wide wrapped about the root and forced up under the gum. A ligature is passed around both; the copper band is burnished down and the ligature drawn tight. The copper band will now fit just as we want the gold band to do. Plaster of Paris is then inserted in this, forced up against the end of the root, and permitted to set. Take it off, and if you use Babbitt-metal, a piece of paper wrapped about it (the copper band) will lengthen it out sufficiently, when the metal may be poured into it, and thus a perfect model of the end of the root will be secured. That part which is inserted in the copper tube is the exact reproduction of the root of the tooth. The model will perhaps need a little dressing down with a file, when the gold band may be fitted around it and soldered, thus avoiding the necessity for the annoying and painful trying-on in the mouth." Fusible metal can be used instead of Babbitt-metal. Dr. Melotte has lately introduced for special cases a novel method of forming a combination plaster and metal model, in which the parts representing the teeth are of fusible metal. The following is a description: The impression is taken in 334 ARTIFICIAL CROWN- AND BRIDGE-WORK. plaster. Iron pins to act as dowels are placed in the molds of the teeth. Pieces of a fusible metal, which melts at a low point, are then melted into each of the molds with a few puffs of the blow-pipe. Plaster is then poured in the remainder of the impression. The advantage afforded by a model of this kind, when gold attachments or clasps are to be shaped to teeth, is obvious. The method applied in the construction of bridge- work is given on page 161. Dr. Melotte's formula for the fusible metal used in the above method is: Bismuth, 8 parts; Lead, 4 " Zinc, 3 " Cadmium, 2 " Melts at about 150° F. CHAPTER IV. SOLDERING. Investments for soldering, and models on which the soldering is to be done for bridge-work, are made of calcined mar- ble-dust and plaster, in the proportion of equal parts for models, and one part of plaster to two of marble-dust for investing; or one part plaster, one cal- cined marble-dust, and one of common white sand. If the investment is large, an iron wire should be passed through or around it in the material. Sulphate of potassium, used in place of common salt, but in smaller quantity, will cause the mixture to set quickly and hard. Soldering.—In soldering crown- and bridge-work or sections of it containing porcelain fronts, the investment should be first uniformly and thoroughly heated, and the heat maintained during the process of soldering. This is espe- cially necessary in the final soldering of gold crowns with porcelain fronts, as the solder is thereby flowed into the interstices between the porcelain and the caps, and gives continuity of struc- ture to the crown. A large piece of charcoal, concave on the side to be used, and the other side invested with a thin covering of plaster, furnishes a good soldering support, as it retains the heat. A hand gasf blow-pipe, operated! by a 336 ARTIFICIAL CROWN- AND BRIDGE-WORK. foot bellows, and so constructed that the flame is under perfect control, is the most suitable (Fig. 628). The Use of Borax.