[American Library of Dental Science.] 
ANATOMY 
OF THE 
DENTAL SYSTEM, 
HUMAN AND COMPARATIVE. 
BY PH. FR. BLANDIN. 
SURGEON OF THE HOTEL DIEU, ASSOCIATE PROFESSOR OF THE FACULTY OF MEDICINE OF PARIS. 
Translated from the French, for the American Journal of Dental Science, 
ROBERT ARTHUR, D. D. S. 
BALTIMORE: 
PUBLISHED BY THE AMERICAN SOCIETY OF DENTAL SURGEONS 
JOHN W . WOODS, PRINTER. 
1845. INTRODUCTION. 
The recent progress of comparative anatomy has rendered it 
very difficult to give, what has not yet been satisfactorily done, 
an exact definition of the teeth. To say with Beclard, that they 
are little bones, implanted in the alveoli of each jaw, would be 
to confine ourselves within too narrow limits; this definition not 
embracing the teeth of some animals; as, for instance, the pala- 
tine and pharyngeal teeth of fishes. On the other hand, to 
adopt the definition of more modern zoologists, and call the teeth 
opposing bodies, placed at, or near, the entrance of the alimentary 
canal, for the purpose of seizing and grinding the food, would 
be to fall into an opposite difficulty, and to confound with the 
teeth, parts which have, perhaps, little analogy to them; the 
greater part of the masticatory organs of the invertebrated 
animals. 
Obliged, however, to characterise my subject, at the outset, I, 
at once adopt the definition of Cuvier, and call the teeth: "me- 
chanical instruments, harder than the bones, placed in verte- 
brated animals, at the entrance of the alimentary canal, and des- 
tined to seize and separate the nutritive substances, or to serve 
as means of attack and defence." 
Circumscribed, even in this manner, the natural history of 
the teeth is still a subject of considerable extent, and embraces, 
in man, and in the series of animals, a great number of facts, 
which, notwithstanding the differences they appear to present, 
at first sight, are reconciled to each other by remarkable analo- IV 
INTRODUCTION. 
gies. We are enabled to study them in two manners, essen- 
tially distinct; either to take up the human anatomy as a start- 
ing point, examine, first, the dental system of man, and then 
comparing with it that of the inferior animals ; or to take up the 
general consideration of the subject, and, then examine, particu- 
larly, the dental organs of each class. 
The first of these methods which I shall adopt, is, doubtless, 
more extended, more attractive, and more philosophical than the 
other, I shall not forget, however, that the human organization 
is of primary importance, and that all facts in comparative 
anatomy should be made to assist in its elucidation. In treating 
my subject, I shall proceed in the following manner: First, I 
shall give a sketch of the history of the anatomy of the human 
dental system; 1 will examine, cursorily, the dental system in 
general; then describe, with the greatest care, the teeth of the 
human species, and conclude by showing the modifications pre- 
sented by these organs in the whole series of inferior animals. ANATOMY OF THE DENTAL SYSTEM. 
PART I . 
HISTORICAL SKETCH OF THE ANATOMY OF THE TEETH. 
There are few subjects connected with the science of medi- 
cine, to which so much attention has been given, as the one we 
propose to take up; what has already been written and publish- 
ed, with regard to it, could scarcely be contained in two hun- 
dred volumes. But are we to conclude, on this account, that all 
useful information with regard to it has been given, and that 
the matter has been exhausted? Certainly not. Much yet 
remains to be said upon this interesting subject, and there 
is more than one doubt to clear up, more than one difficulty to 
solve. Will it be objected to this undertaking, that our libraries 
are, already, overcharged with an immense quantity of super- 
fluous works ? What signifies the number ? What does it matter, 
if each dentist, past and present, has believed it his duty to 
write a volume, and to publish his lucubrations to the profes- 
sion? What does it signify, if each of them, in one of those 
accessions of self-satisfaction, so common amongst authors, 
may have had the presumption to believe that he had, finally, 
discovered the last secret of the dental organization ? It has 
always been the case that this boasted wealth of discovery is 
nothing but pretension. To obtain any adequate idea of the 
slow progress of discoveries in the natural history and anatomy 
of the teeth, it would be necessary, as 1 have been compelled 
to do, to traverse the eternal succession of treatises, essays, 
and rebutting compilations, which have succeeded each other 
with a desperate constancy, from the infancy of the science down 
to the present time, and with the microscope of history in hand, 6 
HISTORICAL SKETCH OF THE 
to search out the smallest truths, amidst an endless and confused 
mass of absurdities. But what has struck me most forcibly in 
these historical researches, is the constancy with which real 
discoveries, have been, successively, combatted and repulsed by 
errors which have taken their places. Thus, for instance, Fal- 
lopius and Eustachius, those skilful correctors of the illu- 
sions of Vesalius,-indicated the true characteristics of the 
structure and developement of the teeth, yet their fine research- 
es were scarcely noticed in their day; and we are now compelled, 
after nearly three centuries of useless controversy, to return almost 
to the point whence they started. 
We shall find, in the course of this historical exposition, 
many, as they are now regarded, novelties, the origin of which is 
of very ancient date,-discoveries with a very numerous paterni- 
ty,-children born before their pretended fathers. 
That this historical sketch may have some degree of order, 1 
will divide it into several periods, which will give the mind of 
the reader time to repose, and will enable me to support, with 
more ease, the ennui consequent upon researches which are not 
without labor and difficulty. 
PERIOD I. 
FROM AN INDEFINITE TIME IN THE DISCOVERIES OF EGYPT, 
CHINA AND GREECE, TO ARISTOTLE. 
According to Herodotus the dental art amongst the Egyptians, 
from the most ancient period, was reserved to a particular caste, 
which gave to it exclusive attention. 
In a report of the examination of a mummy, communicated 
by M. Villeteau to M. Sylvestre de Sacy, it is stated that the 
teeth, although they appeared to have been worn by mastication, 
and had lost their cutting edges, seemed to have escaped disease, 
and were, otherwise, in a good state of preservation. He men- 
tioned also, as a remarkable fact, that the Egyptians of the 
present day have very fine teeth, and preserve them, in good 
condition, to the most advanced periods of life. ANATOMY OF THE TEETH. 
7 
To this meagre result is reduced all my researches in the pre- 
tended anatomical knowledge of the learned sages of Egypt, 
this old cradle of the sciences; and even for these facts it has 
been necessary to make a demand upon the silent tomb. 
The records of this period of China, throws but little light upon 
our subject. It is not surprising, indeed, that a people, who re- 
garded the dissection of a dead body as an unheard of cruelty, 
and for whom the human bones were a frightful spectacle, 
should have made few advances in anatomy. They have, how- 
ever, classed animals, after their external characteristics, and the 
teeth have furnished useful data in this first attempt at a zoologi- 
cal division. 
