TM 8-225 
WAR DEPARTMENT 
TECHNICAL MANUAL 
DENTAL TECHNICIANS 
January 28, 1942 TM 8-225 
TECHNICAL MANUAL 1 
No. 8-225 f 
WAR DEPARTMENT, 
Washington, January 28, 1942. 
DENTAL TECHNICIANS 
Prepared under direction of 
The Surgeon General 
Paragraphs 
Chapter 1. General 1 
Chapter 2. Mouth and teeth. 
Section I. General 2-3 
II. Teeth . 4-7 
III. Regional anatomy 8-14 
IV. Definitions 15 
Chapter 3. Prosthetic technician. 
Section I. General 16 
II. Impression materials 17 
III. Plaster impressions 18-22 
IV. Modeling compound impressions 23-25 
V. Hydrocolloid impressions 26 
VI. Construction of full and partial vulcanite 
dentures 27-48 
VII. Acrylic resin dentures 49-50 
VIII. Denture repair..: 51-58 
IX. Dental castings 59-62 
X. Cast crowns 63-65 
XI. Cast occlusal gold crown 66-67 
XII. Fixed bridge 68-71 
XIII. Clasps and bars for partial dentures 72-78 
XIV. Cast partial dentures and partial denture 
skeletons 79-93 
XV. Splints 94-97 
Chapter 4, Dental X-ray technician. 
Section I. Equipment 98-103 
II. Intra-oral roentgenography 104-125 
III. Extra-oral roentgenography 126-129 
IV. Processing of X-ray films 130-138 
Chapter 5. Dental hygienist. 
Section I. General 139 
II. Structure and physiology 140-142 
III. Dental caries 143-144 
IY. Other diseases of mouth 145-153 
V. Saliva, deposits, and accretions upon teeth. 154-157 
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MEDICAL DEPARTMENT 
VI. Technique of dental prophylaxis 158-161 
VII. System for instrumentation and polishing.. 162-165 
VIII. Instructions to patient 166-167 
IX. Preparations for mouth and teeth 168-170 
Paragraphs 
Chapter 6. Dental assistant. 
Section I. Requisites of dental assistant 171-172 
II. Care of dental clinic 173-174 
III, Sterilization of instruments and dressings. _ 175-181 
IV. Care of equipment and supplies 182-190 
V. Duties at chair 191-200 
VI. Daily routine in clinic 201 
Chapter 7. Record clerk, dental service. 
Section I. General duties and forms used 202-205 
II. W. D., M. D. Form No. 57 (Report of Dental 
Service) 206-207 
III. W. D., M. D. Form No. 79 (Register of 
Dental Patients) 208-210 
IV. W. D., M. D. Form No. 18b (Statement of 
Expenditure of Special Dental Materials) 211-213 
V. Daily work sheet 214 
VI. Hospital clinic records 215-219 
VII, W. D., A. G. O. forms 220-221 
VIII. Dental survey. 222-224 
IX. Dental history of station 225-227 
Page 
Appendix. List of references 191 
Index 193 
2 DENTAL TECHNICIANS 
TM 8-225 
1 
Chapter 1 
GENERAL 
Paragraph 
Purpose and scope 1 
1. Purpose and scope.—a. Many complex problems confront the 
Dental Corps at the present time in the development of its various 
activities in the expansion program. One of the principal problems 
concerns the development of the laboratory service and the training 
of prosthetic technicians and enlisted personnel who are trained as 
dental assistants, record clerks, hygienists, and X-ray technicians. The 
entire training program depends very largely upon a standardization 
of the dental service. This also involves all the activities of enlisted 
personnel. 
h. Chapters 3 to 7, inclusive, cover the essential phases and activities 
of the five assignments which, in the dental service, are usually filled 
by Medical Department enlisted men. 
c. Chapter 2 is a general introduction to the technical aspects of the 
dental service and should be incorporated in the training program for 
all of the assigned dental personnel. The first sections of chapter 5 
may be used as general information useful to all nonprofessional per- 
sonnel with the dental service. 
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MEDICAL DEPARTMENT 
Chapter 2 
MOUTH AND TEETH 
Paragraphs 
Section I. General 2-3 
II. Teeth 4-7 
III. Regional anatomy 8-14 
IV. Definitions 15 
Section I 
GENERAL 
Paragraph 
Form and function 2 
General structure : 3 
2. Form and function.—a. Form.—A dental technician should 
know something about the form and function of the mouth and teeth 
in order that he may have a complete knowledge of his work. As 
artificial restorations reproduce some or all of the teeth and some of 
the supporting structure, the dental technician must know the form 
of each tooth and its related parts in order that he may reproduce these 
teeth in the artificial substitute. This chapter deals with the mouth 
and teeth in a general way. It is very important that the dental 
technician have a detailed knowledge of the form and contour of each 
tooth so that he can carve reproductions of the teeth for artificial 
replacements. This study of the exact shape and contour of each 
tooth, known as dental anatomy, will be taken up in the study of tooth 
carving which will precede the technical work explained in this manual. 
This chapter is confined to a general study of the mouth and teeth, 
leaving the detailed tooth anatomy to be taken up with the exercises 
in tooth carving. 
h. Function.—The mouth or oral cavity is man’s organ for receiving 
food and for preparing that food for the first process of digestion, that 
is, dividing it into small parts by chewing and mixing it with the 
salivary secretions. Man’s diet is both animal and vegetable 
(omnivorous). His teeth differ from the lower animals which are ex- 
clusively meat eaters (carnivorous) or vegetable eaters (herbivorous) 
and are formed for cutting, tearing, and grinding many kinds of foods. 
The incisor teeth situated in the front of the mouth have edges for 
cutting; the cuspids and bicuspids at the sides of the mouth have fairly 
sharp points or cusps for tearing; and the molars at the back part 
of the mouth have broad surfaces with low projections (cusps) for 
grinding the food. 
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DENTAL TECHNICIANS 
3. General structure.—a. The mouth is bounded in back by the 
throat or pharynx and in front by the lips. Above, a vault separates 
the mouth cavity from the nasal passages. This vault is called the 
palate; and in the front and middle part it has a hard surface because 
it is composed of bone with a thin covering of gum tissue (mucous 
membrane) over it. This part is called the hard palate. Behind the 
bony portion a soft sheet of muscular tissue continues downward to- 
ward the throat and terminates in a small tonguelike projection, the 
uvula. This soft portion is called the soft palate (fig. 1). Sometimes 
Figure 1.—Superior and posterior structures of oral cavity. 
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MEDICAL DEPARTMENT 
persons are born with a hole or aperture in the palate which allows a 
communication of the nose and mouth cavities. Such people are 
spoken of as having a cleft palate, and to provide for their speaking 
and eating normally, an operation must be performed to close this 
opening. Sometimes even after operation an opening into the nasal 
cavities persists, and an artificial plate must be made by the dentist 
for the patient to wear in his mouth to cover this aperture. 
1. Sublingual gland. 
2. Anterior gland of tongue. 
3. Ducts of Rivinus. 
4. Opening of submaxillary duct (Wharton's 
duct). 
5. Submaxillary duct. 
6. Genioglossus muscle. 
7. Styloglossus muscle. 
8. Hyoglossus muscle. 
9. Frenum linguae. 
10. Plica fimbriata. 
11. Profunda lingual artery. 
12. Lingual nerve. 
13. Hypoglossal nerve. 
Figure 2.-—Structures of tongue and floor of mouth. 
h. The floor of the mouth is a soft, thick, muscular layer which 
supports the front part of the tongue and in which are located some 
of the salivary glands (fig. 2). The tongue is attached to the upper 
part of the throat and to the floor of the mouth. It is a strong, mus- 
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DENTAL TECHNICIANS 
cular organ used in masticating food, in swallowing, and in talking. 
The teeth are firmly set in the jawbones. The upper jawbone is 
composed of two bones rigidly joined together, the right and left 
maxillary bones. These bones are also firmly attached to the other 
bones of the skull and face. The lower jaw is called the mandible. It 
is a strong, heavy, horseshoe-shaped bone attached to the skull on each 
side just in front of the ear canal by means of ball-and-socket type 
joints, the temporomandibular articulations. These joints permit a 
rather wide range of movement for opening the mouth and for chew- 
ing food. 
Section II 
TEETH 
Paragraph 
Classification 4 
Names and numbers 5 
Surfaces 6 
Roots 7 
4. Classification.—a. Teeth are sometimes roughly divided into 
anterior and posterior. The anterior teeth are those toward the front 
of the mouth, and the posterior teeth are those toward the back of the 
mouth. The anterior teeth include the incisors and cuspids, while the 
posterior teeth include the bicuspids and molars. 
b. Another general classification divides the teeth into incising and 
masticating; th° incising teeth include the incisors and cuspids, and 
the masticating teeth include the bicuspids and molars. 
5. Names and numbers.—a. There are 32 teeth in the human 
mouth; 16 in the upper jaw called the maxilla, and 16 in the lower 
jaw called the mandible. The teeth are called incisors, cuspids, bicus- 
pids, and molars. 
h. The median line is an imaginary perpendicular line drawn 
through the center of the body, dividing the body into right and 
left halves. 
line, the teeth are named as follows: 
Upper right central incisor. 
Upper right lateral incisor. 
Upper right cuspid. 
Upper right first bicuspid. 
Upper right second bicuspid. 
Upper right first molar. 
Upper right second molar. 
Upper right third molar. 
c. Taking the right side as an example, and starting at the median 
Lower right central incisor. 
Lower right lateral incisor. 
Lower right cuspid. 
Lower right first bicuspid. 
Lower right second bicuspid. 
Lower right first molar. 
Lower right second molar. 
Lower right third molar. 
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MEDICAL DEPARTMENT 
The left side is the same, except that the word left is substituted for 
right. 
d. Several systems of numbering the teeth have been devised 
whereby it is much simpler to designate a tooth by number rather 
than by name. The system in use in the Army is as follows: 
(1) Beginning at the median line in the upper jaw and continuing 
backward, the teeth are numbered from 1 to 8; beginning at the 
median line in the lower jaw and continuing backward, the teeth are 
numbered from 9 to 16. Thus, a number between 1 and 8 would 
indicate that a tooth was an upper, whereas a number from 9 to 16 
would indicate that the tooth was a lower. The letter R or L is 
placed in front of the number to designate whether the tooth is in the 
right or left side of the jaw. 
(2) The following diagram may make this clearer: 
Right 
Median line 
Left 
With this system when a tooth is designated as L3, it is known that 
the upper left cuspid is meant. R9 would be the lower right central 
incisor, R14 the lower right first molar, etc. 
6. Surfaces.—Each tooth has five surfaces which can be compared 
roughly to the four sides and top of a box. Each side has a name 
to designate the various surfaces: 
a. The mesial surface is the surface or side of the tooth nearest the 
median line. 
h. The distal surface is the surface or side of the tooth farthest 
from the median line. 
c. The buccal surface is the outside surface of the tooth or the side 
which lies next to the cheek. The term is usually applied to the 
bicuspids and molars. 
d. The labial surface is the outside surface of the tooth or the side 
which lies next to the lips. The term is usually applied to the incisors 
and cuspids. The labial surface of the incisors and cuspids refers 
to the same side that is called the buccal surface in the case of the 
bicuspids and molars. 
e. The facial surface is a term used to designate the side of the 
tooth next to the lips or cheeks and can be applied to either the 
anterior or posterior teeth. Labial, buccal, and facial all refer to the 
same surface of the teeth. 
/. The lingual surface is the inner surface of the tooth or the side 
which lies next to the tongue. 
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DENTAL TECHNICIANS 
g. The incisal surface or incisal edge is the cutting edge of the tooth 
and is used when speaking of this surface of the incisors and cuspids. 
h. The occlusal surface is the top surface or grinding surface and is 
used when referring to this surface of the bicuspids and molars. 
i. The entire name of the surface is ordinarily not used; instead, 
abbreviations which consist of the first letter of the word, as M, mesial, 
D, distal, O, occlusal, etc. Combinations of these letters are used to 
designate more than one surface. For instance, an inlay that extends 
over both the mesial and occlusal surfaces of a tooth is an MO inlay. 
Many combinations are used such as DO. LO. MI, MOD, etc. 
Figure 3.—Maxilla with outer plate of bone removed to show roots of teeth and their 
blood supply. 
j. For descriptive purposes, the crown of a tooth is divided into 
thirds. The third nearest the incisal edge in the case of the incising 
teeth, or the occlusal surface in the case of the masticating teeth, is 
called the incisal third or occlusal third as the case may be. The 
next third is called the middle third, and the third next to the gum 
is called the gingival third. 
7. Roots.—Dental technicians are not as much concerned with 
(he roots of the teeth as with the crowns. However, a brief descrip- 
tion of them is given below. 
a. The central incisors, lateral incisors, and cuspids, in both the 
upper and lower jaws, are all single-rooted teeth. The upper cus- 
pids have the longest and heaviest roots of any of the teeth. The 
lower centra] incisors have the shortest and smallest roots. 
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MEDICAL DEPARTMENT 
b. The upper first bicuspid usually has two frail roots, one placed 
buccally and the other lingually. It is not uncommon for the two roots 
to be fused together, giving the appearance of one single root. The 
upper second bicuspids are nearly always single rooted. 
c. The upper first molar has three roots, two on the buccal and one 
on the lingual. 
d. The upper second molar generally has three roots and is quite 
similar to the first molar except that there is more tendency for the 
roots to be fused together. 
e. The upper third molar may have from one to five roots or even 
more. Often, three roots in this tooth will be fused together so as 
to form one big cone-shaped root. At other times there will be three 
or four small frail roots. The upper third molar and lower third 
molar are subject to far greater variation than any of the other 
teeth. Figure 3 shows the roots of the upper teeth, the bone being 
cut away to demonstrate position of the roots. 
/. The lower bicuspids, both first and second, are single-rooted. 
g. The lower first molar has two roots, one mesial and one distal. 
h. The lower second molar is similar to the first, except that there 
is more tendency for the roots to fuse together. 
i. The lower third molar, like the upper third molar, is subject to 
great variation. Two roots are probably as commonly found as any 
other number, although very often there is only one, or there may be 
three or four. 
Section III 
REGIONAL ANATOMY 
Paragraph 
Relation to dental prosthesis 8 
Hard and soft palates : 9 
Mandible * 10 
Temporomandibular articulation 11 
Muscles of mastication 12 
Frena of mouth 13 
Torus palatinus 14 
8. Relation to dental prosthesis.—Section I referred to the 
parts of the mouth other than the teeth : the hard and soft palate, lips 
and cheeks, tongue, uvula, and maxillary bones and joints. A dental 
technician could do his work very well without a knowledge of these 
parts but he will have a better understanding of his work if he knows 
something of the anatomy of the mouth. In full denture work, 
especially, many steps are taken to conform the denture to the struc- 
ture of the mouth. There are certain areas over which excessive 
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DENTAL TECHNICIANS 
pressure is undesirable, and the denture must be scraped or relieved 
in these areas during its construction. The subject of anatomy with 
its peculiar names is a difficult one at best. However, the following 
is simplified as much as possible and should be accompanied by 
demonstrations by the instructors on models and skulls which will 
make it easier to understand. 
9. Hard and soft palates.—a. The hard palate is the roof of the 
mouth. It is formed by the union of the horizontal portions of the 
maxillary bones and palate bones at the median line. The front and 
side borders of the hard palate consist of that portion of the bone 
which gives support to the teeth. The posterior border is irregular 
and has attached to it a muscularlike curtain which is called the soft 
palate. The hard palate is covered throughout by a thick, firm, 
mucous membrane which is closely adherent to the bone. 
b. In the center of the hard palate is a prominent bony ridge cov- 
ered by mucous membrane. This ridge is called the 'palatal raphe 
or rnedian raphe and indicates the line of union formed during the 
development of the parts. Near the center of the hard palate the 
raphe frequently separates into two smaller ridges which continue 
backward, side by side, thus making it appear wider here than toward 
the front or back. As it runs posteriorly the raphe usually dimin- 
ishes in size, disappearing entirely as the soft palate is approached, 
although occasionally it is quite pronounced the entire length of the 
hard palate. 
c. This ridge is usually much harder and less compressible than 
the mucous membrane on either side of it. Unless one relieves the 
denture over this hard area and allows it to- rest evenly over the 
entire surface of the roof of the mouth, the denture will rock in the 
mouth, using the raphe as a fulcrum. This condition not only causes 
the denture to be unsatisfactory as to fit, but also causes a soreness 
over the ridge. A continued irritation of this kind over a period 
of time might even be the cause of a malignant growth. 
d. On either side of this central ridge, or raphe, in the anterior part 
of the mouth are found a number of fantastically arranged folds of 
mucous membrane which are called rugae. The number and size of 
these folds vary considerably. In some cases they are quite numerous 
and very prominent, while in other cases they are few in number and 
only slightly developed. 
e. At the anterior end of the raphe and just behind the central 
incisors there is an opening in the bone which is called the anterior 
palatal foramen through which certain nerves and blood vessels pass. 
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MEDICAL DEPARTMENT 
/. At the back part of the hard palate are two other openings in the 
bone which are called the posterior palatal foramina. These are 
found on either side of the hard palate and are located about halfway 
between the median line and the gingival border of the molars, and 
about 5 millimeters anterior to the junction of the hard and soft palate. 
g. These openings and their positions are important because it is 
often necessary to relieve over these areas on dentures. Nerves 
and blood vessels pass through them, and in some cases excessive 
pressure by the denture over these areas will cause a very uncomfort- 
able burning sensation over the roof of the patient’s mouth unless 
proper relief has been made. Figure 4 shows the tissues taken off to 
expose these foramina and demonstrates, on the left side of the figure, 
the blood vessels and nerves. 
Figure 4.—Hard palate showing foramina and (on left side) blood vessels and nerves 
which emerge from them. 
h. The soft palate is attached to the posterior border of the hard 
palate from which it is continued as a backward prolongation of its 
soft tissue. It runs downward and backward, and forms part of the 
posterior border of the oral cavity. The soft palate is composed of 
thin, dense, muscular fibers, blood vessels, nerves, and mucous glands. 
It has no underlying bony support. In short, the hard palate is the 
part of the roof of the mouth with underlying bony support, whereas 
the soft palate is the part with no bony support. The soft palate is 
movable, but the hard palate is not. The posterior border of a den- 
ture should never end on the hard palate; it should always extend a 
short distance onto the soft palate. 
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DENTAL TECHNICIANS 
10. Mandible.—a. The mandible or lower jawbone is the heaviest 
and strongest bone ot the head. It supports the 16 lower teeth and 
serves as a framework for the floor of the mouth. It is movable, hav- 
ing no bony union with the skull proper. It is attached to the skull 
by movable joints called the temporomandibular articulations, which 
will be taken up in detail later on. The mandible is symmetrical in 
form and consists of a horizontal portion called the body, and two 
vertical portions each of which is called a ramus (fig. 5). 
Figure -5.—Anterior view of mandible with outer plate of bone removed on left side of 
figure to demonstrate roots of teeth and blood and nerve supply. 
h. The mandible forms from two centers and consists of two iden- 
tical halves which meet at the median line forming a slight vertical 
ridge which indicates the line of union of the two halves. This 
ridge or junction is called the symphysis. Each half of the mandible 
has two surfaces, an inner and an outer one, and on each surface 
are certain points or landmarks which should be recognized. 
c. The external oblique line is a well-defined ridge extending 
obliquely across the facial or outer surface of the mandible. It 
extends from the mental process upward and backward to the base 
of the vertical portion of the bone, and is continuous with the anterior 
border of the vertical portion or ramus. 
d. The mental foramen is an opening in the bone usually situated 
about halfway between the upper and lower borders of the body of 
the mandible, and between the roots of the first and second bicuspid 
teeth. It gives passage to certain nerves and accompanying blood 
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MEDICAL DEPARTMENT 
vessels. Ordinarily, because of its position, no pressure is exerted 
on this nerve by a denture, and no relief is necessary. However, 
in very old persons where teeth have been absent a long time, the bone 
has absorbed a great deal, and the foramen is found very close to the 
upper border of the body of the mandible. In these cases it sometimes 
becomes necessary to relieve the denture over this area to avoid exces- 
sive pressure with resulting pain. 
e. The mylohyoid ridge or internal oblique ridge is a heavy ridge 
on the inner surface of the mandible, which occupies a position closely 
corresponding to the external oblique line on the facial surface. It 
begins near the base of the bone at the median line, and passes back- 
ward and upward, increasing in prominence until the base of the 
vertical portion of the bone is reached, into which it gradually 
disappears. 
/. The inferior dental foramen or mandibular foramen is an open- 
ing in the bone located near the center of the inner surface of the 
ramus of the mandible. It is the entrance to the mandibular canal 
which passes downward and forward through the ramus and body of 
the mandible finding an exit at the mental foramen on the external 
surface of the mandible. 
g. The mylohyoid groove is a depression or groove found on the 
inner surface of the mandible. It starts at the base of the mandibular 
foramen and runs obliquely downward and forward below the mylo- 
hyoid or internal oblique ridge. It accommodates the nerves and blood 
vessels which supply the floor of the mouth. 
h. The sigmoid notch is the crescent-shaped upper border of the 
ramus of the mandible. 
i. The anterior portion of the notch is formed by a flattened cone- 
shaped projection called the coronoid process which serves as an attach- 
ment for one of the muscles of mastication. 
j. The posterior portion of the notch is formed by a rounded or 
oblong projection which is called the condyloid process. The con- 
dyloid process, or condyle, is the portion of the mandible that enters 
into the formation of the joint which is referred to as the temporo- 
mandibular articulation. The condyle is divided into two sections: a 
head which is the rounded upper portion of the process and neck which 
is the somewhat constricted portion joining the head to the main body 
of the ramus. 
11. Temporomandibular articulation.—a. Attention has al- 
ready been called to the fact that the mandible has no bony union with 
the skull proper, but is attached to it by a movable joint. It is this 
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DENTAL TECHNICIANS 
joint or attachment that is known as the temporomandibular articula- 
tion. It receives its name from the two bones which enter into its 
formation, the temporal bone and the mandible. 
b. This joint is the seat of motion in the mandible, and entering into 
its construction are bones, ligaments, cartilage, and synovial mem- 
brane. These are the tissues essential to all movable articulations. 
The various movable joints of the body are classified according to the 
nature of the movement; and they correspond to the mechanical actions 
known as hinge joint, ball and socket joint, gliding joint, pulley joint, 
etc. The temporomandibular joint is a combination of the gliding 
type and hinge type. 
c. The bony parts entering into the formation of this joint are the 
glenoid fossa of the temporal bone and condyloid process of the man- 
dible. The glenoid fossa is a rounded cavity or depression, in the 
temporal bone, into which the head of the condyle fits to form the 
joint. 
d. The movement of the jaw is not limited to a simple opening and 
closing motion. The jaw is protruded (pushed forward), or retruded 
(pushed backward). There are also lateral movements in which the 
mandible is moved to either side. All of these various movements 
and the function of the teeth are closely associated with the temporo- 
mandibular articulation, and for this reason it is important to under- 
stand how it is constructed. The articulators used are made so that 
more or less normal movements of the mandible can be reproduced, the 
metal parts which form the joint of the articulator being similar to the 
bony parts forming the temporomandibular articulation. 
e. There is a wide variation in this joint in various individuals, 
and in many cases the same person will have considerable variation 
between the joint on his right side and that on his left side. 
/. In nonadjustable articulators an average joint has been built 
into the articulator which fits most cases fairly well. Cases which 
vary greatly from the average, or cases in which there is considerable 
difference in the right and left temporomandibular articulations, will 
not be as satisfactory when built on the nonadjustable type of articu- 
lator as when they are constructed on an adjustable type. 
g. Adjustable articulators are so constructed that the angles of 
the joints of the articulator can be varied and set to reproduce exactly 
the angles of the temporomandibular articulation of the patient. 
Group demonstrations will be given in which the temporomandibular 
articulation in a skull will be compared with the temporomandibular 
articulation as it is reproduced in the articulator. 
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MEDICAL DEPARTMENT 
12. Muscles of mastication.—Occupying the back part of the 
side of the face and forming an independent group are four muscles 
which are usually classed as the muscles of mastication. While 
this is true to a great degree, they are not the oidy muscles brought 
into action during this process. These four muscles of mastication 
are— 
Masseter. 
Temporal. 
Internal pterygoid. 
External pterygoid. 
Each one will be taken up separately. As stated previously, some 
difficulty will be experienced with the anatomical terms used. How- 
ever, in the group demonstrations everything will be pointed out on 
a skull to demonstrate where the muscles are attached and what their 
general action is. even though the origin and insertion of each 
muscle by its proper name may not be known. Generally speaking, 
the masseter, temporal, and internal pterygoid elevate or close the 
lower jaw, the principal function of the external pterygoid being to 
extend the lower jaw so that the lower teeth pass beyond the upper. 
The muscles which depress the jaw are certain muscles of the neck 
which will not be considered. 
a. Masseter.—This muscle extends generally from the zygomatic 
arch and the lower border of the malar bone, downward and back- 
ward to the outer surface of the ramus of the mandible. It is a 
strong, heavy muscle whose main action is to draw the jaw slightly 
forward and to close the jaw. 
b. Temporal.—This is a large fan-shaped muscle whose broad end 
is attached to the entire surface of the temporal fossa. From here 
it extends downward passing underneath the zygomatic arch, and is 
attached at its narrow end to the coronoid process of the mandible. 
Its action is to close the lower jaw, some of its fibers drawing the 
jaw backward after certain other muscles have protruded it. 
c. Internal pterygoid.—The internal pterygoid is attached at one 
end to the inner surface of the external pterygoid plate, the tuberos- 
ity of the palate bone, and a small portion of the maxilla. From 
here it extends downward, backward, and outward, its other end 
being attached to the internal surface of the ramus of the mandible 
at its lower and posterior borders. It is a thick, sheetlike muscle 
whose action is to close the jaw; at the same time the action draws 
the jaw backward and throws it toward the opposite side. 
d. External pterygoid.-—The external pterygoid is composed of 
two distinct heads, an upper and a lower. The upper head arises 
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DENTAL TECHNICIANS 
1S-13 
from the greater wing of the sphenoid bone and from the internal 
pterygoid ridge. It is inserted into the interarticular cartilage, into 
the capsule of the joint, and into the neck of the condyle. The lower 
head arises from the outer surface of the external pterygoid plate 
and is inserted into the neck of the condyle. The action of this 
muscle is to draw the condyle and interarticular cartilage forward 
and inward. The combination of these two movements produces 
an oblique movement of the lower molars with respect to the opposing 
upper molars. 
13. Frena of mouth.—In various situations about the labial, 
buccal, and lingual surfaces of the gums, small slender folds of 
mucous membrane are found extending into the surrounding tissues. 
These folds, which act as a bridle or curb to the adjacent movable 
parts, are known as the frena of the mouth. The principal frena, 
three in number, are found at the median line and are named as 
follows: 
Frenum labium* superioris. 
Frenum labium inferioris. 
Frenum linguae. 
a. The frenum labium superioris extends from the inner surface 
of the upper lip to the upper gum, and limits to some extent the 
movement of the upper lip. Its attachment to the gum is quite 
variable, sometimes being attached very high, and in other cases 
extending down to the gingival border of the teeth. The frenum 
labium superioris is usually much larger than the frenum labium 
inferioris. 
b. The frenum labium inferioris extends from the inner surface 
of the lower lip to the lower gum, and limits to some extent the 
movement of the lower lip. As in the upper, the attachment to the 
gum is variable. This frenum is the smallest of the three principal 
frena and in some cases is so small that it cannot be seen unless the 
lip is stretched. 
c. The frenum linguae extends from the under surface of the tip 
of the tongue to the lingual surface of the lower gums at the median 
line. This frenum limits the movement of the tongue to some extent 
and is the largest and strongest of the three principal frena. It is 
much stronger than those connected with the lips. 
d. Similar bridles are found in the buccal region, usually near the 
bicuspid teeth, but they are much smaller than those at the median 
line. The frena are of great importance because allowance must 
be made for them in constructing dentures. If a denture is com 
431511°—42 —2 
17 TM 8-225 
13-15 
MEDICAL DEPARTMENT 
structed without the proper allowance having been made for the 
frena, it will be a matter of only a few hours until they are so sore 
that the denture cannot be worn. 
14. Torus palatinus.—This is a condition occasionally con- 
fronted with in making dentures. It consists of a bony protuber- 
ance covered with mucous membrane. It is usually found in the roof 
of the mouth. The protuberance varies greatly in size in different 
individuals. Some are quite small, while others are so large that 
they almost fill the vault of the mouth. In most cases they should 
probably be removed surgically, but for one reason or another 
they are frequently not removed, and it is necessary to construct 
dentures over them. They are hard, like the median raphe, and good 
relief must always be made over them for the same reasons as for 
the median raphe. These reasons are to permit a more perfect fit 
by eliminating rocking of the denture, and to avoid soreness over 
these areas and eliminate the possibility of malignant growths de- 
veloping due to long-continued irritation. This condition is occasion- 
ally found in other locations about the mouth. Probably the next 
most common place is on the lingual surface of the mandible in the 
region of the cuspids and bicuspids. 
Section IV 
DEFINITIONS 
Paragraph 
Terms used 15 
15. Terms used.—a. Without considerable previous training, 
many terms will be found confusing or meaningless, but they must 
be known because they will be encountered as long as there is any 
connection with dentistry. Definitions of the more important of 
these follow: 
Alloy.—A metal composed of two or more different metals which have 
been mixed in the molten state. In dentistry alloys used are generally 
a mixture of gold and one or more other metals such as copper, 
silver, etc. These metallic mixtures are called gold alloys. 
Alveolar process.—The projection of the maxillary bones which en- 
velops the roots of the teeth and forms their alveoli (sockets). 
Alveolus.—The cavity or socket in the bone in which the root of a 
tooth is embedded or fixed 
Apex.—The terminal end of the root of a tooth. 
Axial surfaces.—Those surfaces of the teeth that are parallel with their 
long axes. They are labial, buccal, linqual, mesial, and distal. 
18 TM 8-225 
15 
DENTAL TECHNICIANS 
Bell-crowned.—A tooth in which the mesio-distal diameter of the 
crown is much greater than that of the neck. 
Gementum.—A tissue resembling bone which forms the outer surface 
of the roots of the teeth. 
Contact 'point.—The point on the proximal surface of a tooth which 
touches a neighboring tooth. 
Grown.—That portion of a tooth which is covered with enamel and 
which projects from the tissues in which the root is fixed 
Cusp.—A pronounced elevation or point on the surface of a tooth, 
more especially on the occlusal surface. 
Gutting edge.—The edge formed by the junction of the labial and 
lingual surfaces of the incisor and cuspid teeth. In the cuspids the 
edge is raised to a point near its center. 
Deciduous teeth.—The teeth of the child which are shed to give place 
to the permanent teeth. They are sometimes referred to as tempo- 
rary teeth, baby teeth, milk teeth, etc. 
Dentine.—The hard tissue of which the main body of a tooth is formed. 
Embrasure.—An opening that widens outward or inward. That por- 
tion of the interproximal space that widens toward the buccal or 
toward the lingual. 
Enamel.—A very hard tissue covering the crown of a tooth. 
Facial.—The outside surface of a tooth which is adjacent to the face. 
Fissure.—A fault in the surface of a tooth caused by the imperfect 
joining of the enamel of the different lobes. Fissures occur along 
the lines of the developmental grooves. 
Foramen (pi. foramina).—An opening in the surface of a bone (or 
at the apex of a tooth) for the passage of blood vessels and nerve 
fibers. 
Fossa.—A round or angular depression in the surface of a tooth. 
These occur mostly in the occlusal surfaces of the molars and in the 
lingual surfaces of the incisors. 
Gingiva.—The portion of gum tissue enveloping the necks of the teeth 
crownwise from the attachment at the gingival line. A shorter 
definition is the free margin of the gum. 
Gingival line.—The line around the neck of a tooth at which the 
gingiva is attached. The line of junction of the enamel and 
cementum. 
Groove.—A long-shaped depression in the surface of a tooth. 
Inclination.—The inclination of a tooth is the deviation of the long 
axis of the tooth from the perpendicular. 
Interproximal embrasure.—That portion of the interproximal space 
which widens toward the lip or cheek, or toward the tongue. 
19 TM 8-225 
15 
MEDICAL DEPARTMENT 
Interproximal space.—The V-shaped space between adjoining teeth. 
This space is formed by the proximal surfaces of the adjoining 
teeth and the border of the alveolar process between the necks of 
the teeth. Normally this space is filled with gum tissue. 
Marginal ridge.—The ridges, or elevations, of enamel on the margins 
of the occlusal surfaces of the bicuspids and molars and on the 
mesial and distal margins of the lingual surfaces of the incisors 
and cuspids. 
Median line.—An imaginary perpendicular line drawn through the 
center of the body, which divides the body into right and left halves. 
Neck.—That portion of the tooth which forms the junction of the 
crown and root. 
Oblique ridge.—A ridge running obliquely across the occlusal surface 
of the upper molars. It is formed by the union of the triangular 
ridge of the disto-buccal cusp with the distal portion of the ridge 
forming the mesio-lingual cusp. 
Pit.—A sharp pointed depression in the enamel. Pits occur mostly 
where several developmental grooves join, as in the occlusal surfaces 
of the molars, and at the endings of the buccal grooves on the buccal 
surfaces of the molars. 
Proximal surface.—The surface of a tooth which lies next to another 
tooth. This nearly always means mesial or distal. 
Ridge.—A long-shaped elevation on the surface of a tooth. 
Rugae.—A series of irregular ridges on the front part of the roof 
of the mouth. 
Septum.—That portion of the alveolar process which lies between 
the roots of the teeth separating their alveoli. 
Sulcus.—A notable long-shaped depression in the surface of a tooth, 
the inclines of which meet at an angle. A sulcus has a develop- 
mental groove at the junction of its inclines. 
Supplemental groove.—A shallow long-shaped depression in the sur- 
face of a tooth, generally with a smoothly rounded bottom. Sup- 
plemental grooves differ from development grooves in that they do 
not mark the junction of lobes. 
Supplemental lobe.—A lobe that does not belong to the typical form 
of the tooth; an additional lobe. 
Supplemental ridge.—A ridge on the surface of a tooth that does not 
belong to the typical form of the tooth: an additional ridge. 
Transverse ridge.—A ridge formed of two triangular ridges, which 
join to form a continuous ridge across the occlusal surface of a 
tooth. 
20 TM 8-235 
15 
DENTAL TECHNICIANS 
Triangular ridge.—A ridge running from the point of a cusp toward 
the central portion of the occlusal surface of a tooth. 
Tubercle.—A slight rounded elevation on the surface of a tooth. 
Tubercles occur frequently on the linguo-gingival ridge of the inci- 
sors and occasionally upon various parts of other teeth. They are 
deviations from typical tooth forms. 
b. See appendix for list of references. 
21 TM 8-225 
16 
MEDICAL DEPARTMENT 
Chapter 3 
PROSTHETIC TECHNICIAN 
Paragraphs 
Section I. General 16 
II. Impression materials 17 
III. Plaster impressions 18-22 
IV. Modeling compound impressions 23-25 
V. Hydrocolloid impressions 26 
VI. Construction of full and partial vulcanite dentures 27-48 
VII. Acrylic resin dentures 49-50 
VIII. Denture repair 51-58 
IX. Dental castings 59-62 
X. Cast crowns 63-65 
XL Cast occlusal gold crown 66-67 
XII. Fixed bridge 68-71 
XIII. Clasps and bars for partial dentures 72-78 
XIV. Cast partial dentures and partial denture skeletons. 79-93 
XV. Splints 94-97 
Section I 
GENERAL 
Paragraph 
Scope 16 
16. Scope.—The term prosthetic dentistry or prosthodontia may 
be defined as that branch of dentistry which has to do with the replace- 
ment of any lost or missing parts of the dental apparatus by suitable 
artificial substitutes. Dental laboratory mechanics is that part of the 
science or art of prosthodontia which has to do with the construction 
of these appliances. The instructions contained in this chapter include 
the laboratory procedures for the construction of full dentures, partial 
dentures, crowns, bridges, and splints. A full denture may be defined 
as a structure replacing the full number of teeth in either jaw. A 
partial denture is a structure replacing the missing natural teeth in 
either jaw and is retained by mechanical means against the remaining 
natural teeth. A crown is an artificial restoration of the crown of 
a natural tooth. A bridge is a fixed appliance which replaces lost 
teeth, retained by attachments other than clasps to abutments sup- 
ported by the roots or crowns of adjoining teeth. A splint is any 
apparatus, appliance, or device employed to prevent motion or displace- 
ment of fractured or movable parts. 
22 TM 8-225 
17 
DENTAL TECHNICIANS 
Section II 
IMPRESSION MATERIALS 
Paragraph 
Description and limitations 17 
17. Description and limitations.-—An impression is an exact 
negative reproduction of a patient’s oral arch and teeth. A positive 
form or cast is obtained from the impression that is identical to the 
mouth. The dental technician’s work begins when he receives the 
completed impression from the dental officer. As a great deal of pains- 
taking care is needed to secure an accurate impression, the importance 
of skillful handling of the impression by the technician cannot be 
stressed too much. Any deviation from this will result in the com- 
pleted denture being unsatisfactory. In an edentulous or toothless 
mouth there are usually no undercuts present, or at least very few. 
Therefore no great problem is presented in getting the impression 
from the mouth. For this reason a material such as modeling com- 
pound can be used. This material becomes plastic upon the addition 
of heat and returns to its hard state when allowed to cool in the mouth. 
However, a dental arch containing some natural teeth presents quite 
a different problem; that is, one concerning the selection of a suitable 
impression material. As can be seen by looking in any mouth, there 
are always undercuts when natural teeth are present. If an impres- 
sion of this type was taken in modeling compound, it would be very 
difficult to remove and when once removed, it would be distorted to 
such an extent as to render it useless. Therefore another type of im- 
pression material must be used. There are two materials commonly 
used for this type of case, each having entirely different characteristics, 
but both giving equally good results. The first is plaster of paris, 
which is placed in the mouth while in its plastic stage and allowed 
to set. It is then broken into several fragments, which permits its 
removal from the mouth, and at the same time preserves the details 
of all the undercuts. These fragments are later reassembled in their 
proper relationship, which gives an accurate reproduction of the dental 
arch. The other type of impression material is the hydrocolloid. This 
material can be softened by moist heat, placed in the mouth, and 
allowed to cool. Due to its great elasticity, it can be removed over the 
undercuts without any distortion of the impression. Various com- 
binations of materials may also be used, and these will be discussed 
later. 
23 TM 8-225 
18-19 
MEDICAL DEPARTMENT 
Section III 
PLASTER IMPRESSIONS 
Paragraph 
General- 18 
Assembling parts 19 
Boxing - 20 
Pouring casts 21 
Separating casts 22 
18. General.—Plaster impressions for partial dentures consist of 
several pieces that must be reassembled in the tray in their proper 
position and relationship. Great care must be taken in the handling 
of these broken fragments, as any further breakage or rubbing of the 
edges will seriously interfere with the accuracy of the impression. 
The steps taken in the assembling of the plaster impression are as 
given in paragraph 19. 
19. Assembling parts.—a. Allow the fragments to dry before 
beginning to assemble the impression. 
h. Remove all crumbs of plaster from the tray. 
c. Gently remove all adhering particles of plaster from the frac- 
tured edges of the impression with a camel’s-hair brush. 
d. Assemble the parts in the tray consecutively so as to avoid under- 
cuts. Never force any fragment in position, as this will mar the 
edges. If the pieces are assembled in the proper order, they will 
easily slip into their correct places. 
e. After the parts are assembled in the tray, apply a slight amount 
of finger pressure on the various pieces of plaster so that the lines 
of fracture are barely noticeable. Be sure that the entire impression 
fits snugly in the tray. 