—In soldering invested sections of a crown or bridge together, borax which has been reduced to a vitreous state by heat and then finely pulverized is the preferred form for its use. Prepared in this manner it should be sprinkled on the part pre- vious to the commencement of the soldering, and a little added at any time it is needed during the continuance of the process.1 In small, fine soldering of invested or uninvested work, the lump borax ground with water on a slab to a cream-like con- sistence and applied with the point of a stick or brush only where it is desired to have the solder flow, is the most suitable. xDr. Parr's " prepared flux," a finely pulverized vitrified flux, can be used in this manner. It is conveniently kept in the form of a saturated solution in a bottle, from which the operator can use it with a brush or stick in fine solderings. It is also prepared in combination with wax cement. In the melting out of the wax when the case is invested and heated for soldering, the flux is carried into the interstices. CHAPTER V. INSTRUMENTS AND APPLIANCES. The dentist who intends to engage extensively in crown- and bridge-work, and who desires to practice it conveniently and suc- cessfully, should supply himself with all the necessary instru- ments, tools, and other appliances. These consist principally of Fig. 629 drills of various styles, among them the Gates-Glidden for root- canals; root-trimming and shaping instruments; corundum- wheels and points; rubber and corundum disks; suitably shaped pliers; clamps of various forms for use in the many soldering processes; some moldine and fusible alloy, and dies for forming gold caps for use in constructing crowns and capping dummies ; 23 337 338 ARTIFICIAL CROWN- AND BRIDGE-WORK. a Lee blow-pipe or Knapp's compound blow-pipe, or both, for use as is most suitable or convenient. The bench on which the principal parts of the work are done should be specially designed and reserved for it. It should be in the same room, and conveniently situated a little behind the dental chair, out of view of the patient. Everything connected Fig. 630 with this bench should be kept in order and ready for immediate use. Such a bench, made of black walnut, with a top that can be closed when not in use, making an unobjectionable piece of furniture, is represented in Figs. 629 and 630. An office lathe should be kept next to the bench, or a small lathe-head can be mounted on the bench and operated by the aid of an electric motor. INDEX. Abrasion of incisive edges of teeth, 101 method of forming crown for, 100,123 199, 284, 243, 315, 317, 321 Abscess, chronic alveolar, treatment of 28 Acid, arsenious, its use and action in devitalizing pulps, 18 Acid secretions, platinum unaffected by, 104, 124 Adaptation of gold collars, 83, 113 of porcelain crowns, method of, 43 Adjuster for use in cementation of crowns, 147 Adjustment of finished bridge-work in the mouth, 168 Advantages of a flange to support crown, 78, 104 Alloy for forming any grade of gold solder, 328 Alloys of tin, their use in crown-work, 332 Alveolar abscess, classification of, 28 treatment of, 28 Ames's method of forming gold tips, 139 Amputation of the apex of a root, 31 Analysis of dentine, 12 Anatomical structure of dentine, 10 Anchorage bars in bridge-work, 139, 160, 173, 182, 241, 305 manner of attaching to the abutments, 160, 169, 183, 310 manner of forming, 160, 183, 185, 260, 305 Anchorages or abutments for bridge- work, preparation of, 158, 172, 174, 177, 179, 183, 189, 279 Dr. Litch's method, 241 Anchorages or abutments for bridge- work, Dr. Parr's method, 248 Dr. Winder's, 238 shell, 175 Ancient bridge-work, 153 Anesthesia in pulp-extraction, 16 Anesthetics, local, for application to gum, 29, 31, 84 use of in crown-work, 84 Antagonizing teeth, preparation of their cusps, 36 Antiseptic agents in treatment of alveo- lar abscess, 29, 31 in treatment of pulpless teeth, 25 Anvil, use of in crown-work, 83, 114 Aristol, use of in pulp-canal, 25 Arsenious acid, use of in devitalization of the pulp, 17, 18 Articulation for bridge-work, manner of taking, 160 Artificial crown-work, 5, 39 the gold system, 77 the porcelain system, 42 Artificial gum in porcelain bridge-work, 230, 311,312 Attachments for removable bridge-work, 209, 225, 238, 242, 245, 248, 250, 256, 260, 318, 321 Backings for porcelain fronts in crown- work, 86, 163, 165, 166, 321, 328 Baldwin's method of mounting crowns. 