Nothing of consequence is to be found in the first annals of 
Greece, with regard to the subject in question; nearly every 
thing has been destroyed by time. And all that I find remarkable, 
in this long series of ages, is, the philosophical definition which 
Homer has given of the teeth, which he calls "little barriers, so 
placed by nature, as to prevent the rambling of the tongue, and 
the abuse of speech." It must also be stated, that Eristratus 
mentions an extracting instrument, of lead, which was suspend- 
ed in the temple of Apollo, to indicate that skill, rather than 
force, was necessary for the extraction of the teeth, as, when 
proper means were used they were unable to resist even so 
fragile an instrument. 
We must come down to the times of the Greek philosophers to 
find any real indications of a knowledge of the teeth ; and we have 
gathered in the works of Hippocrates all the ideas which were 
then held. It is very extraordinary, however, that Alcmeon of 
Crotona, who had a knowledge of the existence of the tympanum 
of the ear; Democritus, who dissected the brain for the purpose 
of finding the seat of madness ; and Empedocles, who, accord- 
ing to Plutarch, had found in the temporal bone, a body in form 
like a snail, should have had no more exact knowledge of the 
teeth, than what has been transmitted to us by the physician 
of Cos. 
Hippocrates said:-Frigidum inimicum ossibus, dentibus, 
nervis, cerebro, dorsali medulce; calidum verb amicum. Some 
authors contend that Hippocrates, in this aphorism, has made 8 
HISTORICAL SKETCH OF THE 
a distinction between the teeth and the bones; but it appears to 
me to be a strained inference. It is more probable, that he wish, 
ed to indicate that the teeth, amongst the bones, were more par 
ticularly affected by the action of cold; indeed, he removes all 
doubt with regard to this point, himself, for, in other aphorisms, 
he distinctly calls the teeth, bones. 
He has dwelt, particularly, upon the phenomena of denti- 
tion ; and upon the disorders of which they are the causes. He 
has also spoken of the symptoms furnished by the teeth in some 
maladies ; and what is more remarkable, in an anatomical point 
of view, has stated, that the germs of these organs are developed 
in the foetus. He called the wisdom-teeth awtppovwpig and was 
of the opinion, in which he has been sustained by many 
authors, since his time, that a great number of teeth is a sign of 
longevity. He believed, also, that the setting on edge of the 
teeth, of a pregnant female, was a symptom of superfoetation. 
PERIOD II. 
FROM ARISTOTLE TO GALEN. 
Aristotle, that superior genius, whose anatomical knowledge 
was so extraordinary for the age in which he lived, is the first 
who has devoted a chapter, of any length, to the consideration 
of the teeth. He is the first writer that treats of them in an 
extended and philosophical manner, and examines them in rela- 
tion to their comparative anatomy. 
This chapter, it is true, contains many gross errors, but it will 
be found not the less worthy of attention, when it is remem- 
bered that Aristotle wrote three hundred and fifty years before 
the Christian era. The progress of this branch of anatomy will 
be better appreciated by giving, at this place, a general view of 
the opinions advanced by him. 
Aristotle noticed that there were marked differences between 
the human teeth and those of the inferior animals, and between ANATOMY OF THE TEETH. 
9 
the different species of the latter. All the viviparous animals, 
according to him, have teeth, but not always an equal number 
in each jaw. In horned animals, the anterior upper teeth are 
wanting, which arrangement is also to be found in some animals 
without horns, as the camel. Some animals are furnished with 
tusks, (des dents saillantes) en dehors as the boar; in some, as the 
lion, panther, dog, &c., they resemble the teeth of a saw, in 
others, the surfaces are flat, as in the horse, ox, &c. No animals 
have at the same time tusks and horns, and those which have 
their teeth arranged like the teeth of a saw, have neither tusks 
nor horns. The front teeth are generally more pointed than 
those in the posterior part of the jaw ; the teeth of the seal, how- 
ever, are all pointed as if to indicate that this animal formed the 
connecting link between quadrupeds and fishes. No animals, 
he says, have a double range of teeth in the same jaw, although 
Ctesias would have us believe that there exists in India an 
animal called Martichore, which has a triple range. 
Aristotle considered the tusks of the elephant positively as 
teeth. He said, also, that the anterior teeth, only in man, were 
shed ; that the molares were never changed in any known ani- 
mal ; that none of the teeth of the hog were shed ; that the age 
of many animals is indicated by their teeth, which assume a 
blackish color as the animal grows old; he mentions the teeth 
of the horse, however, as an exception to this general rule, as 
they become, on the contrary, white with age. That animals 
with pointed teeth, have, generally, a very large mouth. 
Aristotle believes, with Hippocrates, that those animals which 
have a great number of teeth, live longer than those which have 
them in small numbers, and separated. He remarked, also, that 
men have more teeth than women ; which arrangement, he said, 
is found to exist in the females of some animals, as the sheep, 
the she-goat, and the sow. It is difficult to conceive how an 
error like this could have been advanced by such an anatomist 
as Aristotle, and we are forced to conclude, either that his text, 
has been altered, or that he was, as some authors have thought, 
merely the historian of the anatomical discoveries of his time, 
and had never himself, made dissections. 
He considered the beaks of birds as representatives of their 10 
HISTORICAL SKETCH OF THE 
teeth, and as analogous to the horns and nails of animals ; a 
strange contradiction, however, he says, that the teeth are of 
the same nature as the bones, (°i 5* oSovtej xara rw ruvoaGwv uat fvaiw.) 
with this exception, that the former possessed the power of repro- 
ducing themselves. 
From Aristotle to Galen, this branch of anatomy made very 
little progress ; it is probable, however, that Herophilus and 
Erasistratus, those bright ornaments of the Alexandrian school, 
did not allow this subject to pass without throwing some light 
upon it; but, if they have given it any attention, the result of 
their labors have not reached us. From what has been said by 
Celsus, of the diseases of these organs, and the operations prac- 
tised upon them; and from the advice given by Archigeneus, 
to perforate the tooth with a little trepan, when painfully affected, 
it is evident that they had made some advances in the anatomy 
of the teeth, and understood something of their structure. 
We perceive, at once, the depth of the knowledge of Areteus 
with regard to the structure of the teeth, when we find him say- 
ing, that God only knows the cause of tooth-ache. 