/. Maintain this pressure, and with a warm spatula carefully apply 
sticky wax to join the edges of the impression to the tray. Never 
allow the wax to touch the tissue surfaces of the impression. 
g. With a camePs-hair brush, apply an alcoholic solution of orange 
shellac to the impression. It must be thin enough to penetrate the 
plaster to a slight degree without obliterating any of the fine details. 
This is used as a staining medium. Allow to dry. 
h. With a camel’s-hair brush, apply a coat of sandarac varnish over 
the shellacked surface of the impression and allow to dry. It should 
be thin enough so as not to obliterate the fine details. The varnish 
may be made thinner with a little alcohol, if necessary. This is used 
as a separating medium and the impression should now have a glossy, 
24 TM 8-225 
DENTAL TECHNICIANS 
19-20 
smooth finish. A solution of soap in water may be used in place of 
sandarac varnish as a separating medium. 
20. Boxing.—The impression is now ready to be “boxed” pre- 
paratory to the pouring of the model. By this step the impression is 
reenforced by a retaining wall which confines the stone to the impres- 
sion and simplifies the trimming of the cast after it is poured. 
a. With a sharp knife, cut a strip about %e inch in width along the 
entire length of the strip of boxing wax. 
A. Board. 
B. Impression. 
C. Moldine or clay support which attaches 
impression to board. 
D. Sheet lead or tin box. 
h. Seal this strip around the outer edges of the impression about % 
inch away from the crest of the impression’s rim and across the pos- 
terior border. Care should be exercised to prevent the wax from cover- 
ing any portion of the impression. 
Figure 6.—Boxing of upper impression by method not requiring heat 
A. Board. 
B. Impression. 
C. Clay, moldine, or plaster support 
D. Sheet lead or tin box. 
Figure 7.—Boxing of lower impression 
c. Mold the balance of the boxing wax to the outer border of the 
impression. With a warm spatula, seal the wax to the impression 
and along the edges of the boxing wax itself. Before sealing it is 
necessary to make certain that the top of the wax is not too high 
from the top of the impression, as this will create needless bulk in 
the cast; y3 inch is sufficient (fig. 6). 
d. The technique for lower impressions is exactly the same, with the 
exception of one step. In the lower it is necessary to apply a small 
piece of moldine or wax in the space that is occupied by the tongue. 
After this has been done, the case is boxed as described above (fig. 7). 
25 TM 8-225 
21-22 
MEDICAL DEPARTMENT 
21. Pouring1 casts.—This consists of transforming a negative 
impression of the dental arch into a positive reproduction of the same 
arch. 
a. After the plaster impression has been shellacked, varnished, and 
boxed, it should be immersed in water for 10 minutes prior to pouring 
the cast. This is to allow the plaster to absorb a certain amount of 
water which will make the later separation much easier, and also will 
prevent a chalky cast. 
h. Remove impression from water and dry off all excess moisture. 
c. The casts must be made of a material of sufficient strength to with- 
stand usage during the construction of the denture. It must with- 
stand the pressure and temperature changes during vulcanization. It 
must not set too quickly as sufficient time is needed for manipulation, 
and when setting it should not expand or contract. Such a material is 
quick-setting stone. As stone requires less w’ater for mixing than does 
ordinary plaster, the correct proportion is approximately one part of 
water to three parts of stone by weight. This varies slightly accord- 
ing to the manufacturer, and his directions should be followed. 
d. Place the correct proportions of stone and water in a clean plaster 
bowl. Tap the bowl gently against the bench so that all air bubbles 
will be expelled. Leave sufficient time for the stone to absorb the 
water as this will aid in the spatulation. 
6’. Hold the bowd in one hand, and with a plaster spatula mix the 
stone with a cutting motion until it assumes a puttylike consistency. 
Never whip the stone as this will incorporate air into the mix. Ex- 
cessive spatulation after a puttylike consistency has been secured will 
reduce working time, a condition which must be guarded against. 
/. Never add water to a mix after spatulation in order to make it 
thinner. If such is done, crystallization which already has begun 
will be broken up resulting in a weak cast. Place a small portion of 
this stone in the rear of the impression, which is held in the hand. 
Gently jar it against the bench until the mix covers the tissue surface 
of the impression with a thin layer of stone. 
g. Continue adding the stone and allow each addition to settle in the 
impression before the next is deposited. Continue adding the stone 
until the impression is completely filled. Wait until the mix sets 
before proceeding. 
h. Remove boxing wax and score the top of the cast with a sharp 
knife to facilitate attachment to plaster when mounting on the articu- 
lator. 
22. Separating casts.—a. With a sharp knife very carefully 
scrape off the impression plaster until the brown color of the staining 
26 TM 8-225 
DENTAL TECHNICIANS 
22-24 
material becomes visible. This will weaken the impression so that 
it will be easy to remove without injuring the cast. 
h. Insert the sharp point of a knife in the line of fracture and apply 
slight pressure away from the teeth and thin parts of the cast. It is 
best to remove the plaster from around the teeth and undercuts before 
removing that from around the tissue surfaces. Great care must be 
taken in this step to prevent the breaking of teeth on the model. 
c. Eemove any adhering separating media from the casts with cotton 
and alcohol. 
d. All rough edges and overhanging margins are removed with 
knife, file, or sandpaper, and the casts trimmed and shaped as 
desired. 
Section IV 
MODELING COMPOUND IMPKESSIONS 
Paragraph 
General 23 
Boeing 24 
Separating cast 25 
23. General.—A large percentage of the impressions that a dental 
technician must work with is taken in impression compound. It may 
be white, black, red, or brown in color. The boxing of the compound 
impression will require more care than those made from plaster. 
Whereas plaster that has hardened or set is unaffected by the applica- 
tion of hot wax in the boxing process, the compound will absorb some 
of the latent heat from the wax and soften sufficiently to distort it 
under hand manipulation, thus ruining the impression. Therefore it 
must be boxed by a method that does not require heat, A simple 
technique is given in paragraph 24. 
24. Boxing.—a. Place the impression on some moldine or art clay 
which is molded to give evenly distributed support to the impression. 
This material is carried around the labial and buccal flanges of the 
impression to within y8 inch from the crest of the impression and its 
posterior border. The sides should be perpendicular. A piece of tin 
or lead sheet is conformed to the periphery of the impression and held 
secure by elastic bands. The casts may then be poured without dan- 
ger of distortion (fig. 6). 
b. The method of handling the mandibular or lower impression 
is similar but the tongue area space of the lower requires a different 
treatment. The impression is seated on some moldine or art clay 
which is carried around the outside flanges as in the maxillary impres- 
sion. Then the clay or moldine is carried into the tongue area space, 
27 TM 8-225 
24-26 
MEDICAL DEPARTMENT 
filling it up to within y8 inch from the crest of the lingual flanges. A 
strip of tin or lead sheet is then carried around the circumference of 
the impression as before, and held with elastic bands. The cast is then 
poured. If it is impossible to obtain the moldine used in this tech- 
nique, ordinary plaster may be used in its place. It is a little harder 
to manipulate but will serve the same purpose (fig. 7). 
c. The modeling compound impressions do not need a staining and 
separating media unless a plaster wash has been used. This consists 
of a compound impression with a very thin layer of plaster over the 
entire tissue surface. In an impression of this type it is necessary to 
apply a light coat of sandarac varnish to the surface of the plaster 
so that the casts may be more readily separated from the impression. 
A staining coat of shellac is unnecessary. 
25. Separating’ cast.-—a. In the removal of the compound impres- 
sion from the cast, it is necessary to apply sufficient heat to return the 
compound to a soft or plastic state. This is accomplished by immers- 
ing the impression in warm water for a sufficient length of time to 
allow the entire thickness of the compound to become soft. If the 
water is too hot, the compound will become sticky and will adhere to 
the cast. 
h. Insert a knife blade under the edge of the impression and gently 
ease the compound away from the model. If it is sufficiently plastic, 
it should come away very easily. If it is too hard, there is danger of 
breaking the model. Take a small section at a time and then return 
the impression to the warm water for additional heating. In this way 
gradually remove the entire impression from the cast. 
c. The cast is then trimmed and shaped as usual. 
Section V 
HYDROCOLLOID IMPRESSIONS 
Paragraph 
General 26 
26. General.—The third type of impression material that is com- 
monly used is the hydrocolloid. It possesses unusual plasticity, some 
elasticity, and slight compressibility. The impression can be removed 
from undercuts without distortion and gives the finest detail. Casts 
are obtained without the use of separating media and without the 
danger of injury or breakage incident to the removal of the impres- 
sion compound. Duplicate casts may be obtained by the careful re- 
moval of the model from the impression and repouring the impression 
or by making a second impression of the cast. This material is gen- 
28 TM 8-225 
DENTAL TECHNICIANS 
26-27 
erally used in the making of impressions for partial dentures, although 
it may be used in conjunction with modeling compound for full denture 
cases. In either case, it is treated the same by the dental technician. 
The cast must be poured immediately after the impression is taken, 
otherwise the material will dry out and distort the impression. If 
this is impossible, it may be kept in cold water for a short time and 
then poured. 
Section VI 
CONSTRUCTION OF FULL AND PARTIAL VULCANITE 
DENTURES 
Paragraph 
Relief areas 27 
Trial denture base _ _ 28 
Biteplates 29 
Mounting casts on articulator 30 
Selecting artificial teeth 31 
Requirements of tooth forms 32 
Arranging upper anteriors 33 
Arranging upper posteriors 34 
Arranging lower first molar 35 
Arranging lower second bicuspid 36 
Arranging lower anteriors 37 
Arranging cuspids 38 
Arranging lower first bicuspid 39 
Incising bite 40 
Balancing bite 41 
Central dental laboratory assortment of new Trubyte teeth 42 
Denture waxing 43 
Denture flasking (full) 44 
Denture flasking (partial) 45 
Packing the case 46 
Vulcanizing 47 
Cleansing and polishing dentures 48 
27. Relief areas.—The mucous membrane covering the bony tis- 
sues of the mouth is not of uniform thickness over the entire surface. 
There are areas where the membrane is very thin and the bone is quite 
prominent. This is especially true along the median raphe of the 
palate and the crest of the ridge. There are other areas of the mouth 
that have an abundance of connective tissue overlying the bone, ex- 
amples of which are the tissue-bearing areas of the palate and the slopes 
of the ridge. In constructing a denture it is necessary to relieve these 
hard areas so that the soft tissues overlying them will not be com- 
pressed when the denture is worn, and at the same time allow the tissue- 
bearing areas to be evenly compressed. In addition to these bony 
29 TM 8-235 
27-28 
MEDICAL DEPARTMENT 
areas, it is sometimes necessary to relieve pressure on nerves and blood 
vessels, especially where they come through the bony openings. Re- 
lief areas may be prepared in two ways: 
a. The dental officer may prepare the areas to be relieved in the im 
pression before the cast is made. 
Peguee 8.—Area to be relieved on upper model. 
h. The dental technician may prepare the areas indicated by the 
dental officer to be relieved by burnishing on the cast one or more layers 
of Nos. 40, 50, or 60 tinfoil which has been cut to fit the area for that 
particular case. As there can be no standard size and shape, the tinfoil 
must be cut for each case. The hardest areas are covered most thickly, 
but the thickness of the relief area should never be carried to the extent 
of creating a suction chamber, as in time this space would fill with 
hypertrophied tissue, thus defeating the purpose for which it was 
made. If tinfoil is unavailable, two or three layers of lead foil from 
X-ray films may be used in the same manner (fig. 8). 
28. Trial denture base.—Since a denture must fit the mouth 
accurately, it is first made on a trial base, such as wax, or other material 
which can be easily molded. This material should be of sufficient 
strength to hold its shape while the denture is tried in the mouth. 
Baseplate is preferable to wax as a trial denture base, however, because 
it holds its shape better and is not easily distorted by the temperature 
of the mouth. Procedure of adapting baseplate to cast is as follows: 
a. Pass the baseplate through the flame several times until it shows 
signs of wilting. Do not heat it too much as this will melt or burn the 
material (fig. 9). 
30 TM 8-225 
DENTAL TECHNICIANS 
b. Place the softened baseplate over the upper cast and adapt the 
jialatal portion closely to the cast by pressing lightly with the lingers. 
Reheat the baseplate when necessary and continue adapting it over 
the alveolar border and over the buccal and labial surfaces (fig. 10). 
c. Avoid buckling or creasing of the baseplate. 
Figure 9. 
Figure 10. 
d. Heat the partially adapted baseplate, and using plate shears trim 
away the surplus extending beyond the outer edges of the extension 
on the cast made by the carding wax rim in the boxing process. This is 
illustrated by G in figure 11. 
Figure 11. 
Figure 12. 
e. Heat the baseplate which rests on the extension of the cast mate- 
rial by passing it once through the flame and folding the heated portion 
upon the buccal and labial surfaces by pressure, as shown in figure 13, 
and continue to the finished form, shown on the right side in figure 14. 
The folded portion is not heated enough to fuse with the baseplate 
against which it is folded. Fold the extension across the heel in the 
same manner. The margins thus shaped must conform to the muscle 
trim margins of the impression and constitute a valuable reenforcement 
of the baseplate. 
31 TM 8-225 
28-29 
MEDICAL DEPARTMENT 
/. Chill the baseplate with cold water and then carefully remove 
from the cast. 
g. In lower casts adapt the trial baseplate material over the highest 
part of the alveolar ridge in the anterior region of the cast and work 
backward toward the heels. Treat the lingual, buccal, and labial 
margins of the lower baseplate the same as the upper. 
h. If the trial baseplate should be broken, it may be repaired by 
placing the broken pieces on the cast with the edges together and 
fusing with a hot wax spatula. Melt some of the baseplate material 
in a flame and drop it over the break. Smooth the surface. 
i. In partial cases, after adapting the baseplate to the palate and 
alveolar ridges, heat the material in the region of the plaster teeth 
and remove with a hot spatula or shears. This material should be 
removed to within %2 inch from the gum margins of the plaster teeth, 
and the edges of the baseplate smoothed with a file. 
Figure 13. 
Figure 14. 
j. In partial lowers, it is necessary to reenforce the baseplate extend 
ing about the teeth by imbedding a hot wire or paper clip in the base 
plate and smoothing the surface with a hot spatula. 
29. Biteplates.—The mandible or lower jaw is movable, and is 
attached to the skull by two movable joints, giving it a hingelike 
motion. However, this is not a fixed motion as the jaw may also be 
moved in other directions within limits. In a mouth with natural 
teeth in place, the occlusal surfaces of these teeth act as guides which 
permit the jaws to come together in a rest or centric position. When 
the teeth are gone this relationship is missing. Therefore it is neces- 
sary to construct biteplates which will help the dental officer in rees- 
tablishing this relationship. Since the dental technician does not see 
the patient, he can only approximate the required size and shape of 
the biteplates. 
a. Mark on the cast in a place where it can be seen, with the trial 
denture base in place, a line designating the crest of the alveolar ridge. 
This is for future reference in setting up the artificial teeth. 
32 TM 8-225 
DENTAL TECHNICIANS 
29-30 
h. Soften a sheet of basewax by passing it over a flame several times, 
and fold it along its lesser length into a tight roll. 
c. Bend the wax roll to the approximate shape of the alveolar ridge 
of the cast. 
d. Replace the trial baseplate on the cast and attach the roll of wax, 
sealing it with a hot spatula. 
e. Using a template or any flat surface, press the wax to the desired 
height. This is usually about 10 to 13 millimeters in height from the 
anterior portion of the alveolar ridge, and less in the molar region. 
Figure 15. 
/. With a knife and a hot spatula, trim the sides of the baseplate to 
a width of not more than 8’ millimeters. 
g. Add melted wax where necessary to fill in spaces between the wax 
roll and the baseplate on the buccal, labial, and lingual surfaces. 
h. In partial cases be sure that the biteplate does not interfere with 
the teeth on the cast and cut the wax roll to fit the alveolar ridge where 
the teeth are missing, extending the wax about %6 inch above the teeth 
of the cast but not covering the teeth. 
i. Square up the sides and angles of the biteplate, making certain 
that it conforms to the cast and that it is directly over the crest of 
the alveolar ridge. 
j. Polish the biteplate with wet cotton (fig. 15). 
30. Mounting casts on articulator.—The cast or casts, with the 
biteplates constructed, are returned to the dental officer, who records 
the relationship of the patient’s lower jaw to the upper jaw. This is 
known as “taking the bite.” This established, the casts and biteplates 
come back to the dental technician ready to be placed on the artic- 
431511°—42——8 TM 8-225 
30 
MEDICAL DEPARTMENT 
ulator. The articulator used in the Army dental service is known as 
the Gysi simplex articulator, which simulates the movements of the 
jaw and has the plane of the condyle paths set at 30°. The procedure 
in mounting casts is as follows: 
a. Attach the biteplates to the casts with wax at several points. 
b. Place the casts in water until all bubbling has ceased 
c. Place the incisor guide pin in the sleeve of the upper extension 
arm, keeping the top of the pin level with the top of the sleeve. 
Figure 16. 
d. Place the incisal guide on the pin, with the setscrew in the depres- 
sion of the pin and the point directed backward to the median line 
e. Extend the median line mark on the front of the upper cast or 
bite rim vertically upward to the top of the cast. Make a similar 
vertical mark on the rear of the cast, starting from the median line of 
the palate. Draw a straight line across the cast connecting these 
twro lines. 
/. Place an elastic band about the setscrew on the incisor guide point 
and in the notches on the outer sides of the vertical part of the frame. 
This line, as given by the elastic band, will establish the approximate 
occlusal plane. 
g. Place three small pieces of wax or moldine in a tripod arrange- 
ment on the lower extension arm, and force the lower cast down over 
these pieces until the occlusal plane of the biteplate is level with the 
elastic band, and the median line of the biteplate touches the tip of 
the incisor guide. Adjust the casts so that the median line of the 
upper cast is directly below the median line of the upper extension arm. 
34 TM 8-225 
DENTAL TECHNICIANS 
30-32 
h. Attach the upper cast to the upper extension arm with plaster 
and allow to set. Then invert the articulator and attach the lower 
cast to the lower extension arm in the same manner. 
i. Allow plaster to set and trim off all excess plaster (fig, 16). 
j. Carefully separate the biteplates and remove the biteplates from 
the casts. 
31. Selecting artificial teeth.—Before taking up the technique 
of setting the teeth, to which stage the case has been brought, consid- 
eration will be given to the question of selecting artificial teeth, of 
vital importance to both the efficiency and appearance of artificial 
dentures. In selecting artificial teeth, the two principal requirements 
to be considered are appearance, which includes form, proportion, and 
shade, and mechanics such as the length of bite and ridgelap necessary 
to the proper adaptation of the teeth to the ridges. These two factors 
are so often dependent upon each other that any apparent antagonism 
between them calls for judgment in making the necessary compromise. 
It may be stated as a safe rule to follow, that whenever the mechanical 
requirements interfere with the final appearance, the mechanics should 
be sacrificed as much as possible. While this may be questioned by 
some authorities, experience proves that appearance is the most im- 
portant factor with the patient and many dentures which are mechani- 
cally perfect are unsatisfactory because they do not “look right.” 
32. Requirements of tooth forms.—Briefly, all teeth must 
correspond or harmonize in form and contour with the form and con- 
tour of the face which “frames” them in order to blend into the indi- 
viduality of the person wearing them and insure the most pleasing 
effect. There are three typal forms of faces: square, tapering, and 
ovoid. These forms are further modified by an admixture of the ele- 
ments of two or more of these typal forms. There are likewise the same 
typal forms of teeth. Whenever the face forms and tooth forms corre- 
spond and harmonize, the effect is good. To the extent that the teeth 
differ in form with faces, there is a disharmony which is displeasing 
in degree. For instance, wdien square teeth are framed in an ovoid 
face, the effect is unpleasant and the teeth are conspicuous, wffiereas 
when ovoid teeth are framed with an ovoid face the effect is pleasing 
in that the teeth do not seem to obtrude; they “belong” with the face. 
Tooth shade, form, and approximate size are always selected by the 
dental officer to conform with the requirement of the individual case, 
and such instructions should be followed as closely as mechanically 
possible. In the selection of teeth for partial cases the teeth should 
be of such size that after they have been contoured to the adjoining 
clasps or teeth they will completely fill the edentulous area. 
35 TM 8-235 
33 
MEDICAL DEPARTMENT 
33. Arranging upper anteriors. a. Remove the upper bow 
from the articulator. Procure an occlusal plane or a flat piece of wood 
or aluminum 2% inches square, and use it as shown in the illustrations 
to take the place of the occlusal surface of the lower bite rim (fig. 17). 
h. Before waxing the upper central in place, try for mechanical suit 
Figure 17. 
Figure 18. 
ability. If necessary carve away the baseplate under the tooth or 
grind the ridgelap, or both, so that the tooth will not rest directly 
against the cast. The long axis of the upper central should be vertical 
when seen from the front and inclined downward and forward when 
seen from the side, as in B and C, figure 17. The incisal edge is in 
36 TM 8-225 
DENTAL TECHNICIANS 
contact with the occlusal plane. The upper centrals are not set at 
right angles to the median line, but the distal angles are inclined 
slightly backward and begin the curvature of the tooth row to follow 
the contour of the bite rim. 
c. Cut a space through the upper bite rim for the upper lateral and 
try it in place as the central was tried. Set it so that the incisal edge 
is about % millimeter above the level of the occlusal plane and so that 
the long axis is inclined as in B and C, figure 18. This downward 
and forward inclination of the vertical axis of the upper laterals re- 
sults in making the neck of this tooth less prominent than that of the 
upper central. This depression will be found very valuable when 
giving expression to the teeth. The incisal edges of the laterals are set 
to maintain the curvature established by the incisal edge of the upper 
bite rim. as shown at D. 
Figure 19. 
d. Cut a space clear through the upper bite rim to receive the upper 
cuspid. Try the tooth for length as the central and lateral were tried. 
Set the tooth so that its tip just touches the occlusal plane and its long 
axis is inclined as shown in B and G and at the edge of the tooth con- 
tinue the curve of the bite rim as shown at Z>, figure 19. The labial 
ridge of the cuspid is properly the dividing line between the labial and 
buccal sections of the ridge. The labial surface mesial to the ridge 
faces the lip and maintains the general curvature established by the 
central and lateral. The surface distal to this ridge faces the cheek 
and begins the curvature characteristic of the bicuspids and molars. 
The effect of setting the cuspids in this position is to carry the distal 
angles farther inward toward the median line. When the cuspids are 
37 TM 8-225 
33-34 
MEDICAL DEPARTMENT 
set in this way, only the mesial aspect can be seen from the front. This 
permits the use of teeth large enough for the mouth, without their 
appearing too large. The esthetic effect of this arrangement is greatly 
enhanced by the natural shading of the teeth in the set and gives 
prominence to the neck or cervical third of both cuspids. 
Figure 20. 
e. When the central, lateral, and cuspid of one side have been set. 
set the central, lateral, and cuspid on the other side in the same manner 
(fig. 20). 
DELATION Or CUSPS TO OCCLUSAL PLANE — CROSS SECTION 
Figure 21. 
34. Arranging1 upper posteriors.—a. Having determined the 
type of arch, the upper bicuspids and molars are set with their vertical 
axes in the lines shown in figure 21. 
h. The buccal cusp of the upper first bicuspid touches the occlusal 
surface of the lower trial plate, but the lingual cusp does not quite 
38 TM 8-225 
34 
DENTAL TECHNICIANS 
touch. Both cusps of the upper second bicuspids touch the wax (fig. 
22). The buccal cusps of the upper first molar are elevated about a 
millimeter above the wax to begin the compensating curve formed by 
the buccal cusp of both upper molars. The lingual cusps of the second 
molars are in contact with the opposing trial plate, but the buccal 
cusps are elevated about 2 millimeters above the wax. They continue 
the compensating curve which the buccal cusps of the first molars 
began. 
c. It is necessary, while establishing these relations, to secure such 
positions of the teeth over the ridge as to give the dentures maximum 
Figure 22. 
stability and efficiency. Fit each posterior tooth to its position before 
waxing it in place, as the anteriors were fitted. Make sure that each 
tooth is short enough so that there is a free space of at least a milli- 
meter between it and the baseplate. Cut a strip y2 inch wide along 
the side of a sheet of baseplate wax and soften one end of it in the 
flame. Detach a small portion and form it into a cone. Soften the 
end of the cone in the flame and force it about the pins or into the 
recess in the diatoric tooth. Using the tooth as a handle, soften the 
other end of the cone and press it upon the ridge with the tooth in 
approximately the correct position. Close the articular so that the 
incisor guide pin comes into contact with the incisor guide incline. 
Adjust the teeth so that the center of the longitudinal groove is over 
the front-to-back line on the occlusal surface of the lower bite rim. 
39 TM 8-225 
34 
MEDICAL DEPARTMENT 
The buccal cusp of the upper first bicuspid should touch the occlusal 
surface of the lower bite; the lingual cusp should be raised about y2 
millimeter above that rim. When the tooth is first placed, the long 
axis of the tooth, as seen from the buccal, should be vertical, as 
shown at A in figure 22. This may be slightly modified in establishing 
articulation. The second bicuspid should be set like the first except 
that both cusps touch the opposing bite rim, as shown at B in figure 22. 
Rotate both bicuspids upon their long axis so that the occlusal 
surfaces are inclined as shown by the lines in C\ figure 22. With the 
straightedge of the occlusal plane, test the position of the buccal 
Figure 23. 
surface of the bicuspid in relation to the cuspids. When these teeth 
are in proper relation for the average case, the straightedge should 
touch the buccal surfaces of all three teeth. 
d. Attach the upper first molar to the ridge as the bicuspids were 
attached. The long axis of this tooth, when seen from the buccal, 
is inclined downward and backward as shown at A, figure 23. Only 
the mesio-lingual cusp of this tooth should touch the occlusal surface 
of the opposing bite, the disto-lingual cusp being slightly raised and 
the buccal cusp being raised about % millimeter out of contact, as 
shown in A, figure 23. This arrangement produces the average com- 
pensating curve. When a greater curvature is required, the distal 
cusps should be elevated more. The tooth should be rotated upon its 
long axis as shown at C in figure 23. 
40 TM 8-235 
DENTAL TECHNICIANS 
34-35 
e. The upper second molar is now placed in position, with its 
lingual cusps lightly touching the occlusal plane and the buccal cusp 
raised about 1 y2 millimeters out of contact as shown in #, figure 23. 
If a greater curvature is desired, the lingual cusp should be elevated 
out of contact and the buccal cusps elevated in a corresponding degree. 
The long axis, seen from the buccal, is inclined downward and back- 
ward more than was the first molar. 
Figure 24. 
Figure 25. 
35. Arranging lower first molar,—Apply a cone of wax to a 
lower first molar. Open the articulator and attach the molar to the 
ridge in approximately the correct position, but too high. Close the 
Figure 26. 
Figure 27. 
articulator, forcing the molar toward the ridge. Guide it to correct 
occlusal relations with the uppers as in figure 24. Wax the molar 
firmly in position. Move the articulator so as to throw this molar 
into working bite with the uppers, as in figure 25. A black line has 
been drawn along the buccal ridge of the middle cusp of the lower 
molar. It should be continuous with the black line in the buccal 
groove of the upper molar. The break in the line in figure 26 shows 
that the lower molar is too far forward for articulation. Figures 24 
41 TM 8-225 
35 
MEDICAL DEPARTMENT 
and 26 show that teeth may be in good position for occlusion without 
being in position to articulate. In figure 25 the lower molar has 
been moved backward so that the black line is continuous with the 
line on the upper, in working bite, but the buccal cusps do not inter- 
digitate with the upper cusps. Errors of this kind can usually be 
corrected by depressing the buccal cusps of the upper molar, but in 
this case the steep descending inclination of the condyle path, with 
the slight lateral inclination, necessitated grinding the teeth to a 
deeper bite. With a fine-grit, inverted cone stone the mesial mar- 
ginal ridge of the upper molar and the distal marginal ridge of the 
lower molar were ground until they could be properly interdigitated. 
In figure 27 the molars are shown in working bite after deepening 
the sulci by grinding has been completed and the lower molar reset 
to proper contact with the upper. The space between the upper 
Figure 28. 
Figure 29. 
second bicuspid and the lower molar in figure 25 has been decreased 
by deepening the bite of the molars and raising the lower molar. 
The lower first molar in figure 28 is in the same position on the 
ridge that it occupied in figure 27, but the articulator has been moved 
so as to throw this side into balancing relation. The triangular ridge 
of the mesio-lingual cusp of the upper molar should slide in the disto- 
buccal groove of the lower molar, but cusp and groove are separated 
by a slight space. A defect of this kind can usually be corrected by 
depressing the lingual cusp of the upper molar until contact is estab- 
lished and waxing the upper firmly in that position. It may be 
necessary to rotate either the upper or the lower on its vertical axis 
until the cusp works smoothly in the groove. Examine the working 
bite articulation from the lingual, as shown in figure 30. The slight 
prominence of the mesio-lingual cusp of the lower molar, indicated 
by the arrow, prevents correct relations in the working bite. Grind 
this away with the inverted cone stone, being careful to maintain the 
42 TM 8-225 
35 
DENTAL TECHNICIANS 
original inclination of the cusp planes. Do not grind a flat surface 
on the tip of the cusp. The upper and lower molars, in occlusion, 
Figure 30. 
Figure 31. 
should mesh as in figure 29. The buccal cusp of the lower should fill 
the V-shaped longitudinal groove between the lingual and buccal 
Figure 32. 
Figure 33. 
cusps of the upper. The lingually inclined plane of the lower buccal 
cusp should be in contact with the buccally inclined plane of the 
lingual cusp. Figure 81 shows the relation of the upper and lower 
molars in working bite. 
Figure 34. 
Figure 35. 
43 TM 8-225 
36 
MEDICAL DEPARTMENT 
36. Arranging lower second bicuspid.—a. After completing 
the articulation of the upper and lower molars for the case here 
illustrated, the distal marginal ridge of the upper second bicuspid 
was ground in the manner described for the first molars until the 
buccal cusp of the bicuspid could be brought down in contact with 
the buccal cusp of the lower molar when in working-bite relation. 
Figure 36. 
The tooth was then examined from the lingual and adjusted to mesh 
properly with the lower molar in working bite. Attach a cone of 
wax to the neck of the lower second bicuspid and place it on the 
ridge in the manner described for the molar and with a spatula press 
it into approximate occlusion with the upper second bicuspid. Move 
the articulator so as to test the articulation in working bite, which 
is shown in figure 33. 
A. Before grinding in correct 
relation to working bite 
B. After grinding. 
C. Relation of center of stone 
to the long axis of 
cuspid for grinding buc- 
co-liugual pitch on the 
facet. Solid circle, cen- 
ter 1, shows correct 
position ; dotted circles, 
centers 2 and 3, show 
incorrect positions. 
Figure 37—Mesial facet of upper cuspids, 
44 TM 8-225 
DENTAL TECHNICIANS 
36-38 
b. The space between the lower second bicuspid and the molar in 
figure 33 will exist whenever the conditions of the case necessitate a 
compensating curve of more than average steepness. The existence 
of such spaces compensates in part for the shrinkage of rubber in 
vulcanizing and reduces the liability of error from the teeth being 
forced into improper contact through that shrinkage. Occlude and 
articulate the lower second molar as shown in figure 34. Set the lower 
second bicuspid for occlusion and then for articulation by the 
methods described. Arrange the lower molars and the second bi- 
cuspid of the opposite side, using the same technique. Set the lower 
anteriors to approximate positions to determine whether they meet 
the requirements of the case as to width and length. If insufficient 
space exists between the lower bicuspid to permit setting the lower 
anteriors because of irregularities in the alinement of the upper 
anteriors, additional space may be made by grinding the distal side 
of the lower cuspids or the mesial side of the lower first molar. 
Figure 38.—Cuspids in rest and beginning of working-bite relation, dotted line indicating 
proper bucco-lingual inclination for these cusp facets. 
c. If sufficient space cannot be provided by such grinding, select 
lower anteriors of the next smaller size in the same form. 
37. Arranging lower anteriors.—The roots of the lower centrals 
and laterals are parallel, but those of the lower cuspids diverge 
strongly as will be pointed out later when the lower cuspid is articu- 
lated. The lower centrals slope strongly outward from the neck to 
the incisal edge. This prevents the overfullness of the gums so 
common to lower dentures. The lower laterals slope outward con- 
siderably less than do the centrals. This is shown in figure 39. 
38. Arranging cuspids.—a. The upper lateral adjoining the 
cuspid should be removed from its place without heating the wax, so 
45 TM 8-225 
MEDICAL DEPARTMENT 
that it can be easily replaced. This will facilitate articulating the 
lower cuspid. 
h. Set the lower cuspid in position and grind the mesio-distal in- 
clination of the distal half of the cutting edge to be parallel to the 
inclination of the cutting edge of the mesial half of the upper cus- 
pid as in figure 36. The facet on the mesial slope on the upper cuspid 
is to be ground to the lingual inclination shown by the outline in 
figure 37, so that a straightedge placed in contact with the facet will 
touch the wax at the mesio-lingual cusp of the first molar. Grind the 
facet on the distal slope of the cutting edge of the lower cuspid to a 
labial inclination which is the complement of the lingual slope of 
the upper cuspid with which it occludes as shown in figure 38. The 
Figure 39.—Relation of lower cuspids and incisors to ridge, and average inclination 
for long axes. 
inclination of the long axis of the lower cuspid is also shown in figure 
38. In figure 380 the complementary inclination of the facets on 
the cutting edges of the cuspids is shown with the cuspids in occlusion. 
In figure 38@, the cuspids are shown in articulation with the lower 
about to begin the return from an extreme lateral excursion. The 
complementary inclinations of the facets make it possible for the 
cuspids to remain in contact throughout these movements. This form 
of articulation by the cuspids is very important in maintaining the 
stability of the dentures and in protecting the upper laterals from 
breakage. If the lower cuspids are set to too deep an under bite, the 
dentures are almost sure to be tipped out of position by improper cus- 
pid contacts; the force of the closure will be brought upon the thin- 
edged laterals which are not fitted to stand it, and they will be broken 
from the plate. This form of improper contact is very apt to occur 
in finished dentures unless guarded against and is disastrous. 
c. Replace the upper lateral but do not attach it. Move the articula- 
tor to produce the working and balancing relations and grind the 
mesial edge of the lower cuspid so that it clears the slope on the distal 
angle of the upper lateral. The upper laterals and the lower cuspids 
46 TM 8-225 
DENTAL TECHNICIANS 
38-40 
should not come into contact in any movement of the jaw. The facet 
on the cutting edge of the upper lateral should incline upward and 
backward more than that on the edge of the cuspid. When this facet 
has been ground, articulate the lower lateral with it. Do not grind 
facets on the cutting edges of the lower incisors. Grind facets on the 
edges of the upper centrals and articulate the lower centrals with them. 
The lower incisors should be set with the necks directly over the ridge 
and the long axis of the teeth should be inclined as is shown in 
figure 39. 
39. Arranging lower first bicuspid.—The lower first bicuspid 
is the last tooth to be placed. It is articulated in the same manner as 
the second bicuspid. If the indicated space is not adequate to accom- 
modate the lower first bicuspid, the mesio-distal width of the tooth is 
reduced by grinding. Never crowd the lower anterior teeth out of posi- 
tion and off the ridge in order to place this tooth. Figure 40 shows the 
tooth in position. 
Figure 40. 
Figure 41. 
40. Incising bite.—a. Before the teeth are tried in the mouth, 
hold the articulator in the incising position and slightly alter the 
arrangement of the incisors and cuspids if necessary so that they will 
come into proper contact. The upper centrals should touch the lower 
centrals. The upper laterals may, in certain arrangements, touch the 
lower laterals, but they should not touch the lower cuspids. Most in- 
stances of broken laterals not due to careless handling have been found 
to be due to a cuspid striking the lateral in the incising or the working 
bite. The lower cuspids should touch the upper cuspids but not the 
upper laterals in masticating movements. Figure 41 shows the aver- 
age overjet of the upper anteriors over the lower teeth. 
b. When the lower is in central occlusion the lower incisors and 
possibly the lower cuspids should not be in contact. The lower incisors 
should not be allowed to support the dentures in lateral protrusive 
movements but should share this strain with the bicuspids and the cus- 
47 TM 8-225 
40-42 
MEDICAL DEPARTMENT 
pids. The pressure on the cuspids should be heavier than on the upper 
laterals or the lower incisors. The danger of breaking the incisors 
during mastication will be eliminated if the foregoing instructions are 
observed and the errors seen in the finished denture are corrected by 
grinding with a stone while the dentures are examined for these con- 
tacts in the mouth. The lower first bicuspid should be in contact with 
the upper cuspid which acts as a protector for the upper lateral and 
prevents the incisors from receiving any excessive strain. The tip of 
the cusp of the lower second bicuspid may touch the tip of the upper 
first bicuspid cusp but this is not essential. The tip of the upper sec- 
ond bicuspid should come into contact with the mesio-buccal cusp of 
the lower first molar. The lingual cusps of the bicuspids and molars 
also come into contact in the incising-bite relation. Occasionally the 
lingual cusps will touch so heavily that the buccal cusps cannot come 
into contact. If any cusp rides so heavily on an opposing cusp as to 
prevent the teeth from coming into the proper relation with their 
antagonists, a little careful grinding will correct the trouble. 
41. Balancing bite.—The depth of this bite is the distance the 
lower teeth on the balancing side move vertically to maintain balancing 
relations between the dentures during articulation. It is much greater 
than the depth of the working bite, because the steep lingual inclines 
of the lower buccal cusps articulate with the steep inclines of the lingual 
cusps of the upper teeth, and because the lower cusps often travel 
directly across the steepest parts of the upper cusps instead of follow- 
ing the sulci. 
42. Central dental laboratory assortment of new Trubyte 
teeth.—The following charts give the assortment of teeth chosen for 
the central dental laboratories for shades and molds. The data given 
in h below assist in choosing teeth and matching the lower anteriors 
and posteriors with the upper anteriors. The shades of the New Hue 
and the new Trubyte teeth, as selected for Army use, are given below, 
with the corresponding shades for the old Trubyte teeth. 
48 TM 8-225 
42 
DENTAL TECHNICIANS 
a. Shades. 
New Hue 
New Trubyte 
Old Trubyte 
63 
40 
5 
66 
41 
6 
67 
43 
7 
77 
46 
9 
81 
49 
14 
69 
52 
15 
79 
55 
16 
83 
57 
20 
b. Data.—(1) Upper anteriors, 1X6.— (a) Square type. 
Mold No. 
Width of cen- 
tral (mm) 
Posteriors required 
Lower ante- 
riors required 
115 
8. 5 
34M—31L 
25 
117 
9. 5 
34L—35L 
27 
123 
7. 5 
30L—29L 
33 
124 
8 
32 L—31L 
34 
126 
9 
34L—33L 
36 
133s 
7. 5 
30M—29M 
43s 
134 
8 
32 M—31M 
44 
135s 
8. 5 
32 L—31M 
45s 
136s 
9 
34M—33M 
46s 
155 
8. 5 
32M 31M 
34 
431511°—42 4 
49 TM 8-225 
42 
MEDICAL DEPARTMENT 
(b) Tapering type. 
Mold No. 
Width of cen- 
tral (mm) 
Posteriors required 
Lower ante- 
riors required 
214 
8 
32L—31L 
34 
217 
9. 
5 
34L—35L 
27 
222 
7 
28S—29S 
31 
224 
8 
30L—31M 
33 
225s 
8. 
5 
32L—31L 
45s 
225 
8. 
5 
32 L—31L 
34 
226s 
9 
34 M—33L 
46s 
233 
7. 
5 
30M—29L 
32 
234 
8 
32 L—31L 
34 
235 
8. 
5 
34 M—31L 
35 
244 
8 
32L—31M 
34 
262 
7 
28L—29L 
22 
263 
7. 
5 
30L—29L 
23 
264 
8 
32 L—31L 
24 
265 
8. 
5 
34L—31L 
25 
266 
9 
34L—33L 
26 
267 
9. 
5 
34L—35L 
27 
275 
8. 
5 
32L—31M 
45 
(c) Ovoid type. 