70 Bar bridge-work, 160, 172, 182, 241, 285, 305 advantages of, 186 anchoring of the bar, 183. 339 340 INDEX. Bar bridge-work, cast filling to support, 186 extension, 185,191, 260 in bicuspids and molars, 184 in incisors and cuspids, 182 Bars for bridges, 139, 160, 183, 185, 186, 314 Beers's crown, 79 Bing's bridge-work, 154 Blind abscess, treatment of, 29 Blow-pipes, Lee's, 335 Knapp's carbo-oxyhydrogen, 273 Bonwill's porcelain crowns, 43 Borax, method of using in crown- and bridge-work, in constructing root- caps and tubes, 210, 336 Bridge-work, 153 adjustment and insertion, 168 an impartial criticism of, 155, 206 as affecting hygienic condition of the mouth, 206 cantilever, 180 cases illustrating the application of, 189, 315 cementation of, 145, 168, 177, 184 construction of, 158, 169, 171 detachable, 238, 241, 246, 248 extension, 178 extensive application of, 193 foundations for, 158 general application of, 189 manner of taking impression and ar- ticulation for, 160, 161, 169, 179, 218,219, 222, 333 mechanical principles governing the process of construction, 158, 181, 182 method versus tj forming self-cleans- ing spaces, 165 methods in pyorrhea, 193 partial cap and pin, 175, 177, 179, 193, 279 plate, 225, 305 porcelain, 305 removable, 208 removal of, 204 selection of abutments,458, 181 Bridge-work, special processes and ap- pliances in, 171 with replaceable porcelain fronts, 187 Brown's bridge-work, 305 gold crown, 99 porcelain crowns, 63 Burnishers for adapting collars, 84 use of in crown-work, 83, 112 Cantilever bridge-work, 180 crown, 135 Cap for collar, to construct, 85 Capping pulps, methods of, 13 Cast fillings, 139 to support bridge-work, 186 Cement, amalgam, gutta-percha, oxy- phosphate, 145, 148 Cement, to cause oxyphosphate, to ad- here to tooth-structure, 177 to cause to set slowly, 146 Cementation of crown- or bridge-work, 145, 168,177 Chronic alveolar abscess, 28 Circulation in dentine, 10 Clamps, soldering, 83, 93, 94, 172, 276 Cleansing of bridge-work when worn by patients, 207 Cocaine, use of, 16, 18, 31, 84 Collar contractor, 83, 115, 290 crowns hygienically considered, 66, 124 pliers, 80, 113, 292 Collar crowns, 79 bicuspids and molars, 88, 92, 104, 108 incisors and cuspids, 85, 100, 102, 119 Collars, method of adaptation of seam- less crowns, 112, 113, 114, 115 to solder, 82 Collars for crowns, 79, 291 construction and adaptation of, 79, 289 Townsend's fusible die in forming, 68 Connecting bars in bridge-work, 173, 186, 191, 216, 263 Construction of bridge-work, 158, 169, 171 INDEX. 341 Construction of bridge-work : bar, 182, 305 detachable and removable, 208, 217. 238 mechanical principles governing, 158, 181, 182 plate, 225, 305 saddles, 178, 196, 221, 224 small pieces of, 169 special processes and appliances in,171 Corundum-wheels and points, 33, 34 Crown- and bridge-work combined with operative dentistry in dental pros- thesis, 315 instruments and appliances, 337 Crowns, artificial: Baldwin's method of mounting, 70 Bonwill, 43 Bonwill cap, 71 Brown, 63, 99, 305 Evans gold, 108 Farrar's cantilever, 135 Fillebrown's, 99 Foster, 57 Gates, 56 How, 49 Howland, 57 Kirk's method of mounting, 70, 148 Leech, 127 Logan, 58 Low, 128 New