Pliny, the universal compiler and narrator of fables, as he has 
been called, was more of a historian than anatomist, and has 
not progressed farther than Aristotle; he has only added some 
more errors and many anecdotes, more or less absurd, in relation 
to this subject. He says, for instance, that the human teeth con- 
tain a mischievous poison, and that their bite is capable of 
producing the death of weak animals. The presence of two 
canine teeth on the right side, was considered by him, the presage 
of success in life. He relates, that the soldiers of the army of 
Germanicus Caesar,whilst they were encamped in Germany, lost 
all their teeth by drinking, for two years, of the sweet waters of 
a fountain to which they had access. He cites a great number 
of instances of varieties of forms, observed in the human 
teeth. Hercules, he says, had a triple range of teeth ; the sons 
of Prusias, Curias, and Papyrius, whose history is so familiar, 
are also mentioned;-they were born with teeth, on which ac- 
count, they were called the Dentati. He mentioned instances 
of the developement of palatine teeth and other anomalies. 
, Aristotle said, that those animals which were not furnished ANATOMY OF THE TEETH. 
11 
with front teeth, to serve as defensive weapons, had horns, as a 
sort of compensation ; but Pliny, with reason, denies the truth 
of this statenicus and instances the kind which has neither. 
PERIOD III. 
FROM GALEN TO VESALIUS. 
Galen, rich in the labors of his predecessors, particularly the 
Alexandrians, gives a better description of the teeth than any 
one who wrote before his time. He states that they are formed 
during gestation, but remain shut up in the alveoli until the pe- 
riod of birth; that the superior molar teeth have three roots, 
whilst those of the inferior jaw have but two; and says, that 
the canine were designated eye-teeth, because they 
received branches of a nerve which goes, also, to the eye. 
He has written a long chapter upon the forms, the functions, 
and the evolution of the teeth, which he believed to be true 
bones : in ossium numero dentes habendi sunt, etsi secus nonnuli 
sophistce arbitrentur. As he confined his dissections to the 
inferior animals, he gives to the human system parts which do 
not belong to it, for instance, the inter-maxillary bones. He 
believed that the teeth are not endowed with sensibility, 
and gives for proof: Qw®re utriusque doloris sensum ex- 
pertus, alium quidem gengivis, alium ipsius dentis substantia 
esse non dubito. He relates the circumstance of a number of 
slaves, who, after having had their teeth extracted, with violence, 
died of convulsions. 
The teeth, says Actius, are perforated at the extremities of 
their roots, and these openings give passage to filaments coming 
from the fifth pair of nerves, or trigemini; in consequence of 
which, they have a higher degree of sensibility than the other 
bones. These remarks already approach nearer the truth than 
any others with which we have met, and certainly do honor 
to their author, when the remote period at which he wrote is 12 
HISTORICAL SKETCH OF THE 
taken into consideration. This author believed, also, that the 
teeth continued to grow till old age, by the deposition of a ner- 
vous fluid which is secreted in the interior; but at that period 
of life this process of nutrition ceased, the teeth become loose 
and fall out. 
Rhazes described the phenomena of dentition, but in a very 
imperfect manner. What is most remarkable, with regard to 
him, is, that he opposed, according to Sprengel, the use of hard 
bodies, sometimes placed in the hands of infants, to assist first 
dentition, and proposed the substitution of frictions upon the 
gums. 
Avicenne made no more additions than the preceding author, 
to the store of knowledge already accumulated with regard to 
this subject; he was a servile follower of Galen, was able to see 
nothing but what had been discovered by that anatomist; as he 
was easily satisfied, therefore, he did not make great advances. 
Abulcasis was the first who attempted to supply the loss of 
the teeth, by the insertion of others, either human or artificial, 
and he states that it requires a great deal of skill to succeed. I 
have cited this fact on account of its relation to dental physiology, 
and, as I do not wish to return to the subject, I will break in 
upon the chronological order, I had determined to observe, and 
state here, that Ambrose Pare has related the first instance, at 
all authentic, of the successful transplantation of the teeth : "A 
man worthy of credit," he says, "affirmed to me, that a princess 
having had a tooth extracted, had another taken from the mouth 
of one of her maids, and placed in the cavity from which her 
tooth had been taken; after the lapse of some time she was able to 
use it with as much ease, and it was as useful to her as the one 
she had lost. This, however, did not come under my own 
observation." 
Benedictus mentions cases of teeth developed in the palate, 
but has left nothing worthy to be cited. 
Paracelsus considered the premature developement of the 
teeth as anomalous, and called those children, which were born 
with teeth, monsters. 
Fracassator is among the first writers who have indicated the 
sympathetic connection between the ear and the teeth. Si- ANATOMY OF THE TEETH. 
13 
militer esti cutus valde. sit sonus et stridulus, applicationis vim 
patitur membrana auditus ; et quasi ista offenditur, unde contra- 
Kitur repente ac cum easimulet nervuli quidam usque ad radicem 
denlium, in quern locum incidens subito novus ae horrorem quem- 
dam circa dentes facit. 
PERIOD IV. 
FROM VESALIUS TO HARVEY. 
Vesalius did not study the teeth with the same care which 
he gave to the other parts of the body, and he has, consequently, 
left nothing which we can usefully transcribe here ; he gave a 
description of the teeth, but it was very short, and without im- 
portance. He believed them to be analogous to the bones, from 
which they differed, in being uncovered, and each possessing a 
particular sensibility derived from a nervous filament received 
by the root; he thought, also, that the milk-teeth served as 
germs to the permanent. This exposition, it will be perceived, 
leaves much to be desired, and is unworthy of an anatomist as 
distinguished as Vesalius. 
Eustachius devoted more attention to the consideration of the 
teeth than any one who preceded him, and he has added much 
to the store of their anatomy. He gives a full description of 
their different forms, their number, and varieties; he indicates 
their manner of articulation, and the nature of their attach- 
ment to the sockets, which, however, he does not very clearly 
explain ; (adsunt praterea vincula fortissima radicibus pracipue. 
adherentia:^ he afterwards speaks of the adhesion of the teeth 
to the gums as analogous to the attachment of the nails to the 
skin ; (sicut cutis extrema unguium parti adharescit^ ita gin- 
giva dentibus adjuncts sunt.) He thought, with the ancients, 
that the hardness of the teeth of animals was in proportion to 
their ferocity. 
He examined the structure of the teeth with much care, and 
was acquainted with the two substances which enter into their 14 
HISTORICAL SKETCH OF THE 
composition; he compared the enamel to the bark of the tree, 
(duplici substantia veluti arbores tegunter sic, In an article 
upon the developement of the teeth, he describes the dental fol- 
licles, their blood vessels and nerves, and refutes the doctrine 
advanced by those who believed that the roots of the temporary 
teeth served to form the permanent, and that, although, the 
germs of the permanent teeth are too small to be distinctly seen 
in the foetus, they really exist. He maintains, also, that the 
teeth are nourished differently from the other bones, and in- 
stances, to sustain his position, their inability to repair a fracture 
of their substance. 