Mold No. 
Width of cen- 
tral (mm) 
Posteriors required 
Lower ante- 
riors required 
314 
8 
32 L- 
31L 
24 
315 
8. 5 
32L— 
31L 
25 
317 
9. 5 
34L- 
35L 
27 
324 
8 
32L- 
31L 
24 
333 
7. 5 
SOL— 
29M 
23 
334 
8 
32L- 
-31M 
24 
335 
8. 5 
34 M- 
31L 
25 
346 
9 
34L— 
33M 
46 
50 TM 8-225 
DENTAL TECHNICIANS 
42-43 
(2) Lower (interiors, 1X6.—Molds available: 22. 23, 24. 25, 26, 27, 
31, 32, 33, 34, 35, 36. 43. 43s, 44. 45, 45s, 46, and 46s. 
(3) Upper and lower posteriors, 1X8.—(a) Regular.—Molds 
available: 28S, 28M, 28L, 30S, 30M, 30L, 32S, 32M, 32L, 34S, 34M, 34L, 
and 32X, 
(h) Twenty degrees.—Molds available: 29S, 29M. 29L, 31S, 31M. 
31L, 33S, 33M. 33L, and 35L. 
43. Debenture waxing1.—After the teeth are arranged, the tech- 
nician proceeds with the carving of the wax so that he has an exact 
duplicate of the finished denture. By this method the wax denture 
may be placed in the mouth and checked for appearance and mechani- 
cal efficiency by the dental officer, and if any changes are necessary, 
they can be made at this time. The procedure is as follows: 
a. Add melted wax to the case in deficient areas, especially along 
the buccal and labial surfaces of the denture. This will later be 
Figure 42. 
carved so as to simulate the irregularities of the gum caused by the 
roots of the natural teeth. 
h. With a knife or wax spatula, festoon all teeth at right angles to 
the long axis of the teeth. This should be carried to the necks of the 
teeth on the buccal, labial, and lingual surfaces. Do not festoon too 
deeply in the interproximal spaces between the teeth. 
c. Smooth the entire surface of the wax by passing a flame quickly 
over the area. It may be further polished by rubbing with a piece 
of cotton while holding it under running cold water. 
d. The waxed denture is now ready for try-in (fig. 42) 
51 TM 8-225 
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MEDICAL DEPARTMENT 
44. Denture flashing (full).—This is the process by which the 
wax or trial denture is started on a new series of procedures from 
which will emerge the finished denture. The denture base, after having 
been checked in the patient’s mouth by the dental officer, is sealed to 
the cast and invested in a flask so as to retain the exact relationship 
of the teeth and preserve the space from which the wax will be elim- 
inated so that it may be filled with dental rubber or some other material. 
The flashing process will maintain this space and relationship while 
the denture is being vulcanized or cured. The procedure is as follows; 
a. Seal the waxed denture to the cast along its entire periphery and 
make sure that all the teeth are securely waxed in place. 
h. Remove the models from the articulator. 
c. Cut out the palate of the trial denture base and adapt one and 
one-half thicknesses of baseplate wax to the palate of the case. 
d. Place the cast in the lower part of the flask. Then place the upper 
or counterpart of the flask in position, making sure that there is suffi- 
cient room in the flask for the case. Place the cover on the flask, mak- 
ing certain that the teeth do not touch the top of the flask. At least 
34 inch of space should be maintained. 
Figure 43.—Undercut (A) when cast is 
flashed level. 
Figure 44.—Elimination of undercut (B) 
when cast is flashed at an angle. 
e. Remove the cast from the flask and immerse in cold water for a 
few minutes until all bubbling ceases. 
/. Make a plaster of paris mix of a heavy creamy consistency, and fill 
the lower portion of the flask to about two-thirds of its capacity. If 
the plaster is too thin it is difficult to control, and will exrend upon the 
waxed surfaces. 
g. If no undercuts are present on the cast, settle it in the plaster mix 
so that the occlusal plane of the teeth will be parallel with the bottom 
of the flask. If undercuts are present, as they sometimes are around 
the anterior region or the heels, it is necessary to place the cast in 
the plaster at such an angle so as to compensate for the undercut. For 
52 TM 8-225 
DENTAL TECHNICIANS 
44-45 
instance, if the anterior ridge is undercut, it is necessary to raise the 
anterior portion of the cast above the level of the heels (tigs. 43 and 44). 
h. Remove all excess plaster between the peripheral rim of the den- 
ture and the rim of the lower portion of the flask, smoothing the surface 
of the plaster. 
i. Allow plaster to set until hard and then apply a little petrolatum 
or green soap to the surface of the plaster to act as a separating medium. 
k. Make a plaster mix and fill the upper portion of the flask, pouring 
the plaster carefully, and gently jarring the case so as to prevent 
inclusion of air bubbles. 
j. Set the upper portion of the flask in position. 
Figure 45. 
I. Place the top of the flask in position and wipe off all excess plaster. 
45. Denture flashing (partial).—a. (1) Holding of clasps and 
framework to models upon separation.—The first method to be de- 
scribed consists of flashing the denture similarly to that just described, 
but in addition, cutting off the remaining teeth from the cast to within 
y16 inch from the This exposes all the clasps. When removing 
the plaster tooth from within a clasp, extreme caution should be exer- 
cised. It is often advisable to remove such teeth with a bur. After 
removal of the plaster tooth from the clasped area, any adjacent voids 
in the wax should be filled with wax. These clasps as well as any 
other metal parts such as lingual bars, etc., are then covered with 
plaster mix in the lowTer portion of the flask, leaving just the wax 
surfaces and artifical teeth exposed. From this point the flashing 
is carried out as given above (fig. 45). 
(2) Removal of clasp and framework from model upon separation.— 
Another method of flashing partial dentures is frequently used, 
53 TM 8-225 
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MEDICAL DEPARTMENT 
especially in the acrylic resin cases that require tinfoiling. It consists 
of cutting off all the teeth from the model to within %6 inch from the 
wax. The exposed clasps, bars, etc,, are then incorporated into the 
Figure 46. 
upper portion of the flask instead of the lower. It is often advisable 
in the case of palatal and lingual bars to remove a portion of the cast 
from about the bar to insure their retention and more stable relation- 
ship when using this method. When the plaster in the upper half has 
set, the wax eliminated and the flask opened as described in the next 
step, the clasps, etc., will be pulled away from the model, but still will 
maintain their correct relationship (fig. 46). 
b. Either method of flashing may be used, depending upon the indi- 
vidual case under construction. In either method, prior to the pouring 
of the upper half of the flask, make doubly sure that all undercuts are 
eliminated in order to prevent fracture or irreparable damage to the 
models upon separation of the flask. 
46. Packing the case.—The case is now ready to be packed with 
any material that has been selected. Dental rubber or vulcanite and 
acrylic resin are the most satisfactory and the most commonly used. 
Therefore, only these materials will be discussed. All cases should 
be carefully packed with the right quantity of material. There is 
no reason for overpacking and thus inviting danger of breakage of 
the cast and the destruction of the occlusion of the teeth. The “dry” 
method of packing vulcanite cases is the most desirable. 
a. The pink gum rubber is cut into strips which are wide enough 
to cover the ridge lap of the teeth and extend to the border of the ma- 
trix. A narrow strip is then cut into small, triangular pieces which 
54 TM 8-225 
46 
DENTAL TECHNICIANS 
will fill the spaces between the teeth. The base rubber is cut into the 
desired size pieces for the lingual and hidden parts of the case. Pink 
rubber is used on the labial and buccal surfaces of the denture because 
it has a much more natural appearance. Base rubber is used on 
the palatal and hidden surfaces of the denture because it is much 
stronger and more durable than the pink rubber. 
h. The lower part of the flask is placed in a heated oven and warmed 
throughout to a temperature of about 212°. It is then removed from 
the oven and placed on a towel which will serve as a heat retainer 
during the packing process. 
c. Using suitable packing tools, carefully place the triangular pieces 
of rubber between the interproximal spaces of the teeth. 
d. Fold a strip of dark rubber about 14 inch wide along its greater 
length, and cut a piece long enough to fit from the first bicuspid region 
of one side to the first bicuspid region of the other. Insert this piece 
of rubber under the pins of the anterior teeth. 
e. Pack the small square pieces of the dark rubber into each one of 
the diatoric openings of the posterior teeth (fig. 47). 
Figure 47. 
/. Place two strips of the pink rubber, about y2 inch in width, one 
over the other, and lay them over the triangular pieces and the edge 
of the teeth along the buccal and labial surfaces from the median line 
to the region of the second molar. Place two more strips of the pink 
rubber in identical positions on the other side. These pink strips 
should extend from about 1 millimeter above the pins and diatoric 
openings to about 1 millimeter above the rim of the denture. 
g. Place small strips of the dark rubber close against the pink rub- 
ber in the region of the buccal surface of the second molars. 
55 TM 8-235 
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MEDICAL DEPARTMENT 
h. Place additional strips of dark rubber against the bicuspids and 
molars on the palate. 
i. Cover the remaining portion of the palate with the dark rubber, 
and add sufficient rubber over the entire surface to fill completely the 
space formerly occupied by the wax. It should be filled so that a 
little excess may be squeezed out around the edge of the denture when 
the flask is closed (fig. 48). 
j. The lower denture is packed in a similar manner as the upper 
with the exception of having the tongue space instead of the palate. 
The lingual flanges of the lower denture are packed with the dark rub- 
ber, and are carried just 1 millimeter beyond the periphery of the 
denture. The tongue space is left free from rubber. 
Figure 48. 
k. If much time has been consumed in packing the case and it has 
become cold before the packing operation is completed, it may be 
returned to the oven and reheated. 
I. When the packing of the case has been completed, a piece of wet 
cellophane is laid over the entire lower half of the flask, and the two 
parts of the flask are then brought together. 
m. Place the flask in a flask press and immerse both in a pan of 
boiling water for about 15 minutes. Remove from water and cau- 
tiously apply pressure with the screw. Too much pressure must not 
be applied in closing the flask. 
n. The flask is removed from the press and opened. If too much 
rubber has been expressed, the excess is removed and the operation 
repeated. 
o. If rubber is insufficient, add more and repeat the process (fig. 49). 
56 TM 8-225 
DENTAL TECHNICIANS 
46-47 
p. Adapt a piece of wet cellophane to the cast before the final closing 
of the case. As the tissue surface of the completed denture is never 
polished, this step is necessary to insure a dense, smooth surface. Tin- 
foil may be adapted to the case in place of the cellophane, if desired. 
47. Vulcanizing.—a. Fill the vulcanizer pot with warm water to 
a depth of 1 inch. 
b. Place the flask clamp containing the flask in the vulcanizer and 
adjust the vulcanizer cover. 
Figure 49. 
c. Open the blow-off valve 
d. Light the burner under the pot and adjust it until the blue flame 
just covers the bottom of the vulcanizer. Never allow it to reach up 
the sides. 
e. Set the gas regulator to 320°, or according to vulcanizing 
directions. 
/. Allow all air to escape and when steam begins to be expelled, close 
the blow-off valve, using a wrench. 
g. Set the time clock to shut off the gas at the required interval. 
h. Vulcanize for iy2 hours from the time the blow-off valve is closed. 
Allow 35 minutes to reach 320°. Maintain this temperature for 55 
minutes. 
i. The time regulator will shut off the supply of gas as regulated. 
j. Allow vulcanizer to cool for 15 minutes, then open blow-off 
valve until steam begins to escape. 
k. After all steam has escaped, remove the vulcanizer cover. 
l. Remove flask from vulcanizer and allow to cool for 15 minutes. 
Then place it in cold water until thoroughly chilled. 
57 TM 8-225 
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MEDICAL DEPARTMENT 
48. Cleansing and polishing dentures.—a. Remove the flask 
cover. 
h. Using a plaster knife, remove the plaster from around the 
edges of the upper part of the flask until the teeth are exposed, as 
well as the buccal and labial surfaces of the denture. 
c. With a knife inserted between the upper and lower portions of 
the flask, carefully open it without applying too much pressure. 
d. Carefully remove the denture from all surrounding plaster. 
e. Wash all excess plaster from the denture with a stiff bristle 
brush while holding it under cold water. 
/. With a sharp pointed knife peel away all the tinfoil or cello- 
phane from the tissue surface of the denture. 
g. Cut away all excess vulcanite from the rim of the denture, being 
careful not to mar the peripheral border. 
h. Partial dentures are removed in the same manner, only more 
care must be taken in their removal as they are easier to distort or 
fracture. 
i. Using either a half-round vulcanite file or an abrasive wheel 
mounted on the lathe, remove all excess vulcanite from around the 
edge of the denture. 
j. In partial dentures, use a rat tail vulcanite file around the cer- 
vical edges to bring it to the proper limits. 
k. Remove all roughness from labial, buccal, palatal, and lingual 
surfaces of dentures by using a vulcanite scraper. 
I. Carefully smooth the denture with sandpaper. In using sand- 
paper it is easy to take away too much vulcanite, thus exposing some 
dark rubber on the labial surface or making the denture too thin. 
It is also possible to harm the denture permanently by generating 
too much heat in this polishing process. 
m. Carefully trim the vulcanite about the necks of the teeth on 
the buccal, labial, and lingual surfaces with sharp vulcanite trim- 
mers. A sharp trimmer must always be used in this procedure to 
avoid undue pressure and to give a polished finish to the vulcanite. 
n. All the steps previously described are preliminary to putting 
the final polish on the denture. It is necessary to obtain this high 
polish for the health and comfort of the patient. Vulcanite dentures 
are more or less porous and have a tendency to absorb saliva and 
accumulate food particles. High polish will reduce this porosity. 
Make a puttylike mix of fine pumice and water and, with a brush 
wheel rotating toward the operator, proceed to polish the denture. 
It should be held firmly in the hands, rocking it in a semicircular 
motion so that grooves will not be cut into the vulcanite. Always 
58 TM 8-225 
DENTAL TECHNICIANS 
48-50 
keep the surface of the denture wet with pumice and use gentle 
pressure. Too much pressure will warp and burn the denture. 
o. Repeat this process using a linen rag wheel with pumice in 
place of the brush wheel. 
p. Mount large or small felt cones to the chuck of the lathe and 
polish all areas inaccessible with the rag wheel. 
q. Make a mixture of chalk and water and with a soft flannel 
wheel continue to polish all surfaces of the denture. 
r. Wash with water and check to make sure that all scratches 
have been removed. Then with a soft flannel wheel apply powdered 
oxide of tin for the final polish. 
Section VII 
Paragraph 
General 49 
Procedure 50 
ACRYLIC RESIN DENTURES 
49. General.—The acrylic resins are used by the dental profession 
in order to have a denture material with better esthetic qualities than 
vulcanite and, at the same time, without sacrificing strength and 
durability. A great many synthetic materials have been developed 
and marketed from time to time, but the acrylic resins seem to be 
the best so far developed. There are various acrylic resins on the 
market and the procedure may vary slightly according to the 
material, but the basic technique is very much the same. 
50. Procedure.—a. Wax up as if the denture were to be made of 
vulcanite, except that the wax should be a little fuller in the inter- 
proximal spaces to allow for tinfoiling. 
h. Invest the case in the lower portion of the flask as for a vulcanite 
denture. 
c. The cast is now ready for tinf oiling. This is a most important 
procedure in the construction of acrylic resin dentures as any error 
in this step will result in the final denture being weakened and spotted. 
It is necessary to have all surfaces covered completely with tinfoil. 
For the upper cast cut four pieces of tinfoil, one piece to fit the palate, 
two to fit the buccal surfaces, and one to fit the labial surface of the 
denture. Additional tinfoil is then cut to cover the plaster in the 
flask. The tinfoil for the lower case is the same with the exception 
of the part that will cover the lingual surfaces and the tongue spaces. 
This should be cut square and then rounded in front. 
d. Cut the palatal piece of tinfoil into two triangular pieces. With 
a small piece of cotton, burnish the tinfoil on the wax of the palatal 
59 TM 8-225 
MEDICAL DEPARTMENT 
surface of the upper denture and overlap these two pieces in the 
center of the palate about inch. Extend the tinfoil to about y8 
inch below the incisal and occlusal surfaces of the teeth. 
e. Cut little V-shaped grooves in the tinfoil, covering the teeth on 
the labial, lingual, and buccal surfaces so it may be adapted into the 
interproximal spaces between the teeth. 
/. Remove one side of the palatal tinfoil and aj)ply glue to the over- 
lapping margin and replace on the waxed case. 
g. Adapt the labial and buccal pieces of tinfoil to the waxed sur- 
faces from about % inch below the incisal and occlusal surfaces of 
the teeth. Use the separate pieces of tinfoil to cover the plaster 
surface. Seal the overlapping margins with glue (fig. 50). 
Figure 50. 
h. In lower cases adapt a piece of tinfoil to cover the tongue space. 
i. The remainder of the flashing procedure is identical to that used 
in vulcanite. 
j. Boil out the wax in the same manner as previously described, 
washing the cast with chloroform followed by acetone. Make sure all 
acetone has evaporated before proceeding to pack the case. 
k. In acrylic resin dentures it is necessary to tinfoil the cast. Tins 
is done after the case has been flashed and separated. 
I. Acrylic resins usually come in two types. One type is the cake, 
and the other is the powder and liquid. The last mentioned is prefer- 
able and will be the one described. Have a clean sheet of paper about 
8 inches square on the bench. Place the powder cup in which the 
material comes in the center of the sheet of paper and pour the powder 
into the cup until it overflows. Scrape off all excess powder with a 
60 TM 8-225 
DENTAL TECHNICIANS 
straightedge until the powder is level with the rim of the cup. Do 
not pack the material or jar it into the cup. Pour the powder so 
measured into any porcelain vessel such as a coffee cup. Measure out 
about 8 cc of the liquid and add to the powder in the cup. Imme- 
diately begin mixing vigorously with a clean, stiff, stainless steel 
spatula. Continue this mixing until the material begins to be homo- 
geneous and loses most of its stickiness. This should take about 1 
minute. Then roll the mixed material between the palms of the hands 
from 5 to 10 seconds. The hands should be clean and dry. For repairs, 
or if it is desired to make smaller or larger mixes than by the measuring 
cup, different quantities in correct proportions should be used. 
m. The case is then ready to be packed. This should be done as 
quickly as possible after mixing. When first mixed, the material is 
very soft and easy to pack, but upon standing it becomes stiffer and 
requires more pressure to close the flask. The flashing should be done 
soon after boiling out so that the flask will be warm but not hot. A 
good temperature is 100° to 125° F. Roll between the hands a piece 
of the material about the size of a lead pencil and sufficiently long to 
cover the teeth. Pack this well down against the teeth, making sure 
that no air is inclosed. Next roll up another piece about the thickness 
of the little finger and long enough to go around the arch. Imme- 
diately press this to place with the fingers. In upper cases it is neces- 
sary to put a sheet of the material over the palate. 
n. The flask may be trial-separated by placing a strip of moist 
cellophane over the material in the flask before closing. Close as 
quickly as possible in any convenient press. Do not apply any extra 
heat to the flask to facilitate closing as this will only hasten the setting 
of the material. The flask is then reopened and material either added 
or cut away as necessary. It is now ready for curing. 
o. The case may be cured in a vulcanizer or in boiling water. 
Either way gives good results. In the vulcanizer, any curing tem- 
perature from 212° to 320° F. and a minimum time of 1 hour may 
be used. Cooling after curing is done in the same manner as for 
vulcanite. 
p. The simplest manner in which to cure the denture is to place 
the case and the flask in a pan of cold water. This water is then 
brought to a boil and allowed to boil for about 40 minutes. The case 
is then allowed to cool very gradually (preferably overnight) before 
opening. The case is opened, the denture removed and polished in 
the same manner as previously described. 
61 TM 8-235 
51 
MEDICAL DEPARTMENT 
Section VIII 
DENTURE REPAIR 
Paragraph 
Simple repair 51 
Loose or broken teeth 52 
Teeth added 53 
Loose clasp 54 
Refacing' 55 
Rebasing 56 
Duplicating denture 57 
Repairing acrylic resin dentures 58 
51. Simple repair.—a. Bring the fractured edges of the denture 
into apposition and seal them together with a little sticky wax. 
Pieces of stiff wire are laid over the fractured denture at right angles 
to the line of fracture and waxed in place. This gives the denture 
additional support. 
h. Lubricate the tissue surface of the denture with petrolatum. 
Figuek 51. 
c. Place boxing wax around that part of the periphery of the den 
ture that makes contact with the natural teeth. 
d. Make a plaster mix and pour a matrix or cast of the denture 
as described in pouring impressions. 
e. When the plaster has set, remove the denture parts and with abra- 
sive chucks and vulcanite burs grind away a large portion of the palate 
on each side of the fracture. Also remove about 2 millimeters of vul- 
canite from the periphery of the denture over those areas containing 
artificial teeth. The margins of the palatal area are then dovetailed 
as shown. 
62 TM 8-225 
DENTAL TECHNICIANS 
51-52 
f. Replace the fractured parts on the cast, fill in the missing parts 
of the vulcanite with wax, making this wax a little thicker than the 
original vulcanite. This will allow for the finishing and polishing 
of the denture (fig. 51). 
g. Pour the lower and upper portions of the flask as done in a 
new case. 
h. After the plaster has set, the wax is eliminated and the flask 
carefully opened. The denture will be contained in the upper half 
of the flask. 
i. With a vulcanite bur remove about y2 millimeter of vulcanite 
from the entire tissue surface of the denture. The surface 
is roughened (fig, 52). 
j. Proceed to pack the case as usual and then place a piece of 
wet cellophane over the case before the final closing. 
k. The case is then vulcanized and finished as previously described. 
Figure 52. 
52. Loose or broken teeth.—a. When the original tooth has be- 
come loosened and can be replaced, it is only necessary to make 
certain it fits in its exact position as marked on the vulcanite. Then 
cut a dovetail in the lingual or palatal surface of the vulcanite 
adjacent to the tooth, replace the tooth in its original position, and 
secure it by wax. The case is then carried forward as in the simple 
repair. 
h. When the tooth has been broken or lost and a new tooth is 
necessary but the denture base at the site of the tooth is intact, 
it is necessary for the dental officer to supply the technician with 
a wax bite indicating the relationship of the teeth of the opposing 
jaws. Proceed as in simple repair until matrix is poured. Pit the 
63 TM 8-225 
52-55 
MEDICAL DEPARTMENT 
teeth of the denture into the depressions on the bite, and seal it to 
the denture. Fill the depressions left in the bite by the teeth of 
the opposing jaw with plaster. The matrix of the denture and the 
poured bite are then mounted on an articulator, after which the bite 
is removed. Place the new tooth in the correct position, as governed 
by the adjacent and opposing teeth. Do not grind away any of 
the vulcanite found around the neck of the tooth, but do all necessary 
grinding on the tooth itself. Wax into position and proceed as in 
simple repair. 
Figure 53. 
53, Teeth added.—Often a tooth is extracted requiring the addi- 
tion of an artificial tooth to a partial denture. The technician 
receives the impression of the mouth that has been taken with the 
denture in place. If the impression has been taken in plaster, it 
must be painted with a separating media. A wax rim is placed 
around the periphery of the denture and the cast is poured. The bite 
is placed in its correct position on the denture and waxed in place 
and poured. The denture, cast, and bite are then mounted on an 
articulator. The bite is removed and the additional teeth are added 
to the denture, as described above, and the process followed as in a 
simple repair. 
54. Loose clasp.—The dental officer has taken an impression of 
the clasped tooth with the clasp and denture in position. The im- 
pression is poured as directed for adding teeth to a partial denture. 
The vulcanite is cut out from around the tailpiece of the clasp, and 
this area filled with wax. The case is then carried to completion 
as previously described. 
55. Refacing.—Lubricate the inner surface of the denture and 
fill with plaster, forming a matrix. Allow to set. Cut away the 
64 TM 8-225 
DENTAL TECHNICIANS 
55-57 
labial and buccal vulcanite to about one-half of its original thick- 
ness, making certain the rubber is removed from around the necks 
of the teeth. Honeycomb the remaining gum rubber to roughen it. 
Wax the labial and buccal surfaces of the denture. Flask the case 
by filling the lower part of the flask with fairly stiff plaster and 
setting the denture into this plaster with the teeth down. Make 
sure that the teeth are at least inch from the bottom of the 
flask, and that all the waxed parts are exposed. Smooth the plaster 
around the teeth and over the rear of the denture. The upper part 
of the flask is poured after lubricating and the case is continued 
as in simple repairs (fig. 53). 
56. Rebasing.—Often the gums will shrink or pull away from 
the denture after it has been worn for some time. This causes the 
denture to become loose and irritating to the patient. If the denture 
is in good condition otherwise, it may be repaired by adding a new 
base or foundation of vulcanite. The technician receives the denture, 
to the base of which has been added a sufficient amount of ma- 
terial to correct the deficiency in the mouth of the patient. This 
material is usually modeling compound, but it may be plaster or 
both. A strip of boxing wax is placed around the periphery of the 
denture and the cast is poured as described. The case is then 
flashed the same as if it were a new denture. After the two parts 
of the flask have been separated, the impression material is removed. 
The tissue surface of the denture is roughened by vulcanite burs 
and stones to facilitate the addition of the new vulcanite. Sufficient 
vulcanite should be removed to allow for about 1 millimeter of new 
rubber. The case is packed with strips of base rubber, the flask is 
closed and the case carried to completion as previously described. 
57. Duplicating denture.—Frequently it is necessary to replace 
the entire denture base with new material. The technique as given 
here does not require the case to be mounted on an articulator. Pro- 
ceed as in any simple repair until the matrix is poured. Make sev- 
eral deep grooves on the buccal and labial surfaces of the old denture. 
Lubricate the teeth and the buccal and labial surfaces of the denture 
and matrix. Build a plaster index around the entire outer surfaces 
of the denture and matrix, extending the plaster to about 14 inch 
from the incisal and occlusal surfaces of the teeth. Before the 
plaster sets too hard, make a cut opposite each cuspid tooth. This 
weakens the plaster index which is carefully removed as soon as it 
is sufficiently hard. Lift the denture from the matrix and remove 
all the teeth from the denture by covering them with a layer of 
431511°—42 5 
65 TM 8-225 
57-59 
MEDICAL DEPARTMENT 
melted basewax and then passing the denture several times through 
a flame to soften the vulcanite. The teeth are arranged in their 
proper position as indicated on the plaster index, and are secured 
with sticky wax. A baseplate is constructed over the matrix and the 
plaster index containing the teeth is arranged around the matrix 
with the baseplate. Melted basewax is flowed into the spaces between 
the teeth and the baseplate. The sticky wax holding the teeth is 
removed as well as the index. The waxing is finished where neces- 
sary without disturbing the position of the teeth. Proceed with 
the flashing as described. It is sometimes necessary to use basewax 
instead of the baseplate to avoid displacing the teeth in the index. 
58. Repairing acrylic resin dentures.—Bring the broken parts 
of the denture into apposition and wax them securely together. A 
cast is then poured as in the vulcanite case. The model is then re- 
moved and tinfoiled. Replace the denture on the model and rewax 
if necessary. Tinfoil the complete denture, holding it in place with 
a little thin glue. Do not tinfoil the wax portions. Flask as for 
a vulcanite repair. Boil out the wax, but do not use chloroform 
or acetone to clean the cast. Tinfoil the plaster in the upper half 
of the flask that will come in contact with the denture or the repair 
portions. A small mix of the powder and liquid is made, as previ- 
ously described, and this material is packed in the repair portion 
and the flask closed. The denture is cured as for a full denture. 
If the case has undercuts so that the denture cannot be removed from 
the cast, it is necessary to tinfoil the denture before pouring the 
model. 
Section IX 
DENTAL CASTINGS 
Paragraph 
General 59 
Requirements 60 
Methods 61 
Procedure 62 
59. General.—Many dental restorations, completely or in part, 
are made by carving a wax pattern and reproducing that wax pattern 
in gold by a process known as casting. Castings of gold alloys may be 
made with considerable accuracy for anything from the largest partial 
denture to the smallest inlay. However, this section takes up only 
the construction of the smaller pieces. The fundamental procedure is 
the same for the large castings as for the small, the technical differ- 
66 TM 8-225 
DENTAL TECHNICIANS 
59-62 
ences which must be observed in large castings being brought out in 
section XIV, 
60. Requirements.—There are many requirements in making a 
satisfactory casting. The wax pattern must be carefully prepared to 
fit the model or die, and the casting made from the wax pattern must 
approximate the size and shape of the wax pattern very closely. The 
metal used must have satisfactory properties for casting as well as for 
making it capable of withstanding the forces to which it will be sub- 
jected. Assuming the alloy to be of the desired composition it must 
then be cast properly to prevent imperfections in the final structure. 
After casting, the alloy must be cleaned, polished, and often heat- 
treated to produce the desired physical properties in the metal. 
61. Methods.—a. The dentist sometimes carves the pattern for 
the inlay or crown in the mouth of the patient and furnishes the dental 
technician with the completed wax pattern. This is known as the 
direct method and is used extensively, especially on smaller castings. 
b. However, the dentist often takes a compound impression of the 
tooth and a metal die is made from this. This is known as the indirect 
method. In this method the dental technician will be presented with 
the impression from which he must first make an amalgam die and 
then make a wax pattern on the amalgam die. The die is made by 
wrapping a sheet of thin wax around the impression of the tooth, 
imbedding the whole in a ring of plaster, and packing amalgam tightly 
into the mold thus formed to give a reproduction of the crown of the 
tooth together with a rootlike extension for handling in the subsequent 
steps. The procedure for constructing a die is taken up in greater 
detail in section X. 
c. When large castings are made, a model of part or all of the jaw 
is poured in the actual casting investment and the wax pattern formed 
directly on this model. This procedure is taken up in section XIV. 
62. Procedure.—The following are the steps for making a small 
casting, using a metal die: 
a. The die is lubricated with a thin coating of cocoa butter. Petro- 
latum or light machine oil may be used but cocoa butter is not absorbed 
as readily by the wax and makes the later removal of the wax pattern 
easier. 
b. Soften the wax in an open flame or in an oven or water bath until 
it is uniformly and thoroughly plastic. 
c. Adapt the softened mass of wax to the die and press forcibly to 
place so that the wax will be closely conformed to the surface of the die. 
d. Add melted wax with a spatula to make up for any deficiencies or 
correct any flaws in the wax mass. 
67 TM 8-225 
62 
MEDICAL DEPARTMENT 
e. Carefully carve the wax to the desired shape, reproducing the 
anatomical characteristics of the tooth. 
/. Attach a short section of round wire (sprue) to the pattern and 
gently remove it from the die, using the sprue pin as a handle. The 
sprue pin is attached at its free end to a sprue base or crucible former 
which fits on the end of the casting ring and forms a depression in the 
investment for the melting of the gold during the casting process. 
While no set rule exists as to the placing of the sprue pin, it should 
be placed in a position to facilitate the flow of the molten gold into 
the mold. The following rules should be observed in placing the 
sprue: 
Figure 54.—Materials used in investing pattern for casting: Plaster bowl and spatula; 
correct amount of water (weighed or measured) ; correct amount of investment; casting 
ring containing an inner lining of asbestos ; wax pattern fixed to crucible former ; and 
camel’s-hair brush. 
(1) The sprue should not be attached to the center of a broad, flat 
surface. 
(2) The sprue should not be attached so that the molten metal will 
strike directly against a fine margin. 
(3) A minimum number of sprues should be used (only one on small 
castings). 
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DENTAL TECHNICIANS 
Figure 54 shows the materials used in investing the wax pattern. 
The wax pattern affixed to a brass crucible former by a sprue pin is 
shown at the extreme right. 
g. Wash the wax pattern thoroughly in cold water with a fine 
camel’s-hair brush and a soap solution. 
h. Mix the casting investment according to the manufacturer’s di- 
rections, being careful to avoid incorporating air bubbles in the mix. 
Air bubbles can be avoided by mechanical spatulation, spatulating the 
mix for a considerable time, and vibrating the mix either by hand or 
on a mechanical vibrator for a few seconds after mixing. 
Figure 55.—Coating wax pattern with investment prior to placing it in ring. 
i. Carefully paint some of the investment on the wax pattern with 
a camel’s-hair brush, flowing a small amount of investment ahead of 
the brush to avoid trapping air bubbles on the surface of the pattern 
(fig. 55). 
j. After coating the pattern for the first time, blow off as much 
of the investment as possible, thus exposing any trapped air bubbles. 
Then coat the pattern again, being careful to flow the investment 
ahead of the brush so as not to incorporate air bubbles. 
k. Fill the casting ring with the investment and carefully set the 
investment-covered pattern in the ring (fig. 56). 
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62 
MEDICAL DEPARTMENT 
I. After the investment sets, remove the sprue former and sprue, 
and place the ring in an oven to eliminate the wax. The ring is 
ready for casting when a cherry-red glow can be seen down the sprue 
hole. 
Figure 56.—Immersing coated pattern into investment-filled casting rin 
m. The ring is placed in a casting machine and the gold alloy 
melted with a blowtorch flame. The correct temperature of the 
molten gold is determined by experience in observing the color of the 
gold which should be heated to light yellow (almost white) heat. 
Enough gold alloy must be used to fill competely the mold and sprue 
and leave an excess in the crucible; this excess is known as the button. 
The period of time between taking the ring from the oven and 
making the casting should be as short as possible; less than 1 minute 
if best results are to be obtained. 
n. After casting, the metal is removed from the investment and 
cleaned with a brush. The gold is then pickled by boiling in a con- 
centrated solution (30 to 40 percent) of sulfuric or hydrochloric 
acid. The pickling removes oxides and other debris in preparation 
for finishing. 
Section X 
CAST CROWNS 
Paragraph 
General 63 
Obtaining model 64 
Investing and casting 65 TM 8-325 
DENTAL TECHNICIANS 
63-64 
63. General.—Three-quarter crowns and full crowns are generally 
used as attachments for fixed bridges. The three-quarter crown has 
the advantage over the full gold crown in that it does not show as 
much gold. The three-quarter crown is retained on the tooth by 
two parallel grooves which are cut in the mesial and distal surfaces 
Figure 57.—Cross section diagram of tooth impression set in ring of plaster ready to 
receive die amalgam. 
of the tooth. In addition to these grooves, often a groove is cut on 
the incisal edge or holes for pins are placed on either the incisal 
edge or lingual surface for added stability and retention. 
64. Obtaining model.—a. For full or partial crowns an impres- 
sion is taken of the tooth and a metal die or model is made usually of 
amalgam as was mentioned in section IX. As is described in that 
section, the dentist takes an impression of the tooth with compound 
in the copper band. For a crown, additional impressions are taken 
in plaster or other materials of the surrounding teeth and of the 
opposing teeth. The die or model of the tooth to be crowned is made 
first by packing amalgam into the impression which has been boxed 
by wrapping wax or gummed paper around the brass band and sinking 
it in a ring of plaster (fig. 57). 
b. An amalgam model is made by mixing in a mortar and pestle 
seven parts of amalgam alloy and five parts of mercury by weight, and 
triturating for 3 minutes. This amalgam is worked in the palm of 
the hand for 2 or 3 minutes until it has been thoroughly mixed. Then, 
using a small amalgam plugger, it is packed into the impression of 
the tooth, a small amount at a time. The mold is filled even with the 
plaster so that a rootlike extension is formed on the amalgam die or 
model of the tooth. After the amalgam has set, the plaster is broken 
away and the band removed after immersing in hot water. The 
rootlike part of the die is trimmed with stones. 
c. This die is now put into place in the plaster impression of the 
jaw and a stone model is poured with the amalgam die in place. This 
will give a stone model of the jaw or section of the jaw, with the amal- 
gam die in place in the model. With a stone model of the upper 
poured and both models mounted on a small crown and bridge articu- 
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MEDICAL DEPARTMENT 
lator, the wax pattern on the die then can be carved. The wax pat- 
tern is constructed as described in section IX. However, it must be 
carved to articulate properly with the opposing model. 
65. Investing1 and casting.—-The technique for investing and 
casting the gold crown, whether three-quarter or full, is the same as 
described in section IX. The sprue pin is usually placed on the dis- 
to-incisal edge in an anterior three-quarter crown and on a lingual 
cusp for a posterior crown. When cast, the crown is fitted on the 
die, trimmed and adjusted as to occlusion, and smoothed and polished. 
Figure 58. 
Section XI 
Paragraph 
General - 68 
Procedure : 67 
CAST OCCLUSAL GOLD CKOWN 
66. General.—The cast occlusal gold crown is another type of 
full crown frequently used. In this technique a gold band is adapted 
around a model of the tooth and only the occlusal is cast. Due to the 
requirements of esthetics, it is employed for restoring posterior teeth 
only. The primary requirement in the construction of the cast gold 
crown is an accurate tit at the gingival line. One of the most serious 
72 TM 8-225 
DENTAL TECHNICIANS 
66-67 
faults of the full gold crown is the frequent occurrence of caries under 
the band. This can nearly always be traced to the failure in securing 
close adaptation of the band to the tooth at the margin. In order to 
obtain this adaptation the dental officer will take two measurements 
with a dentimeter of the prepared tooth stump. The first is taken 
around the neck of the tooth at the gum line and the second measure- 
ment is taken in a similar manner at a point about one-third the length 
of the stump from the occlusal surface. These measurements are taken 
by looping a piece of wire around the tooth at each one of the points 
mentioned above, and tightening the wire by twisting the ends. The 
two loops thus formed are removed from the tooth and cut. When 
they are straightened out they will give the exact circumference of 
the crown of tlie tooth at each one of these points (fig. 58). 
67. Procedure.—a. The measurement wires are cut and straight- 
ened out. 
h. A piece of 22-carat, 30-gage gold plate is cut slightly wider than 
the length of the tooth stump. It is cut to a length that is y2 millimeter 
longer than that of the longer measurement wire to allow for beveling. 
The shorter wire is placed along the lower edge of the gold plate, equidis- 
tant from the ends and its length marked on the gold with a pointed 
instrument. This measurement is also increased y2 millimeter to allow 
for beveling. It is seen that since one of the measurement wires is 
shorter than the other, the gold plate will not be cut as a rectangle, 
but the ends will converge slightly toward the shorter wire. Cut the 
band along these guide lines, as illustrated in figure 58. 
c. Bevel the gold band at each end at an angle of 45°. using a flat 
file. The file is passed over the band in only one direction. The bevel 
is placed on the opposite side at the other end of the band so that the 
two beveled surfaces will overlap when the band is curved. 
d. The best method of uniting the ends of the band is autogenous 
soldering or sweating. This can only be done when pieces of gold of 
the same carat are to be united. By this means the parts are melted 
or welded together without using solder. When this method is used 
there is no danger of the joint becoming disunited in subsequent solder- 
ings. The beveled ends of the band are bent around and under each 
other until the ends overlap. These ends are then pulled back and 
allowed to spring together upon each other, thus pressing together 
by the elasticity of the metal. This exact contact of the ends is nec- 
essary in autogenous soldering. The joint is fluxed with a saturated 
solution of borax, and the band is placed on a piece of charcoal with 
the lapped edges up. Using a blowpipe, start with a small brush flame, 
73 TM 8-225 
67 
MEDICAL DEPARTMENT 
continue to apply heat until the band is brought to a cherry red. When 
the gold begins to glisten the surfaces are nearly ready to fuse. Re- 
move the flame immediately after the parts are united. The band is 
returned to the dental officer, who trims and fits it to the gum line of 
the tooth. 
e. The united band is then placed upon a flat surface and the occlusal 
edge is filed until it is in flat contact with the file. When the band is in 
place on the tooth stump, the occlusal edge should be the exact height 
of the occlusal surface of the preparation. 