Richmond, 64 Parker's, 107 Parr, 126 Patrick, 99 Perry, 130 Richmond, 85 Rynear, 99 Simplicity, 72 Stowell's method of mounting, 90 Van Woert, 78 Weston, 73 all-gold, in sections, 92 attachments for all-gold and seamless gold, 37, 117, 118 cementation, process of, 145 contouring of collars, 92 Crowns, countersunk, 94 dies for use in construction of, 89, 93, 96, 102, 106,107, 118, 120, 332 expanding, 83, 112 finishing and polishing, 146 for abraded teeth, 101, 123, 315 for separate molar roots, 284 gold and porcelain, for teeth with living pulps, 119 gold and porcelain, without a collar, 77 gold collar, 79, 287 gold seamless cap, 102, 108 gold seamless contour, 108 mandrel system, 287 partial, 137 porcelain, with collar attachment, 68 porcelain, with rubber attachment, 76 preparation of crown or root for, 9, 33 process of adjustment of gold contour, seamless, 111 remarks on the use of collar or porce- lain crowns, 66, 124 removal of, 204 repair of, 202 shell, 175, 179, 193 Curtis removable bridge, 262 Cusps of antagonizing teeth, preparaiion of, 36 Davenport removable plate bridge- work, 234 Decayed roots, special preparation of for crown-work, 36 Dentine, circulation in, 10 chemical analysis of, 12 Detachable bridge-work, 238, 241, 245, 248 Detachable porcelain front, 187 Devitalization of pulps, 10, 16 heroic or instantaneous, 16 instant, 16 usse of arsenic for, 17, 18 use of cocaine in, 16 Die-plate, 95 342 INDEX. Dies, 89, 93, 96, 102, 106, 107, 118, 120, 332 Dr. Baker's method, 333 Dr. Melotte's method for forming, 332 counter, 103, 106, 333 fusible metal, 332, 334 Diseased pulps, classification of, requir- ing extirpation, 12 Diseased teeth or roots, badly, 9 with necrosis of alveoli, 9 Disinfection of root-canals and dentine, 24, 25, 26 Disks, forms of, 34 Drills, Gates-Glidden, form of and method of using, 22 Dummies, definition of, 165 Dwinelle's crown, 79 Enameling gold crowns, method of, 122 English bridge work, 154 Evans gold crowns, 108 method of constructing dummies in bridge-work, 164 non-fusible crown, 108 Excision of crown, 16, 35 and instantaneous extirpation of the pulp, 16 • when to avoid, 12 Expansion of a collar or crown, 83, 112 Extension bar-bridge, 185, 310 Extension bridges, 178 leverage in, 180 Extirpation of pulps, 16, 17, 18 Facing, glass, for gold crowns, 122 Farrar's cantilever crown, 135 Ferrules for root-crowns, 79, 291 Files for trimming roots or crowns, 34 Fillebrown's crown, 99 Filling of root-canals, 26 Banishing and polishing bridge-work, 167 crown-work, 145 Flange to better support a gold crown, 78, 102 Forceps for excising crowns, 17 for repairing, 202 Formulas for fusible metals, 332, 334 for gold solders, 327 Foster crown, 57 Foundations for bridge-work, 158 Fracture of porcelain teeth in soldering, 331 Fractured teeth and roots, treatment of for crowning, 132 French bridge-work, 154 Fusible alloys of tin, 332 Melotte's, 332, 334 Gartrell bridge, 260 Gates crown, 56 Gold, all-, crowns for front teeth, 100 solid, 116, 172 Gold collar crowns, 79, 287 preparing natural teeth for, 9, 33 Gold, method of using, 85, 327 Gold plate lined with platinum, 327 crown-metal, 80, 327 solder filings, 80, 115, 330 solders, formulas for, 328, 329 standard of carat and gauge required, 85, 327 tips for natural crowns, method of constructing, 139 wire, 328 Gutta-percha for forming molds of crowns or roots, 102 in filling root-canals, 26 in preparation of roots, 36, 43 use of, for cementing crown- and bridge-work, 148, 169 Hkat, use of as a disinfectant, 13, 24 Hollow wire for posts, 86, 127 How crowns, 49 How screws, 49, 56 How's root-trimmers, 34 Howland crown, 57 Hub-mold, 97 Hygienic condition of the mouth as affected by bridge-work, 206 Hygienic consideration of collar crowns, 124 Hygienic preparation of the mouth, 6, 9 INDEX. 