Eustachius supposed that the sensibility of the teeth has its 
origin from the nerves of the follicle, or investing membrane, 
which he believed, penetrates their substance, and that odontal- 
gia is always more violent when these nerves are strongly com- 
pressed ; as will be seen from his text; however, he did not 
affirm this positively, but only hazarded it as a conjecture. 
Ego quamquam certain demonstrationem non habeo, conjecture 
nihilominus adducor, ut suspicer nervum, qui in concavitate den- 
tium penetrat, in minutissimos surculos diffusum cum intima 
ipsorum substantia, qua, mucosa est initio generationis com- 
misceri. 
He describes, at length, the eruption of the teeth, contends 
that no analogy exists between the temporary and permanent 
set, and concludes by a well written chapter upon their func- 
tions and utility ; he remarks, here, that the most ferocious dogs 
become timid and cowardly when they lose their teeth. He 
left, also, some details upon their comparative anatomy, and de- 
scribed, particularly, the teeth of the ape; finally, to leave no part 
of his subject untouched, he makes mention of a number of cu- 
rious anomalies, and speaks of four successive dentitions. 
Sylvius devotes a chapter to the description of the teeth, but 
there is nothing new to be found in it; he not only made no 
further advances than Galen, but copied all his errors. He an- 
swered those who brought forward the discoveries of Vesalius 
to expose the errors of this anatomist, that the physician of Per- 
gamus was not deceived, but that, since his time, the human 
organization, itself, had undergone a change. ANATOMY OF THE TEETH. 
15 
Columbus advises great caution in the extraction of the tem- 
porary teeth; as their roots, he says, are necessary to the devel- 
opement of the permanent set. He makes no mention of the 
dental follicles, and says, that he is unable to understand why 
the teeth do not make their appearance until sometime after 
birth. He thought that, although, they had an unlimited growth, 
possessed a particular sensibility, and were uncovered by the 
soft tissues, they should not be classed separately from the bone. 
(Quamvis, a reliquis ossibus dentes distinguanlur, turn sensu et 
quia denudati sunt, quod cceterorum nullis contingit, turn et quod 
toto vilce tempore incrementum suscipiant, ^*c.) He spoke, also, 
of the adhesion of the teeth to the alveoli, &c. 
E'allopius {Opera omnia, Frankfort edition) says : "Dentes hi, 
dum nascitur puer, diversa ex materia constant, altera ossea et 
dura, altera molli. Prior pars qua erupturi sunt ossea et cava, 
posterior verb mollis admodum et humida est, atque pellicula 
quadam tenui vestita videtur ; quod etiam in origine pennarum 
dum adhuc tenerce sunt, apparet. Quoniam pars ilia quce extra 
cutem proeminet cornea et dura est, ilia quce in aliis latitatmollis, 
humidave, velpituita concreta apparet^ It is worthy of remark, 
that he calls the dental substance cornea. He notices the disap- 
pearance of the alveoli after the loss of the teeth. 
He has described the iter dentis, not as a passage which the 
tooth traverses, but as a prolongation of the follicle to the 
gum : he notices, also, a bony foramen through which it escapes 
outwardly. It is, undoubtedly, the iter dentis which he de- 
scribes after his manner, and we shall find that the difference is 
not very great. " Geminum, apicem possidet folliculus alterum, 
posteriorem, cui nervulus et arteriola et venula applicantur, alter- 
num vero priorem a quo veluti cauda qucedam, pendet nervea, 
quce foramen ossis angustissimum ad latus illius dentis, cui novus 
successurus est, usque ad gingivas egrediturP (It is evident 
that it is in the teeth of the second dentition that Fallopius 
notices this particularity.) He then adds, "Erumpit tandem 
unusquique dens per id foramen dilatatum per quod anted angus- 
tissimum existens, transmittebatur folliculi cauda a medicta, 
atque folliculus disrumpitur et dens nul dus, durusque extat, tem- 
porisque successu in partibus posterioribusperJiciturP The au- 16 
HISTORICAL SKETCH OF THE 
thor observes, that it is only by a good deal of patience, labor, 
and minute research, that he has been able to discover these 
parts, the existence of which he states to be certain. 
Ingrassias had, also, a correct knowledge of the formation of 
the teeth; he admits four dentitions, one of which occurs in 
utero, the other three after birth. He has added nothing, how- 
ever, to the previous stock of knowledge upon the subject. 
Ambrose Pare, in the sixth book of his anatomy, which, as 
we are aware, preceded his surgical works, has also described 
the teeth. He gives as a reason why the teeth of the superior 
jaw are larger, and have more roots than those of the inferior 
jaw, "that the latter is more solid than the superior jaw, and the 
teeth resting upon it, and not being suspended like those above, 
require less support." 
Goiter, who has treated the subject of osteology with so 
much ability, asserts, positively, that the teeth are not analogous 
to the bones, that they are formed from a peculiar mucus, and 
do not pass through the cartilagenous state in their formation; 
quum ossa fount per intercessionem cartilaginum, dentes vero ex 
conversione mucoris in dentium substantiam, nullo interveniente 
medio, opinor dentem non esse, sed proprium aliquod corpus du- 
rius, candididius ct solidius. He has described the fangs, and 
receptacle of the venom of the viper. 
Rousset (lib. de homines primordiis) relates the case of a wo- 
man in Flanders, who menstruated by the alveolus of a molar 
tooth, which she had lost. 
Plater thought that the teeth did not possess any inherent 
sensibility, and that their apparent sensitiveness should be at- 
tributed to the gum which surrounds them. 
Forestus mentions an Ethiopian slave whom no one would 
purchase, because his teeth were all of the canine class, which 
was considered a bad omen. ANATOMY OF THE TEETH. 
17 
PERIOD V. 
FROM HARVEY TO BICHAT. 
We find that, during this long period, the greatest attention 
was given to the study of the anatomy of the teeth. A great 
number of treatises were published upon this subject, but science 
has gained so little, and new ideas are so rare in them, that I 
shall be forced to pass silently by the greater part. I will make 
mention of the most important only, and notice those portions 
of them only, which are most striking. 
Spiegel was aware of the fact, that teeth, with curved roots, 
were more firmly fixed in their sockets than any others. Scaliger 
called them bones sui generis ; he denied that they possessed a 
particular sensibility, and supposed them, in this relation, to be 
analogous to the nails. Kerkring found them entirely analogous 
to the bones: besides this, he has said but few words upon the 
subject: de dentibus nihil dicam aliud^ quam nihil esse quod hie 
peculiariter sit commemorandum! It is really extraordinary 
that this author, who studied with so much care, and who was 
the first to publish a generally esteemed treatise upon osteology, 
should have passed so lightly over a subject of this importance. 