/. In constructing a gold crown for a pulpless tooth, a piece of 22- 
carat, 30-gage gold plate of a size large enough to cover the occlusal 
end of the band is selected. One side is coated with a solution of 
borax. The gold band is then placed on the gold plate and they are 
held in a bunsen burner with a pair of tweezers until the band is 
sweated to the gold plate. The excess gold of the plate is cut away 
so that the margins are smooth and the crown boxlike. This step is 
only used for pulpless teeth. The technique for vital teeth will be 
taken up later. 
g. A wax bite and a plaster impression are now taken by the dental 
officer. 
h. Select a porcelain tooth having a well-developed occlusal anatomy 
and of a width which will fill the space formerly occupied by the natu- 
ral tooth. The occlusal surface of this tooth is covered with a coating 
of oil and then forced into a small block of modeling compound, the 
surface of which has been softened. The compound is chilled and the 
porcelain tooth removed, leaving an impression of its occlusal surface 
in the compound. The surface of the impression is covered with a thin 
coat of oil and softened inlay wax is forced into the impression. The 
wax is chilled and trimmed flat and level with the block of modeling 
compound. It is then removed from the block. The gold coping 
is placed on the cast and the wax occlusal form is placed in position 
on the coping. The wax is then carved and adjusted where neces- 
sary to conform to the occlusion of the opposing teeth. Inlay wax 
is added to the approximal, lingual, and buccal surfaces of the gold 
coping and carved until the proper contour of the tooth is obtained. 
About 1 millimeter of gold band is left exposed at the gum margin. 
i, Attach the sprue at one corner of the crown, invest, and cast as 
described under the three-quarter crown. 
j. Twenty-two-carat gold solder is fused over the exposed band with 
the blowpipe to perfect the contour around the gingival margin of the 
crown. The crown is cleaned in acid and polished. TM 8-225 
67-70 
DENTAL TECHNICIANS 
k. When the cast gold crown is used on a vital tooth, no attempt 
is made to place a gold floor on the band, due to the irregular border 
at the occlusal surface, which is usually unavoidable in vital teeth. 
After the gold band has been accurately fitted at the gingival margin, 
the occlusal surface of the band is reduced with stones to the same 
height as the tooth stump. An impression and bite is then taken 
with the modeling compound, and the gold band is placed in the mod- 
eling compound impression. From this bite impression articulated 
stone casts are prepared. Wax cusps are added and carved to occlusal 
adaptation and the crown is then cast and finished, as described. 
Section XII 
FIXED BRIDGE 
Paragraph 
General 68 
Models 69 
Construction of bridge 70 
Other methods 71 
68. General.—The fixed bridge consists of artificial teeth sup- 
ported by crowns or inlays affixed to natural teeth adjoining the 
space. Because the artificial teeth so placed are rigidly fastened to 
each other and also fastened to crowns or inlays at both ends, this 
restoration is called a bridge. The crowns or inlays which support 
the appliance are called abutments and the natural teeth which re- 
ceive these restorations are called abutment teeth. Crown construc- 
tion and dental casting have been discussed in previous sections. The 
first step in constructing a bridge is the construction of crowns or 
inlays for the natural teeth adjoining the space. 
69. Models.—After the construction of the crowns (or other cast- 
ings) which are to hold the bridge, the dentist takes an impression 
of the mouth with the crowns in place. This impression containing 
the abutment crowns is poured in an investment material so that the 
model so formed may be used for casting or soldering. Also an 
impression of the opposing teeth is taken and a bite to articulate the 
two models thus obtained. The dental technician therefore starts a 
bridge from an investment model which contains the abutment 
crowns and a model of plaster or stone of the opposing teeth. These 
models are mounted on a crown and bridge articulator. The dental 
surgeon also furnishes the technician with the shade of the porcelain 
teeth desired. 
70. Construction of bridge.—a. The first step consists of select- 
ing the type of porcelain bridge tooth which will be used. Many 
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70 
MEDICAL DEPARTMEiSTT 
types of porcelain tooth replacements for use on fixed bridgework are 
manufactured. The most commonly used are the Steele's type fac- 
ing, This consists of a facing of porcelain which slides on a key 
affixed to a metal backing. The porcelain has a groove molded in the 
back which accurately fits the key and so retains the facing (fig. 59). 
Other types of porcelain facings include the long-pin facing and the 
short-pin facing. These are facings which are retained by means of 
two metal pins baked into the back of the porcelain. The long-pin 
facings are used in constructing cast gold bridges and the short-pin 
facings are used in constructing the old solder-type bridge. In addi- 
tion to facings, there are bridge politics. These are porcelain mem- 
bers which are so constructed that they furnish a complete porce- 
lain contact with the soft tissue, and the gold portion of the bridge 
Figure 50.—Steele's facing showing slot which is molded in back to receive metal key 
of backing. 
will not touch the gum tissue at all. These are the best type of 
bridge teeth from all standpoints if the length of the abutment teeth 
and other mechanical factors permit their use. However, the most 
commonly used type is the Steele facing which is on the supply 
table. 
h. The next step consists of grinding and fitting the porcelain 
politics or facings. The proper facings are selected by placing some 
soft wax on the model in the space and trying in various sizes and 
molds of teeth until the best possible selection is obtained. The 
best size facing for a case is one which is exactly the right width but 
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70 
DENTAL TECHNICIANS 
which is somewhat longer than the space because it must be ground 
to fit the ridge. If the facings fit the case very well, little grinding 
is needed. The facings, however, must accurately fit the ridge and 
this fit is accomplished by grinding. The incisal or occlusal edge 
of the facing should be ground very little if at all (fig. 60). 
Note.—Black portion represents finished gold casting and shows proper relation of gold 
portion to facing. Notice how porcelain facing is protected in each case by slight 
extension of gold. 
Figure 60.—Cross section diagrams of facings ground to fit ridge 
Note.—In this case porcelain pontics are used but template is used in same manner with 
facings. 
Figure 61.—Plaster template in place on model. 
c. A metal backing is selected to fit the porcelain facings. The back- 
ing should extend slightly above the incisal or occlusal edge of the fac- 
77 TM 8-225 
70 
MEDICAL DEPARTMENT 
mg to protect the facing from breakage. The backing is then ground 
flush with the facing on all sides except the incisal; here it is beveled 
toward the porcelain so that a hair line of backing extends above the 
porcelain to take the biting stress (fig. 60). 
d. The facings with the backings in place are now arranged in the 
exact position desired in the finished bridge and fixed in this position 
with sticky wax. The outside surface of the model is lubricated with 
vaseline in the region of the facings and a small amount of plaster is 
poured over the facial side of the facings and on the surface of the 
model around the facings. When this little plaster section hardens, 
it is removed and serves as a guide which may be used to establish 
the facings in their proper position during the subsequent steps. This 
plaster piece is called a template (fig. 61). 
Note.—When facings are used instead of pontics, case is handled in same manner. 
Figure 62.—Pontics sticky-waxed to model prior to adding casting wax to form wax 
pattern. 
e. The facings are assembled in the proper position by means of 
the template and then affixed by sticky wax in that position (fig. 62). 
Melted inlay wax is then placed on the backings and in such bulk 
as to form a sizable reinforcement and to restore the shape of the 
teeth that the facings represent. This wax is then carved to the desired 
shape, reproducing the anatomy of the lingual or tongue side of the 
facing. In posterior teeth this wax restoration must be made to 
occlude with the opposing teeth for this will be the shape of the fin- 
ished bridge. 
/. This wax pattern of the gold portion of the pontics is then re- 
moved from the model with the porcelain facings in place. One or 
more sprues are added and the porcelain facings are slipped off the 
backings (fig. 63). The whole is invested and cast. Care must be 
taken not to heat the case too hot in the burning-out process as the 
metal backings are invested and it is not desired to melt or distort 
(hem. 
78 TM 8-225 
70 
DENTAL TECHNICIANS 
g. After casting, the backings usually will be satisfactorily united 
to the casting in the process. Where any flaws exist between the 
backing and the casting proper they must be corrected by solder. 
Note.-—Notice that sprues are placed so that the molten gold will not strike directly 
against metal backings when casting. 
Figure 63.—Wax patterns and attached backings of single-tooth bridges (one anterior 
and one posterior) sprued and ready for casting. 
h. After cleaning and shaping the casting, the porcelain facings are 
placed on it and the whole assembled on the model with the aid of the 
plaster template (fig. 64). 
Note.—Metal portion of bridge will now be sticky-waxed to abutment crowns, pontics 
(or facings) removed, investment material placed in space to affix casting to model, and 
casting then soldered to abutments. 
i. The bridge casting is sticky-waxed in place, the template re- 
moved, and the facings slipped out, leaving the metal part of the 
bridge sticky-waxed to the model in the proper position. 
Figure 64.—Whole bridge assembled prior to soldering. 
T9 TM 8-225 
70-72 
MEDICAL DEPARTMENT 
j. After soaking the model, investment material is mixed and 
placed on the model and over the facing part of the casting, firmly 
joining the casting to the model to which the abutments are affixed. 
k. With the case so invested, the bridge portion is firmly soldered 
at each end to the abutments. 
l. All of the investment is then removed. The case, pickled and 
polished, with the porcelain facings is now ready for delivery to the 
dental surgeon for trial in the mouth. 
71. Other methods.—There are numerous variations of the 
above-described technique and many other techniques of constructing 
bridges. Most of these techniques are satisfactory, but the above 
procedure will give excellent results and is a fairly simple and rapid 
system. It may be mentioned that a common procedure consists of 
uniting all the backings by a large quantity of gold solder and adding 
enough solder to give the whole thing bulk so that no casting is nec- 
essary. This method, however, will only do where anterior teeth are 
replaced as the occlusal surface cannot be constructed with it. and 
also it does not give as precise and fine a result as a cast bridge. 
Section XIII 
CLASPS AND BARS FOR PARTIAL DENTURES 
Paragraph 
General : 72 
Wrought clasps 73 
Occlusal rests 74 
Heat treatment of gold- 75 
Crib clasps 76 
Cast clasps 77 
Lingual and palatal bars 78 
72. General.—a. Clasps are simple, direct retainers applied to two 
or more opposite, sloping, or convex surfaces of remaining natural 
teeth, which are chosen for that purpose during the designing of the 
denture. For convenience clasps may be divided into three classes, 
one-arm, two-arm, and three-arm clasps, according to the number 
of arms which are applied to the surfaces of the tooth. These may 
be either wrought or cast clasps. The former are constructed by 
bending a piece of gold clasp wire to conform to the tooth, and the 
latter are constructed by casting the clasps, using a special gold alloy. 
Both types have a definite place in dentistry and although there are 
many variations of both, this manual will deal only with those types 
that are commonly used. In order to understand the construction of 
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72 
DENTAL TECHNICIANS 
a clasp, no matter what type it may be, it is necessary to study the 
shape and contour of the crowns of the teeth so that these surfaces 
may be used to the best advantage. The fundamental reason behind 
(D Diagrammatic sketch illustrating line of greatest circumference of tooth. 
A. Body of clasp. B. Shoulder of clasp. C. Arm of clasp. D. Line of greatest circumfer- 
ence on tooth. 
® Arms of clasp below line of greatest circumference 
A. Body of clasp showing occlusal rest. B. Shoulders of clasp. C. Arms of clasp. 
@ Sketch of clasp illustrating various parts. 
Figure 65. 
all clasps is to obtain the maximum amount of retention for the 
denture, and still allow it to be easily inserted and removed from the 
mouth. It must be understood that it is impractical to clasp some 
431511°—42 6 
81 TM 8-225 
72-73 
MEDICAL DEPARTMENT 
teeth due to their anatomical characteristics or position; therefore, it 
is essential that the dental officer take great care in the designing of 
the case. The three simple diagrams in figure 65 will clarify the 
fundamental mechanical theory which must be understood in order to 
construct efficient clasps. 
h. Figure 65(T) shows that each tooth is divided into two separate 
parts by its line of greatest circumference. Nothing above this line 
can be used for retention. Therefore the parts of the clasp for which 
no retention is obtained are placed on this half of the tooth. This 
includes the body or rigid portion and the occlusal rest. The parts of 
the clasp that extend out from the body for a short distance are 
known as the shoulders. As the shoulders are relied upon for rigidity 
and not for retention, they should be placed either on the line of 
greatest circumference or just crossing it. Extending from these 
shoulders are the thin flexible arms from which the retention is 
derived. These arms must always be below the guideline and in the 
undercut of the tooth. Therefore they are placed below the line of 
greatest circumference, as shown in figure 65(5). The body and oc- 
clusal rest of the clasps are above the line, the shoulders on or crossing 
the line, and the arms below the line. If this rule is followed, the 
clasp will give maximum efficiency. It is the duty of the dental 
officer to survey each case before giving it to the dental technician, 
marking on the cast the teeth to be clasped, the outline of the clasp 
and rest areas, and the outline of the entire denture. In a partial 
denture with two or more clasps, it is necessary to take into consid- 
eration the fact that while one clasp may be easily removed from the 
tooth, another clasp when attached to the denture may be in such a 
position as to make its removal impossible. Therefore, a mean vertical 
plane must be determined when the case is surveyed, which will coin- 
cide with the path along which the clasps will tend to seat themselves 
when attached to the denture. This is known as the path of insertion. 
73. Wrought clasps.—Wrought clasps are constructed by bending 
a piece of either round or half-round gold clasp wire of the desired 
gage to conform to the tooth to be clasped. One of the most commonly 
used methods is to clasp a tooth adjoining a space caused by the 
extraction of one or more teeth. This allowrs sufficient room for the 
body of the clasp. However, it is frequently necessary to clasp a 
tooth which is in contact with the teeth on each side of it. As there 
is no room between the teeth to accommodate the body of the clasp, a 
different design must be used. However, the actual bending of the 
wire is done the same in each case. In the simple three-arm clasp, 
using a tooth adjoining a space, the following technique is followed: 
82 TM 8-225 
73-74 
DENTAL TECHNICIANS 
a. Anneal the wire before any bending is attempted. This is done 
by holding it in an open dame until it assumes a cherry-red color. 
It is then plunged in cold water which removes the stiffness from 
the wire and makes it much easier to bend into shape. This anneal- 
ing process should be repeated after each bending during the con- 
struction of the clasp. 
h. Place one end of the wire on the lingual surface of the tooth 
where the outline of the clasp terminates, and note the point where 
the wire leaves the surface of the tooth. Grasp the wire with suit- 
Figure GO.- Diagram of construction of occlusal rest 
Figure 67. 
able wire bending pliers and bend it slightly so that a greater length 
of the wire comes in contact with the tooth when tried on the model. 
It is then annealed and the point where it again leaves the tooth is 
noted and bent as before. This procedure is carried out until the 
clasp is conformed to the entire outline of the clasp on the model. 
As the buccal end of the clasp is approached, the length of wire to be 
used is judged and the remainder cut off with a pair of cutting 
pliers. The ends of the clasp are rounded with stones and burlew 
disks. 
Figure 68. 
74. Occlusal rests.—a. In practically every partial denture case 
it is necessary to construct a third arm or occlusal rest as part of the 
83 TM 8-225 
74-75 
MEDICAL DEPARTMENT 
clasp. This part will extend from the body of the clasp over the 
marginal ridge of the tooth and rest on a small section of the occlusal 
surface. 
In this way the tooth can actually be made to bear most of the 
stresses of mastication instead of the tissue surfaces, and prevent the 
denture from settling down and forcing the clasp onto the gingival 
tissue around the neck of the tooth. Since the occlusal rest must 
bear quite a load it must be of sufficient strength to prevent breakage. 
A small piece of 36-gage pure gold plate is placed against the model 
at a point corresponding to the body of the clasp (fig. 66). 
h. The clasp is placed over the tooth, and the end of the gold plate 
below the clasp is bent up and around the wire clasp, and secured 
with sticky wax. The lug and the clasp are removed from the model 
and soldered together with a very small piece of solder, making cer- 
tain that the relationship is not destroyed. The clasp with the lug 
is then replaced on the model and the pure gold is burnished over 
the small part of the occlusal surface, as outlined on the model. The 
gold is trimmed to conform with the outline, leaving a small excess 
around the margins (fig. 67). 
c. A short piece of half-round wire is bent to the shape of an L 
and laid over the rest as shown in figure 68. When soldered, this 
wire will reinforce the occlusal rest. 
d. The clasp, lug, and wire are removed from the model and care- 
fully invested in a small amount of investment material. The 
investment is allowed to come just to the margins of the lug. The 
investment is allowed to set and then gradually heated over an open 
flame until quite hot. Using a blowtorch, small pieces of either 18- 
or 20-carat gold solder are fused over this lug, further attaching it 
to the clasp and at the same time adding thickness to the lug so 
that it will have sufficient strength to withstand the stresses of mas- 
tication. The clasp with the occlusal rest is removed from the in- 
vestment and polished. It is returned to the model and checked for 
accuracy. This procedure is repeated for all clasps requiring occlusal 
rests. 
75. Heat treatment of gold.—As the repeated annealing of the 
gold clasp wire causes it to become soft and pliable, it is necessary 
to restore its hardness and elasticity by retempering after the work 
has been finished. To do this, the clasp is placed in an oven and 
heated to a temperature of 840° F., and held at that temperature for 
10 minutes. It is then allowed to cool to 480° F. over a period of 
30 minutes. If an oven is not available, heat in an open flame to 
a cherry red and allow to cool in air. 
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DENTAL TECHNICIANS 
76. Crib clasps.—a. The design of the clasps may be altered to 
suit the case. Frequently it is necessary to construct a clasp for a 
tooth which is in contact with the adjoining teeth. An example of 
this type of clasp is shown in figure 69. 
b. In this type of attachment the body of the clasp is placed in 
the embrasure between the teeth instead of beside the distal or mesial 
surfaces. Preparation for this should be made in the mouth before 
the impression is taken, and the technique of bending the clasp is 
exactly as described previously. This may be either a single clasp 
or a double clasp, as shown in figure 69. In the double crib clasp a 
slight modification is used. Instead of bending the gold clasp wire 
around one tooth, it is bent in the shape of an S, starting at the 
lingual surface of one of the teeth to be clasped, continuing to the 
proximal surface of the tooth, and crossing the embrasure between 
Figure 69. 
the teeth, as described. But instead of continuing around the buccal 
of the same tooth, it is bent so as to form the buccal arm of the clasp 
for the other tooth to be clasped. When this S-shaped wire is 
formed, two other pieces of wire are bent to complete the unfinished 
arms of the clasp. These pieces are soldered to the S-shaped wire 
in their correct positions, thus completing the double crib clasp. 
Always construct an occlusal rest for all crib clasps in order to 
prevent the wire from separating the teeth, thus endangering their 
continued usefulness. 
77. Cast clasps.—The designs as already given for wrought clasps 
will also apply to cast clasps. Frequently in the designing of partial 
dentures this is the type indicated. The impression of the teeth to be 
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MEDICAL DEPARTMENT 
clasped is usually taken in plaster or hydrocolloid impression material. 
The impression is boxed in either moldine, if a metal model is to made, 
or wax, if the model is to be poured with investment plaster. The fit 
of the clasp is usually more accurate when cast directly on the invest- 
ment plaster model. Therefore this will be the technique described 
herein. The outline of the clasp is traced on the model by the 
dental officer. A piece of 30-gage basewax is wrapped around the tooth 
and sealed with a warm spatula so that it will not move from position. 
The outline of the clasp which shows through the wax is then covered 
with a thin layer of either green or blue casting wax. After applying 
the wax, it is carved and smoothed to the shape of the clasp, which 
should also include the tail portion or that part that is to be used for 
anchorage. It is much easier to cast the tailpiece as part of the clasp 
than to make it of wire and then solder the two parts together. This 
anchorage should be of sufficient length to allow maximum retention 
in the denture material and should be made in the form of a loop to 
facilitate this retention. The outline of this loop should be marked on 
the model at the same time that the clasp is outlined and the waxing 
done as the clasp is waxed. When the wax clasp and tailpiece are 
carved and smoothed, the case is sprued by attaching a tapered wire 
such as a phonograph needle to the wax clasp, and holding it in place 
until it has cooled sufficiently to secure it. The clasp can then be 
invested and cast the same as any gold inlay or three-quarter crown. 
(See sec. IX.) 
78. Lingual and palatal bars.—a. A lingual bar consists of a 
connecting piece of material running adjacent to the soft tissue on 
the linqual side of the lower front teeth beneath the tip of the tongue, 
joining the two sides of a lower partial denture and making it one unit. 
-Palatal bars may be defined as metal bars constructed to fit the surface 
of the vault of the palate and connecting the two lateral sections of an 
upper partial denture. Lingual bars may be obtained in a ready-made 
form and all that is required is to adapt it to the individual model. 
However, in a few cases this is not entirely satisfactory, and it is better 
to cast the lingual bar as well as the palatal bar for these cases. The 
design of the bar is drawn on the model with an indelible pencil by 
the dental officer. It is frequently necessary to place a strip of ad- 
hesive tape on the model to provide relief before adapting the wax. 
The outline of the bar on the model is oiled, and over this outline is 
adapted a piece of 30-gage baseplate wax. Blue inlay wax is melted 
and placed over this outline, which shows through the first layer of 
basewax. It is then trimmed and carved to the exact shape of the 
completed lingual bar (fig. 70). 
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DENTAL TECHNICIANS 
h. After smoothing the wax it is sprued, removed from the cast, 
washed with green soap and water, invested, and cast in saddle and 
bar gold. 
Section XIV 
Figure 70. 
CAST PARTIAL DENTURES AND PARTIAL DENTURE 
SKELETONS 
Paragraph 
General 79 
Models 80 
Preparation of master model 81 
Surveying model 82 
Steps of survey 83 
Location of retention 84 
Eliminating undesirable undercuts 85 
Tripoding 86 
Duplicating model 87 
Surveying casting model 88 
Marking design on casting model 89 
Waxing 90 
Spruing 91 
Investing 92 
Burn-out and casting 93 
79. General.—Many times it is desirable to cast the entire partial 
denture or a skeleton of the bars and clasps of the denture entirely 
in one piece. This type of partial denture makes a very fine restora- 
tion and the technique for its construction is very exacting. Where 
the entire partial denture is cast, a porcelain tooth, known as a tube 
tooth, is used. This tooth has a cylindrical cavity through the center 
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MEDICAL DEPARTMENT 
which allows provision for its retention on the finished denture by 
means of a dowel or peg which is cast with the denture and on 
which the tube tooth fits. When the denture is finished, the tube 
teeth are permanently affixed to the denture by cementing them to 
place over the dowel with ordinary crown and bridge cement. In 
other cases, cast the bars and clasps of the denture joined with a 
skeletal framework. Vulcanite or other denture base material is 
later utilized to cover this framework and to attach the teeth to the 
partial denture. The two types of partial dentures are constructed 
in the same manner; that is, by casting them in one casting opera- 
tion and in one piece. 
80. Models.—A master model is obtained from the impression of 
the mouth. This master model is poured in stone as is described in 
paragraph 21. For this type of work a second model of casting 
investment must be obtained. This is accomplished by a process 
called duplicating the model. This second model is called a casting 
model as it is constructed of casting investment and is used directly 
in casting the partial denture. 
81. Preparation of master model.—a. Designing the partial 
denture on the master model is the first step. The designing of the 
partial denture requires a direct knowledge of the condition found 
in the mouth of the patient. It also demands a knowledge of the 
effect of various forces on the various teeth and the tissue changes 
which are expected as a result of forces exerted. The dental 
mechanic is not required or expected to possess this knowledge, so 
the designing of the denture should be the work of the dental surgeon. 
h. There are, however, a few fundamental facts which the dental 
mechanic should know. The two forces involved for which provision 
must be made in designing a denture, are— 
(1) Down 'pressure against the ridges and remaining teeth brought 
to bear by the opposing jaw in closing the mouth. This pressure 
is sustained by occlusal rests on the denture which are little fingers 
fitting onto the occlusal surface of remaining natural teeth and are 
in most cases incorporated with each clasp. Paragraph 74 describes 
and illustrates one type of occlusal rest. 
(2) Up pressure away from the ridges, which tends to unseat the 
denture. This is caused by sticky food, the weight of the appliance 
if in the upper jaw, etc. Up pressure is resisted by the retentive 
power of the clasps and by indirect retainers (finger projections 
which prevent tipping). 
c. Three points firmly held on any object will in turn firmly hold 
that object. If three points (not in a straight line) are fixed firmly. 
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DENTAL TECHNICIANS 
the denture will be held securely. Usually then three clasps are 
needed to hold the denture in place. In order to prevent movement 
of the teeth, settling and displacement, the following must be ob- 
served : the denture must hold the abutment teeth rigidly in place 
be rigid itself, and be solidly supported so that it will not rock or tilt. 
If the soft tissue, as well as the remaining teeth, is utilized in the 
support of the denture, wrought wire clasps or stress breakers 
should be employed to equalize the forces between the semirigid 
teeth and the semisoft tissue. This problem will not be discussed in 
this manual as it is the prerogative of the dental surgeon and out of 
the field of the technician. 
A. Flat base. 
B. Vertical member. 
C. Horizontal arm. 
E. Carbon point for marking model. 
F. Movable base for mounting cast. 
G. Mounting wax. 
H. Cast. 
K. Lock nut. 
Figure 71.—Surveying instrument. 
82. Surveying model.—Before the design is drawn in pencil on 
the model, the exact design of the clasps is determined. This is done 
with the aid of a surveying instrument (fig. 71) which marks the 
height of contour of each tooth surface. With the relative points of 
highest contour marked as a line on each tooth to be clasped, the out- 
line of the clasp may be accurately drawn on the tooth. In this type 
of work it is necessary to obtain such accuracy in the design of each 
clasp. The reason is that these cast clasps are more rigid than the 
wire clasps taken up in section XIII and their success depends upon 
their accuracy in design. 
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MEDICAL DEPARTMENT 
83, Steps of survey.—The surveying instrument (fig. 71) con- 
sists of a fiat base A, a metallic disk which is placed on the base F, 
an upright supporting a horizontal arm (7, which in turn supports 
the vertical member containing a carbon point E for marking the 
model. 
a. The model is mounted on the metallic disk by means of a ball 
of wax as shown in figure 72. It is placed on the wax in the position 
which will afford desirable undercuts on the abutment teeth for the 
clasps. This may be determined by looking down on the model from 
above while adjusting it. 
Figure 72.—Marking line of greatest circumference on tooth to be clasped. 
h. The vertical side of the carbon is placed against each tooth 
that may be involved in the case, and it is moved around all surfaces 
of these teeth by moving the movable base F and by swinging the 
horizontal arm C to facilitate this. The circumference of greatest 
contour is located wherever the vertical side of the surveying tool 
touches the tooth. Wherever light shows between the tool and the 
tooth below this circumference the undercut area is located. The 
carbon point will effectively mark this line of greatest circumference 
on the tooth. 
84. Location of retention.—By this procedure the desirable and 
undesirable undercuts immediately show up. The teeth to be used 
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DENTAL TECHNICIANS 
for retention can quickly be determined. If possible these teeth 
should be well-formed, strong, and widely distributed in the mouth. 
85. Eliminating undesirable undercuts. — The undercuts 
which show up after surveying will be used largely in designing the 
clasps so that they provide retention for those clasps. However, in 
some places, especially on the surfaces of the teeth adjoining the 
edentulous spaces, undercuts are not desired. Construction of the 
denture into these undercut areas would prevent its going to place. 
These undercuts are eliminated by filling them with wax on the mas- 
ter model (fig. 73). In this way, in the next step (duplicating the 
model) these undesirable undercuts will not appear on the casting 
model. 
(J) Undercut area. 
Figure 73. Filling in undesirable undercut with wax, 
® Placing wax in undercut. 
86. Tripoding.—Before removing the master model from the 
mounting wax, a determination of its position must be made so that 
the investment model may be placed back on the surveyor in the same 
position as the master model. This procedure is called tripoding. 
In order to tripod, it is only necessary to determine three points in 
the same horizontal plane on the master model. This is done by 
locking the spindle in position by using the lock nut (fig. 71, K), 
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MEDICAL DEPARTMENT 
placing a drop of ink on the tip of the surveying tool, and touching 
the model at three points. These three points will be in a plane 
parallel to the fixed base. 
87. Duplicating model.—After surveying the master model, 
drawing the design on the master model in pencil, and filling the 
undesirable undercuts on the model with wax, a casting model can 
then be made. This step is called duplicating the model. 
a. Soak the master model in water for a short period of time. 
Figure 74.—Marking three points with tip of tool so that duplicate model can be replaced 
on conveyor in same plane. 
h. Touch the three tripod points with an indelible pencil after 
soaking the model. 
c. Place the master model in a duplicating flask. Several flasks 
are on the market for this purpose. However, if none are obtainable 
a small can with top and bottom removed can be used by placing 
over the model after the model has been fixed to a flat surface. 
d. Hydrocolloid impression material is prepared by heating in a 
hydrocolloid heater or an ordinary double boiler. Old impressions 
and scrap pieces are best for this if an equal volume of water is 
added before heating. As soon as the material begins to boil, stir 
to facilitate an even mix. 
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DENTAL TECHNICIANS 
e. Let the hydrocolloid material cool to the proper consistency 
before pouring (140° F.). Pour the material first around the sides 
of the model and then all over it, completely filling the flask or can. 
After the hydrocolloid material has completely set (15 to 30 minutes) 
invert the flask or can and gently remove the master model. 
f. Dry out the excess water from the impression and immediately 
pour an investment model of any model investment. This same ma- 
terial will later be used to invest the case for actual casting. 
g. Before pouring the investment, it should be noted that the tri- 
pod marks appear on the impression. These should be touched with 
indelible pencil so that they will carry through into the investment 
model. The model investment should be thoroughly mixed to ob- 
tain its maximum strength. The use of measuring cups and mechan- 
ical mixer is highly recommended. As soon as the investment is 
poured, dust some dry investment powder on the back of the model 
to draw out the excess water. 
h. Allow the investment to set for 1 hour in the hydrocolloid. The 
hydrocolloid should then be broken away from the investment. Do 
not attempt to save the impression by pulling the investment model 
out in the same manner that the master model was removed, as the 
freshly set surface of the investment may be marred by the friction. 
It will be found that the tripod marks now appear on the investment 
model. 
88. Surveying casting model.—After the casting model is 
thoroughly dry, mount it on the mounting wax, manipulate the model 
until the three tripod points can be touched by the tip of the survey- 
ing tool without raising or lowering the spindle. In other words, 
arrange the model so that the three tripod points will be a plane 
parallel with the fixed base. The investment model will now be 
in exactly the same tilted position as the master model was when 
surveyed. Mark the circumference on the teeth to be clasped on 
the casting model and remove from instrument. 
89. Marking design on casting model.—The denture design 
decided upon on the master model is now traced out in pencil on the 
casting model. The exact outline of the clasps, with the aid of the 
survey marks, are placed on the model. This outline of the design 
should be done by the dental officer. 
90. Waxing.—Generally, ordinary blue casting wax is used. It 
is applied to the model in a molten state with a spatula and later 
trimmed to the desired shape and size with wax-carving instruments. 
Thin sheet wax, where available, may be used in places where sad- 
dles are being constructed. In this way the desired thickness is 
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MEDICAL DEPARTMENT 
more accurately determined than if the inlay wax were applied. 
Also, wax shapes are supplied in proper sizes for clasps and bars; 
these may be used if available. The waxing step is important and 
should be carefully done so that little grinding will be necessary after 
the denture is cast. 
Figure 75.—Wax pattern on model and wax pattern sprued ready for investment. 
91. Spruing.—Sprues are distributed about the case. Usually one 
sprue to the body of the partial below each clasp will be sufficient. 
In long saddle areas it is well to place one sprue at each end of 
the saddle. It is not advisable to attach a sprue to a bar or clasp 
as the point where the sprue attaches is usually a weak spot in the 
denture. Three sprues in most cases are enough. The sprues are 
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DENTAL TECHNICIANS 
joined about 1/4 inch above the highest point of the pattern and 
sealed together. Above this point the sprues are sealed together to 
provide one large sprue (fig. 75). 
92. Investing.—Such large castings are best invested by first 
coating all parts of the pattern with investment and bringing well 
up on the sprue. A second batch is then mixed to insert the previ- 
ously coated pattern in the investment ring. First the invested 
model with the sprued pattern is soaked well in a pan of water. 
Next, a generous coat of investment is painted on the pattern, arid 
finally a second batch of investment is mixed and the coated model 
is placed in the ring. A crucible is cut in the investment after the 
investing material sets. 
Figure 76.- Finished cast ready for cementation of porcelain tube teeth. 
93. Burn-out and casting.—After the investment has set 45 min- 
utes, it is placed in the furnace to burn out the wax. The casting is 
made as described in section IX. The gold should be melted in the 
casting machine while the flask is still in the furnace. This will 
prevent the cooling of the case while melting the large amount of 
gold necessary for casting. Allow the investment to stand 4 or 5 
minutes after casting and then plunge in water. When cold, dig 
and brush the investment away from the casting. The casting is 
pickled and finished in the usual way. The master model is utilized 
in fitting, finishing, and polishing the casting. Figure 76 shows a 
finished cast gold partial denture on the master model; tube teeth fit 
over the dowels and later will be cemented. 
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MEDICAL DEPARTMENT 
Section XV 
SPLINTS 
Paragraph 
General 94 
Vulcanite splint 95 
Acrylic resin splint 99 
Cast silver splint 97 
94. General.—Splints are becoming more and more important in 
the Army dental service. In warfare, injuries to the face and jaws 
are very common, and are becoming increasingly so. The most prac- 
tical method of controlling fractures of the jaw is by splinting. 
It must be understood that no two cases will be the same or will use 
exactly the same design of splint, but they are all sufficiently similar 
to follow the same general basic fundamentals of design and con- 
struction. The following designs can be used for either maxillary or 
mandibular splints and can be constructed of vulcanite, acrylic resin, 
or cast silver. The variations in material and design will be taken 
up in detail. 
95. Vulcanite splint (fig. 77).—a. The prepared model will 
come to the dental technician for the construction of the splint. 
b. The designing of the case will be done by the dental officer and 
will be outlined on the model. It is important that the dental tech- 
nician know the following fundamentals in the designing of all 
splints so that the maximum efficiency and serviceability will be ob- 
tained. 
(1) The splint should cover all free gingival margins on the lin- 
gual, buccal, and labial surfaces at least 2 or 3 millimeters from the 
necks of the teeth. 
(2) The splint must cover the cervical two-thirds of the teeth and 
must include as much of the occlusal third as possible without inter- 
fering with the masticatory processes. 
c. Adapt a piece of 28-gage casting wax to the model to cover the 
design of the splint. Make certain the wax is in all the interproximal 
spaces. 
d. Soften a piece of baseplate wax and fold it over on itself, 
making a double thickness. Adapt this wax over the wax already in 
place, on both the lingual and buccal surfaces of the cast. Trim wax 
to conform with design of splint, as outlined on the cast. 
e. Make a small button of the labial surface of the wax pattern in 
the median line. This wax button may be stamped out of a piece of 
wax, using a lead pencil from which the rubber has been removed. 
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DENTAL TECHNICIANS 
This small disk is attached to the wax pattern, forming the small 
button which will be used to secure the finished splint in place in 
the mouth. 
/. The edges of the wax must be sealed to the model. 
g. Chill the wax in cold water and polish with cotton. 
h. Flame the wax and repolish, which will give a very smooth 
finish to the splint and will minimize the amount of polishing to be 
done later. 
i. A piece of 14-gage half-round wire is bent to conform to the 
distal surface of the last molar tooth. It extends forward on both 
the lingual and buccal surfaces of the tooth, only touching the tooth 
on the distal surface. The ends should come forward to almost the 
mesial of the tooth and then bend out at right angles, extending be- 
yond the surface of the wax pattern. These two projections of the 
wire, along with that portion around the distal of the tooth, will he 
imbedded in plaster during the flashing process, thus holding the 
wire in its correct position. 
j. In some fractures, it is necessary to design the case so that a 
loose or broken fragment of bone in an area which is edentulous 
may be held in place. This is accomplished by constructing projec- 
tions of wire which will extend out from the splint and hold these 
fragments in place. A piece of nickel tubing 10- by 14-gage is incor- 
porated into the splint by soldering it to the buccal surface of the 
half-round wire, so that it will be parallel to the buccal surface of 
the teeth. A piece of 14-gage square wire is inserted into the tub- 
ing and the other end is bent so that it will rest on the buccal tissue 
over the fragment requiring stabilization. 
k. Wax is melted around the nickel tubing so that it is flush with 
the surface of the wax pattern. 
l. The case is now ready for flashing. Trim off all occlusal sur- 
faces of the teeth flush with the wax pattern. Soak the model in cold 
water until all bubbling has ceased. Flask the case in the lower part 
of the flask, as described in section VI, making certain that the 
plaster comes up to the lower border of the wax splint. The tubing 
and wires are left exposed. Use any type of separating medium on 
the plaster surface and then pour the upper half of the flask, as 
previously described. 
m. The wax is eliminated, the case is packed with rubber, vulcan- 
ized, and polished, as previously described. 
n. lu every space where there is a tooth missing the buccal and 
lingua] parts of the splint are separated by sawing. The button in 
the median line is also sawed vertically in half. Thus, the splint is 
431511°—42 7 
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MEDICAL DEPARTMENT 
in two parts connected by wire, which can be placed in the mouth, 
brought into position, and the two halves of the button wired 
together. 
Figure 77.—Vulcanite splint with posterior extension arm for stabilizing posterior 
fragment. 
96. Acrylic resin splint.—The construction of a splint, using 
the acrylic resin material in place of the vulcanite, is exactly the 
same as previously described with the exception of tinfoiling the 
wax pattern and the model. This tinfoiling procedure is carried 
out the same as already described under acrylic resin dentures. The 
acrylic resin used in the construction of the splints is colorless, which 
has the advantage of being transparent, allowing the dental officer 
Figure 78.—Acrylic resin splint. 
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DENTAL TECHNICIANS 
to observe the condition of the teeth and gums underlying the splint 
at all times. Frequently a fracture case will have one or two missing 
anterior teeth. It is a simple procedure to add the necessary arti- 
ficial teeth to the splint, which will replace the missing teeth until 
the splint can be removed. When teeth are added, it is necessary 
to tinfoil over the labial surfaces of the artificial teeth before the 
case is waxed. This will prevent the material from adhering to the 
labial surfaces of the teeth. Acrylic resin splint showing teeth 
added is illustrated in figure 78. 
97. Cast silver splint.—a. The third type of splint that is com- 
monly used is the cast silver splint. 
(1) Prepare a duplicate model of investment plaster. 
(2) Adapt one thickness of 28-gage wax to the investment plaster 
model as outlined by the dental officer. 
Figure 79.—Wax pattern on model and sprued for casting splint in silver. 
(3) Soften a piece of baseplate wax and adapt one thickness of it 
over the wax already in place. 
(4) Add sufficient wax so that the surface of the wax pattern is 
smooth and even, 
(5) Fourteen-gage wire is used, as previously described. 
(6) The button in the median line is constructed as usual and 
smaller buttons are placed in the cuspid and first molar region of 
both sides. 
(7) Seal the edges of the wax to the model. 
(8) Smooth and polish the pattern as this will save needless work 
in the final polishing. 
(9) There are various ways of spruing the case preparatory to 
investing and casting, but the method described in this manual will 
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MEDICAL DEPARTMENT 
be found very satisfactory. Drill a hole through the center of the 
model about the size of a dime. On the inner lingual surface of the 
pattern are attached six small 14-gage sprues. On the outer surface 
leading from the main sprue are attached four 14-gage sprues at- 
tached to the buccal surface of the wax pattern. From the cuspid 
Figure 80.—Another view of wax pattern for silver splint. 
Figure 81.—Finished silver splint. 
and molar regions of the buccal surface of the pattern are attached 
14-gage sprues for air vents. These air vents stop at the edge of 
the model. Grooves should be cut in the model, both lingual and 
buccal, to accommodate these sprues (figs. 79 and 80). 
b. Soak model until bubbling ceases. Using a camel’s-hair brush, 
paint wax pattern with casting investment, making certain that all 
100 DENTAL TECHNICIANS 
TM 8-335 
97 
air bubbles are eliminated. Select casting ring to fit the case and 
fill with remaining investment. Place the model in the investment 
with the teeth down and the main sprue which comes through the 
hole in the center of the model sticking out of the investment 
material. Let set for at least 1 hour. Place casting ring in cold 
oven and heat for 2 hours at 1,200° F. Add not more than 10 percent 
copper to the amount of silver. Melt silver and copper in crucible. 