343 Impressions of crowns or roots, 93, 102, 105, 332 Impressions, cups for taking, 87, 168 for bridge-work, 160, 168 impression and articulation com- bined, 161 materials for taking, 102, 105, 332 Insertion and cementation of crown- and bridge-work, 145 Instantaneous extirpation of the pulp, 16 knocking out of the pulp, 17 Instruments and appliances, 337 Investments for soldering, 335 in bridge-work, 162 in crown-work, 88 Iodoform, methods of using, 25 Iridio-platinum wire for posts, 328 Irregularities of the teeth, methods of crowning in, 136 Isinglass (mica), use of in crown- and bridge-work, 89, 164 Judicial decision regarding the public use of bridge-work, 266 Kingsley's method of forming all-gold crowns, 94 Kirk's method, 70, 148 Knapp's methods in crown- and bridge- work, 270 Land's method in partial porcelain crown-work, 144 Lead counter-dies, method of forming, 93, 103, 106, 332 Leech's crown, 127 Leverage in bridge-work, 158, 159 in extensive bridge-work, 180 Litch's method of crowning, 104 detachable bridge, 241 partial cap and pin bridge, 279 Logan crown, 58 Dr. Baldwin's method of mounting, 70 Low bridge, 266 crown, 128 Mandrel system, 287 Mandrels for forming collars, 82, 288 Materials and processes used in crown- and bridge-work, 326 molds and dies, 332 porcelain teeth, 331 soldering, 335 Measuring the size of necks of crowns or roots for collars, 80, 82, 294 natural crowns or roots for ready-made gold crowns, 111, 113 Melotte's method, 275 metal, 332, 334 method of making model and articu- lation in constructing bridge-work, 161 moldine, 332 Metal flange to support crown, 78, 102 Metallic dies and counter-dies, 332 Metallic dies for forming caps with cusps for crowns, 93, 94 Models for bridge-work, 160 Moldine, 332 Molding, methods and materials used in, 93, 94, 102, 104, 332 Molds and dies, 332 Morrison's crown, 79 Mouth, preparation of, 6, 9 Necks of teeth, average forms of, 81 methods of measuring, 80, 82, 294 New Richmond crown, 64 Objections urged against bridge-work, 155 against collar crowns, 124 against porcelain crowns, 66 Obtundents, use of in alveolar abscess, 29,31 use of in crown-work, 84 use of in extirpation of pulp, 17 Ottolengui root-reamers and facers, 60 Oxyphosphate cement, 145 properties suitable for crown-work, 145 to cause to set slow, 146 Parker gold crown, 107 Parr's crown, 126 344 INDEX. Parr's detachable and removable bridge- work, 248, 264 Partial crowns, gold, 137 Dr. Ames's method, 139 Dr. Land's method, 144 Dr. Littig's method, 141 Dr. Parr's method, 139 porcelain, 140, 144 Patrick's cap-stamping machine, 110 crown-work, 99 formula for gold for collars, 327 Perforation of side of root, treatmenl of. 134 Perry's crown, 130 Pin-bridge, partial cap and, 279 Plaster impression and articulation, method of taking, 160, 161, 169, 179, 218, 219, 222, 333 Plate and solders, 327 Plate bridge, Brown's porcelain, 307 removable, 225 Platinum plate, 328 unaffected by acid secretions, 104 wire, 328 with gold, 327 Pliers for shaping collars, 80 Polishing and finishing crown- and bridge-work, 145, 167 Porcelain and gold crown without a col lar, 77 Porcelain bridge-work, 305 Porcelain crown with gold collar attach- ment, 68 with rubber or vulcanite attachment, 76 Porcelain crowns, remarks on the use of, 66 method to facilitate the adaptation of to the root, 43 Porcelain faces for crowns, 86, 89, 119, 162, 187 Porcelain fronts, backing