Becker and Schroeder have said nothing with regard to the 
teeth, but what is absurd : they assure us, for instance, that 
those extracted from a dead body will serve as a preservative 
against poison, (venejicia.) 
Thomas Bartholin and Genga,make mention of a tooth which 
occupied the whole of the alveolar arch. The first says, he saw 
a man who had an iron tooth, and advances some trifling reasons 
to explain this phenomenon. Since 1 am upon this subject I 
will speak, also, of the famous golden tooth which has occupied 
so much of the attention of- more recent authors, and upon 
which they have exhausted themselves with ridiculous explana- 
tions and puerile commentaries. Ungebaur, who so justly sneers 
at those who credited this absurd story, thought an explanation 
of the error might be drawn from a fact, which is sometimes 
observed in ruminating quadrupeds; the teeth of these animals 18 
HISTORICAL SKETCH OF THE 
take the yellow tinge of the juice of the plants upon which they feed. 
We find in a dissertation by Fulschius (de vaccillat. ct palingen- 
sia dentium,) that Rhumbaumius saw a child who had a so 
called, golden tooth, which was exhibited to the public, as a rare 
curiosity. Rhumbaumius employed a goldsmith to test a small 
piece of the tooth, which he cut away, who declared it to be 
really gold. The next day, however, Rhumbaumius made a 
new examination and found that the tooth was as perfect as it 
had been before the piece, which the goldsmith tested, was taken 
away, no trace of the violence which had been done was ap- 
parent. This aroused his suspicions, and in examining it with 
more care, he discovered on a level with the gum, a small hole, 
into which he inserted an instrument and tore away a layer of 
gold which exposed to view a natural tooth. 
Diemerbroeck has spoken of teeth developed in the palate, the 
point of which wounded the tongue. By an error very extra- 
ordinary for the period at which he lived, enriched as was the 
anatomy of the teeth by the labors of those of whom we have 
spoken, he has sustained that the teeth are not formed till after 
birth, and that they are composed of the superfluous material 
intended for the general ossification ; this is an error for which, 
however, he is but indirectly responsible, as we find it advanced 
by Hippocrates. Deimerbroeck has mentioned many curious 
anomalies; he had, himself, a canine tooth extracted at an ad- 
vanced age, which was replaced by another; and says, he 
saw, at Utrecht, a woman, fifty-six years of age, who had two 
new incisors that supplied the place of those which she had 
lost two years before. 
Gagliard believed the enamel was formed in parallel fibres, 
and was composed of a concretible juice, which acquired a much 
firmer consistence than the other bones; it became so hard, he 
said, as to produce sparks when struck against another tooth or 
a piece of steel. 
Fredericus in a dissertation entitled, De dentium statu natu- 
rali etpreeter naturali, has shown great erudition, and has pre- 
sented a very complete history of the dental system. He opens 
with a long article upon the importance and dignity of the 
teeth, (dignitas dentium.) He says, that in certain parts of the ANATOMY OF THE TEETH. 
19 
Indies, the teeth were formerly so highly esteemed, that they 
were offered by the people in sacrifice to their deities. He said, 
also, that the ancients, according to some of their historians, ob- 
serving that the teeth did not decay, after death, like other por- 
tions of the human frame, supposed that in them, was contained 
the germ from which a new body was to be reproduced at the 
resurrection. He compares the forming tooth to a grain shut 
up in its husk, and calls the whole of the phenomena of den- 
tition, germination. Totus dens primum inclusus est folliculo 
sue membrand tenui ac pellucidd, non secus ac granun in arista. 
He says, that the teeth of the Ethiopians and Indians are whiter 
than those of the people of the north, but that they lose much 
of their beauty by the use of the betel to which they are ad- 
dicted. He notices, in these words, the sympathetic connection 
between the teeth and the ear; baculum terra infixum si dentibus 
arripiasy facilius aliquem e longinquo noctu advenientem percipies. 
Higmore first related an instance of the penetration of the 
root of a canine tooth into the maxillary sinus ; it occurred in 
the mouth of a female, who was very much frightened to find 
an instrument thrust so deeply into her head. 
We are indebted to Duverney for a good treatise upon the 
teeth. He compares the membrane which surrounds the form- 
ing tooth, to that which envelopes the foetus, and calls it 
the choroid, tunic. He says, that the follicle has the form 
of the tooth it is destined to produce, which he supposes to 
be formed by super-imposed layers, the external being hardest. 
The teeth make their appearance successively, according to 
him, only to save the infant the great amount of violent pain, to 
which it would be subjected, if they were all to cut the gum at 
one time. When the tooth passes through the gum, he says it 
is abandoned by the choroid membrane, which remains in the 
alveolus to form its periosteum. He believed that a close analo- 
gy exists with regard to their development and nourishment, 
between the tusks of the elephant, the feathers of birds, the hair 
and the teeth ; and gave a good description of the dental vessels 
and nerves. 
"At a certain age," says Duverney, "the cavity in the root is 
so much diminished in size, that the vessels are much com- 
pressed, and disappear almost altogether. At this period, having 20 
HISTORICAL SKETCH OF THE 
lost the power of renewing themselves, they are rapidly worn 
away by the friction of mastication, and this may be termed the 
age of the decadence of the teeth." He notices, also, the com- 
plete seclusion of the alveoli in old persons, which he attributes 
to a particular process of absorption, caused by the mechanical 
action of the gum, and the pressure exercised, during mastica- 
tion. He says, that if the inferior, in old persons, passes in front 
of the superior jaw, it is in consequence of the disappearance 
of the alveoli, which, in younger persons, present a greater pro- 
jection in the latter than in the former. 
Duverney mentions the fact, that if a tooth is lost either in 
the upper or lower jaw, the one which is opposite will become 
elongated a little, as if, he says, it were making an effort to fill 
up the vacant place. He admits, that the gums have a vascular 
connection with the teeth, because it is rarely that the latter re- 
main unaffected, when the former are diseased. He concludes 
by a special chapter upon the horns of animals, the develop- 
ment of which, he considers in very nearly the same manner as 
Malpighi. 
Bidloo thought, but without offering any proof, that the atmos- 
phere assisted in the induration of the teeth. 
Clopton Havers, believed the enamel to be of a stony nature, 
and the ivory* a bony substance; especially the root, which 
last, he says, is covered by a periosteum. He thought that the 
follicle no longer furnishes any nutriment to the enamel after it 
is once formed. He assures us, that he has observed with a mi- 
croscope, nervous filaments coming off from the pulp, traversing 
the ivory and reaching the periosteum by little canals; by which 
anatomical arrangement he explained the sensibility of the teeth. 