Place ring in casting machine. Add borax or any reducing flux to 
molten metal and cast. Remove from investment and polish. Make 
cuts the same as previously described. A finished splint is shown in 
figure 81. 
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MEDICAL DEPARTMENT 
Chapter 4 
DENTAL X-RAY TECHNICIAN 
Paragraphs 
Section 1. Equipment 98-103 
IT. Intra-oral roentgenography 104—125 
III. Extra-oral roentgenography 126-129 
IV. Processing of X-ray films 130-138 
Section I 
Paragraph 
General 98 
Dental X-ray machine 99 
Films 100 
Emulsion 101 
Physics 102 
Intensifying screen 103 
EQUIPMENT 
98. General.—The Army dental surgeon, in connection with 
routine professional procedures, is called upon to make numerous and 
varied dental surveys; surveys for evidence of dental foci of infection ; 
surveys in connection with different boards requiring physical exami- 
nations of the individuals; annual and semiannual surveys; surveys 
of commands, etc. Each of these is of particular value in connection 
with the regulation requiring the examination. Therefore, the find- 
ings must be accurately recorded and reported as indicated. The sur- 
vey for evidence of dental foci of infection is of particular importance 
in connection with general and localized conditions that may be attrib- 
uted to or influenced by oral or dental foci. Good roentgenographic 
studies are of inestimable value in connection with a thorough clinical 
examination in order that a complete and correct oral diagnostic report 
can be rendered. Roentgenographic studies include roentgenograms, 
or X-rays as commonly called, plain and stereoscopic views, also fluoro- 
scopic observations. The images or shadows shown on the film and 
those viewed on the fluoroscopic screen should be clearly and sharply 
outlined, giving good detail and contrast. The correct interpretation 
of these studies, in connection with the clinical examination, will 
greatly assist the operator in locating and viewing the normal as well 
as abnormal conditions. The opportunity to see the parts in X-ray 
studies is of material aid in rendering a diagnosis of invisible condi- 
tions. Therefore, it is evident that the real value of X-ray studies as 
diagnostic aids will be in direct proportion to their quality. 
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DENTAL TECHNICIANS 
99. Dental X-ray machine.—The majority of dental X-ray ma- 
chines are shockproof and, with few exceptions, have oil immersed 
tubes. The head is small and mounted so that adjustment of position 
is easily accomplished. The newer machines are capable of adjustment 
of voltage, kilovoltage, and milliamperage. The panel is located on 
the top of the cabinet and for adjustment has “on” and “off” switch, 
control knob to adjust the voltage so that the specified voltage for 
that machine is registered on the voltmeter when the machine is in 
operation, knobs to adjust the kilovoltage from 50 to 70 kilovolts, and 
another knob to control milliamperes which are recorded on a 
milliammeter. 
100. Films.—Films for roentgenographic work are supplied in 
various sizes and usually a dozen or more are in each container. Stor- 
age is important, and a lead-lined box or chest should be provided 
in which unexposed and undeveloped films can be kept to protect them 
from radiation. The storage should be in a cool, dry place; high tem- 
peratures, moisture, chemicals, or the like deteriorate or ruin the emul- 
sion of the films for X-ray work. An expiration date is stamped on 
each package indicating the manufacturer’s time limit on the emulsion. 
Films should not be overstocked. Sufficient films should always be 
on hand, but in such quantities that they will be used within the expira- 
tion date. However, films stored and protected as outlined should pro- 
duce satisfactory X-rays long after the expiration date. 
101. Emulsion.—a. The emulsion referred to is the dull surface 
side of the film, and in case of a duplitized film both sides are coated. 
This emulsion is a thin coating of special gelatin in which the minute 
particles of sensitive silver halide salts are incorporated. The base on 
which the emulsion is placed is a transparent cellulose acetate support 
with a slight bluish tint or color. Films that do not have this bluish 
tint or color may be viewed over tinted ground glass, giving better 
photographic effect. 
b. Films for X-ray, like those for photography, have various emul- 
sion speeds indicating their sensitivity to radiation. The terms used 
for marking the speed of X-ray films are regular, medium, fast, extra- 
fast, or similar words indicating the emulsion’s sensitivity to radia- 
tion. The effect of developing solutions on the emulsion is discussed in 
section IV. Extra-fast dental films require about 75 percent less expo- 
sure time than regular films to give the same photographic effect, other 
factors being equal. The duplitized will require 50 percent less time 
than the regular to obtain the same results. An example would be 2 
seconds for extra-fast, 4 seconds for duplitized, and 8 seconds for 
regular. The more important factors that influence and affect the pro- 
103 TM 8-225 
101-102 
MEDICAL DEPARTMENT 
duction of the image or shadow (photographic effect) on the emulsion 
are: kilovoltage, milliamperage, target film distance, object film dis- 
tance, thickness and density of the object, emulsion speed of the film, 
intensifying screen speed, and processing. It is evident that a good 
roentgenogram will be the result of an exacting technique and from 
this there must be no deviation. Sufficient exposures should be made 
and the factors governing photographic effect considered until the 
X-rays produced are up to a high standard. An exposure chart can 
then be made that will give the technician information on that equip- 
ment and assure him of producing films of satisfactory quality. 
102. Physics.—It is not the purpose of this manual to go into too 
much detail as to the physics of the X-ray machine, but rather the 
technique involved in its handling so that the technician will be able 
to take consistently good pictures. The X-ray technician may be 
called upon to understand and operate several types of units. They 
may vary, but it is believed the technique described in this manual will 
give the technician sufficient knowledge to operate the various makes 
of dental X-ray apparatus and obtain excellent results. 
a. Voltage.—When the switch is turned to “on,” the voltage is regis- 
tered on the voltmeter. The line voltage should register 110 volts 
on the voltmeter when the machine is in operation. Some machines 
advise adjustment of the voltage for exposures made at 10 milliamperes 
and 15 milliamperes, with a line on the voltmeter indicating each. The 
manufacturer’s instructions for each machine should be followed. 
h. Kilovoltage.—Machines with variable kilovoltage have adjust- 
ments from 50 to 70 kilovolts. This factor is the driving or rather pen- 
etrating power of the rays. The use of higher kilovoltage gives more 
penetration of the bones or tissues being exposed, resulting in more 
rays reaching the film which gives it a flat appearance lacking in con- 
trast. Therefore, lower kilovoltage will produce a film with greater 
contrast. 
c. Milliamperage.—The milliamperes can be regulated by adjusting 
the resistance unit of that circuit. Dental machines usually operate 
on 10 or 15 milliamperes and as a rule should not be used below 6 or 
above 15. The time of exposure in seconds multiplied by the num- 
ber of milliamperes, as shown by the milliammeter, gives the number 
of milliampere seconds. For example, 4 seconds of exposure using 
10 milliamperes equals 40 milliampere seconds. The dose necessary 
to produce erythema causing a temporary redness of the skin is 
approximately 1,200 milliampere seconds at a target distance of 8 
inches. At 16 inches, it would be 4,800 milliampere seconds. It has 
been suggested that operators never exceed one-half the erythema 
104 TM 8-225 
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DENTAL TECHNICIANS 
dose, or 600 milliampere seconds. If this limit is exceeded, it may 
subject the patient to grave danger. If the patient states that he 
has been subjected recently to considerable radiation, the examination 
should be deferred until 3 weeks after the last exposure. Two com- 
plete dental surveys of 16 exposures each may be safely made as it 
will be well within the safety limit. However, if skull pictures, 
sinuses, or facial bones are to be exposed in addition to the dental 
survey, consideration should be given to avoid overexposure of the 
patient in a 3-week period. 
d. Target film distance.—A uniform target film distance is essen- 
tial to produce films of uniform density. To effect this, always place 
the cone of the machine in close proximity to the patient’s face when 
making intra-oral exposures. This automatically adjusts the target 
distance at 8 inches, the distance recommended for most dental 
machines. If greater target film distance is desired the tip of the 
cone may be placed 1, 2, or 3 inches from the skin surface. 
e. Rays.—The tip of the cone acts as the guide in determining the 
direction of the rays or beams of radiation, as it is always in aline- 
ment with the target of the tube. The correct angle of the rays is 
most important as this will distribute the flow of radiation evenly 
over the area to be exposed. 
/. Precautions.—Under no circumstances should the operator hold 
the films in the patient’s mouth. This is to be done by the patient. 
In those cases where it is impossible for the patient to hold the films, 
the film packet may be grasped with a hemostat and held by an 
assistant from such a position that he will not be in the line of expo- 
sure. During the exposure, the operator should place himself as far 
away from the unit as possible. If a large number of roentgeno- 
grams are to be taken daily, he should protect himself by placing 
a lead screen between himself and the unit. It must be remembered 
that carelessness on the part of the operator in this matter will cause 
overexposure of himself or his assistant and possibly with serious 
results. If precautions are taken, the operator has nothing to fear, 
although the machine may be in frequent use. 
103. Intensifying screen.—Due to the fact that less than 1 per- 
cent of the X-ray energy is absorbed by the sensitized film emulsion 
in the formation of the image, a device known as the intensifying 
screen has been developed to utilize the wasted rays so that the ex- 
posure time may be reduced. The screen consists of a flexible but 
substantial cardboard coated with finely divided crystals of calcium 
tungstate. Two of these screens are mounted in a cassette designed 
to hold the film between them during the exposure. The loading of 
105 TM 8-225 
103-104 
MEDICAL DEPARTMENT 
the cassette must be clone in a dark room. The black piece of paper 
must be removed from around the film when using the intensifying 
screen; otherwise, the result is about the same as though the screens 
were not used. 
Section II 
INTRA-ORAL ROENTGENOGRAPHY 
Paragraph 
Vertical angle 104 
Horizontal angle 105 
Position of head 106 
Interproximal or bite-wing examination 107 
Molar and bicuspid 108 
Central, lateral, and canine 109 
Periapical examination 110 
Maxillary molar 111 
Maxillary bicuspid 112 
Maxillary canine 113 
Maxillary incisor 114 
Mandibular molar 115 
Mandibular bicuspid 116 
Mandibular canine 117 
Mandibular incisor 118 
Occlusal examination ! — 119 
Maxillary occlusal (full view) 120 
Maxillary central and lateral incisor 321 
Maxillary canine, bicuspid, and molar — 122 
Mandibular central and lateral incisor 123 
Mandibular canine, bicuspid, and molar 124 
Mandibular occlusal (full view) 125 
104. Vertical angles—In making dental roentgenograms, it is 
usually necessary to direct the rays upon structures that lie at an 
angle with the film. If the following rule is strictly adhered to, 
approximately correct images of the teeth can be recorded on the 
film: direct the rays from the tube so that they will be perpendicular 
to the plane that bisects the angle formed by the long axis of the 
tooth and the plane of the film packet (fig. 82). Any deviation from 
this will result in the image either being elongated or shortened. 
a. In figure 83 the rays are striking the film from too low an angle 
with the result that the image of the tooth is lengthened as shown. 
h. In figure 84 the rays are striking the film from too high an 
angle with the result that the image of the tooth is shortened. 
c. In figure 85 the rays are striking the film from the correct 
angle; that is, they are striking the film perpendicularly to the 
bisecting plane midway between the film and the tooth. This results 
106 TM 8-225 
104 
DENTAL TECHNICIANS 
in the image of the tooth being imposed upon the film in the correct 
proportion. 
d. This applies mostly to the maxillary teeth due to the palatal 
arch, although it also applies to the lower anterior teeth. The 
lower molar teeth do not present this problem as the film can usnally 
Figure 82.—Correct projection angle for maxillary canine. 
PLANE OF TOOTH 
BISECTING PLANE 
PLANE OF 
DENTAL FILM 
INCORRECT PROJECTION 
ELONGATED IMAGE 
Figure 83.—Roentgen rays striking film from too low an angle. Tooth image lengthened 
in resulting roentgenogram. 
be placed in such a position that it is nearly parallel to the long 
axis of the teeth. Thus the rays can be directed almost perpendicu- 
larly to both the teeth and the film. 
e. The vertical angles will vary in different cases and certain 
modifications of angles must be made accordingly. The following 
107 TM 8-235 
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MEDICAL DEPARTMENT 
PLANE OF TOOTH 
BISECTING PLANE 
PLANE OF 
DENTAL FILM 
INCORRECT PROJECTION 
FORESHORTENED IMAGE 
Figure 84.—Roentgen rays striking film from too high an angle. Tooth image shortened 
in resulting roentgenogram. 
PLANE OF TOOTH 
-BISECTING PLANE 
PLANE OF 
DENTAL FILM 
CORRECT PROJECTION 
NORMAL IMAGE 
Figure 85.—Roentgen rays striking film from correct angle. Tooth image in correct 
proportions. 
table, however, is a usable guide and in the majority of cases will 
give good results: 
Upper 
Degrees 
Lower 
Degrees 
Molars 
+ 20 
Molars 
-5 
Bicuspids 
+ 30 
Bicuspids 
-10 
Canine _ 
+ 45 
Canine 
-20 
Centrals 
+ 40 
Centrals 
-15 
105. Horizontal angle.—a. If the horizontal angle is not correct 
the result will be an overlapping of the images of the crowns of the 
teeth. When this occurs, the chief value of the X-ray is gone as two 
of the most important areas to be examined are distorted, namely, the 
contact point between the teeth and the periodontal membrane sur- 
rounding the roots of the teeth. This error is illustrated in figure 86. 
b. To obtain the correct direction of the rays in the horizontal plane, 
it must be directed through the teeth, parallel to the proximal sur- 
108 TM 8-235 
105-106 
DENTAL TECHNICIANS 
faces and perpendicular to the antero-posterior plane of the film. This 
is illustrated in figure 86. 
106. Position of head.—Tn this method where fixed angles are 
used, it is important to have the patient’s head in a fixed position with 
® Overlapping image caused by incorrect 
horizontal projection of rays. 
© Correct image obtained by proper hori- 
zontal projection of rays. 
Figure 86. 
Figure 87.—1’ositiou of head with occlusal plane of upper arch horizontal 
the occlusal surfaces of the teeth to be X-rayed in a horizontal plane. 
Thus when the upper teeth are to be exposed, the occlusal surfaces of 
all the upper teeth should be horizontal. An imaginary line drawn 
from the tragus of the ear of the ala of the nose will act as a convenient 
guide line. This is illustrated in figure 87. The position of the head 
109 TM 8-225 
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MEDICAL DEPARTMENT 
for exposing the lower teeth and having the occlusal surfaces horizontal 
is illustrated in figure 88. In this instance the imaginary line is drawn 
from the tragus of the ear to the angle of the mouth. 
107. Interproximal or bite-wing examination.—The purpose 
of using the bite-wing film is to obtain an image of the coronal portion 
of the teeth without the distortion that usually occurs in a periapical 
examination. This is due to the fact that a low vertical angle of pro- 
jection is used and the film packet is placed in a vertical position, 
permitting the X-rays to pass straight through the crowns of the teeth. 
This reveals areas that are obscured in the periapical roentgenograms 
where a high angle of projection on standard dental films is necessary. 
Figure 88.—Position of head with occlusal plane of lower arch horizontal. 
108. Molar and bicuspid.—After adjusting the head so that the 
occlusal surfaces of the maxillary teeth are horizontal, place the bite- 
wing film packet in the patient’s mouth so that the teeth when brought 
together will close on the wing, thus holding the film snugly against 
the lingual surfaces of the teeth. In a full mouth survey, it is best 
to start with the posterior teeth on one side and work around to the 
other side. Place the packet so that it will include the last tooth, 
guiding the lower part in first and then allow the upper part to slant 
into the palatal vault. Have the patient close normally. Incline 
the tube of the machine to a +8° above horizontal and direct slightly 
disto-lingually so that the rays will pass straight through the inter- 
proximal spaces perpendicular to the plane of the film (fig. 89). For 
exposure time see chart at end of section. 
109. Central, lateral, and canine.—Use an anterior bite-wing 
film for the examination of the incisor teeth. This differs from the 
posterior film in having its long axis in a vertical direction instead 
of a horizontal. Place the packet in the patient’s mouth with the 
110 TM 8-225 
109 
DENTAL TECHNICIANS 
middle of the film on the median line. The lower part is guided into 
place, letting the upper part slant into the palatal vault. Have 
patient close, bringing the teeth end to end. For an examination of 
3) Resulting bite-wing roentgenogram. 
® Head position with occlusal plane 
of upper arch horizontal and tube 
inclined 8° above horizontal. 
Fjguhe 89,—-Molar and bicuspid area. 
® Head position with occlusal plane of upper arch horizontal and tube inclined 8° above 
horizontal. 
® Resulting bite-wing roentgenogram. 
Figure 90.—Central, lateral, and canine areas. 
Ill TM 8-225 
109-110 
MEDICAL DEPARTMENT 
the lateral-canine region, place the packet in the central region as 
described above, having the patient bite gently, then shift the wing 
distally until the mesial edge is even with the mesial surface of the 
central incisor. Have patient close teeth, end to end. Incline the 
tube 8° above horizontal, directing the rays straight through the 
upper lateral for lateral-canine region (fig. 90). 
® Correct position of head, index finger, film, and tube. 
® Diagram of relation of rays to film. Tube inclined 20° above horizontal for average 
ease. 
® Resulting roentgenogram. 
Figure 91.—Maxillary molar area. 
110. Periapical examination.—These exposures are made on 
standard dental films with an increase in the vertical projection angle 
as compared with the bite-wing exposures. The images recorded are 
approximately their correct size, giving views of the periapical region, 
the teeth, and their supporting structures. A very complete dental 
survey can be made by using 14 standard dental films. Seven films 
112 TM 8-225 
110-111 
DENTAL TECHNICIANS 
are used for each arch; two molar, two biscuspid, two canine, and one 
for the central area. Assuming that a full mouth roentgenographic 
examination is to be made, it is best to follow a definite sequence in 
taking the pictures so that the movements of the machine and the 
patient will be at a minimum. A good plan to follow is to start with 
the upper right third molar region and include all teeth of the upper 
arch, ending with the upper left third molar. The lower exposures 
® Position 
® Diagram of relation of rays to Aim. Tube inclined 30° above horizontal for average case. 
@ Resulting roentgenogram. 
Figure 92.—Maxillary bicuspid area. 
are started with the left molar area and include all teeth in the lower 
arch, ending with the lower right molar region. 
111. Maxillary molar.—Adjust the head so the occlusal surfaces 
431511°—42 8 
118 TM 8-235 
ill 
MEDICAL DEPARTMENT 
of the maxillary teeth are horizontal and the median plane of the face 
is vertical. Place the film packet in the mouth so that the long axis is 
horizontal and the anterior border of the film is at the middle of the 
second bicuspid, the lower border of the packet parallel to and slightly 
below the occlusal surfaces of the molars. The patient’s index finger 
of the hand from the opposite side, other fingers closed, is placed 
® Position. 
@ Diagram of relation of rays to film. Tube inclined 45° above horizontal for average case 
Figure 93.—Maxillary canine area. 
® Resulting roentgenogram. 
against the surface of the packet holding it in contact with the crowns 
of the teeth and adjacent tissues. The film packet should not be bent 
and only sufficient pressure applied to stabilize the film during expo- 
sure. The tube is inclined to an average angle of 20° above the 
114 TM 8-225 
111-112 
DENTAL TECHNICIANS 
occlusal plane and the rays directed slightly distally, perpendicularly 
to the bisecting plane, through the second molar tooth and straight 
through the interproximal spaces (fig. 91). Maxillary impacted or 
malposed teeth may require special positioning of the film packet to 
give a satisfactory view. For exposure time see chart. 
112. Maxillary bicuspids—Place the film packet in the mouth so 
that the long axis is vertical, the anterior border of the film at the 
Position. 
® Diagram of relation of rays to film. Tube inclined 40° above horizontal for average cast 
@ Resulting roentgenogram. 
Figure 94.—Maxillary central incisor area. 
middle of the canine, the lower border parallel to and slightly below 
the occlusal surfaces of the bicuspids. The tube is inclined to an 
average angle of 30° above the occlusal plane and the rays directed 
slightly distally, perpendicularly to the bisecting plane, straight 
115 TM 8-225 
112-114 
MEDICAL DEPARTMENT 
through the apical thirds of the roots of the bicuspid teeth (fig. 92). 
For exposure time see chart. 
113. Maxillary canine.—Place the film packet in the mouth with 
the long axis vertical and the lower border of the film parallel 
to and slightly below the incisal edges of the lateral and canine teeth. 
The anterior border bisects the central incisor on the same side with 
the canine opposite center of packet (do not bend the film). The 
® Position. 
@ Diagram of relation of rays to film. Tube inclined 5° below horizontal. 
Figure 95.—-Mandibular molar area. 
® Resulting roentgenogram. 
tube is inclined to an average angle of 45° above the occlusal plane 
and rays directed through the apical third of the root of the canine 
tooth, perpendicularly to the bisecting plane, and straight through 
the interproximal spaces (fig. 93). 
114. Maxillary incisor.—Place the film packet in the mouth with 
the long axis vertical, the center of the film on the median line of 
the upper arch, the lower border of the packet parallel to and slightly 
below the incisal edges of the incisors (do not bend the film). The 
116 TM 8-225 
114-115 
DENTAL TECHNICIANS 
tube is inclined to an average angle of 40° above the occlusal plane 
and the rays directed straight through between the apical thirds 
of the roots of the centrals, perpendicularly to the bisecting plane 
(fig. 94). 
® Position. 
® Diagram of relation of rays to film. Tube inclined 10° below horizontal. 
® Resulting roentgenogram 
Figure 96.—Mandibular bicuspid area 
115. Mandibular molar.—Place the patient’s head so that the 
occlusal plane of the mandibular teeth is horizontal and the median 
plane of the face is vertical. Place the packet in the mouth with 
the long axis horizontal and the upper border of the film parallel 
to and slightly above the occlusal surfaces of the molars. It is placed 
alongside the tongue and far enough distally so that the third molar 
area will be included, anterior edge at middle of the second bicuspid. 
Mandibular impacted or malposed teeth may require special posi- 
tioning of the film packet to give a satisfactory view. The patient’s 
index finger of the hand from the opposite side, other fingers closed, 
117 TM 8-235 
115-116 
MEDICAL DEPARTMENT 
is placed against the surface of the packet, holding it in contact with 
the crowns of the teeth and adjacent tissues. The packet should 
not be bent and only sufficient pressure applied to stabilize the film 
during exposure. The tube is inclined to an average angle of 5° 
below the occlusal plane and the rays directed through the roots 
of the second molars, perpendicularly to the bisecting plane, and 
straight through the interproximal spaces (fig. 95). 
® Position. 
® Diagram of relation of rays to film. Tube inclined 20° below horizontal 
® Resulting roentgen ogram. 
Figure 97.—Mandibular canine area. 
116. Mandibular bicuspid.—Place the film packet in the mouth 
with the long axis vertical and the upper border of the film parallel 
to and slightly above the occlusal surfaces of the bicuspids. The 
anterior border should be about the middle of the canine. The tube 
118 TM 8-225 
116-117 
DENTAL TECHNICIANS 
is inclined to an average angle of 10° below the occlusal plane and 
the rays directed between the apical thirds of the roots of the bicuspid 
teeth, perpendicularly to the bisecting plane, and straight through 
the interproximal spaces (fig. 96). For exposure time see chart. 
® Position. 
® Diagram of relation of rays to film. Tube inclined 15° below horizontal. 
(D Resulting roentgenogram. 
Figure 98.—Mandibular incisor area. 
117, Mandibular canine.—Place the packet in the mouth with 
the long axis vertical and the upper border of the film parallel to 
and slightly above the incisal edges of the lateral and canine teeth. 
The anterior border of the film should be about the distal surface of 
the opposite central incisor, canine opposite the center of packet. 
The tube is inclined to an average angle of 20° below the occlusal 
plane and the rays directed through the apical third of the root of 
the canine tooth, perpendicularly to the bisecting plane, and straight 
through the interproximal spaces (fig. 97). For exposure time see 
chart. 
119 TM 8-225 
118-119 
MEDICAL DEPARTMENT 
118. Mandibular incisor.—Place the film packet in the mouth 
with the long axis vertical and the upper border parallel to and 
slightly above the incisal edges of the incisor teeth, the center of the 
film on the median line of the lower arch. The patient’s index finger 
of either hand is placed against the center of the film with just 
enough pressure to hold it in place without bending it. The tube is 
inclined to an average angle of 15° below the occlusal plane and the 
rays directed between the apical thirds of the roots of the centrals, 
X> Position of head, film, and tute. 
Occlusal roentgenogram. 
Figdke 99.—Maxillary occlusal area (full view) 
perpendicularly to the bisecting plane, and straight through the 
interproximal spaces (fig. 98). 
119. Occlusal examination.—A third type of infra-oral exami- 
nation is the occlusal film. In no way should it be substituted for 
the other types but it does have a very great value in certain situa- 
tions. It assists in locating fractures, residual roots, impacted teeth, 
foreign bodies, cysts, sialolithiasis (stones), etc. It also can be used 
120 TM 8-225 
119 
DENTAL TECHNICIANS 
to advantage in cases of trismus where it is impossible for the patient 
to open the mouth sufficiently to use standard films. Occlusal films 
are supplied in lead-backed packets similar to the standard dental 
films, but measuring by 3 inches. 
Position of head, film, and tube 
® Occlusal roentgenogram. 
Figure 100.—Maxillary central and lateral incisor areas (occlusal view). 
® Position for occlusal film 
@ Occlusal roentgenogram. 
Figure 101.—Maxillary canine, bicuspid, and molar areas (occlusal view). 
121 TM 8-225 
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MEDICAL DEPARTMENT 
120. Maxillary occlusal (full view).—Adjust the head so that 
the occlusal surfaces of the maxillary teeth are horizontal; median 
line of face vertical. The film packet is placed in the mouth with 
either the short axis or long axis at right angle to median line of 
face. The teeth are closed gently but firmly against the film packet. 
The tube is adjusted so that the point of the cone touches the top 
of the forehead in the median line and the rays are directed down- 
ward, perpendicularly to the plane of the packet (fig. 99). For 
exposure time see chart. 
121. Maxillary central and lateral incisor.—The tube is in- 
clined to an average angle of 65° above the occlusal plane, centering 
the cone slightly above the tip of the nose in the median line, directing 
® Position of head, film, and tube, 
® Occlusal roentgenogram 
Figure 102.—Mandibular central and lateral incisor areas (occlusal view) 
122 TM 8-225 
121-123 
DENTAL TECHNICIANS 
the rays downward and distally through the nose and apical thirds 
of the roots of the maxillary central incisors toward the plane of the 
packet (fig. 100). For exposure time see chart. 
122. Maxillary canine, bicuspid, and molar.—The tube is 
inclined to an average angle of 60° above the occlusal plane and the 
cone centered on the canine fossa, directing the rays through the 
periapical region of the canine and first bicuspid toward the plane 
of the packet (fig. 101). For exposure time see chart. 
123. Mandibular central and lateral incisor.—The patient’s 
head is tilted backward so that the occlusal plane of the teeth is 55° 
Note.—This is same position and technique as illustrated in figure 104 except that small 
dental film was used. 
Figure 108.—Occlusal roentgenogram of mandibular molar area on standard dental film. 
® Position for occlusal film. 
(D Occlusal roentgenogram on occlusal film (for same technique using dental film, see fig. 103). 
Figure 104.—Mandibular area (full view). 
123 TM 8-225 
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MEDICAL DEPARTMENT 
above horizontal. The median line of the face is vertical. The 
packet is placed in the mouth with either the long or short axis 
at right angles to the median line of the face. The teeth are closed 
gently but firmly against the film packet. The tube is horizontal 
and the cone centered on the point of the chin, directing the rays 
through the apical thirds of the mandibular central incisors (fig. 102). 
124. Mandibular canine, bicuspid, and molar.—Adjust the 
head so that the occlusal plane is perpendicular to the horizontal 
plane and place packet in the mouth parallel to the mandibular oc- 
clusal plane. The tube is horizontal and cone centered on the 
lower border of the mandible below the first molar, directing the 
rays toward the plane of the film (fig. 103). For exposure time 
see chart. 
125. Mandibular occlusal (full view) .—Adjust the head so 
that the occlusal plane is perpendicular to the horizontal plane 
and place packet in the mouth parallel to the mandibular occlusal 
plane. The tube is horizontal and the cone is centered in the median 
line, directing the rays perpendicularly toward the packet (fig. 104). 
For edentulous cases cotton rolls may be used to assist in the reten- 
tion of the film in the mouth. For exposure time see chart. 
EXPOSURE TIME CHART 
O 
Regular film 
Radiatized film 
Extra-fast film 
Area 
| Average degn 
angulation 
I Small-sized 
face 
1 Medium-siz- 
ed face 
| 
Large-sized 
| face 
[ Small-sized 
face 
Medium-siz- 
ed face 
Large-sized 
face 
Small-sized 
face 
Medium-siz- 
ed face 
Large-sized 
face 
Maxillary— 
Seconds 
Seconds 
Seconds 
Seconds 
Seconds 
Seconds 
Seconds 
Seconds 
Seconds 
Molar 
+ 20 
7 
8 
9 
3 'A 
4 
4/9 
2 
2}i 
2k 
Bicuspid 
+ 30 
3 
4 
5 
2 
2K 
3 
1 
w 
Cuspid 
+ 45 
4 
5 
6 
2/2 
3 
3/2 
1/4 
iH 
1% 
Central 
+ 40 
4 
5 
6 
2K 
3 
3 >2 
I/4 
IK 
i3K 
Mandibular— 
Molar 
-5 
4 
5 
6 
2% 
3 
3 K 
iH 
1/2 
1% 
Bicuspid 
-10 
3 
4 
5 
2 
2/2 
3 
1 
1/4 
1H 
Cuspid 
-20 
3 
4 
5 
2 
2% 
3 
1 
1/4 
IK 
Incisor 
-15 
3 
4 
5 
2 
2% 
2/2 
1 
1/4 
IK 
Note.— For edentulous mouths increase degree of angulation from 5° to 10° and shorten above exposure 
time by 2.5 percent. TM 8-225 
126 
DENTAL TECHNICIANS 
Section III 
EXTRA-ORAL ROENTGEN()GRAPHY 
Paragraph 
General 126 
Body of mandible and ramus 127 
Temporomandibular articulation 128 
Bones of face : 129 
126. General.—The second type of dental X-ray examination is 
extra-oral roentgenography. It is, as the term applies, a roentgeno- 
gram taken with the film outside the mouth. The intra-oral method 
of taking roentgenograms of the teeth is the one usually followed 
to diagnose conditions involving small areas such as abscesses, root 
canal fillings, caries, etc. Such films are desirable as they give more 
contrast and detail than extra-oral films, since they are taken in 
much closer relation to the object and have less superimposition of 
shadows. But frequently this type of roentgenogram leaves some 
doubt or only shows part of the area involved. In cases of this type, 
extra-oral roentgenograms should be taken to give a more complete 
view of the region involved. It is also indicated in locating frac- 
tures, impacted teeth, cysts, etc. 
a. Extra-oral roentgenography includes X-ray examination of—• 
(1) Body of mandible. 
(2) Angle of mandible. 
(3) Ramus of mandible. 
(4) Temporomandibular articulation. 
(5) Bones of face. 
h. For extra-oral X-rays larger films are necessary. Pictures of 
the maxillae and mandible and other facial bones are usually made 
on 8- by 10-inch films. Full skull pictures require 10- by 14-inch size. 
These films are packed, 12 in a box, and wrapped in black paper 
with a separate sheet folded over each film, separating them from 
each other. Cassettes or paper film holders should be loaded in the 
darkroom and unused films kept in a box to protect them from 
exposure to light. 
c. The technique described in the following paragraphs has been 
found to be very satisfactory, requiring only three films to give a 
good view of the mandible and other facial bones, one film for lateral 
view of the temporomandibular articulation. These may be made 
stereoscopically or angulation modified to improve the view of cer- 
tain areas. The same technique can also be employed on litter cases 
or bed patients which is a distinct advantage in roentgenographing 
sick or seriously wounded patients. 
125 TM 8-225 
127 
MEDICAL DEPARTMENT 
127. Body of mandible and ramus.—Have the patient sit erect 
in the chair, head forward (headrest supporting it), median-line 
plane vertical, shoulders back, chin up so that the lower border of 
the mandible is parallel to the floor (fig. 105). By keeping the head 
well forward and chin up, the cervical vertebrae are kept from over- 
shadowing the condyloid process and ramus. In case of bed patients 
or litter cases the chin is elevated and head raised so that the lower 
border of the mandible will be parallel to the walls. Adjust the 
head of the machine so that the cone is about 4 inches from the skin 
and points under the angle and body of one side of the mandible, 
using the alveolar process region of the third molar tooth of the 
opposite side as the center of the field. Further adjust the angle of 
Note.—Headrest is adjusted in forward position so that patient sits erect with chin up 
and head well forward (lower border of mandible parallel to floor). 
the cone so that rays from the target can pass under the near side 
of angle of mandible and expose the condyloid head of the opposite 
side. This gives an angle from the horizontal of 15° to 20°. If 
the cassette is held so that the center rays from the target are per- 
pendicular to it, an angle is formed between the plane of the film and 
plane of the long axis of the ramus (verticle angle) (fig. 106(1)). Bi- 
sect this angle and move the cassette into the new position. Another 
angle is now formed by the plane of the film and the long axis 
of the body of the mandible (horizontal angle) (fig. 106(2)). Bisect 
this angle and move the anterior edge of the cassette into the new 
position (fig. 106(3) and 107®). This exposure will project an image 
of the body and ramus of the mandible on the film with the length 
of each approximately correct (fig. 107®). 
Figure 105.—Position of head for lateral extra-oral roentgenography of mandible. 
126 TM 8-225 
128 
DENTAL TECHNICIANS 
128. Temporomandibular articulation.—Palpate the sigmoid 
notch of the opposite side to be exposed and have patient open the 
mouth to move the condyles forward (about 3 centimeters between 
anterior teeth). Remove the cone and adjust the head of the machine 
® Vertical angle formed between plane of cassette and plane of long axis of ramus. 
® Cassette moved to bisect vertical angle. Horizontal angle between plane of cassette 
and long axis of body of mandible is now indicated in sketch. 
® Keeping vertical plane of cassette constant, forward edge is now moved so that hori- 
zontal plane is bisected (this is correct position). 
Figure 106. 
127 TM 8-225 
128-129 
MEDICAL DEPARTMENT 
so that the target will be close to the space above the sigmoid notch 
and under the zygomatic arch, so that the rays can pass directly through 
toward the articulation of the opposite side. The film is held per- 
pendicular to these rays and the exposure made (fig. 108). Due to 
the short target film distance, the images are slightly enlarged and the 
condyloid head is shown with little or no superimposed shadows. 
® Position of head, cassette, and tube for correct image of body and ramus of mandible 
(same as fig. 108@). 
® Resulting roentgenogram of body and ramus of mandible. 
Figure 107. 
129. Bones of face.-—Lower the arm of the dental chair and place 
the cassette on the seat, using this as an adjustable table for exposure. 
Have patient sit on an ordinary chair facing the side of the dental 
128 TM 8-325 
129 
DENTAL TECHNICIANS 
® Diagram of relation of head, tube (cone removed), and film for roentgenography of 
temporomandibular articulation. 
® Photograph of this position. 
(D Resulting roentgenogram of temporomandibular articulation. 
Figure 108, 
431511 '-42 9 
129 TM 8-225 
129 
MEDICAL DEPARTMENT 
$ Position for antero-posterior view of bones of face. 
® Roentgenogram of bones of face. 
Figure 109. 
130 TM 8-235 
129-131 
DENTAL TECHNICIANS 
chair, close enough to lean over the cassette, one hand on either side 
to steady the position; place forehead and nose on the cassette so that 
the mandible and facial bones can be projected on the film. A target 
film distance of 24 inches is used and rays directed in the median-line 
plane between the condyloid processes of the mandible, forming about 
a 10° angle from the perpendicular toward the patient’s shoulders. 
This gets the rays through under the occipital portion of the skull 
(fig. 109). 
Section IV 
PROCESSING OF X-RAY FILMS 
Paragraph 
General 180 
Darkroom 131 
Illumination 132 
Processing tank 133 
Thermometer 134 
Clock 135 
Film holders 136 
Processing solutions , 137 
Technique of processing films by time-temperature chart 138 
130. General.—Precise methods in the developing of X-ray films 
are just as essential in attaining good results as the utilization of precise 
exposure technique. If the correct procedure is followed throughout, 
the resulting roentgenogram will leave nothing to be desired and the 
technician can perform his work with every assurance that he is pro- 
viding roentgenograms of the maximum quality. If, on the other 
hand, the processing procedure is carelessly done and directions not 
carefully followed, all the care that was exercised during the exposure 
of the films will be time lost. The method to be followed is known 
as the standardized time-temperature processing procedure. 
131. Darkroom.—As the films used in X-ray work are very sensi- 
tive to light, much more so than ordinary photographic films, it is 
important to have a good darkroom. It need not be such a large room, 
but it must be constructed so that no light could enter through cracks 
or crevices. In addition, the door should have an inside lock so that 
no one could accidentally open it or enter while films are being processed. 
A better type of construction plan would be to have a maze for entering 
the darkroom provided with enough turns to keep out light. The walls 
should be painted black and the ceiling may be white, which will reflect 
sufficient illumination when the correct type of safelight is used. The 
room should be supplied with both hot and cold water and the pipes 
should lead to a mixing valve so that the temperature of the flow can 
131 TM 8-225 
131-137 
MEDICAL DEPARTMENT 
be regulated. Adequate ventilation must not be overlooked and the 
use of some forced change of air employing a ventilator fan is advisable. 
132. Illumination.—For the illumination of the darkroom a 
light that is photographically safe must be used. There are 
numerous kinds of these lights available, but the standard for a safe- 
light is as follows: It must be possible to permit undeveloped films 
to be exposed to the light at a distance of 3 feet for a period of 1 
minute without the least evidence of fogging. 
133. Processing tank.—A suitable tank for processing films is an 
important part of the darkroom equipment. The tank should be 
constructed of corrosion-resistant material such as porcelain, hard 
rubber, or certain rust-resistant metals. Compartments or divisions 
are provided for the developing and fixing solutions with a larger 
section for water. A connection with a mixing valve, hot or cold 
water, for temperature control is desirable, thereby eliminating 
guesswork. 
134. Thermometer.—As it is essential to process the film at the 
predetermined temperature, the tank must be equipped with a 
thermometer that will register the exact temperature of the circu- 
lating water. 
135. Clock.—Because of the direct relationship between tempera- 
ture and time in the processing procedure, it is necessary to know the 
exact time that any given film is to be left in each solution. For this 
purpose a good watch will serve, but it is much better to use an 
interval timer. This gives the time in minutes and fractions of 
minutes and is equipped with an alarm which sounds to indicate the 
expiration of the time interval selected. 
136. Film holders.—There are two types of film holders. For 
the small intra-oral films, clip holders; for the larger extra-oral 
films, frame holders (fig. 110). 
137. Processing solutions.—The chemicals for developing and 
fixing are put in moistureproof containers and in the proper pro- 
portions, ready to mix with water. They come in sizes which will 
make 5 gallons of solution. The developing solution and the fixing 
solution are each prepared according to manufacturer’s instructions 
on the package. 
a. Frequently the processing chemicals are not obtainable in the 
ready-to-mix form. Therefore it is necessary for the X-ray tech- 
nician to know the formula of a developer and a fixing solution and 
the method of making each from their component parts. The fol- 
lowing formulas are for making 6 gallons of each solution, but may 
132 TM 8-225 
137 
DENTAL TECHNICIANS 
® Intra-oral. @ Extra-oral 
Figure 110.—Placing film on developing hanger. 
Figure 111.—Dental films in standard mount. 