for, 86, 327, 328 Porcelain teeth, selection of, 331 some causes of fracture in soldering, 331 Porcelain tips to natural crowns, 141 Posts for retaining crowns, 37, 49, 55, 56, 57,58,77, 86, 117, 118 use of in crown-work, 37 Pouring fusible alloy or metal, manner of, 93, 103, 332, 334 Preparation of natural crowns or roots for gold crown-work, 33 for Logan crown, 60 for porcelain crowns, 36, 43, 45, 50 Preparation, special, of badly decayed teeth and roots, 36 Preparatory treatment of the moutb, 6, 9 Pulp, capping of, 13 diseases of requiring extirpation, 12 instantaneous devitalization, with ex- cision of crown, 16 lesions of, 12 preservation or devitalization, 10 use of arsenic in devitalization of, 17, 18 Pulpless teeth, their treatment and dis- infection, 23 Punch forceps for riveting, for use in repairing bridge-work, 202 Pyorrhea alveolaris, bridge-work in cases of, 193 collar crowns in cases of, 124 Ready-made crowns, the Evans, 108 the Rynear, 99 Reaming of root-canals, 21, 22 Removable bar-bridges, 260 Removable or detachable bridge-work, 208 Dr. Curtis's method, 262 Dr. Litch's, 241 Dr. Morey's, 260 Dr. Parr's, 248 Dr. A. S- Richmond's, 220 Dr. Starr's, 243 Dr. Waters's, 255 Dr. Winder's, 238 connecting bars for, 216, 220 methods of forming attachments for, 209 INDEX. 345 Removable crowns and attachments for bridge-work, 209,225, 233, 238, 240, 242, 245, 249, 250, 257 Removable plate bridges, 225 Dr. J. L. Davenport, 234 Dr. Parr's methods, 254 Dr. Waters's methods, 255 Removal of crown- and bridge-work, 204 Repair of crown- or bridge-work, 202 Dr. Starr's method, 203 Dr. Williamson's method, 203 Repair of gold crowns, 204 Retaining-pin for all-gold crown, 37, 118 Richmond erown, the original form of, introduced, 85 Root-canal, antiseptic agents for treat- ment of, 25 drier, 24 method of filling, 26 method of treatment, 21 Root-reamers and facers, Ottolengui's, 60 Root-trimmer?, 34 Starr's, 246 Roots intervening between abutments, 174 Roots, special preparation of badly de- cayed, 36 Rubber or vulcanite attachment for crown. 76 Rules governing the insertion of bridge- work, 158, 180 Rynear's crown, 99 Screws to support crowns, 37, 51, 55, 56, 57, 69, 86 for use in crown-work, 49, 55, 56 Seamless gold collars, 291 Seamless gold crowns, 102, 108 method of contouring, 109 method of forming from an impression, 104 process of adjustment and insertion, 111 Self-cleansing spaces, 163, 164 Sensitive dentine, treatment of, 13, 36 Shapes of necks of teeth, 81 Shaping teeth and roots for crowning, process of, 33 Shell anchorage or crown, 175 seamless, 176 Shoulders on the anterior teeth, 87, 171, 316 Slots for anchorage bars, 172, 182, 185, 186 Solder, gold, formulas for, 328 Dr. Dorrance's, 329 Dr. Litch's, 329 Dr. Low's, 329 Dr. Richmond's, 329 Soldering, manner of, 88, 89, 164, 335 investments for, 335 Solid gold crowns, 116, 171, 172 Special forms and methods in crown- and bridge-work, 126, 171 Dr. Curtis's, 262 Dr. Knapp's, 270 Dr. Litch's, 241 Dr. Low's, 128, 266 Dr. Melotte's, 275 Dr. Morey's, 260 Dr. Parr's, 248 Dr. Winder's, '238 mandrel system, 287 Special preparation of badly decayed teeth or roots, 36 Spencer's method of removable bridge- work, 240 Spur support in bridge-work, 180 Stamping press for caps, 110 Starr's method of detachable bridge- work, 243 root-trimmers, 246 Sterilization of root-canals, 23 Stowell's porcelain gold collar crowns, 90 Simplicity crown, 72 Strengthening gold seamless crowns, 115 Sulphuric acid, care in the use of, 31 Syringes, hot-air, 23 abscess, 29 24 346 INDEX. 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