Verheyen,in consequence of the analogy which he supposed 
to exist between the teeth and the hair, thought, as was then 
believed, that they increased, indefinitely, even after death. 
* Throughout the treatise, it will be found that this word is used to desig- 
nate what is understood in our denial works as the bony portion of the 
tooth. It will be seen, that it was necessary to retain the word in this sense, 
as the author includes in his definition of a tooth, both the investing and 
lining membranes, which he calls the follicle, and the tooth proper, which 
he calls the bony portion, and divides the latter into the ivory and enamel. 
Translator. ANATOMY OF THE TEETH. 
21 
Raw, it is said, has stated that the permanent incisors are 
situated posteriorly to the corresponding milk teeth, that the 
canine permanent teeth, on the contrary, are placed in front of 
those which precede them; and that the secondary molares are 
situated immediately under the deciduous teeth of this class. 
From this supposed arrangement, he advised, when the tempo- 
rary teeth remained after the permanent teeth had made their 
appearance, the extraction of the anterior for the incisors, and 
the posterior for the canine teeth. 
Tenn, in a thesis, sustained under the presidency of Sigis- 
mondi, has said nothing worthy of notice with regard to the 
teeth ; he renewed only the old belief that worms were devel- 
oped in the internal cavity, and caused violent pain. 
Sermes, in a letter published in the "Ephemerides Germani- 
ques," gives an account of a dinner which he gave to a number 
of physicians. Amongst whom was Averduin, where the follow- 
ing question was raised: "Whatbecomes of the roots of the 
temporary teeth?'' Some contended that they were destroyed, 
others that they never existed. Sermes believed with the former, 
and attributed their destruction to the action of the permanent 
teeth; he offered, in support of his opinion, an instance of a 
temporary tooth which was destroyed only on the side where it 
was affected by the pressure of the rising permanent tooth. He 
said, that the dental follicle appeared to him to be a dependence 
of the gum, (here bursula mihi videtur a gingivas mutuata ; si 
enim avellgingivas, simul extraho bursulam illam cum dente, etc.) 
Christian Schwardt, in a dissertation, upon the dentes sapien- 
tice, gives a good description of the teeth, and indicates a num- 
ber of disorders to which they give rise ; he says, also, that in 
his time, those who were born with teeth were regarded as 
having a cruel and tyrannical disposition, (an, hcec res crudelita- 
tis, uti vulgo opinatur, et tyrannidis fuerit indicium, etc.) 
Fouchard, in his treatise upon the teeth, entitled the Chirur- 
gien Dentiste, has presented nothing new ; he was contented 
to recapitulate what had been said by those who preceded him; 
he called the little membrane, which surrounds the embryo tooth, 
the choroid, and relates an instance of third dentition. 
Diechmann sustained his inaugural thesis in 1737, upon the 22 
HISTORICAL SKETCH OF THE 
wisdom teeth, and commenced by criticising the definition itself; 
for, said he, minime sapientiam adaugent, nec adferunt, et ubi 
nulla adest, ibi hisce dentibus non introducitur. We believe this 
without difficulty, but has he understood the true meaning, the 
philosophical intention of this designation? He relates some 
interesting cases of retarded dentition, and cites an instance, 
mentioned by Pliny, of a man one hundred and four years of 
age, whose teeth were reproduced. ' He thought that the teeth 
increased continually, and were worn away in the same propor- 
tion, until the period of old age, when this equilibrium of 
organization was no longer kept up. 
Ungebaur,in a thesis upon second dentition, sustained under 
the presidency of d'Hebenstreit, in 1738, has distinguished 
himself by some new and ingenious views which he presented. 
He compared the tooth to an egg, and said that the bony laminae 
were formed successively, from the circumference to the centre : 
ante omnia crusta ossea dentibus inducitur, sub qua non aliter ac 
testa ovorum albumen continent, mollis aliquis mucus stabulatur 
qui paulatim laminarum more a peripheria versus centrum con- 
densatur. I do not wish it to be understood that I sanction this 
view of the formation of the teeth, 1 am at present only acting 
in the capacity of a historian. He says, the tooth is primitively 
entirely enclosed in the capsule of the follicle, which, in de- 
veloping itself, it ruptures. He believed that there exists a 
coincidence between the disappearance of the processes of the 
bones and the last periods of dentition: (coincidit adeoque totius 
dentitionis negotium cum apophysibus totius corporis obolitis, etc.) 
Ungebaur has, also, described the iter dentis, in a manner 
which no longer leaves any doubt upon the subject; but we 
will let him speak for himself: (quod si inspicias maxillas in- 
fantum, quibus primores dentes nondum effluxerunt, a tergo 
prima dentium sirici videre licet foramen per maxillam hians 
valde parvum, per quod follicidi dentem comprehendentis portio 
adperiosteum externum et gingivas tendit. If it were not very 
evident that Fallopius considered the prolongation of the follicle 
which he named cauda, was hollow, this same question is not 
admissible for Ungebaur; nothing is more evident than this 
deduction. 23 
ANATOMY OF THE TEETH. 
Kornmann states, that, in the time of Tiberius, bodies were 
discovered in Sicily, belonging to the human species, having 
teeth a foot long. 
Godfrey Jancke published a dissertation upon the teeth, in 
1751, of which I will present, in a few words, all that appears 
to me worthy of notice. He said, that the large molars appear 
to be formed by an union of four canine teeth ; he offers for a 
reason why the alveolar border of the lower jaw is thrown 
inward, that the permanent are situated on a plane posterior to 
the deciduous teeth; he indicated the remarkable hardness- 
almost cartilaginous-of the gums, before the first dentition ; he 
described the form of the alveoli, the relations which they bear 
to the teeth, and the modifications which the jaws undergo in 
consequence of the development of the latter. He believed that 
the fall of the deciduous teeth was to be explained by the fact of 
the obliteration of their vessels by the compression of the per- 
manent teeth. (Cadunt igitur circa annum septimum., quia ea, 
cetate circiter, tantam magnitudinem secundi dentes acquirunt, 
ut priorum vasa comprimendo claudere queant.) 
Ludwig, in a dissertation, entitled De Cortice Dentium, de- 
votes his attention particularly to the structure of the enamel. 
He asserts that this substance is of a fibrous nature, attempts to 
indicate the direction of the fibres in many points of the crown, 
and says that they are implanted upon the ivory ; he has ob- 
jected, very justly, to the opinion that exposure to the atmos- 
phere is necessary to the completion of the enamel, that, upon a 
tooth found in the thickness of the palatine process of the supe- 
rior maxillary bone, and consequently sheltered from all action 
of external agents, the enamel was as well formed as upon the 
other teeth. 