133 TM 8-225 
137 
MEDICAL DEPARTMENT 
be cut down by the technician to apply to any amount that may be 
necessary. 
(1) Formula for developer. 
Elon 60 grams. 
Sodium sulfite 2. 500 grams. 
Hydroquinone 240 grams. 
Sodium carbonate 1.250 grams (desiccated). 
Potassium bromide 150 grams. 
Cold water to make 24 liters (6 gallons). 
(a) Weigh out the individual chemicals on small pieces of paper. 
Mix in white enameled containers. 
(b) Dissolve them individually in as small a volume of warm 
water as possible (125° F.). 
(c) Mix a handful of dry sulfite with the elon and hydroquinone 
before dissolving them. 
(d) Pour the solutions of elon and hydroquinone together. 
(e) Pour the solutions of sodium sulfite and sodium carbonate 
together. 
(/) Add the potassium bromide solution to the solution just mixed. 
(g) Add the elon and hydroquinone mixture to the mixture of soda 
and bromide solutions. 
(h) Add cold water to make the necessary volume. 
(i) Filter each solution before mixing through six thicknesses of 
gauze. 
(2) Formula for fixing hath {hypo). 
Sodium thiosulfate (hypo) 66 kilograms. 
Water to make 16 liters. 
When fully dissolved add following hardening solution: 
Water 4 liters. 
Sodium sulfite 300 grams. 
Acetic acid (glacial) 260 cubic centimeters. 
Potassium alum (granular) 300 grams. 
Cold water to make 8 liters (total 24 lit- 
ers (6 gal.)). 
(a) Dissolve the chemicals in water at about 125° F. in the order 
given. 
(h) The sodium sulfite must be completely dissolved before adding 
the acetic acid. 
(c) Add the alum to the sulfite-acid solution and stir until a clear 
solution appears. 
134 TM 8-225 
137-138 
DENTAL TECHNICIANS 
(d) When this clear sulfite-acid-alum solution has cooled, add it 
slowly, stirring constantly, to the cool and thoroughly dissolved hypo 
solution. 
{e) Filter through six thicknesses of gauze. 
h. The developing solution is poured into one of the hard rubber 
tanks and the hypo solution in the other. It is most important to 
have these tanks absolutely clean before adding the solutions. They 
should also be equipped with a cover and the solutions kept covered 
when not in use. This prevents oxidation which is an important 
factor in solutions becoming inactive. 
138. Technique of processing’ films by time-temperature 
chart.—All necessary equipment should have a definite place in the 
darkroom for when the lights are turned out and development begun, 
the technician will not be able to locate misplaced objects. The hands 
must be clean and dry, otherwise the films when finished will contain 
finger marks which cannot be removed. 
a. Remove the lightproof wrapper from around the film. 
h. Place the film on the film holder, holding the film lightly by the 
edges, avoiding touching the surface with the fingers as this will leave 
fingerprints and smudges. 
c. Adjust the time interval clock for the developing time prescribed 
by the chart, or place a watch where the time can be noted, 
d. The timing should start just as soon as the film is placed in the 
developing solution. 
e. Place the film holder with the film attached in the tank containing 
the developing solution. Make certain that the film does not touch 
the side of the tank or other films. The emulsion will adhere to either 
and will not develop properly at the contact point. This will leave 
a spot on the film having the appearance of a radiopaque area. Film 
holders that have not been thoroughly washed after they have been once 
immersed in hypo may also cause streaks. The dried hypo dissolves 
in the developing solution and runs over the emulsion of the film, 
dissolving the silver halide salts, causing streaks of underdevelopment. 
/. When the prescribed developing time has elapsed for the film as 
given on the chart, it is removed and placed in circulating water for 
30 seconds or longer to remove all traces of the solution. If this is not 
done the developer will be carried over into the fixing bath, neutral- 
izing its acid content and contaminating it. 
g. The films are placed in the hypo or fixing bath and should remain 
there for twice the time required to remove these salts. Under no cir- 
cumstances should they be taken out of the solution until they are 
clear, 8 to 10 minutes being advisable. The purpose of fixation is to 
135 TM 8-235 
138 
MEDICAL DEPARTMENT 
remove all unexposed silver salts from the emulsion, permanently fix 
the image brought up by the developer, and harden the emulsion. 
h. Upon completion of fixation the films should be immersed in cir- 
culating water, 65° F., and washed for 30 minutes to assure the com- 
plete removal of the fixing bath from the emulsion. This is a most 
important step in the processing because the radiograph will in time 
turn yellow and fade if any chemicals of the fixing bath remain in the 
solution. 
i. Drying is the last step in processing. Quick drying can be accom- 
plished by placing the film in a dryer, a box-shaped cabinet with a 
heating element at one end and an electric suction fan at the other. 
The flow of warm air over the films suspended on the hangars in the 
cabinet hastens drying. Films can also be dried in the open air and 
somewhat hastened by having a fan so placed that the air is kept 
circulating around them. 
PROCESSING CHART 
Minutes 
Temperature TM 8-225 
139-140 
DENTAL TECHNICIANS 
Chapter 5 
DENTAL HYGIENIST 
Paragraphs 
Section I. General 139 
II. Structure and physiology 140-142 
III. Dental caries 143-144 
IY. Other diseases of mouth 145-153 
V. Saliva, deposits, and accretions upon teeth 154-157 
VI. Technique of dental prophylaxis 158-161 
VII. System for instrumentation and polishing 162-165 
VIII. Instructions to patient 166-167 
IX. Preparations for mouth and teeth 168-170 
Section I 
GENERAL 
Paragraph 
Definitions 339 
139. Definitions,—Dental hygiene is the science of the health of 
the teeth and their surrounding tissues. It is maintained by dental 
prophylaxis and daily home care of the mouth. Dental prophylaxis is 
that scientific effort either operative, educational, or therapeutic which 
tends to prevent diseases of the teeth and their surrounding tissues. 
The dental hygienist has been developed as a co-worker in dentistry 
to assist in securing clean mouths, sound teeth, and healthy gums for 
the patients by dental prophylaxis and education. 
Section II 
STRUCTURE AND PHYSIOLOGY 
Paragraph 
Structure of teeth 140 
Occlusion 141 
Mastication 142 
140. Structure of teeth.—A tooth is divided into two parts, the 
crown and the root. The crown is that portion which projects above 
the gum; the root is that portion which normally is surrounded by gum 
and alveolar process. The bulk of the tooth is composed of dentine 
which gives it shape and incloses the pulp cavity. The crown portion 
of the dentine is covered by cementum which slightly overlaps the 
enamel at the gingival margin. The pulp cavity is in the center of 
the tooth extending the whole length of the root and into the crown. TM 8-225 
140-141 
MEDICAL DEPARTMENT 
Within the pulp cavity is located the tooth pulp, a soft, highly sensi- 
tive, vascular organ, commonly but incorrectly called the nerve. The 
pulp cavity is divided into two parts, that in the crown is known as 
the pulp chamber, and that in the root is known as the root canal. 
The root canal communicates with the exterior through one or more 
openings at the end of the root known as apical foramina through 
which pass the nerve and blood vessels of the tooth. Surrounding the 
E horn a / 
C Y'own 
Pulp 
C h \mb er 
J&) r> y i v*. 
Pu!p_ 
C 
-Dentin 
.Pa rlt/entof 
A7 a** 4r4«a 
Root. 
c crryo-n t U tn 
A pi o*l 
B ori a 
Co^tioi/ 
Bono. 
Fiodbb 112.—Cross-section diagram showing various tissues which make up tooth, bone, 
and gingiva. 
root and separating it from the bony socket is a fibrous tissue known 
as peridental membrane which binds the tooth to the supporting bone. 
Covering the bony process (alveolar process) is a dense fibrous connec- 
tive tissue covered with epithelium which we call the gingiva or 
gum (fig. 112). 
141. Occlusion.—The teeth are arranged in two curving arches, 
the lower of which is somewhat smaller so that the upper overlaps it. 
The teeth of one arch do not meet those of the other in an end to end 
arrangement but cusps of the lower are dovetailed with the cusps of 
138 TM 8-225 
141-143 
DENTAL TECHNICIANS 
the upper. It is the sliding together of these various cusps in a scis- 
sorlike action that properly prepares the food for digestion. Normal 
arrangement of the arches when the jaws are closed is known as 
occlusion. Any deviation of the teeth or arches from the normal 
relationship is termed malocclusion. 
142. Mastication.—a. Mastication is a voluntary act which is 
continued reflexly and automatically by the muscles active in moving 
the mandible. These may be divided into two sets: muscles of mas- 
tication which bring the lower teeth in contact with the upper in the 
process of chewing by raising the mandible; and depressor muscles or 
those which pull the mandible downward as in opening the mouth. 
(1) The muscles of mastication are— 
Temporal. 
Masseter. 
Buccinator. 
Internal pterygoid. 
External pterygoid. 
(2) The depressor muscles are— 
Geniohyoid. 
Mylohyoid. 
Digastric. 
Platysma. 
b. The chief muscles of the tongue are the genioglossus and the 
styloglossus. Their action is to thrust the tongue forward, retract, 
and depress it. Working in balanced harmony with the muscles that 
move the mandible and those that move the tongue are the muscles 
of expression. They are found in the lips and cheeks and produce 
many varied facial expressions. 
c. During the process of mastication, saliva is poured in large quan- 
tities into the month. The secretion of saliva is the result of reflex 
stimulation of the nerves supplying the salivary glands. The nerves 
are stimulated by the movements of mastication and the taste and 
smell of food. 
Section III 
DENTAL CARIES 
Paragraph 
General , 143 
Theory of cause 144 
143. General.—Dental caries (tooth decay) is a destructive 
process affecting the hard dental tissues, the enamel, dentine, and 
cementum. Dental caries always has its inception upon the external 
or exposed surface of a tooth and travels toward the pulp. Certain 
139 TM 8-225 
143-144 
MEDICAL DEPARTMENT 
surfaces of the teeth are more susceptible to tooth decay than others. 
In general those surfaces of the teeth that are subjected to the 
cleansing action of the tongue, lips, and cheeks or those tooth sur- 
faces which are kept clean by the friction of tough or fibrous foods 
are less likely to decay. Locations where food particles can find an 
undisturbed lodgment such as natural pits and depressions in the 
masticating surfaces of the molars and bicuspids, sulci between the 
cusps, and especially the approximating surfaces of the teeth are 
very susceptible to the carious process. 
144. Theory of cause.—The most generally accepted theory for 
the cause of dental caries is that of Dr. W. D. Miller, who, through his 
extensive research, demonstrated that dental caries is produced by 
bacterial fermentation of carbohydrate food debris about the teeth 
which results in decalcification of the inorganic material of the teeth 
by the acids so formed, with a simultaneous invasion and destruction 
of the organic material of the teeth. It is known from experience 
that teeth decay more rapidly in early life than in adult life, that 
some individuals are markedly more susceptible to decay than others, 
and that some individuals with extremely filthy mouths are immune to 
caries. These facts can only be explained by assigning another fac- 
tor to the cause of dental decay which must in some way be concerned 
with the general health of the individual. This factor, because it is 
connected with the general health and because it must act before the 
local cause of the decay does, is referred to as a predisposing factor 
or a systemic factor. About this predisposing factor very little is 
known and authorities have variously attributed it to faulty diet, 
imperfections in the calcified tooth structure, endocrine gland dis- 
turbances. and various other causes. However, it is generally agreed 
that teeth decay more readily in a filthy mouth and that if proper 
hygiene is maintained tooth decay may be controlled. 
Section IV 
OTHER DISEASES OF MOUTH 
Paragraph 
Periodontal diseases 145 
Periodontoclasia 146 
Causes of periodontoclasia 147 
Vincent’s stomatitis 148 
Stomatitis apthous 149 
Bismuth stomatitis 150 
Gingivitis 151 
Hypertrophic gingivitis 1. 152 
Atrophy or recession of gingivae or gums 153 
140 TM 8-225 
145-148 
DENTAL TECHNICIANS 
145. Periodontal diseases.—A number of diseases affect the tis- 
sues immediately surrounding the tooth root. These diseases involve 
first the gum tissue (gingiva), then the periodontal membrane, and 
finally involve the bone. The dental diseases of this group are called 
periodontal diseases. 
146. Periodontoclasia.—Periodontoclasia (paradentosis) is the 
most common of the periodontal diseases. It produces a progressive 
destruction of the supporting tissues of the teeth until after many 
years the teeth become so loose that they must be extracted. There 
is more than one type of periodontoclasia; however, this manual will 
not deal with the different types. Generally, periodontoclasia begins 
with an inflammation of the tissues around the necks of the teeth. 
This inflammation of the gingival tissues is called a gingivitis. If not 
treated, generally the gingivitis progresses to the deeper tissues and 
the disease is established. Periodontoclasia is a very slowly progress- 
ing disease which becomes chronic and is difficult to cure. As the dis- 
ease progresses, the tissue nearest the tooth root is destroyed and a 
pocket is formed. As these pockets around the teeth become deeper, 
the teeth loosen and finally must be extracted. 
147. Causes of periodontoclasia.—These may be divided into 
two groups : systemic and local. 
a. The systemic causes of periodontoclasia are not fully understood 
but they exist because patients with some systemic diseases, such as 
diabetes or certain diseases of the thyroid gland, are definitely more 
susceptible to periodontoclasia. Also, improvement in the general 
health by proper diet, rest, and elimination of other infectious con- 
ditions will improve the periodontoclasia. 
h. The local causes of periodontoclasia include any factor which 
chronically irritates the gum margin, abnormal forces exerted over 
a long period of time on the tooth or teeth, and finally bacterial in- 
vasion of the tissues. The irritating factors are, in most cases, cal- 
careous deposits on the teeth (calculus) and poorly finished dental 
restorations. The dental hygienist assists in the treatment of this 
disease by removing deposits on the teeth which are responsible for a 
large part of the irritation and by helping the patient to maintain a 
high degree of oral hygiene. 
148. Vincent’s stomatitis.—This disease is an acute infection of 
the mouth which is characterized by deep painful ulcers on the mu- 
cous membrane. The ulceration usually appears around the necks 
of the teeth but may appear on the cheeks, tongue, palate, or tonsils. 
The disease is characterized by pain, a gray membrane covering the 
ulcers and adjacent tissues, a foul odor, and acute inflammation of 
141 TM 8-325 
148-154 
MEDICAL DEPARTMENT 
the involved tissues. This infection is contagious and may be trans- 
mitted from person to person by using a common drinking glass, 
passing a cigarette from one to another, kissing, or using another’s 
eating utensils which had not been thoroughly washed. The treat- 
ment is the responsibility of the dentist. 
149. Stomatitis apthous.—This appears as a yellowish-white, 
depressed, painful ulcer; sometimes there are more than one of these 
ulcers. They are commonly called canker sores. 
150. Bismuth stomatitis.—This is caused by taking bismuth 
compounds, usually in the treatment of syphilis. It is characterized 
by sore and swollen gums and a metallic taste. 
151. Gingivitis.—Gingivitis or inflammation of the gums may 
appear temporarily as a result of poor hygiene or it may be a pre- 
cursor of periodontoclasia. 
152. Hypertrophic gingivitis.—This is an inflammation of the 
gums characterized by marked swelling. This commonly appears 
as a response to some irritant either local or systemic. It appears 
in response to the ingestion of certain drugs and is commonly found in 
pregnant women as a reaction to their gestation. 
153. Atrophy or recession of gingivae or gums.—This is an- 
other response of the gingival tissues to certain irritants. The tissues 
shrink away from the necks of the teeth, exposing part of the root. It 
generally accompanies old age and may appear in response to long 
continued irritation from some source such as abuse from improper use 
of the tooth brush. 
Section V 
SALIVA, DEPOSITS, AND ACCRETIONS UPON TEETH 
Paragraph 
Saliva 154 
Mucin plaques 155 
Calculus 151! 
Green stain 157 
154. Saliva.—Saliva is the fluid secretion found in the mouth and 
consists of a mixture of the secretions of the parotid gland, the sub- 
maxillary gland, the sublingual gland, and from innumerable mucous 
glands of the mucous membrane of the floor of the mouth, the palate, 
cheeks, and inner lining of the lips. Saliva consists of water, inor- 
ganic salts, some mucin, and an enzyme called ptyalin. It is normally 
colorless, odorless, and tasteless, and has a slightly alkaline reaction. 
Saliva has the following distinct functions: 
142 TM 8-225 
154-157 
DENTAL TECHNICIANS 
a. By softening and moistening the food with mucin it lubricates 
it and insures smooth passage along the oesophagus. 
h. By dissolving dry and solid food it provides a necessary step 
in the process of stimulating taste nerves, and taste sensations play 
an important part in the secretion of gastric fluid. 
c. By virtue of the enzyme which it contains it changes starch to 
simple substances, that is, dextrin and maltose. 
155. Mucin plaques.—Mucin plaques are precipitated upon the 
teeth by the action of weak acids and acid salts upon the mucin in the 
saliva. These acids usually are formed by the acid-forming action 
of certain bacteria on sugar. These plaques so formed are localized 
on all tooth surfaces that are unprotected by the friction of food in 
mastication, of tongue, or lips. The bacterial plaque is the essential 
factor in the localization of tooth decay and the most important 
characteristic cause. The bacteria] plaque is soluble in a solution of 
three parts wTater and one part hydrogen peroxide. This solution 
may be used as a dentifrice by patients who are constitutionally sus- 
ceptible to caries. 
156. Calculus.—The precipitation of mucin by acids is the gen- 
eral factor which underlies the deposition of practically all deposits 
and accretions on the teeth. The earthy salts (phosphates and car- 
bonates) that are held in the solution in the saliva by the escape of 
carbon dioxide combine and are precipitated within the substance 
of the mucin plaque to form a mass called calculus or tartar. Cal- 
culus varies in the rapidity with which it is formed, in its density, 
and in the tenacity with which it adheres to the tooth structure. 
Calculus which is formed rapidly and in large masses is usually soft. 
The hardness of calculus depends on the amount of its lime con- 
stituent in proportion to the mucin constituent. The hardest cal- 
culus is found just under the gum margin and is somewhat more 
difficult to remove than the soft type which is found on the crowns 
of the teeth. It occurs more abundantly near the orifices of the 
salivary ducts, and therefore is most often seen on the lingual surface 
of the lower incisors and the buccal surfaces of the upper molars. 
Calculus causes an inflammation of the gingival tissues, which is a 
factor in the cause of periodontoclasia. All deposits should be 
removed from the teeth by instrumentation and the surface polished. 
157. Green stain.—-The green stain frequently seen on children’s 
teeth may be caused from the decomposition of blood elements or from 
certain color-producing bacteria. It can readily be removed by 
applying iodine to the tooth and then polishing with pumice. 
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MEDICAL DEPARTMENT 
Section VI 
TECHNIQUE OF DENTAL PROPHYLAXIS 
Paragraph 
Instruments , 158 
Technique 159 
System of instrumentation 160 
Polishing 161 
158. Instruments.—The technique of instrumentation, as de- 
scribed in this manual, will confine itself to instruments available in 
the Army dental clinics. 
a. Mouth mirror.—This instrument is used as— 
(1) Reflector of images. 
(2) Reflector of light. 
(3) Tongue depressor. 
(4) Cheek distender. 
lo. Scalers.— (1) Scalers Nos. 3 and 6 are hooked or sickle-shaped 
instruments and are used chiefly to remove gross deposits from the 
teeth. Scaler Younger-Good No. 15 is also sickle-shaped but has a 
smaller blade and is used to remove small deposits of calculus from 
more inaccessible places such as between the teeth. Scalers Nos, 33 
and 34 are used for the removal of heavy deposits especially from 
Figure 113. 
144 TM 8-225 
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DENTAL TECHNICIANS 
the lingual surfaces of the upper anterior teeth and the lingual sur- 
faces of the lower anterior teeth. The instruments used by the Army 
dental service (Nos. 3 and 6; Younger-Good Nos. 15, 33, and 34) are 
all pull instruments (fig. 113), that is, they remove the calculus by a 
pulling or scraping movement. This type of scaler is called a hoe 
type for this reason. 
(2) Younger-Good No. 15 scaler is used in this operation to check 
carefully each surface of every tooth to make sure that every piece 
of calculus has been removed. It should never he forgotten that all 
the other 'pieces of calculus are of minor, even negligible importance 
as compared with the last piece. 
(3) If the teeth are so shaped or the interproximal span so filled 
with tissue that the blade does not pass easily around the free margin 
of the gum no effort should he used to force the instrument in such 
a way as to injure the delicate supporting tissues. 
159. Technique.—If the patient presents a mouth in which there 
is evidence of food debris, the necks of the teeth and the inter- 
proximal spaces should be bathed with a solution of hydrogen per- 
oxide. Aside from the germicidal action, the effervescence of the 
peroxide will mechanically aid in loosening the minute particles of 
food debris. The mouth should then be rinsed with warm water and 
then sprayed with a compressed-air atomizer containing a pleasant 
mouthwash. The air pressure should be at least 25 pounds, so that 
it will have enough force to blow the spray between the teeth. This 
premilinary step is very important in mouths of this type as there 
is danger of infection if instruments are used around the gingival 
borders where decomposed food is present. 
160. System of instrumentation.—In order to perform a 
prophylactic operation intelligently, one must work by a system and 
the instrumentation as well as the polishing must have a definite start- 
ing point in the mouth and proceed in the same given direction over 
the surfaces of the teeth in the case of every patient. This is necessary 
for thoroughness and also useful in case of interruption, for if the 
operator will make a mental note of the last tooth being worked on 
when leaving the chair, the chain will remain unbroken on resuming. 
A good system is to begin on the lingual surface of the right lower 
last molar and proceed left to the last lower left molar, around to the 
buccal surface and proceed right to the right lower last molar (fig. 
114). The same procedure can be used in the upper jaw. In using 
instruments in the mouth it must be remembered that each and every 
motion of the hand and fingers should always be under control of the 
431511°—42 10 
145 TM 8-225 
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MEDICAL DEPARTMENT 
operator as a slip might cause a great deal of damage to the mouth 
tissues or the teeth. An instrument must never he used unless the hand 
holding it is steadied against some adjoining part of the mouth. The 
instrument should be grasped very much the same as a pencil, between 
the thumb and index finger. The blade of the instrument is placed 
against the surface of the tooth and is carefully carried under the 
shoulder of the calculus deposit; with a slight pulling motion of the 
hand and fingers, and rotating of the wrist, the mass is removed. This 
same motion is repeated a sufficient number of times to clean thor- 
oughly the surface of the tooth. 
Figure 114.—Diagram of dental arch illustrating system of scaling lingual and facial sur- 
faces with definite starting point, procedure, and finishing point which is used on all 
cases and is conducive to careful yet rapid treatment. 
161. Polishing.—a. The materials used in polishing the teeth are 
a contra-angle handpiece and rubber polishing cups. The object of 
the polishing process is threefold : 
(1) Removal of stains, plaques, and films on the exposed surfaces 
of the teeth. 
(2) Polishing of the enamel surfaces and a stimulating effect that 
seems to be imparted to the living tissues around the tooth by the 
vigorous massage. 
(3) Beneficial results obtained on the gingival margin by the slight 
pressure from the rubber cup. 
h. The main benefit derived from polishing the teeth is the preven- 
tion of initial decay. 
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DENTAL TECHNICIANS 
Section VII 
SYSTEM FOK INSTRUMENTATION AND POLISHING 
Paragraph 
Instrumentation 162 
Polishing 163 
Use of dental floss 164 
Disclosing solution 165 
162. Instrumentation.—The following outline presents a sys- 
tematic procedure, giving the order in which the different teeth and 
tooth surfaces are scaled, the scalers used, and the point used to steady 
the hand holding the instrument (fulcrum point). 
a. Division Teeth.—Right lower molars, bicuspids, cuspids, 
lateral, and central. 
(2) Surface.—Lingual, 
(3) Instrument.—Scalers Nos. 3, 6, and 33 (No. 31 also for cuspid, 
lateral, and central). 
(4) Fulcrum point.—End of third finger between left lower cuspid 
and bicuspid on occlusal surface. 
h. Division 2.— (1) Teeth.—Left lower central, lateral, cuspid, 
bicuspids, and molars. 
(2) Surface.—Lingual. 
(3) Instrument.—Scalers Nos. 3, 6, and 34 (No. 33 also for cuspid, 
lateral, and central). 
(4) Fulcrum. point.—End of second finger on cutting edge of right 
lower second bicuspid for left lower central, lateral, and cuspids. 
End of third finger on cutting edge of lower centrals for bicuspids 
and molars. 
c. Division 3.— (1) Teeth.—Left lower molars, biscuspids, and 
cuspid. 
(2) Surface.—Buccal. 
(3) Instrument.—Scalers Nos. 3 and 15. 
(4) Fulcrum point.—End of third finger on labial surface of lower 
incisors. 
d. Division J/,.— (1) Teeth.—Lower incisors, right cuspid, 
bicuspids, and molars. 
(2) Surface.—Facial and buccal. 
(3) Instrument.—Scalers Nos. 3 and 15. 
(4) Fulcrum point.—End of second or third finger between left 
lower cuspid and bicuspid for lower incisors and move posteriorly 
for molars. 
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MEDICAL DEPARTMENT 
e. Division S.— (1) Teeth.—Right lower molars, bicuspids, and 
cuspid. 
(2) Surface.—Approximal. 
(3) Instrument.—Scaler No. 15. 
(4) Fulcrum point.—Occlusal surface of right lower bicuspids 
and move anteriorly for cuspids. 
/. Division 6.—(1) Teeth.—Lower anteriors. 
(2) Surface.—Approximal. 
(3) Instrument.—Scaler No. 15. 
(4) Fulcrum point.—Occlusal surface of left lower cuspid. 
g. Division 7.— (1) Teeth.—Left lower cuspids, bicuspids, and 
molars. 
(2) Surface.—Approximal. 
(3) Instrument.—Scaler No. 3 or No. 15, 
(4) Fulcrum point.—Labial surface of bicuspids and move poste- 
riorly. 
h. Division 8.— (1) Teeth.—Right upper molars, bicuspids, cuspid, 
lateral, and central. 
(2) Surface.—Lingual. 
(3) Instrument.—Scaler No. 33 (also No. 34 for central, lateral, 
and cuspid). 
(4) Fulcrmn point.—End of third finger on occlusal surface be- 
tween left lower cuspid and bicuspid. 
i. Division 9.— (1) Teeth.—Left upper central, lateral, cuspid, 
bicuspid, and molars. 
(2) Surface.—Lingual. 
(3) Instrument.—Scaler No. 34 (also No. 33 for central, lateral, and 
cuspid). 
(4) Fulcrum point.—End of second finger on cutting edge of right 
upper cuspid. 
j. Division 10.— (1) Teeth.—Left upper molars, bicuspids, cuspid, 
lateral, and central. 
(2) Surface.—Buccal or facial. 
(3) Instrument.—Scaler No. 3 or No. 34. 
(4) Fulcrum point.—End of second finger on labial surface of left 
upper central and lateral and ends of third finger on lingual surface 
of right upper central and lateral, for molars, cuspids, and bicuspids. 
End of third finger on cutting edge of right upper cuspid for lateral 
and central. 
k. Division 11.— (1) Teeth.—Right upper central, lateral, cuspid, 
bicuspids, and molars. 
(2) Surface.—Buccal or facial. 
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DENTAL TECHNICIANS 
(3) Instrument.—Scaler No. 3 or No. 33. 
(4) Fulcrum point.—Back of third or fourth finger on chin. 
l. Division 12.— (1) Teeth.—Right upper molars, bicuspids, and 
cuspid. 
(2) Surface.—Approximal. 
(3) Instrument.—Scaler No. 3 or No. 15. 
(4) Fulcrum point.—End of third finger on labial surface of lower 
incisors. 
m. Division 13.— (1) Teeth.—Upper incisors. 
(2) Surface.—Approximal. 
(3) Instrument.—Scaler No. 15. 
(4) Fulcrum point.—Incisal edge of upper incisors. 
n. Division -(1) Teeth.—Left upper cuspid, bicuspids, and 
molars. 
(2) Surface.—Approximal. 
(3) Instrument.—Scaler No. 3 or No. 15. 
(4) Fulcrum point.—Back of hand resting on chin. 
163. Polishing.—The following is a step-by-step outline of the 
procedure used in polishing the teeth, using a paste of flour of pumice, 
rubber cups, brush wheels, and the dental engine: 
a. Division 1.— (1) Teeth.—Right lower molars, bicuspids, and 
cuspid. 
(2) Surface.—Lingual. 
(3) Instrument.—Contra-angle handpiece and rubber cup. 
(4) Fulcrum.—Lower left second bicuspid. 
I). Division 2.— (1) Teeth.—Lower anteriors. 
(2) Surface.—Lingual. 
(3) Instrument.—Contra-angle handpiece, rubber cup. 
(4) Fulci'um,.—Lower right cuspid. 
c. Division 2.— (1) Teeth.—Left lower cuspids, bicuspids, and 
molars. 
(2) Surface.—Lingual. 
(3) Instrument.—Contra-angle handpiece, rubber cup. 
(4) Fulcrum.—Lower right cuspid. 
d. Division U—(1) Teeth.—Left lower molars, bicuspids, and 
cuspids. 
(2) Surface.—Buccal. 
(3) Instrument.—Contra-angle handpiece and rubber cup. 
(4) Fulcrum.—Incisal edge of lower anteriors. 
e. Division 5.— (1) Teeth.—Lower anteriors. 
(2) Surface.—Facial. 
(3) Instrument.—Contra-angle handpiece and rubber cup. 
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MEDICAL DEPARTMENT 
(4) Fulcrum.—Back of hand on chin. 
/. Division 6.— (1) Teeth.—Right lower cuspid, bicuspids, and 
molars. 
(2) Surface.—Buccal. 
(3) Instrument.—Contra-angle handpiece and rubber cup. 
(4) Fulcrum.—Back of hand on chin. 
g. Division 7.— (1) Teeth.—All upper teeth. 
(2) Surface.—Buccal, facial, and lingual. 
(3) Instrument.—Contra-angle handpiece and rubber cup. 
(4) Fulcrum.—Back of hand on chin. 
h. Division 8.— (1) Teeth.—All molars and bicuspids. 
(2) Surface.—Occlusal. 
(3) Instrument.—Straight handpiece and wheel brush. 
(4) Fulcrum.—Same as for other surfaces of the respective teeth. 
After the polishing procedure is completed with pumice it can be 
repeated with powdered chalk to give the teeth a high polish. 
164. Use of dental floss.—After the teeth have been polished 
with cup and brush wheel, there still remain the contact points and 
areas on the approximal surfaces that have not been reached. These 
areas are best cleaned with dental floss. A piece of floss about 10 
inches long is used for this purpose, and is wrapped around the index 
finger of one hand and held tightly by the thumb of the other hand. 
The finger and thumb should not be more than 1 inch apart as this 
will prevent the floss from snapping against and injuring the gum 
tissue between the teeth. The dental floss is carefully worked between 
the teeth and through the contact points until the approximal sur- 
faces of the teeth are reached. It is then drawn over these surfaces 
several times until all food debris has been loosened and removed. 
It is then pulled straight out from between the teeth and not past the 
contact point again. This is repeated between all the teeth, and to 
facilitate the polishing the floss may be dampened and dipped in 
pumice before using. 
165. Disclosing solution.—a. The teeth are then checked for 
cleanliness by painting a disclosing solution on the dried surfaces. 
This will make visible all stains and mucinous plaques that have not 
been removed. A very effective iodine disclosing solution consists of 
the following: 
Iodine crystals 3. 3 gm 
Potassium iodide 1. 0 gm 
Zinc iodide 1. 0 gm 
Glycerin 16. 0 cc 
Distilled water 16. 0 cc 
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DENTAL TECHNICIANS 
h. A substitute solution of tincture of iodine and glycerin, equal 
parts, may be used if desired. The patient is allowed to rinse his 
mouth at frequent intervals during the entire prophylactic treatment. 
When all the teeth have been thoroughly cleaned and polished, the 
mouth is sprayed with any pleasant mouthwash. 
Section VIII 
INSTRUCTIONS TO PATIENT 
Paragraph 
Method of tooth brushing 166 
Massage 167 
166. Method of tooth brushing.—Prevention in dentistry is one 
of the most important factors to be considered. It is much better to 
prevent the occurrence of a dental disease than to treat it after it has 
obtained a start. Probably the most common of all dental conditions 
is caries or decayed teeth. For a tooth to decay, the process must have 
a starting point. This is usually brought about by the retention of 
food debris against the tooth surfaces, which when not removed, will 
be incorporated into the tartar deposits and, if allowed to remain for 
several hours, cannot be removed with a brush. Therefore one of the 
most important duties of the dental hygienist is to understand a good 
practical method of tooth brushing and to be able to instruct the pa- 
tient in this method. The instruction will consist of the following*. 
Advise the patient to buy two hard bristle brushes, preferably with 
different colored handles. One brush to be used in the morning and 
the other at night. The different colored handles will enable him to 
know exactly which brush to use. The brushes should be rather 
small, preferably with two rows of bristles. Place some tooth paste 
on the dry brush and, using a slight wrist motion, start with the bris- 
tles against the gums and sweep them down over the surfaces of the 
teeth toward the biting edges. The motion should always be from 
gum to biting surface, and never crosswise. The posterior or back 
teeth should be brushed first. Then proceed forward until all the 
teeth are brushed, both inside and out. In this manner, the upper and 
lower teeth are brushed for 3 minutes by the clock, twice daily. Pa- 
tients with badly neglected mouths should be told that this manner 
of brushing might cause their gum tissues to be slightly sore for a 
day or twro, but shortly their mouths will be improved by the massage 
action of the brush. After the teeth have been thoroughly brushed, 
there still remain certain areas that are impossible to reach with the 
brush and must be cleaned with dental floss. Instruct the patient in 
the use of dental floss as given in paragraph 164. 
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MEDICAL DEPARTMENT 
167. Massage.—Frequently the gums of a neglected mouth will 
be inflamed and swollen. This condition previously described is 
known as gingivitis, and can generally be cured or remedied by pro- 
phylaxis and massage. Instruct the patient to massage his gums at 
least twice a day by squeezing or milking the inflamed or soft gums 
between the ball of the thumb and index finger, downward for the 
upper arch, and upward for the lower arch. In other words the 
motion, as in brushing, should always be toward the biting surfaces 
of the teeth. 
Section IX 
PREPARATIONS FOR MOUTH AND TEETH 
Paragraph 
Oral hygiene 168 
Tooth powder and tooth paste 169 
Mouthwash 170 
168. Oral hygiene.—The science of the health of the mouth 
treats of the normal equilibrium of the oral cavity and its contents. 
The medications intended for the maintenance of the health of the 
mouth and teeth may be divided into those prescribed for specific 
diseases and those employed as hygienic measures for daily use. Only 
those employed for hygienic measures are of interest to the dental 
hygienist. 
a. A good oral preparation should possess the following properties: 
(1) Indifference in regard to— 
(a) Mucous membrane (not caustic). 
(b) Teeth (nondecalcifying). 
(c) Organism as a whole (nonpoisonous). 
(2) Noninterference with the normal physiologic cleansing of the 
mouth, that is, it must not— 
(a) Inhibit the flow of saliva. 
(b) Alter or destroy the reaction of the saliva. 
(3) Sufficient cleansing action combined with good taste and odor. 
b. The following should be avoided in constructing a formula for 
mouth and tooth preparations: 
(1) Strong precipitants of albumen (concentrated alcohol, mineral 
acids with the exception of boric acid, metallic salts, phenol, and 
salicylic acid and most of their derivatives, etc.) 
(2) Strong astringents (formaldehyde solution, etc.). 
(3) Caustics (potassium and sodium hydroxide and many of the 
potassium salts). 
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DENTAL TECHNICIANS 
(4) Gritty substances (pumice stone, charcoal, crude chalk, etc.). 
(5) Fermentable substances (sugars, starches, vegetable powders). 
(6) Staining substances (organic and inorganic). 
c. Preparations used for the mouth and teeth are conveniently 
divided into mouthwashes, tooth powders, and tooth pastes. 
169. Tooth powder and tooth paste.—Tooth powders and 
pastes are principally employed for the purpose of mechanically 
cleansing the accessible surfaces of the teeth. Their antiseptic effect 
on the bacteria of the month is of questionable value, as they remain 
hardly long enough in the mouth to be completely dissolved. Tooth 
powders or pastes should not contain gritty or fermentable sub- 
stances or corrosive chemicals which are destructive to tooth struc- 
ture. The wasting away of tooth structure, usually referred to as 
erosion or abrasion, is largely the result of the continuous use of 
powders, pastes, etc. The principal materials employed in the manu- 
facture of commercial tooth powders and pastes are prepared chalk, 
precipitated chalk (precipitated calcium carbonate), magnesium car- 
bonate, soap, pumice stone, charcoal, and powdered vegetable drugs 
such as licorice, orris, myrrh, etc. Prepared chalk and pumice stone 
are highly abrasive and should never be used in a tooth preparation 
for daily use. A light preparation of magnesium carbonate has no 
abrasive or polishing action on tooth structure and is used in the 
manufacture of tooth powder for bulk. Charcoal is a fine black 
powder. It should never be used in tooth powder as the sharp par- 
ticles imbed themselves in the gum tissue producing a bluish line 
near the free gum margin. A good tooth preparation should contain 
not more than 2 or 3 percent of the best quality castile soap. 
Powdered vegetable drugs are added to give flavor and increase bulk, 
and they can be readily substituted by their respective essential oils. 
A simple, cheap, effective powder may be made from the following 
formula: light English precipitated chalk, 94 parts; powdered castile 
soap, 5 parts; saccharin, i/2o part; flavoring, 1 part. A perfectly 
satisfactory tooth, paste cannot be produced without the use of a 
massing fluid such as gelatin or mucilage of acacia (gum arabic 2 
parts, water 3 parts) and glycerin. Tooth pastes may be prepared 
according to the following formula; tooth powder body, 10 parts; 
massing fluid, 4 to 6 parts. 
170. Mouthwash.—A mouthwash is usually prescribed as a 
gargle to be used in conjunction with a tooth brush and paste or 
powder. The components of the wash should be so adjusted that 1 
teaspoonful mixed with y2 glass of warm water (approximately 1 to 
30) furnish the correct proportions of its active ingredients. A 
153 TM 8-225 
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MEDICAL DEPARTMENT 
most beneficial mouthwash can be made by combining y2 tablespoon- 
ful of lime water and y2 teaspoonful of salt to y2 glass of warm 
water. It acts as a solvent on the mucin deposits on and about the 
teeth which mechanically retain food debris and bacteria, and its 
mild astringent effect favors the recovery of inflamed mucous sur- 
faces, This mouthwash corresponds more closely to an artificial 
saliva, nature’s protection of the teeth and mucous membrane, than 
any mouthwash on the market. 
154 TM 8-225 
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DENTAL TECHNICIANS 
Chapter 6 
DENTAL ASSISTANT 
Paragraphs 
Section. I. Requisites of dental assistant 171-172 
II. Care of dental clinic 173-174 
III. Sterilization of instruments and dressings 175-181 
IV. Care of equipment and supplies 182-190 
V. Duties at chair 191-200 
VI. Daily routine in clinic 201 
Section I 
REQUISITES OF DENTAL ASSISTANT 
Paragraph 
General 171 
Personal hygiene 172 
171. General.—a. The chair assistant personally associates with 
all of the patients who receive dental service. The chair assistant 
directs the patient to the proper chair, sees that the patient is com- 
fortable by adjusting the chair before the dental officer comes into 
the room, fixes a towel around the patient’s neck to protect the cloth- 
ing, and often arranges appointments for patients. This type of 
duty demands certain attributes in a dental assistant. First, he 
must be clean and neat about his person as intimate association with 
the patients demands this. He must be able to keep the operating 
room and other rooms of the dental clinic clean and sanitary largely 
on his own initiative. Finally, he must be respectful, quiet, and 
dignified, able to arrange appointments courteously with officers, de- 
pendents, and enlisted men. In short, the dental assistant must keep 
himself and the clinic immaculate and must possess the necessary 
tact to deal with all personnel of the post from the commanding 
officer down. To carry out these duties successfully, the dental 
assistant must take pride in his work and must have the greatest 
respect for the officer for whom he works and for the profession of 
dentistry. The dental assistant is often the first person whom the 
patients meet when reporting for dental treatment and their attitude 
toward the dental service is often influenced by the actions of the 
dental assistant. 
b. Most soldiers presenting themselves for treatment are apprehen- 
sive and many are in pain. It is the duty of the dental assistant to 
see that these patients are assured that they are to receive gentle, 
scientific treatment, and that their needed dental treatment is nothing 
155 TM 8-225 
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MEDICAL DEPARTMENT 
to fear. The dental assistant in his duties associates with the varied 
personnel of the post more often and intimately than any other en- 
listed member of the Medical Department, and the reputation and 
good name of the Medical Department enlisted personnel often 
depend on his manner and attitude. 