Bertin has described the teeth very fully, in his treatise upon 
osteology, and has advanced an opinion with regard to the 
enamel, which I will mention : "It has always appeared tome," 
he says, (p. 242,) "that the enamel which covers the crown of 
the tooth, notwithstanding the contrary opinion of most authors, 
is extended also upon the root, but that it gradually diminishes 
in thickness from the crown to the extremity of the root." He 
indicated, also, a third substance, that, he says, fills up the 24 
HISTORICAL SKETCH OF THE 
cavity of the tooth, and is the production of a lymphatic juice, 
which has become thickened without acquiring a bony consis- 
tence. "This," he adds, "is what I call the third substance of 
the tooth, differing from the ivory and enamel," &c. He said, 
also, that this substance sometimes formed a bony shell, distinct 
from the ivory and enamel, but which, however, at length iden- 
tifies itself with the former. He explained the mechanism of 
the eruption of the tooth in this manner: he said that the root, 
finding an invincible resistance in the bottom of the alveolus, 
was carried towards the gum, which it perforated. The great 
pain and convulsions which are often attendant upon first den- 
tition, arise, according to this author, from the pressure exercised 
upon the nerves at the bottom of the cavity, caused by the resis- 
tance of the gums. The treatise of Bertin is undoubtedly the 
best which 1 have noticed up to this period. 
We find, in the "Memoires de VAcademie des Sciences" a 
paper by Herissant, upon the formation of the enamel and the 
disposition of the gums. He admits the existence of two species 
of gum, the one temporary, the other permanent. The tempo- 
rary gum, according to Herissant, is of a tough, leathery consis- 
tence, covering the whole upper border of the alveolar arch, 
before the eruption of the teeth, for the purpose of closing the 
sockets, and is destroyed, in lamellae, by a kind of exfoliation, 
when the teeth pass through it. According to this author, also, 
the sac which contains the dental follicle is a prolongation of 
the temporary gum, and the drawing he gives of it resembles, 
very closely, those which represent the iter dentis. He thought, 
too, that this sac secretes the enamel, and that its surface is 
covered with an infinite number of little vesicles, filled with a 
fluid which forms this substance by concretion. He adds,"We 
are no longer at a loss to understand by what mechanism the 
crown of the tooth is, little by little, plastered over with this 
fluid enamel. What has been said of the destruction of the sac, 
which takes place at the same time, and in proportion as the 
crown of the tooth issues from the alveolus, is understood, for 
all the adhesions of the internal surface of the membrane with 
the crown are then ruptured, and the vesicles which contain 
the enamel are broken up; thus the liquid is poured out upon ANATOMY OF THE TEETH. 
25 
each portion of the crown, preparatory to its eruption." Heris- 
sant has indicated, then, in this paper, the fibro-cartilaginous 
gum and the iter dentis, and has offered a new exposition of the 
formation of the enamel; more has been said by him, that tends 
towards the advancement of the science, in a few lines, than is 
contained in the enormous volumes of some other authors. 
Haller has treated, with the superiority for which he is so 
eminent, of the development and structure of the teeth; he did 
not, it is true, make any important discoveries, but he has, un- 
doubtedly, given the most philosophical exposition of the sub- 
ject, and one of the most elevated order, of any author of his 
time. What he has said with regard to the arteries of the teeth 
is original. 
Lassone, also, devoted much attention to the subject of den- 
tition, and has left a long dissertation. He believed he had 
discovered a cartilaginous substance, which is placed between 
substance is secreted this membrance make an immediate en - 
tire alveolus and root of the tooth, forming a sort of intermediate 
partition, and adhering equally to both. He was not satisfied, 
however, that this is a real cartilage, but supposed, rather, that 
it is the periosteum itself, thickened by compression. 
Bourdet, in a paper placed amongst those of the Academy of 
Sciences, states, that he detected, in large animals, the little vesi- 
cles destined to secrete the enamel, and confirmed the disco- 
veries of Herissant. 
Spallanzani, in his first researches upon the properties of the 
gastric juice, asserts that that of a dog possesses the property of 
corroding the vitreous substance of the teeth. 
De la Fiere, the younger, advanced the opinion, that the fibres 
of the enamel are developed very much like those of the nail, 
for he supposed them both to be of a fibrous nature. 
Jourdain, in his essay upon the formation of the teeth, de- 
scribes, minutely, the dental follicle, and traces it, in all its 
successive evolutions, from its first appearance up to the period 
of birth. He describes also, two canals in the inferior jaw of 
the foetus, one of which, a semicircular furrow, is destined to 
give passage to the vessels and nerves of the deciduous teeth ; 
the other, which is a true canal, for the passage of the same parts 
to the permanent teeth. This long paper, devoted entirely to 26 
HISTORICAL SKETCH OF THE 
the consideration of the development of the teeth, possesses great 
interest, because we clearly perceive that the author speaks only 
de visit, and that what he has said is the result of observation. 
Albinus has, also, described, with much exactitude, the de- 
velopment and structure of the teeth, and has presented a 
recapitulation of all the facts which enriched the science up to 
his time. He added to this his own knowledge of the subject, 
and the result of his own observations. He makes mention of 
two teeth which were found buried in the nasal process of the 
superior maxillary bone, in an inverted position, the crowns 
being directed upwards; they were of the canine class, and of 
considerable length and size, whilst those occupying the usual 
position of these teeth in the alveolar arch, were very small. 
From this fact, Albinus supposed, and not without some appear- 
ance of reason, that the anomalous teeth were the true perma- 
nent canines, whilst those which occupied their place in the 
arch of the alveoli, were of the temporary set, and had never 
been shed. 
In a treatise, entitled "Historia Naturalis Dentium Humana- 
rum" translated by Boddaert, (1761,) the celebrated Hunter has 
presented an anatomical history of the teeth, with an order and 
clearness unknown before his time; and has given the result of 
a great number of experiments made by him, for the purpose of 
elucidating this subject. He said that the enamel, which he 
called the lamina vitrea, is composed of striae, directed from the 
circumference to the centre; he believed it to be entirely inor- 
ganic, because he was unable to convert it, by any means which 
he was able to employ, into an animal mucus ; he separated it, by 
the action of heat, from the ivory. He called the ivory the bony 
portion of the tooth, and believed it to be analogous to the other 
bones. He said, however, that when madder was given to 
young animals, only those layers of the tooth were reddened 
that were forming whilst the animals were feeding upon this 
substance, those which were formed previously not being af- 
fected, in this respect differing from the other bones. He found, 
also, that the coloring matter did not pass away from the tooth, 
when it was once impregnated with it, but that it retained the 
red color ever afterwards ; from which facts he drew the follow- ANATOMY OF THE TEETH. 