172. Personal hygiene.—The entire person of the assistant must 
be scrupulously clean. This means daily baths and change of under- 
wear, a clean regulation uniform at frequent intervals, a daily shave, 
and frequent haircuts. The hands and nails need particular atten- 
tion. Before approaching the patient to aid the dental officer always 
scrub the hands. Let the patient know that this is being done by 
the thorough use of soap and brush at a basin within his hearing. 
The nails should be cut close and filed smooth. The orangewood 
sticks to be found in any office are ideal when properly shaped for 
cleaning under the nails. After handling infectious material or 
after handling instruments which were used in treating an infectious 
disease such as Vincent’s infection, special precautions should be 
used in scrubbing up afterward. One such precaution is to rinse 
the hands and arms thoroughly in 70 percent alcohol or some similar 
antiseptic. As to dress, there is no reason why the Medical Depart- 
ment enlisted man should not be as smart in appearance as any 
enlisted man of the line. The true soldier, with an erect carriage, 
neat, precise dress, prompt and exact attention to duty, cheerful 
attitude toward all those who come in contact with him, inspires 
confidence in the prospective patient. Such a soldier also has 
confidence in himself. 
Section II 
CARE OF DENTAL CLINIC 
Paragraph 
General 173 
Cleaning 174 
173. General.—The dental clinic must be kept ready for inspec- 
tion at all times. There are sufficient cabinets and drawers to keep all 
instruments and equipment under cover and out of dust and contam- 
ination. If tables are used from which to operate, these also may be 
kept covered with sterile towels or sheets. The assistant should learn 
where the dental officer habitually keeps his equipment and, after 
sterilization, should replace it there every time it is used. Many 
officers like to be able to find things in their offices “in the dark.” At 
least, every officer has a definite place for each item of equipment and 
it is necessary for the assistant to learn his particular officer’s system. 
156 TM 8-325 
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DENTAL TECHNICIANS 
174. Cleaning1.—a. Soap and water and the diligent use of “elbow 
grease” can keep a clinic spotless at all times. Not only should the 
floor be scrubbed frequently, but the baseboards, woodwork, cab- 
inets, chairs, waste containers, and similar items of equipment should 
be scrubbed periodically. The towels or paper covers in the cabinets 
should be changed at regular intervals or at any time they become 
soiled. If the floor is waxed, use the proper amount of wax; too much 
makes it gummy, thus retaining dirt. Such floors should be polished 
daily. If too much wax has been used and black spots appear, the 
judicious use of small amounts of kerosene, either alone or to dilute 
the wax, and hand scrubbing and rubbing will soon remove these spots. 
Terrazzo floors should never be waxed, but should be scrubbed daily 
with liberal amounts of soapy water without too much rinsing. The 
soap thus remaining eventually gives the floor a polished appearance. 
h. Windows and glass in cabinets need frequent attention. Door 
handles and plates or those places most frequently touched in passing 
through a door must be kept clean, and if metal, must be kept polished. 
c. The dental chair must be kept clean and the headrest kept covered 
with a towel or paper napkin. Paper napkins which are listed on the 
medical supply table as item No. 73310 are ideal for this purpose when 
affixed over the headrest cups with rubber bands. When cleaning up, 
it is a good idea to pump the chair up so that all parts of it can be 
easily seen and cleaned. As the chair is used so much of the day, 
special care must be taken to see that it is kept in the best possible 
condition. It is so constructed that it rarely needs mechanical 
attention. 
d. The unit and especially the cuspidor, must be kept spotless. This 
last item must be washed after each patient. New covers for the 
bracket table must be provided for each patient. The water syringe 
point and the hot air nozzle should be wiped off with 70 percent alco- 
hol after each patient, or these may be disconnected for other means 
of sterilization, but care must be taken to preserve the gaskets. Any 
other item on the unit for use in the mouth may be disconnected for 
sterilization either by chemical means or by boiling. 
e. After cleaning everything in the clinic for the day, sit down in 
the chair and look around; from there, the vantage point of the patient, 
see what things look like. One will discover things here and there 
that need going over which were not seen while standing at the chair. 
/. Do not overlook the fact that every article of equipment, other 
than those mentioned, such as tables, desks, waste receptacles, work- 
bench, and washbasin, must be kept clean at all times. The wash- 
basin may have to be cleaned any number of times during the day, but 
157 TM 8-225 
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MEDICAL DEPARTMENT 
at the end of the day, it should be thoroughly polished with scouring 
soap such as Bon Ami; all metal parts should be kept polished at all 
times. In this connection chrome finished metal needs different care 
than either nickel or brass. Ask the dental surgeon for instructions 
on this. 
Section III 
STERILIZATION OF INSTRUMENTS AND DRESSINGS 
Paragraph 
General 175 
Bacteriology 176 
Sterilizers 177 
Sterilizing rules 178 
Autoclave 179 
Hypodermic syringes and needles 180 
Sanitation 181 
175. General.—Scientific sterilization of the instruments and 
dressings used is an essential part of dentistry. Sterilization means 
the destruction of disease germs and their spores through the agency of 
heat or chemicals. 
176. Bacteriology.—So that the dental assistant will take his 
responsibility seriously and will be able to work more intelligently, 
the following brief explanation of disease germs is given: 
a. Bacteria are organisms invisible to the naked eye and can be 
seen only through a microscope. They belong to the plant family and 
are parasitic, that is, they live on and at the expense of another organ- 
ism. They cause most of the infections with which dentistry is con- 
cerned. Micro-organism, microbe, and germ are terms which are 
sometimes used to mean bacteria. 
h. Protozoa are minute organisms somewhat similar to bacteria in 
that they produce infections and diseases and cannot be seen without 
the aid of a powerful microscope. However, protozoa belong to the 
animal kingdom. 
c. The two most common classes of bacteria are— 
(1) Bacilli (sing., bacillus), rod-shaped organisms when seen under 
the microscope and some forms produce spores (seedlike forms) which 
are very hard to kill with heat and chemicals. 
(2) Cocci (sing., coccus), round-shaped organisms which, when 
viewed under the microscope, appear as small dots. This type of bac- 
terium causes most of the infections. It is further classified into a 
number of subgroups, the chief of which are staphylococcus and strep- 
tococcus. The staphylococcus appears under the microscope in 
clusters and is the cause of most of the pus-forming infections such 
158 TM 8-235 
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DENTAL TECHNICIANS 
as pimples and boils. The streptococcus appears under the micro- 
scope in long strings and causes many very serious infections. 
177. Sterilizers.—The sterilizers used in the Army are the elec- 
tric intrument sterilizer and the sterilizing pan containing a strong 
disinfectant. However, the hospitals will be equipped with a steam- 
pressure sterilizer called an autoclave. If the dental clinic is large 
enough it may be equipped with an autoclave and then the dental 
assistant must familiarize himself with its operation. 
178. Sterilizing1 rules.—The following are some sterilizing rules 
for instruments, utensils, files, orangewood sticks, etc.: 
a. Boil water 15 minutes before starting sterilization. 
h. Clean instruments thoroughly with brush, soap, and water (or a 
5-percent solution of Lysol) as soon after using as possible. Take 
special care to brush grooves and joints. 
c. Place in sterilizer and boil for 15 minutes. 
d. Place all cup-shaped instruments on side or upward so that they 
will not form air pockets. 
e. Never add fresh water to the sterilizer during the sterilizing 
period and do not add instruments during this period. Either act 
will contaminate the instrucents already in the sterilizer. 
/. At the end of the boiling period, remove the instruments imme- 
diately. Sterilized tongs may be used or the instruments may be 
rolled out on a sterile towel or cloth. Do not touch these instruments 
with the hands but pick them up with a sterile towel and wipe dry 
while still warm. 
g. These instruments should now be placed in a cabinet with glass 
trays which are sterilized from time to time. 
h. To be completely safe, instruments not recently used should be 
resterilized before operating (this is especially true in oral surgery). 
i. Instruments will not rust if removed and dried immediately after 
the sterilizing period is up. Allowing them to rest in an elevated 
tray over boiling water is harmful to them. 
j. Never use any form of soda when sterilizing aluminum-handled 
instruments or when sterilizing hypodermic syringes and needles (a 
separate sterilizer may be used for these instruments). 
h. Although the sterilizer is emptied, scrubbed with soap and water, 
and dried every evening, a scale from the lime salts in the water will 
form after a time on the inside of the sterilizer. This should be taken 
off from time to time by filling the sterilizer with a weak solution of 
any acid. A little hydrochloric acid well diluted or a cup of vinegar 
left in the sterilizer overnight will facilitate the removal of this boiler 
scale. 
159 TM 8-225 
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MEDICAL DEPARTMENT 
I. Sharp, fine-edged instruments are damaged by boiling in water. 
Sterilize these instruments in a compound cresol solution kept in a 
pan or tray for this purpose. This solution is a liquid containing 
about 50 percent cresol in a neutral potassium soap and is known by 
the trade name of Lysol. For the sterilization of instruments, it is 
used in a dilution of 1 to 3 percent. 
179. Autoclave.—The autoclave is an expensive, complicated 
sterilizing apparatus which sterilizes by the action of live steam. The 
advantages obtained by the autoclave are: higher temperature can be 
obtained, and the material sterilized comes from the sterilizer dry 
and ready to use. Hence this method is used for sterilizing cotton, 
gauze dressings, gauze and cotton sponges for oral surgery, and cot- 
ton points for root canal work. The material to be sterilized, after 
being prepared according to the directions of the dental officer, is 
wrapped in muslin and pinned to make a neat and secure pack. These 
muslin packs are brought to the sterilizing room by the dental assistant 
for autoclave sterilization. After sterilization, the packs are stored 
away unopened, and a sterilized reserve of cotton, gauze dressings, 
gauze and cotton sponges for surgery, and cotton points is always 
on hand. 
180. Hypodermic syringes and needles.—A special sterilizer 
should be set aside for sterilizing syringes and needles. This steri- 
lizer should not be used for any other purpose and should have care- 
ful attention. Syringes and needles should be boiled for 20 minutes. 
Only distilled water should be used in sterilizing hypodermic needles 
and syringes. Special care is necessary in the sterilization of needles 
and syringes because these instruments are used to inject solution 
deep into the tissues. Any slips in the sterilizing technique of these 
items will seriously endanger the patient. 
181. Sanitation.—Besides actual sterilization of instruments, it 
is very necessary to maintain ordinary sanitary measures to prevent 
spread of infection from patient to patient. Most of this sanitary 
precaution is accomplished in the daily scrubbing and cleaning of 
the office (see secs. II and IV). However, under the heading of sani- 
tation will come many things too numerous to mention, frequent 
washing of the operator’s and assistant’s hands; wearing of clean 
white gowns or clothing; proper disposal of soiled tongue depressors, 
cotton rolls, and applicators; use of rubber gloves on luetic patients; 
and many other simple acts of cleanliness. The dental assistant 
should develop a sense of asepsis and with some experience should 
be able to do many things on his own initiative to avoid contamina- 
tion of equipment and instruments. 
160 TM 8-225 
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DENTAL TECHNICIANS 
Section IV 
CARE OF EQUIPMENT AND SUPPLIES 
Paragraph 
Expendable and nonexpendable property 182 
Medicaments 183 
Hand instruments 184 
Dental burs 185 
Engine and handpiece 186 
Care of miscellaneous items 187 
Dental lathe 188 
Vulcanizer 189 
Other items 190 
182. Expendable and nonexpendable property.—It is most 
important to know that there are two kinds of equipment in the clinic: 
expendable and nonexpendable. Expendable equipment consists of 
(hose items which are used up in carrying on the work of the clinic 
such as cement, impression materials, paper cups, paper covers, burs, 
and similar items. Nonexpendable articles such as hand instruments, 
forceps, and pliers are charged to the responsible officer and must be 
accounted for at all times. If nonexpendable equipment breaks or 
otherwise becomes unserviceable, the parts must be kept and turned 
in to the hospital medical supply officer for disposal and credit. 
Nonexpendable property must never be thrown away regardless of its 
condition. The assistant should ask the officer about each item before 
it is thrown away until he is thoroughly familiar with these two 
classes of property. A dental clinic has many, many items of equip- 
ment and supply. They are for the most part very expensive and the 
assistant must learn to take good care of them to prolong their use- 
fulness. Figure 115 shows a supply room with a well-arranged sys- 
tem for storing the different items. « 
183. Medicaments.—The dental cabinet should contain only 
those instruments and medicaments that are frequently used. It 
should never be used as a storage space for surplus supplies as this 
will only complicate the care of the cabinet. Medicaments are best 
kept in small, square, ground-glass-stoppered bottles, well labeled 
with the stock bottle left in the storage room. As the materials are 
used, they should be replaced from the bulk of the supply. Each 
bottle should have a certain place in the cabinet and should be kept 
there when not in use. Number and label the bottles so that the 
numbers one and two will contain the medicaments most frequently 
used. They must be spaced on the cabinet shelf so that selected 
bottles may be removed without tipping one of the others over. In 
431511°—42 11 
161 TM 8-225 
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MEDICAL DEPARTMENT 
arranging them, it is best not to have medicaments of the same color 
next to each other. For example eugenol should not be next to 
phenol. The alcohol bottle may be placed between them. The dan- 
Figure 115.—Well-arranged supply room showing how expendable and nonexpendable 
supplies are stored. 
ger of taking the wrong bottle is greatly reduced and the speed in se- 
lecting is materially increased. Iodine should not be kept in the 
cabinet as it will tend to rust the instruments. 
184. Hand instruments.—Hand instruments should be arranged 
in the cabinet drawers to suit the dental officer. Each instrument has 
a definite place. The scalers should be placed together, preferably 
162 TM 8-225 
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DENTAL TECHNICIANS 
pairing the rights and lefts. The same is done with the cutting 
instruments such as chisels, hatchets, excavators, etc. 
185. Dental burs.—The assistant should avoid having a large 
number of each type and size of burs out in use at one time. With 
many of the burs partly worn it is difficult for the operator to find a 
sharp one. Consequently he gets a new one from stock. This is used 
once and then is placed with the remainder of the old burs and prob- 
ably never used again. This goes on indefinitely, and consequently 
many burs that are still serviceable are needlessly thrown away. A 
very satisfactory method of handling the burs is by the use of any 
type of bur block that may be available whether it is round or square. 
The block will contain many holes in which the burs may be placed in 
regular order. They should be placed so that all types and sizes are 
readily available but have no more than two or three burs of each 
kind in the bur block. There are two lengths of burs, those for the 
straight handpiece and those for the contra-angle handpiece. The 
burs should be placed so that those for the two handpieces are in the 
same section of the block for convenience. The different type burs 
should be placed in groups with the large size burs to the left and 
graduating down to the small sizes. If after using the bur is still 
serviceable, it may be cleaned with a wire brush and sterilized and 
then replaced in the block. If the bur is not serviceable it is thrown 
away and a new bur replaces it in the bur block. In this manner 
all the types and sizes of burs are always available and it is a simple 
matter to replace discarded burs. 
186. Engine and handpiece.—The dental engine must be kept 
clean and free of dust and must be oiled at frequent fixed intervals 
designated by the dental officer. Oil not only the motor, but the pul- 
leys and the handpieces, using the oil furnished the clinic for this pur- 
pose. If the contra-angle is of the all-metal type it should be taken 
apart and boiled after each period of use and reassembled, using the 
handpiece grease (“handpiece ease’’) in all the gears and shafts. 
Never use pliers on this handpiece. With each handpiece furnished, 
there is a detailed description and cuts showing best how to care for 
it. Study this and follow the manufacturer’s directions. If the 
handpiece is of the old type that cannot be taken apart and boiled, it 
should be immersed in a bottle of sterilizing fluid (70 percent alcohol 
is good) while still on the engine, run forward and backward, then 
disconnected from the engine and allowed to set in the fluid for a 
period of sterilization, then removed and oiled; the sheath on the 
straight handpiece can be boiled, but care must be taken to dry 
thoroughly the inside of this sheath and in oiling it before replacing 
163 TM 8-235 
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MEDICAL DEPARTMENT 
it on the handpiece mechanism. It must be remembered that abra- 
sives such as are used for cleaning teeth and polishing restorations are 
very hard on the handpieces, and great care must be taken to remove 
thoroughly all particles of pumice or other abrasive when cleaning 
these handpieces. 
187. Care of miscellaneous items.—There are a few items 
which may be cleaned or cared for in some special way which expe- 
rience has proved to be best. Impression trays with impression com- 
pound adhering to them may be cleaned by applying a liberal coat 
of vaseline, holding in a flame for a few seconds, and wiping clean with 
a cloth or paper towel. Plaster bowls and spatulas must be cleaned 
immediately after use before the plaster or investment material begins 
to set. This preserves the rubber bowl and makes cleaning these 
articles easier. Cement slabs and spatulas should also be cleaned im- 
mediately after use. This is done by immersing them in a solution 
of bicarbonate of soda and rubbing the cement off with the fingers 
before it hardens. By this method the spatula or slab is not scraped 
and so is kept free from scratches. Extracting forceps will become 
stiff after being sterilized many times. The joints of these instru- 
ments may be loosened by the simple expedient of applying some 
spirits of ammonia in the joint and working back and forth a few 
times. The ammonia will loosen any rust in the joint and restore the 
forceps to their normal usefulness. 
188. Dental lathe.—This is another important item in the clinic. 
It should be kept free from dirt and be cleaned immediately after each 
period of use. It should be oiled at regular intervals, the frequency 
depending upon the amount of usage it gets. By carefully cleaning 
the cup covers before operating them for oiling, no abrasives or foreign 
materials can get in the bearings. By lightly tapping on the chucks 
and by removing them by turning the handles mounted on the side of 
the housing no injury ever will be done to the shafts. With reasonable 
care this piece of equipment will last many years and is rarely out of 
order. 
189. Vulcanizer.—This is not an item found in many clinics at 
present, its use being confined to the central dental laboratories. Its 
care and upkeep are explained in almost any textbook on prosthetic 
dentistry. Prothero’s “Prosthetic Dentistry” has a very good article 
on the vulcanizer, and the book is found in practically all dental 
libraries. 
190. Other items.—The air compressor is one of the most trouble- 
some items in the clinic. It should be given daily care and inspection. 
Great care should be taken to see that there are no leaks in the air lines. 
164 TM 8-225 
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DENTAL TECHNICIANS 
It should he shut off or disconnected from the electric current every 
night. If any unusual knocking is heard or overheating is found, it 
should be disconnected at once and the dental officer notified. Uo not 
tamper with the pressure-regulating switch unless ordered to do so by 
the proper authority. Condensation of moisture in the tank causes 
water to form and this should be drained at regular intervals. This 
holds true for the lines themselves, there being an outlet at the back 
of the unit for this purpose. There is a booklet of instructions on the 
unit in every dental office telling how to take care of it and how to 
drain the lines as suggested above. If this booklet is misplaced in 
the office a post card to the company making the unit, stating type, 
model, and number, will bring this booklet which is invaluable in 
learning the use and upkeep of all items on the unit. It should be 
studied thoroughly. All items not in daily use, or those recently ob- 
tained from supply sources and not yet opened for use, should be kept 
in a cool dry place. Instruments or other items liable to rust should 
be left in their original oilpaper covers or wrapped in oilpaper or 
gauze covered with petrolatum. If it is possible to have a small store- 
room, all items kept in it should be placed on the shelves in numerical 
order corresponding to the supply table number allotted to that item 
(fig. 115). This makes for quick inventory and sensible requisition 
of needed items. 
Section V 
DUTIES AT CHAIR 
Paragraph 
General 191 
Handling patients 192 
Anesthetic solution 193 
Impression materials 194 
Filling materials 195 
Silver amalgam 196 
Copper amalgam . 197 
Oxyphosphate of zinc cement 198 
Silicate __ 199 
Zinc oxide — 200 
191. General.—During the time that the dental officer is working 
on the patient the chair assistant should stand by, ready to render 
any assistance that may be necessary. If there are other duties to be 
performed in the operating room, he may do them but always within 
sight of the operator. The best procedure to follow is to stand on 
the opposite side of the chair from which the operator is working and 
observe the progress of the work. With a little experience the assis- 
165 TM 8-225 
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MEDICAL DEPARTMENT 
tant will be able to anticipate most of the dental officer’s wishes and 
have the necessary instruments ready before they are called for. 
He should note on the appointment sheet the type of work that is 
to be done for the patient so that he can have the necessary instru- 
ments and materials ready. If it is a prophylaxis, a mouth mirror, 
scalers, fine pumice, rubber cups, and brush wheels for the handpiece 
should be placed on the operating tray. If a carious tooth is to be 
prepared, a mouth mirror, exploring points, handpiece, burs, alcohol, 
phenol, silver nitrate, etc., should be placed on the tray. This 
routine is carried out for every patient. 
192. Handling patients.—a. As brought out in the first section 
of this chapter the dental assistant comes in closer contact with 
patients than any other enlisted man in the Medical Department. 
Many of these patients are suffering actual pain or are in acute dis- 
comfort. Do not treat it lightly. This is a serious moment in the 
patient’s day. In all likelihood he approaches the chair in apprehen- 
sion if not in downright fear. The dental assistant should use the 
dental surgeon’s behavior with patients as a precept of his treatment 
of them. Remember, there is nothing more painful than an aching 
tooth, nor anything more uncomfortable than a sore spot under a 
denture. 
h. The main guidepost in handling patients is to conduct oneself 
as a true gentleman. Be kind and courteous, sympathetic but not 
gushing, be cheerful and gentle, especially with the timid, be tactful, 
and show due respect to age and grade. Do not engage in needless 
and endless conversation with patients. Speak intelligently when 
spoken to and answer questions when necessary as well as possible 
although they may seem to be pointless. Never become familiar. 
c. Telephone calls should be answered in the following manner: 
“Dental clinic, Private (name) speaking.” Get the correct name 
and the desires of the person calling. If the call is for an appoint- 
ment, arrange it in consultation with the dental officer; see that it is 
noted in the appointment book and make sure that the person knows 
the exact date and hour. If the call is for the dental officer, call 
him, and if he cannot answer the call, make definite arrangements 
for completing the call at a later time. 
d. Always make definite appointments, exactly recorded on the 
appointment book and on W. D., M. D. Form No. 65 (Dental Engage- 
ment Slip) for patients coming to the clinic for routine appoint- 
ment. Never give a patient who is suffering pain an appointment 
for deferred work. Make some arrangement for alleviating the pain. 
166 TM 8-225 
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DENTAL TECHNICIANS 
e. In seating the patient in the chair see that it is in a low com- 
fortable position for the patient, and in a workable position for the 
dental officer. Be sure the headrest is comfortable and has a clean 
cover; place a clean towel on the patient, and secure it about the neck 
with the holder. Then wash the hands before placing a clean mirror, 
explorer, and cotton pliers on the bracket table. The patient’s W. D., 
M. D. Form No. 79 (Register of Dental Patients) is placed on the 
desk, and the patient is ready for the dental officer. 
193. Anesthetic solution.—a. Ringer’s solution may be made up 
in 100-cc lots as often as necessary. Equipment necessary for making 
the anesthetic solution is dissolving cup with holder, procaine tablets, 
sterile gauze, alcohol or gas flame, and a 10-cc graduate with straight 
sides. As this solution is to be injected into the patient it is abso- 
lutely necessary for it to be sterile. Any carelessness on the part of 
the assistant might endanger the life of the patient. The dental officer 
will state how many cubic centimeters of anesthetic solution he wants. 
If 3 cc are desired, three tablets of procaine hydrochloride are emptied 
from the little vial upon the sterile gauze. They should not be touched 
by the hands at any time. The use of cotton pliers is indicated in the 
handling of the tablets. Measure 3 cc of Ringer’s solution in the 
graduate and pour into a clean dissolving dish. Heat the solution 
over the flame until it reaches the boiling point. Drop into the solu- 
tion the three tablets of procaine and heat a little more until they are 
completely dissolved. The solution is now ready to be placed in the 
syringe. Since it is convenient not to remove the needles from the 
syringe once they are placed on, two syringes should be available, one 
having the 1%-inch needle, and the other syringe equipped with the 
1-inch needle. Take whichever syringe is indicated from the cabinet, 
and remove the little piece of wire that is placed through the needle. 
This is carefully laid to one side where it can be found again after 
the syringe has been used. Place the needle in the solution and draw 
up until the syringe is filled with anesthetic solution. Place the barrel 
of the syringe against the inside of wrist to test for temperature. 
The ideal temperature for the solution is about body temperature. 
The needle is then passed several times through the flame until 
it becomes slightly red in color. This can only be done with iridio- 
platinum needles, however, and if steel needles are used they should 
not be flamed. Hold the syringe so that the needle is pointing up- 
ward and slowly push the plunger until all the air has been expelled 
from the syringe. It is then handed to the dental officer or placed on 
the operating tray, taking precautions so that the needle does not 
touch anything. If this happens it is necessary to reflame the needle 
167 TM 8-225 
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MEDICAL DEPARTMENT 
before using. After the syringe has been used, the plunger is removed 
from the barrel, the wire is placed in the needle, and the entire syringe 
is placed in the sterilizer and boiled for a minimum of 15 minutes. 
After sterilizing, the syringe is assembled and placed back in the 
cabinet where it is ready to be used again. 
b. Cartridge-type syringes are now available, and if this type of 
local anesthetic equipment is in use in the clinic, the sterilization and 
preparation are much simplified. The anesthetic solution comes in a 
sealed glass cartridge which is placed in a sterile syringe with the 
needle affixed. The cartridge containing the sterile solution becomes 
the barrel of the syringe. In using this type of syringe, the needle 
and syringe must be sterilized immediately before the injection. The 
needles should be sterilized in a separate compartment and should 
not be touched by hand after sterilizing. These needles are rustless 
steel and should never be flamed. 
c. The syringe should be completely disassembled periodically, 
scrubbed, cleaned thoroughly, and a drop of light oil applied to the 
plunger bearing to assure its mechanical efficiency. 
194. Impression materials.—If an impression is to be taken, the 
necessary impression materials will be made available, depending 
upon the type of impression. If modeling compound is used, the 
assistant should place a pan of water over the fire and heat it until 
the water is just a little too warm to allow the hand to be kept in the 
water. Several cakes of modeling compound are laid on a clean towel 
beside the hot water. The tray that has been selected by the dental 
officer is oiled slightly over its outer surface. If a hydrocolloid mate- 
rial is used, it is necessary to heat the pan of water to the boiling point. 
After the tray has been selected and attached to the water connections 
of the unit by rubber tubing, the stick of hydrocolloid material is 
placed in the boiling water. The manufacturer’s directions are fol- 
lowed as to the length of time that it is to be heated, but it is usually 
about 8 minutes. The tube containing the softened material is re- 
moved from the hot water and placed in water that is lukewarm. The 
tube is kneaded between the fingers for a minute and then placed 
against the wrist to test the temperature. When it is warm but not 
uncomfortable it is ready to be taken into the operating room for use 
by the dental officer. 
195. Filling materials.—The mixing of the various dental fill- 
ing materials is one of the most important duties of the chair assistant. 
The durability and appearance of the filling will depend upon its 
proper manipulation during this stage. Several types of materials 
are used: gold, silver amalgam, oxyphosphate, copper amalgam, zinc 
168 TM 8-225 
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DENTAL TECHNICIANS 
oxide, silicate, gutta percha, etc. The filling materials that the chair 
assistant must prepare are known as plastics; that is, they are 
prepared and inserted while in a plastic stage and become hard 
after being placed in the tooth. This includes the amalgams and 
silicates which are known as permanent filling materials, and also 
oxyphosphate, zinc oxide, and gutta percha which are known as the 
temporary filling materials. 
196. Silver amalgam.—The most common type of material used 
is the silver amalgam. It consists of the powdered metal portion 
containing silver, tin, and copper. This is mixed with mercury in the 
proportion of seven parts of alloy to five parts of mercury by weight 
or according to the manufacturer’s directions. The mixture is placed 
in a glass mortar and triturated for 3 minutes or until the particles 
of metal have been thoroughly incorporated into the mercury. The 
mix is then placed in the palm of one hand and using the thumb of the 
other hand, it is thoroughly mixed until the material gives a slight 
metallic sound. Excess mercury should be expressed from the 
amalgam by the operator. 
197. Copper amalgam.—Copper amalgam comes in small pellets 
with the mercury already included in the material. The pellet is 
placed in a spoon and heated slightly over a flame until the amalgam 
becomes soft. It is then placed in a mortar and triturated as was the 
silver amalgam. The excess amalgam left after the filling is inserted 
may be saved and used again. 
198. Oxyphosphate of zinc cement.—Oxyphosphate of zinc 
cement can be used as a temporary filling material or as a cement for 
gold crowns and inlays. The consistency of the mix should vary 
slightly according to the use to which it is put. If it is to be used 
for cementing crowns and inlays, the cement should be of a rather thin 
consistency so that it will occupy a minimum of space under the filling. 
If it is to be used as a filling material it should be mixed a little heavier 
in order to obtain a greater degree of strength for the filling. The 
more powder used in the mix, the stronger the cement will be. The 
powder comes in various shades ranging from dark yellow to snow 
white. When the shade of the powder is determined by the dental 
officer three small portions of the powder are placed on a clean glass 
slab. Three or more drops of the phosphoric acid liquid are placed on 
the slab about 1 inch away from the powder. Using a small metal 
spatula, the powder is gradually incorporated into the liquid, adding 
small portions of powder at a time and spatulating thoroughly. If 
the powder is added too fast, the mix will become hard and unmanage- 
169 TM 8-225 
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MEDICAL DEPARTMENT 
able as the setting time will be decreased. Continue adding small por- 
tions of powder and spatulating with a rotary motion until the cement 
has a tendency to string out from the spatula when it is raised and 
then falling back, forming a little mound which retains its shape. A 
great deal of practice will be required before the proper mixture can 
always be obtained. The chair assistant should always mix the cement 
under the supervision of the dental officer until he has attained this 
proficiency. 
199. Silicate.—The silicates or synthetic porcelain filling mate- 
rials require the greatest care in mixing. There are so many variable 
factors which influence the silicates that the most rigid routine must 
be followed. The silicate powders come in numerous shades, each one 
having a number. The desired shade is determined by the dental officer 
from the silicate shade guide. The shade decided upon, the next step 
is to make certain that all the equipment necessary for the filling is 
ready. None of the materials such as glass slabs, spatulas, etc., should 
be used for any other purpose than for silicate fillings. The metal 
spatula for mixing and the plastic instruments used in inserting the 
filling in the tooth are made from a special alloy, either stainless steel 
or stellite. As the various powders may be mixed to give the exact 
shade desired, a special silicate shade guide is used on which are given 
the correct proportions of each powder to obtain this shade. Some 
of the shades will require an even mix of two powders and other shades 
will require one portion of one powder to two portions of another 
shade. Each silicate set contains a metal scoop used to determine the 
correct amount of the powder. This scoop has small spoonlike ends, 
one end smaller than the other. The small end is used to measure the 
powder when a mix calls for one portion of one powder to two portions 
of another powder. The larger end is used to measure the powder 
when the mix calls for equal portions of two powders. Depending 
upon the shade selected, the powder is measured as directed, and placed 
upon a clean, dry glass slab. A word of warning about the slab: In 
hot weather the slab should first be cooled with cold water and dried 
before attempting to mix the silicate. The ideal temperature is between 
65°and 75° F. Moisture of any sort will affect the strength of the final 
filling. The silicate set contains a box of celluloid strips. One or 
two of these strips are placed upon the operating tray. They will be 
used by the dental officer as a matrix in the insertion of the filling. 
Three full drops of the liquid are always used when the powder is 
measured out as directed. These three drops are placed on the glass 
slab about an inch away from the powder. Add about one-third of 
170 TM 8-225 
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DENTAL TECHNICIANS 
the powder to the liquid and spatulate for not more than 20 seconds. 
Add another third of the powder and spatulate for the same time. 
The final third of the powder is then added and the spatulation is com- 
pleted when the mixture has the consistency of soft putty. The entire 
mix should never be spatulated for more than 1 minute, and the spatu- 
lation should be done lightly, using a patting motion instead of the 
rotary motion used in mixing cements. 
200. Zinc oxide.—Zinc oxide and eugenol are used extensively as 
a temporary filling material because of their sedative action. Three or 
more drops of eugenol are placed on a glass slab. Enough zinc oxide 
powder is placed on the slab for that particular filling. The powder is 
incorporated into the eugenol with a metal spatula until it is thor- 
oughly mixed. The resultant mixture is rolled into a small ball and 
squeezed between two pieces of gauze, thus expressing some of the oil. 
When the mixture is of the proper consistency for insertion in the 
cavity, it is placed on the operating tray. 
Section VI 
DAILY KOUTINE IN CLINIC 
Paragraph 
General 201 
201. General.—a. If some routine schedule can be followed each 
morning before the actual work in the clinic begins, nothing will be 
overlooked and this daily, rather monotonous task will be made to pass 
quickly. Therefore the following schedule is suggested : In the morn- 
ing, thoroughly air the clinic; turn on appliances on units; start water 
running in the cuspidors; fill and start the sterilizer; start the air com- 
pressor; attend to the linen supply; fold towels and place them in 
cabinets; check spray bottles; have soap and towels at all wash basins; 
check paper towel and paper cup supply; assemble W. D., M. D. Form 
No. 79’s for the day’s appointments; if the type of work to be done is 
known, make the initial preparations for the first patient; have a clean 
gown in readiness for the dental officer; make a final check for dust. 
During the noon hour, sweep out the clinic; rearrange office, desk, and 
waiting room. At the end of the day, thoroughly clean and dust the 
clinic; rearrange office and waiting room; drain and clean the steril- 
izer; turn off all water, gas, and electricity; check and record all Form 
No. 79’s; record all changes in classification; file the day’s records and 
X-rays; empty all wastecans; get linen ready for exchange in the 
morning; and check all medicine bottles, refilling if necessary. 
171 TM 8-225 
201 
MEDICAL DEPARTMENT 
b. In addition to the routines mentioned, it is usually the duty of 
the dental assistant to close the office each evening. Elevate the chairs 
close and lock all windows, see that all water has been turned off. see 
that all electric switches have been turned off {it is especially important 
to make sure that the sterilizers are turned off), see that the safe is 
locked, and on the way out see that all doors are locked. 
172 TM 8-225 
202 
DENTAL TECHNICIANS 
Chapter 7 
RECORD CLERK. DENTAL SERVICE 
Paragraphs 
Section T. General duties and forms used 202-205 
II. W. D., M. D. Form No. 57 (Report of Dental 
Service) 206-207 
III. W. D.. M. D. Form No. 79 (Register of Dental 
Patients) 208-210 
IV. W. D.. M. D. Form No. 18b (Statement of Ex- 
penditure of Special Dental Materials) 211-213 
V. Daily work sheet 214 
VI. Hospital clinic records 215-219 
VII. W. D., A. G. O. forms 220-221 
VIII. Dental survey 222-224 
IX. Dental history of station 225—227 
Section I 
GENERAL DUTIES AND FORMS USED 
Paragraph 
Routine reports 202 
Other forms used 203 
Record of annual dental survey 204 
Appointment book 20.r> 
202. Routine reports.—There are three principal reports and 
records that are routinely required from all stations where a complete 
dental service is maintained. These are as follows: 
a. W. D., M. D. Form No. 57 (Report of Dental Service).—This 
is a report required monthly from every station where a dental sur- 
geon is on duty and from every tactical unit having a dental officer 
assigned. This report is signed by the dental surgeon, indorsed by 
the surgeon, and forwarded to higher authority in compliance with 
existing directives. It is explained in detail in section II. 
b. W. D., M. D. Form No. 79 (Register of Dental Patients).—This is 
the patient’s card, and one is made for each individual admitted 
to the dental clinic. These reports are filed permanently in the 
hospital and under present regulations are not forwarded. It is 
taken up in detail in section III, 
c. W. />., M. D. Form No. 18b (Statement of Expenditure of Special 
Dental Materials).—This form, together with Form No. 57, is for- 
warded monthly from all stations or commands having dental labora- 
173 TM 8-225 
202-205 
MEDICAL DEPARTMENT 
tory facilities. Where dental work is accomplished with only chest 
No. 60, M. D., as in the dispensaries of tactical units, this form need 
not be forwarded. It is explained in detail in section IV. 
203. Other forms used.—a. W. D., M. D. Form No. 65 (Dental 
Engagement Slip) is the appointment card. It should be given the 
patient for every appointment made for him at the clinic. The pa- 
tient should be instructed to give the card to his first sergeant imme- 
diately so that he will be excused at the proper time for the appoint- 
ment. A better way to arrange for appointments is to send this form 
through post headquarters to the individual’s organization. In this 
way it becomes an order for the individual to report at the dental 
clinic at the specified time. 
b. W. D., M. D. Forms Nos. 16a, 16b, 16c. and 16d are property 
forms and are all similar except that they are used for different pur- 
poses. Form No. 16a is a request for expendable medical property; 
Form No. 16b is a request for issue of nonexpendable medical prop- 
erty; Form No. 16c is a credit slip for nonexpendable property 
turned in to the medical supply officer; and Form No. 16d is a re- 
quest for exchange of nonexpendable medical property. These four 
forms are used when requisitioning property, turning in property, or 
exchanging property. They are initiated in the dental clinic and 
forwarded to the hospital medical supply officer for action. 
c. W. D., M. D. Form No. 124 (Prosthetic Case Record) is filled out 
in duplicate and mailed with each case sent to the central dental lab- 
oratory. W. D., M. D. Forms No. 123 (Label. Penalty) is merely an 
address sticker to apply to mailing cases when sending them to the 
central dental laboratory. These last two forms are obtained from 
the central dental laboratory. 
d. All other forms are obtained by the medical supply officer from 
the medical supply depot on semiannual requisition. 
204. Record of annual dental survey.—'This is a record of 
vital importance in the clinic. It is a complete roster of all military 
personnel of the command with their grade, age, organization, nativ- 
ity, length of service, and dental classification. The Army classifica- 
tion of I, II, III, IV is used, indicating relative urgency for dental 
treatment. The dental officer will explain exactly what is meant by 
these four classifications. 
205. Appointment book.—The appointment book is the dental 
officer’s work schedule. Record every appointment made; write 
plainly the grade, name, and hour. Always consult the dental officer 
about appointments, if possible, before making them. 
174 TM 8-235 
206 
DENTAL TECHNICIANS 
Section II 
W. IX, M. D. FORM NO. 57 (REPORT OF DENTAL SERVICE) 
Paragraph 
General 206 
Daily compilation of Form No. 57 207 
206. General.—Although Form No. 57 is rendered monthly, all 
the admissions, sittings, changes in classification, and work accom- 
plished must be recorded on the form daily so that at the end of the 
month the form will be up to date and will only need to be typed in 
good form to be completed. The method of daily recording the work 
on Form No. 57 from the patient’s cards is explained later in this 
section. The completed form will conform to the following; 
a. Paragraph 1.—State station or command to which assigned or 
attached for duty with its location. If the dental service is with a 
tactical unit, state the number and name of the division, regiment, or 
other unit with its location as the case may be. 
h. Paragraph 2.—Give the month or the beginning and end of 
period if less than the calendar month. This shoidd only cover a 
single calendar month. If the period is less than a month but ex- 
tending into a second calendar month, say from June 20 to July 3, two 
reports must be made out and forwarded, one from June 20 to June 30 
and another from July 1 to July 3. However, most dental clinics 
will be functioning indefinitely and reports will be made out for the 
whole calendar month each month. 
c. Paragraph 3.—The same as paragraph 1, plus any additional 
stations or commands which were provided regular and routine treat- 
ment. Others receiving treatment, Civilian Conservation Corps pa- 
tients or any other nonmilitary personnel should not be listed under 
this paragraph. 
d. Paragraph 4.-—(1) Admissions, routine, military.—Record total 
admissions of military personnel admitted for treatment as a routine 
procedure. 
(2) Admissions, emergency, military.—Record total admissions of 
military personnel admitted for the relief of pain or other intolerable 
conditions. A case may be admitted but once. If a case is not com- 
pleted during one calendar month, it is not recorded as an admission 
for the following month. If a case is discontinued, interrupted, or 
postponed for an indefinite period and the patient later returns for 
further treatment, it may be recorded as a new admission at the dis- 
cretion of the dental officer concerned who will be governed by the 
elapsed time and circumstances of the case. 
175 TM 8-235 
206 
MEDICAL DEPARTMENT 
(3) Siftings given, military.—Each visit of a patient to a dental 
office for treatment is considered a sitting. Sittings for purpose of 
examination should be recorded. 
(4) Others.—All three headings are to be divided into two parts. 
The admissions and sittings for Civilian Conservation Corps enrollees 
are entered in right-hand column so formed, and those for all “others” 
are entered in left-hand column so formed. 
e. Paragraph 5.— (1) Initial classification.—When an annual sur- 
vey or any other complete survey of the command covered by the 
report is made, the results of the survey are entered as the initial classifi- 
cation. Otherwise, the final classification of the previous monthly re- 
port is entered as the initial classification of the current report. When 
an initial classification resulting from a complete survey is entered, 
all previous tabulations in paragraph 5 will be dropped and a new 
tabulation will be initiated. 
(2) Additional classification.—Enter the results of any partial sur- 
veys covering personnel not present for previous surveys. Enter 
classification of personnel applying for treatment who have not been 
classified by survey. 
(3) Changes in classification.— (a) When a patient’s classification 
is changed as the result of work accomplished, enter in appropriate 
plus and minus columns. Example: A class I case which has been com- 
pleted to class IV will be entered as “1” on the minus line under class 
I and also as “1” on the plus line under class IV. 
(b) The total of the initial classifications, the additional classifica- 
tions, and the plus classifications should be entered on the line provided 
between the plus and minus lines. 
(4) Final classification.— (a) Subtract the figures in the minus 
columns from the totals of the initial, additional, and plus classifica- 
tions and enter these as the final classifications. 
(b) It is recognized that changes in personnel are frequent and 
that the classification will not be entirely accurate. However, certain 
valuable statistical data can be obtained from the figures given which 
will be relatively accurate. To obtain greater accuracy, the dental 
service under favorable conditions may be able to check the transfers 
of personnel from the station and drop those transferred from their 
surveys. Under the same circumstances all new arrivals could also 
be checked, surveyed, and listed under additional classifications. 
Wherever this procedure is established, those transferred permanently 
from the command should be dropped by entry below the final classifi- 
cation. Subtraction of these figures from the final classification fig- 
176 TM 8-225 
206 
DENTAL TECHNICIANS 
ures will then provide a corrected final classification which in* turn 
becomes the initial classification of the following month (fig. 116). 
5. CLASSIFICATION OF MILITARY PERSONNEL 
Class I 
Class II 
Class III 
Class IV 
Initial classification 
300 
600 
50 
400 
Additional classification 
40 
50 
5 
55 
Plus _ 
30 
2 
50 
Changes in classification* 
340 
680 
57 
505 
Minus 
42 
37 
3 
Final classification 
298 
643 
54 
505 
Transferred from command 
10 
20 
15 
Corrected final classification 
288 
623 
54 
490 
/, Paragraphs 6 and 7.—(1) These two parts of the form are re- 
corded from paragraphs 10 and 11 of Form No. 79, the patient’s card, 
a form which is completed for each patient recording the disease or 
injury and the operation performed. The manner in which this is 
accomplished is explained later in this section. 
(2) Most of the diagnoses and operations performed are self- 
explanatory as listed on the Form No. 57, but a few may be misinter- 
preted. Enter after “mandible edentulous” and “maxillae edentulous” 
only those cases for which replacements have been inserted during the 
current month. Thus, if 7 partial dentures replacing a total of 40 
missing teeth and 6 bridges replacing a total of 12 missing teeth were 
inserted during the month reported, the total after tooth missing 
should be 52. Do not enter teeth replaced by full dentures under 
tooth missing. 
(3) The dental clinic in which the impression is taken and the 
appliance inserted will take credit for such denture, bridge, or repair. 
(4) Divide the “others total” column into two parts in both para- 
graph 6 and 7 and enter CCC at the head of the right-hand column 
so formed. Record totals for Civilian Conservation Corps enrollees 
in this column and the totals for all “others” in left-hand column so 
formed. 
Figure 116. 
431511°—42 12 
177 TM 8-225 
206 
MEDICAL DEPARTMENT 
(5) In paragraph 7 restorations of a temporary nature should not 
be entered but should be considered as treatments. Thus, there should 
be no entry after “gutta percha” nor should “zinc oxide and eugenol” 
be entered as an addition to the column of restorations. 
(6) In the blank spaces under the last printed entry in paragraph 
7, a list of causes of extractions should be made. 
DUTY PERSONNEL 
8. COMMISSIONED 
Mean strength Assigned 
Number of dental officers on duty Attached Total days of duty 
9. ENLISTED 
Name 
Grade 
Special Qualifications 
Rating 
Efficiency 
Figure 117. 
g. Paragraph 8.—(1) Number of dental officers on duty.—fa) Due 
to the probable fluctuation of officers on duty both assigned and 
attached, particularly in the large clinics, only a figure showing the 
mean strength of each will be of value. Consequently, over “number 
of dental officers on duty” type the words “mean strength.” Then 
type two headings, “assigned” and “attached” (fig. 117). 
(b) To compute the mean strength for each group, add the num- 
ber of days each officer was assigned or attached to the organization 
during the month. Example: To compute mean strength of assigned 
officers in a clinic to which ten officers have been assigned during 
the month—five on duty the full month, two for 15 days, two for 10 
days, and one for 5 days. 
Computation: 
5X30-150 
2X15= 30 
2X10= 20 
IX 5= 5 
Total days = 6.8 mean strength 
178 DENTAL TECHNICIANS 
TM 8-225 
206-207 
(c) Repeat the same procedure to obtain mean strength of attached 
officers. 
(2) Total days of duty.—Take the total days figures from the 
computations used in determining mean strengths of assigned and 
attached officers and deduct days lost from duty. Example: In (1) 
above the total days figure for assigned personnel is 205. Assume 
that the figure for attached personnel was 150. Then the total as- 
signed or attached days was 355. One officer was sick in hospital 
10 days and one for 12 days. One officer was on leave of absence 
for 8 days. Thus, 30 days were lost from duty. 355 minus 30 equals 
325 days of duty. 
h. Paragraph 9.— (1) Enter permanently assigned enlisted person- 
nel only, as of last day of month. 
(2) Following last entry of assigned enlisted personnel type in: 
“Enlisted personnel attached from other units, mean strength.” 
(3) Next list all civilian personnel by occupation, that is, hygien- 
ists, chair assistants, dental mechanics, etc. 
(4) If space is insufficient, paste an additional sheet at bottom of 
page. When completed, fold upward over face of form carrying 
paragraphs 8 and 9. 
i. Paragraph 10.— (1) List all dental officers assigned to unit or 
units covered by the report giving grade, name, status (RA, Res, 
NG), duty performed, dates of leave, detached service, sick in hos- 
pital, etc. 
(2) Following last entry of assigned officer personnel, type in 
“Officer personnel attached from other units. 
(3) Record the amount of time devoted to purely instructional 
purposes by both officers and men. Example: 
Hours 
Instruction of officers 12 
Instruction of enlisted men 9 
(4) Record all conditions which interfere with or diminish the 
amount of professional service during the month such as lack of 
suitable equipment or supplies, lack of availability of military per- 
sonnel for treatment, or other adverse conditions. 
(5) For additional space, paste an additional sheet above the word 
“certificate” so that paragraph 11 and its contents are not per- 
manently covered. 
207. Daily compilation of Form No. 57.-—As was brought out 
in paragraph 206, the information on Form No. 57 must be kept from 
day to day, although the completed report is forwarded only once a 
179 TM 8-225 
207 
MEDICAL DEPARTMENT 
month. It was also stated that the information for Form No. 57 
was obtained from Form No. 79. The simplest and easiest way for 
the record clerk to obtain and record this information is as follows: 
a. Each officer will keep a daily work sheet on wffiich the officer 
records all of the diseases or injuries treated and the operations per- 
formed for each patient. 
h. At the end of the day the record clerk collects these daily work 
sheets from each officer and records the operations performed for that 
day upon each individual patient’s Form No. 79. 
c. On a Form No. 57, used for this purpose, each card (Form No. 79) 
is taken in turn, and the information from the card is recorded on 
the Form No. 57. 
d. The information transferred in this way completes paragraph 4. 
the changes in classification part of paragraph 5, paragraph 6. and 
paragraph 7. Each patient who has a card made out for him on that 
day is entered as a sitting. Each change in classification appearing 
on the cards is entered once as minus in the old classification and once 
as plus in the new classification. Paragraphs 10 and 11 on Form No. 
79 correspond, respectively, with paragraphs 6 and 7 on Form No. 57. 
All the notations under paragraphs 10 and 11 are transferred to para- 
graphs 6 and 7 on Form No. 57. The best way to record these admis- 
sions, changes in classification, cases diagnosed, and operations per- 
formed is by using small tally marks on the Form No. 57 for each entry 
on the patient’s card. At the end of the month these tally marks are 
added, and the total obtained is entered on the Form No. 57 which is 
to be forwarded. Figure 118 shows a Form No. 79 properly filled out 
and figure 119 shows paragraphs 6 and 7 of Form No. 57 with these 
data transferred. 
180 TM 8-225 
207 
DENTAL TECHNICIANS 
REGISTER OF DENTAL PATIENTS AT 
FORT BLANK, VIRGINIA 
(1) 
Surname 
(21 
Christian name 
Jones, 
Charles 
G.- 
15792486 
(3) Rank 
j (4) Company i 
(5) Regiment or Staff Corps 
Pvt. 
1 
B 
4th Engrs. 
(6) 
Age years 
(7) Race 
(8) Nativity 
(9) Service, years 
24 
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Charles F 
Smith 
Charles 
F. 
Smith, 
Maj or 
Dental Corps, 
[7. S. 
A. 
Form 79 
—Medical Department, U. S. A. 
(Revised Feb 
24, 1941) 
Figure 
118. 
181 TM 8-235 
207 
MEDICAL DEPARTMENT 
CASES DIAGNOSED AND OPERATIONS PERFORMED 
6. CASES DIAGNOSED 
7. OPERATIONS PERFORM 
ED 
NTS 
Diagnoses 
Patients 
Nature of operations 
Patie 
Military 
Others 
13 
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s 
1 
13 
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11 
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Is 
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1. Abscess, parietal 
i 
RESTORATIONS 
Amalgam 
Gold, foil. 
Gutta-percha _ _ . 
Inlay _ _ 
Inlay recemented 
Oxy phosphate 
Oxyphosphate and 
amalgam 
Root canal _ _ 
Silicate 
3 
1 
1 
-- 
2. Abscess, periapical 
3. Abrasion. 
4. Adenitis 
5. Ankylosis, bony. 
6. Ankylosis, fibrous 
7. Bridge, defective 
8. Calculus 
9. Caries _ 
5 
10. Cellulitis. 
11. Cleft-palate 
12. Crown, defective 
13. Cyst, dentigerous 
1 
14. Cyst, radicular 
15. Denture, defective 
16. Erosion. 
PROSTHESES 
Bridge (all types) 
Bridge, recemented. 
Bridge, repaired 
Crown (all types) 
Crown, recemented. 
Crown, repaired 
Denture (all types) _ 
Denture, adjusted.. 
Denture, re based 
Denture, repaired 
Splint.. 
17. Filling, defective 
18. Fracture of mandible 
19. Fracture of maxilla 
20. Fracture of tooth 
21. Gingivitis 
22. Hypercementosis 
23. Leukoplakia _ 
24. Malocclusion 
25. Mandible, edentulous 
26. Mandible, necrosis of 
27. Maxillae, edentulous. 
28. Maxilla, necrosis of 
29. Neuralgia, facial 
1 
30. Osteitis 
31. Osteomyelitis 
32. Periodontitis 
OTHER OPERATIONS 
Abscess, incision of. 
Alveolectomy _ 
Anesthesia, general 
1 
-- 
33. Periodontoclasia _ 
34. Periostitis 
35. Pulp, devitalization 
of 
36. Pulpitis._ _ - 
Anesthesia, local 
Apicoectomy 
— 
-- 
37. Sequestrum _ 
38. Sinusitis. 
Figure 119. 
182 TM 8-225 
207-208 
DENTAL TECHNICIANS 
6. CASES DIAGNOSED 
7. OPERATIONS PERFORMED 
Diagnoses 
Patients 
Nature of operations 
Patients 
Military 
Others 
Military, total 
Others, total 
Prmary 
disease 
Total 
Primary 
disease 
Total 
39. Stomatitis, apthous 
Calculus, removal of 
40. Stomatitis, catarrhal 
Examination 
41. Stomatitis, mercurial 
Fracture, reduction of 
42. Stomatitis, ulcerative.. 
Gingiva-alveolus, de- 
43. Stomatitis, syphilitic. 
bridement of 
Gums, excision of 
Gums, treatment of. 
1 
Figure 119—Continued. 
Section III 
W. D., M. D., FORM NO. 79 (REGISTER OF DENTAL 
PATIENTS) 
Paragraph 
Personal data 208 
Recording diseases and treatments 209 
Filing 210 
208. Personal data.—Form No. 79 is the individual patient’s 
record which remains on file in the dental clinic. When a patient re- 
ports at the clinic for the first time, a Form No. 79 is prepared for him 
before any dental operations are started. Uniformity in the prepara- 
tion of the form is very important. The patient’s last name, first name, 
middle initial, and Army serial number should be entered on the first 
line of the register in that order. On the second line the grade, com- 
pany, and regiment or arm or service are entered for enlisted per- 
sonnel ; the grade and arm or service will be entered for commissioned 
officer personnel. For all cards on others receiving treatment, this line 
will be used to record their connection with the Military Establish- 
ment, such as civilian employee, Quartermaster Corps; civilian, wife 
of major, Infantry; or civilian. WPA worker. On the third line, para- 
graph 6, the age at the nearest birthday is required. In paragraph 8 
the State or country, if other than the United States, in which the 
patient was born is entered. In paragraph 9, the years’ service is 
188 TM 8-225 
208-211 
MEDICAL DEPARTMENT 
entered as years and monthly fractions of a year such as 2%2, 3y12. 
etc. 
209. Recording diseases and treatments.—Paragraphs 10, 11, 
and 12 of this card are used to record the diseases treated and the opera- 
tions peidormed. The standard terms for diagnosis and the abbrevia- 
tions which are permitted are given in AR 40-1010. The date treat- 
ment is given is entered under paragraph 11, The year may be entered 
at the head of the column at the left side just above the first line (fig. 
118). Under paragraph 12 type of admission is entered, either routine 
or emergency, and the classification. Any subsequent changes in 
classification are also entered in this section. 
210. Filing.—When a patient is confined to quarters or hospital 
as a result of dental conditions, the dental surgeon will furnish the 
surgeon with a duplicate of the patient’s case record. Form No. 55E-5. 
When a patient is referred to a dental clinic by a medical officer for 
treatment, a duplicate of the patient’s case record, showing treatments 
given and operations performed, will be furnished the commanding 
officer of the hospital for incorporation in the patient’s clinical record. 
When space provided on the card is insufficient to complete the record 
of a case, an additional card will be fastened to it and entries continued 
thereon. The register cards will be kept in two hies, the current hie 
and the permanent hie. The current hie will consist of register cards 
of patients whose case records are not closed; the cards will be arranged 
alphabetically, according to the surnames of the patients. The per- 
manent hie will comprise all register cards of closed cases. The cards 
will be arranged alphabetically in the same manner as cards in the 
current hie. The permanent hie will be kept yearly, a new hie being 
started January 1 of each year. The cards of the old year’s hie will 
then be placed with the dental history of the station. 
Section IV 
W. D., M. D. FORM NO. 18b (STATEMENT OF 
EXPENDITURE OF SPECIAL DENTAL MATERIALS) 
Paragraph 
Where required 211 
System of weights used 212 
Preparation 213 
211. Where required.—This report is required from every mili- 
tary station or separate command where a dental clinic with labora- 
tory facilities is established and a dental officer is in attendance. It 
184 TM 8-225 
211-213 
DENTAL TECHNICIANS 
will be forwarded monthly in accordance with circular letter No. 61, 
S. G. O., June 16, 1941. 
212. System of weights used.—To understand this form one 
must first be familiar with the system of weights used in weighing 
gold. This system differs from the decimal system which is used in 
the accounting of funds, and therefore at first presents some difficulties. 
The scale used is as follows: 
24 grains = 1 pennyweight. 
20 pennyweight = 1 ounce. 
Form No. 18b makes provision for recording only pennyweight (dwt) 
and grains (gr). 
213. Preparation.—a. Heading.—The name of the station is 
entered on the top of the report preceded by the code number of the 
station. Code numbers have been assigned to all stations by the Chief 
of Finance. These numbers will precede the names of the stations 
on all papers pertaining to medical supplies (that is, 429—Fort Jay, 
N. Y.). 
b. Paragraph 1.—Enter the following under paragraph 1; name, 
grade, organization, nature of appliance, amount of gold used, and 
date of insertion of all appliances (for military personnel). In the 
description of the appliance, first the teeth replaced or repaired are 
entered (including surfaces involved for inlays) ; then the appliance 
constructed using authorized abbreviations. Examples: B4, mod 
Inlay, gold; R13, 14, 15, L13. 14. 15. Dtr. Pr. C/3 B/l. 
c. Paragraph 2.—Under paragraph 2 the same is accomplished for 
others entitled to treatment. 
d. Paragraph 3.—In paragraph 3, statement of materials, amounts 
of special materials on hand last report, amounts received, amounts ex- 
pended, and amounts remaining on hand at close of period will be 
entered together with such explanatory remarks as may be necessary. 
The report will be signed by the dental officer immediately responsible 
for the special dental materials. 
e. Computing weights.—In adding the columns of pennyweights 
(dwt) and grains (gr), it must be remembered to treat these columns 
separately. First, the grains column is added and the total is divided 
by 24. This will give the pennyweight and the remainder will be the 
number of grains. The remainder is entered as the grains total and 
the whole number is added in the pennyweight (dwt) column. One 
must keep in mind when computing or checking this report that he is 
not dealing with the decimal system and that 24 grains equal 1 
pennyweight. 
185 TM 8-225 
214-215 
MEDICAL DEPARTMENT 
Section Y 
DAILY WORK SHEET 
Paragraph 
Preparation 214 
214. Preparation.—The daily work sheet is not an officially 
designated dental record and no Medical Department form is fur- 
nished for its preparation. It is, however, a very important record 
and some form of work sheet is of great value. This record is made 
out at the chair at the completion of each sitting and serves as a 
temporary record from which Form No. T9 is made, and a permanent, 
easily tabulated record of work performed by each officer for any 
given period. A very satisfactory work sheet can be made locally, 
either mimeographed or printed on 8- by 13-inch paper. Lines 
should extend the length of the paper to form a space for each patient. 
Lines across the paper should divide it into columns for name, Army 
serial number, grade, organization, age, State of birth, length of serv- 
ice, diagnosis, treatment, and classification. These data should be 
complete on all new admissions and in addition should show whether 
the patient is a routine or emergency admission. At subsequent sit- 
tings only sufficient personal data to identify the patient’s card are 
necessary, but a complete diagnosis of conditions treated and opera- 
tions performed must be entered at each sitting. The data to fill out 
and complete Form No. 79 are taken from the daily work sheet, hence 
it is very essential that all entries are comprehensive and complete. 
Section YI 
HOSPITAL CLINIC RECORDS 
Paragraph 
General 215 
Forms used 216 
W. D., M. D. Form No. 55E-4 (Clinical Record, Dental Examination) 217 
W. D., M. D. Form No. 55E-5 (Clinical Record, Dental Record) 218 
Other forms 219 
215. General.—The clinical records of patients in military hospi- 
tals are probably the most important records for which the Medical 
Department of the Army is responsible. In addition to furnishing 
a valuable source from which statistical data may be obtained, they 
often form the basis for claims against the Government and other 
similar actions. For the protection of both the Government and the 
individual concerned, if for no other reasons, clinical records should 
be complete and accurate. 
186 TM 8-225 
216-219 
DENTAL TECHNICIANS 
216. Forms used.—The new clinical record forms are on type- 
writer size paper and compose a group of about 33 forms. Of these, 
W. D., M. D. Forms Nos. 55E-4 and 55E-5 are the dental forms. Every 
sheet of the clinical record must be authenticated by the officer pre- 
paring it. The first entry made in the record by any officer must be 
signed; subsequent entries may be initialed. The component parts 
of the clinical record are kept in the chart holder and in the correct 
order. The chart holder is kept in the ward office on the ward to which 
the patient is assigned. The clinical record should not be entrusted 
to the patient for delivery from one department or ward to another, nor 
should patients be allowed to read them. 
217. W. D., M. D. Form No. 55E-4 (Clinical Record, Dental 
Examination).—This form is a combined request for a report of a 
special examination and the finished report of that examination. The 
ward surgeon uses the top part of the front page of this form to refer 
patients to the dental clinic. The form is so arranged that the ward 
surgeon may indicate whether the patient has been referred for emer- 
gency or routine treatment, the elimination of dental foci, or for only 
examination and report and no treatment. This form may also be 
used to notify the dental service that a patient has been admitted for 
dental treatment only. The reverse side of this form is used by the 
dental officer when conducting his examination. The chart should 
be filled out using the key to indicate the conditions noted. All the 
findings or diagnoses determined as a result of the dental examination 
should be recorded in the order of their importance on the lower half 
of the front page. The form is then returned to the ward and becomes 
a part of the patient’s clinical record. In the event that a definite 
diagnosis cannot be determined immediately, this form should be re- 
turned to the ward with a tentative diagnosis and a list of the labora- 
tory tests, consultations, and other diagnostic procedures contemplated. 
218. W. D,, M. D. Form No. 55E-5 (Clinical Record, Dental 
Record).—This form is prepared by the dental service; a duplicate 
of Form No. 79 was formerly used for this purpose. It should contain 
a summary of the treatment rendered by the dental service together 
with the final diagnosis. In the cases where foci have been eliminated, 
the form is to be prepared in duplicate. The ward officer notes any 
improvement in the condition of the patient as a result of treatment 
and returns one copy to the dental service. The data so obtained are 
used to compile statistics. 
219. Other forms.—When the patient is hospitalized primarily 
for a dental condition, the dental officer will be responsible for more 
of the clinical record than the two purely dental forms mentioned 
187 TM 8-225 
219-222 
MEDICAL DEPARTMENT 
above. However, the record clerk, dental service, will not have to 
assist in preparing any other forms except Forms Nos. 55E-4 
and 55E-5. 
Section VII 
Paragraph 
W. D., A. G. O. Form No. 63 (Report of Physical Examination) 220 
W. D., A. G. O. Form No. 258 (Physical Record) 221 
W. D.. A. G. O. FORMS 
220. W. D., A. G. O. Form No. 63 (Report of Physical Exam- 
ination).—This form contains a section for dental examination. A 
chart of the teeth appears on this form, and a restorable carious tooth 
is marked by a circle around the number representing that tooth; a 
nonrestorable carious tooth is marked by a diagonal line; and a missing 
tooth is indicated by an X through the number representing the tooth. 
Bridges and dentures may be indicated on the chart by the symbols 
illustrated on the reverse side of W. D.. M. D. Form No. 79. 
221. W. D., A. G. 0. Form No. 258 (Physical Record).—This 
is a form which is filed with the enlisted man’s service record, but it 
should be brought to the dental clinic when the enlisted man reports 
for dental attendance. All routine dental operations and treatments 
must be recorded briefly on this form; it must be signed and dated by 
the dental officer. Abbreviations authorized in AR 40-1010 may be 
used on this form, and all dental operations should be described thereon 
as briefly as possible. 
Section VIII 
DENTAL SURVEY 
Paragraph 
Purpose 222 
Procedure 223 
Use 224 
222. Purpose.—The dental survey, the record of which is de- 
scribed in section I. is the process by which the dental efficiency of the 
group is determined. It serves for the group as does the dental exam- 
ination for the individual. By a study of the record of the dental 
survey, it is possible to make an accurate estimate of the dental needs 
of the command. It is the basis upon which the dental officer deter- 
mines those who should receive treatment and the priority in which 
they should receive it. It is for this reason an essential preliminary 
188 TM 8-225 
222-224 
DENTAL TECHNICIANS 
step to the institution of dental service for any command. The con- 
solidated results of a dental survey represent the estimate of the dental 
situation which must be met by the dental service. 
223. Procedure.—Dental officers serving with troops will some- 
times find that much time can be saved by surveying organizations in 
places other than the dental office. Generally the following procedure 
is followed: 
a. The organizations report at a designated place with two copies 
of pay roll roster on 8- by 10%-inch standard letter paper, which 
lists the grade, name, age, place of birth, and years of service of 
every man in the organization. 
h. The officer or noncommissioned officer in charge will form the 
men in single file as their names appear on the roster. 
c. A noncommissioned officer who knows most of the men in the 
organization by name will act as clerk during the survey. He is 
instructed to place the classification (I, II, III. or IV) before each 
man’s name as the dental officer indicates. Sometimes the survey- 
ing officer prefers to indicate relative urgency in a given classification 
by adding the symbols plus or double plus as the case may be. 
d. The dental officer stations himself with the enlisted assistant 
at a selected spot with the light, artificial or natural, coming from 
behind. 
e. A sufficient supply of wooden tongue depressors, mouth mirrors, 
explorers, and suitable means for sterilizing the mirrors and explor- 
ers in use is provided. 
/. Each man steps up before the dental officer and opens his 
mouth. The dental officer, usually with only the use of a tongue 
depressor, examines the mouth and indicates the classification of the 
individual to the clerk. 
g. At the conclusion of the survey, the dental officer directs the 
noncommissioned officer acting as clerk to make a list of all ab- 
sentees. It is arranged to have these report to the dental office at 
a designated time. 
224. Use.—Tlie completed dental survey is entrusted to the record 
clerk in the dental office who uses it to obtain data for the reports. 
The record clerk is responsible for changing the classification on the 
survey as the men come to the clinic for treatment. 
189 TM 8-225 
225-227 
MEDICAL DEPARTMENT 
Section IX 
DENTAL HISTORY OF STATION 
Paragraph 
General 225 
Composition 226 
Filing 227 
225. General.—Regulations require that a dental history be main- 
tained at each station in the zone of the interior where a dental offi- 
cer is on duty. The compiling and filing of this record will be one 
of the duties of the record clerk. 
226. Composition.—The dental history will consist of the re- 
tained copies of the reports and records (W. D., M. D. Forms Nos. 
57 and 18b) together with the following: 
a. Reports of dental opinions on clinics. 
h. Schedules of instruction for enlisted assistants. 
c. Memoranda recommended for incorporation in sanitary orders. 
d. Special reports and articles for publication. 
e. Such other data as are deemed pertinent. 
227. Filing1.—At the close of each month and upon completion of 
all reports required for the month, the retained copies of the reports 
will be filed, fastened together as “Dental History, Fort , 
for the month of ”. At the close of each calendar year 
an index of all items mentioned in the preceding paragraphs will be 
prepared and filed as an index to the dental history for that year. 
190 DENTAL TECHNICIANS 
TM 8-225 
Appendix 
LIST OF REFERENCES 
“Dental Anatomy”—Black, G. V. Philadelphia: S. S. White Co., 
1897. 
“Dental Anatomy”—Diamond, M. New York: MacMillan Co., 1935. 
“Practical Dental Anatomy and Tooth Carving”—Schwartz, J. R. 
Brooklyn : Dental Items of Interest Publishing Co., 1935. 
191 TM 8-225 
INDEX 
Acrylic resin : Paragraph Page 
Dentures 49 59 
Repair 58 66 
Splints 96 98 
Use 50 59 
Adjustable articulators 11 14 
Air compressor 190 164 
Alloy 15 18 
Alveolar process 15, 140 18, 137 
Alveolus 15 18 
Amalgam: 
Copper 197 169 
Silver 196 169 
Anatomy, regional 8-14 10 
Anesthetic solution 193 167 
Angles in X-ray technique 104, 105 106, 108 
Apex, root 15 18 
Apical foramina 140 137 
Appointments 192 166 
Apthous stomatitis 149 142 
Areas, relief in dentures 27 29 
Articulation, temporomandibular 11 14 
Articulators 11 14 
Assembling plaster impressions 19 24 
Atrophy of gingivae 153 142 
Autoclave 177 159 
Axial surfaces 15 18 
Bacilli 176 158 
Bacteria 176 158 
Bacteriology of sterilization * 176 158 
Band crown 66 72 
Bars: 
For partial dentures 72-78 80 
Lingual and palatal 78 86 
Bell crowned 15 18 
Bismuth stomatitis 150 142 
Biteplates 29 32 
Boxing impressions 20, 24 25, 27 
Bridge, fixed 68-71 75 
Buccal surface 6 8 
431511°—42- 13 
193 TM 8-225 
INDEX 
Paragraph Page 
Buccinator muscle 142 139 
Burs 185 163 
Calculus 156 143 
Care: 
Dental clinic 173, 174 156, 157 
Mouth and teeth 168-170 152 
Caries 143, 144 139, 140 
Cartridge-type syringe 193 167 
Cast clasps 77 85 
Casting: 
Dental 59-62 66 
Investment 62 67 
Partial dentures 93 95 
Cast occlusal crown 66 72 
Casts; 
Mounting on articulator 30 33 
Partial dentures 79 87 
Pouring 21 26 
Separation 22, 25 26, 28 
Cement 198 169 
Cementum 15, 140 18, 137 
Chair assistant 171, 172 155, 156 
Clasp: 
Cast 77 85 
Crib 76 85 
For partial dentures 72-78 80 
Repair of loose, 54 64 
Wrought 73 82 
Classification of patients 206 175 
Cleft palate 3 5 
Clinic, care and cleaning 173-174 156 
Cocci 176 158 
Compound impressions 23 27 
Contact point 15 18 
Copper amalgam 197 169 
Cresol 178 159 
Crib clasp 76 85 
Crown: 
Band 66 72 
Cast 63-65 71 
Die 64 71 
Three-quarter 63 71 
Crown and bridge cement 198 169 
Cusp 15 18 
Cutting edge 15 18 
Daily work sheet 218 187 
Darkroom, X-rav 131 131 
194 TM 8-225 
INDEX 
Paragraph Page 
Deciduous teeth 15 18 
Dental— 
Burs 185 163 
Caries 143 139 
Engine 186 163 
Floss 164 150 
History 225-227 190 
Hygiene 139 137 
Hygienist 139 137 
Lathe _ 188 164 
Survey 222 188 
Dentine 15, 140 18, 137 
Denture: 
Acrylic resin 49 59 
Base, trial , 28 30 
Duplicating 57 65 
Flashing 44, 45 52, 53 
Polishing 48 58 
Rebasing 56 65 
Refacing 55 64 
Repair 51-58 62 
W axing 43 51 
Depressor muscles 142 139 
Designing partial denture 81 88 
Digastric muscle 142 139 
Disclosing solution 165 150 
Diseases of mouth 145-153 141 
Distal surface 6 8 
Embrasure 15 18 
Enamel 15 18 
Engine and handpiece 186 163 
Equipment, care 182 161 
Eugenol 200 171 
External pterygoid muscle 12, 142 16, 139 
Extra-oral roentgenography 126-129 125 
Facial _ 15 18 
Facial surface 6 8 
Filling materials 195 168 
Films, X-ray 100 103 
Fissure 15 18 
Fixed bridge 68-71 75 
Flashing 44-45 52 
Floss, dental 164 150 
Foramen: 
Anterior palatal 9 11 
Definition 15 18 
Posterior palatal 9 11 
195 TM 8-235 
INDEX 
Paragraph Page 
Formina. See Foramen. 
Forceps, care 187 164 
Forms; 
A. G. O.: 
63 220 188 
258 221 188 
Medical Department: 
16a, b, c, d 203 174 
18b 211-213 184 
55E-4 and 55E-5 216 187 
57 206, 207 175, 179 
65 203 174 
79 208-210 183 
Fossa 15 18 
Frenum: 
Labium inferioris 13 17 
Labium superioris 13 17 
Linguae 13 17 
Gargle 170 153 
Genioglossus__ 142 139 
Geniohyoid muscle 142 139 
Gingiva. 15, 140 18, 137 
Gingival 
Atrophy 153 142 
Line 15 18 
Margin 140 137 
Gingivitis 151, 152 142 
Glenoid fossa 11 14 
Gold: 
Heat treatment 75 84 
Report 211 184 
Green stain 157 143 
Groove 15 18 
Gum 140 137 
Hand instruments 184 162 
Handling patients 192 166 
Handpiece 186 163 
Heat treatment, gold 75 84 
History, dental 225-227 190 
Hospital clinic records 215-219 186 
Hydrocolloid impressions 26 28 
Hygiene 139 137 
Hypertrophic gingivitis 152 142 
Hypodermic syringes 180 160 
Impression: 
Boxing 20 25 
Hydrocolloid 26 28 
Materials 17 194 23, 168 
196 TM 8-225 
INDEX 
Paragraph Page 
Incisal surface-- 6 8 
Inclination 15 18 
Instrumentation 160 145 
Instruments 158, 184 144, 162 
Intensifying screen 103 105 
Internal pterygoid muscle 12, 142 16, 139 
Interproximal embrasure 15 18 
Interproximal space 15 18 
Intra-oral X-rays 104-125 106 
Investing, partial denture pattern 92 95 
Kilovoltage, in X-ray 102 104 
Labial surface 6 8 
Lathe 188 164 
Lingual— 
Bars 78 86 
Surface : 6 8 
Lysol 178 159 
Malocclusion : 141 138 
Mandible 10 13 
Marginal ridge 15 18 
Massage of gums 167 152 
Masseter muscle 12, 142 16, 139 
Mastication 142 139 
Median line 5, 15 7, 18 
Medicaments 183 161 
Mesial surface 6 8 
Microbe 176 158 
Milliamperage, in X-ray 102 104 
Mirror, mouth 158 144 
Model, duplication 87 92 
Modeling compound impressions 23-25 27 
Monthly reports 206 175 
Mounting casts on articulator 30 33 
Mouth 2-15 4 
Mirror 158 144 
Mouthwash 170 153 
Mucin .. 155 143 
Mucous membrane. 3 5 
Muscles 12, 142 16, 139 
Neck, tooth 15 18 
Needles, hypodermic 180 160 
Nerve, tooth 140 137 
Oblique ridge 15 18 
Occlusal: 
Rests 74 83 
Surface 6 8 
197 TM 8-225 
INDEX 
Paragraph Page 
Occlusion 141 138 
Oxy phosphate cement 198 169 
Packing the case 46 54 
Palate r 3, 9 5, 11 
Paradentosis 146 141 
Partial denture: 
Cast 79 87 
Casting 93 95 
Design 81 88 
Flashing 45 53 
Investing 92 95 
Spruing 91 94 
Waxing , 90 93 
Periodontal diseases 145 141 
Periodontoclasia 146 141 
Personal hygiene 172 156 
Physical record 221 188 
Physiology, mouth and teeth 140-142 137 
Pickling 62 67 
Pit 15 18 
Plaster impressions 18-22 24 
Platysma muscle 142 139 
Polishing, oral hygiene 163 149 
Porcelain, synthetic 199 170 
Pouring of casts 21 26 
Precautions, in X-ray 102 104 
Processing X-ray films 130-138 131 
Prophylaxis 158-161 144 
Prosthetic dentistry 16 22 
Prosthodontia 16 22 
Protozoa 176 158 
Proximal surface 15 18 
Pulp 140 137 
Raphe, palatal 9 11 
Rebasing dentures 56 65 
Refacing dentures 55 64 
Regional anatomy 8-14 10 
Register of dental patients 208-210 183 
Relief areas 27 29 
Report: 
Dental service 206, 207 175, 179 
Physical examination 224 189 
Root canal 140 137 
Routine, clinical 201 171 
Rubber packing 46 54 
Rugae 9 11 
Rules of sterlization 178 159 
198 INDEX 
TM 8-225 
Paragraph Page 
Saliva 142, 154 139, 142 
Sanitation 181 160 
Scalers 168 144 
Separation of casts 22 26 
Septum - 16 18 
Silicate 199 170 
Silver splints 97 99 
Slab, care 187 164 
Solutions, X-ray 137 132 
Splints 94-97 96 
Stain 167 143 
Staphylococcus 176 158 
Statement of expenditure of special dental materials 211-213 184 
Sterilization 175-181 158 
Sterilizers 177 159 
Stomatitis 148-150 141 
Streptococcus 176 158 
Structure, mouth 3 5 
Styloglossus 142 139 
Sulcus 16 18 
Supplemental groove and ridge 15 18 
Supplies, care 182 161 
Survey, dental 222-224 188 
Surveying model 82 89 
Synthetic porcelain 199 170 
Syringes, hypodermic 180, 193 160, 167 
Systemic cause of caries 144 140 
Tartar 166 143 
Teeth: 
Added to denture 53 64 
Arranging 33—41 36 
Arranging upper anteriors 33 36 
Artificial, selection 31 35 
Broken or loose on dentures 52 63 
Central dental laboratory assortment 42 48 
Classification 4 7 
Loose, in dentures 52 63 
Roots 7 9 
Setting up 33-41 36 
Structure 140 137 
Surfaces 6 8 
System of naming and numbering 5 7 
Telephone calls 192 166 
Temporal muscle 12, 142 16, 139 
Temporomandibular roentgenography 128 127 
Tongue muscles 142 139 
Tooth: 
Brushing method 166 151 
Forms 32 35 
199 TM 8-225 
INDEX 
Tooth—Continued. Paragraph Page 
Nerve _ 140 '137 
Paste 169 153 
Powders 169 153 
Torus palatinus 14 18 
Transverse ridge 15 18 
Trial denture base 28 30 
Tripoding 86 91 
Trubyte teeth 42 48 
Tubercle 15 18 
Uvula 3 5 
Vincent’s stomatitis 148 141 
Voltage in X-ray 102 104 
Vulcanite splints 95 96 
Vulcanization 47 57 
Vulcanizer 189 164 
Wax pattern _ 60,61 67 
Waxing 43,90 51,93 
Wrought clasps 73 82 
X-ray: 
Bite wing 107 110 
Darkroom 131 131 
Extra-oral 126-129 125 
Films : 100 103 
Intra-oral 104-125 106 
Machine 99 103 
Occlusal 119 120 
Physics 102 104 
Processing 130-138 131 
Solutions 137 132 
Temporomandibular joint 128 127 
Zinc oxide 200 171 
[A. Q. 062.11 (10-7-41).] 
By order of the Secretary of War : 
G. C. MARSHALL, 
Chief of Staff. 
Official : 
E. S. ADAMS, 
Major General, 
The Adjutant General. 
Distribution : 
X. 
(For explanation of symbols see FM 21-6.) 
200 
For sale by the Superintendent of Documents, Washington, D. C. 
U. S, GOVERNMENT'PRINTING OFFICE: 1942