27 
ing general conclusions : ex his experimentis patet dentes con- 
siderari debere ut corpora anomala respectu circulation's per 
eorum substantiam. 
Continuing his description, Hunter thought that the root is 
surrounded by a periosteum, which comes off from the alveolus 
and is extended into the cavity of the tooth ; that the ivory is 
formed of concentric lamellae; that the ossification of the inci- 
sors commences by three points, the canines by one, and the 
molares by three or four; that the tooth, from the moment of its 
eruption, becomes a foreign body in relation to the gums ; that 
the enamel is probably secreted by the capsule which invests 
the crown of the forming tooth ; and he adds : Post secretionem 
terrea pars attrahitur a parte ossea dentis jam formati atque 
superficie crystallisatur. 
He also said, that the deciduous teeth fell by a law of the 
organization and not by the mechanical action of the permanent 
teeth. If it be considered that the treatise in question is de- 
veloped with talent, and founded upon observation, some idea 
may be formed of its importance. 
Courtois said that it was not necessary to be very careful in 
filing the teeth, to preserve the enamel, as this substance was 
usually reproduced with facility. I will here mention a fact re- 
lated by Cook, in his first voyage, (trad, dans la Biblioth. por- 
tative des voy.} He says, that certain people of the Indies, are 
in the habit of rubbing down the free edges of the teeth, with a 
stone, until they are perfectly equal and polished, and that they 
hollowed, in the middle of these teeth, a furrow, parallel to the 
gum, of a depth equal to a fourth of the thickness of the tooth, 
but that notwithstanding this rough usage, not one of these In- 
dians had decayed teeth; he did not say, however, that this 
furrow was effaced by a new deposition of enamel. 
Auzebi, a dentist of Lyons, in a treatise upon odontology, has 
had the presumption to controvert all that had been advanced 
before him, with regard to the germ of the tooth. He has denied 
all, and contented himself with saying that the vessels and 
nerves of the part, spread themselves upon a little musculo- 
membranous vesicle, which has been erroneously taken for the 
germ. He attempts then, in a long and fastidious explanation, 28 
HISTORICAL SKETCH OF THE 
to give his ideas of the evolution of the teeth; but it is impos- 
sible to follow him, he is unintelligible. He calls this revery, 
however, a new theory, and the only true one founded upon 
direct observation. 
Sabatier stated that the diversity of the sensibility of the 
teeth, depends upon the nature of the openings in the extremities 
of the roots, which are sometimes obliterated, especially in ad- 
vanced age, so that the dental nerves are entirely cut off, and 
are no longer continuous with the trunk from which they take 
their origin. 
Wooffendale was the first to notice an anatomical peculiarity, 
which it seems to me I should mention here, not that I look 
upon it as a very rare thing, but because it is a fact which de- 
mands another interpretation than that which is given to it. 
He says, we often see upon the teeth little yellow spots, which 
resemble holes gnawed by worms; and their occurrence was 
more frequent at the time he wrote, in consequence of the 
custom which then prevailed of inoculating children for the 
small pox, before the formation of the teeth was completed. He 
attributed the appearance of these little yellow spots to the small 
pox, and said that they were always less marked if the disease 
had been contracted either a short time after birth, when this 
development of the teeth is but little advanced, or at such a 
length of time after, that the formation of the teeth is nearly 
completed. He states, also, that the teeth, affected in this man- 
ner, make their appearance later than the others. He remarked, 
also, that in jaundice, the enamel takes a slightly yellow tinge, 
from which fact he concluded that it was endowed with lym- 
phatic vessels. This is about the amount of what his treatise 
upon the teeth offers, that is worthy of attention. He observed 
many cases of supernumerary teeth. 
Broussonnet wrote a treatise upon the teeth, of such merit as 
to attract the attention of the Academy of Sciences. It is de- 
voted to a consideration of the teeth in general, and the organs 
connected with them ; the author made many excursions in the 
field of comparative anatomy. This dissertation is remarkable 
for reflections, which, if they are not always ingenious, are at 
least marked with the stamp of originality. ANATOMY OF THE TEETH. 
29 
Tenon has also offered a paper deservedly esteemed, upon the 
subject before us ; but as it is devoted to comparative anatomy 
and particularly the teeth of the horse, and as 1 shall have occa- 
sion to refer to it many times, with distinction, in the course of 
this treatise, 1 shall be contented with merely citing him now, 
without attempting to develope the opinions he has advanced. 
This period, it has been seen, presents a great number of 
works, and although I have noticed a great many, I have not 
touched upon the tenth part, which, during this time, was writ- 
ten upon the teeth. To avoid overcharging this work, and 
fatiguing the reader with an useless display of erudition, always 
easy when libraries are at one's disposal, I believed it my duty 
to confine myself to those authors that have distinguished them- 
selves by the originality of their views, or their reconcilement 
of differences. Without having adopted such a course, this vol- 
ume would have been of double the size, and one half would 
have been but an insipid catalogue. Indeed nearly the whole 
of those authors I have passed by in silence, have offered but 
idle repetitions and compilations without end, which had not 
always, even the merit of being exact and faithful. Let us now 
pass to the sixth period. 
PERIOD V I . 
FROM BICHAT TO THE PRESENT TIME. 
Although I shall have fewer authors to mention in this last 
period, than in the one preceding, it must not be supposed on 
this account, that the anatomy of the teeth has made but little 
progress; on the contrary, all the phenomena of the develop- 
ment of the teeth, have been described with a rare precision, and 
errors which time had consecrated, have been combatted and 
overturned. When an error is exposed, a step is made forwards 
in the way of truth. Many truths which, from neglect and pre- 
judice, were abandoned, have been drawn from their unjust se- 30 
HISTORICAL SKETCH OF THE 
elusion, and elevated to the rank of fundamental principles, 
and many things which escaped the observation of our prede- 
cessors, have been discovered under the intelligent scalpel of 
some modern authors. 
Bichat, the first in order, has, I regret to say, given but little 
attention to a subject so worthy the attention of a man of his 
sagacity; and has done but little toward the advancement of 
the anatomy of the teeth. He starts out, indeed, in his consider- 
ation of the subject, with a doubt, which he makes no effort to 
clear up; he asks, is the enamel organized, or is it only a liquid 
secreted upon the surface of a tooth, where it concretes and har- 
dens ? His answer is but a doubt, and his mind generally so 
ardent and so impatient, to trace things to their depth, is con- 
tented, in this instance, to remain at the surface. But when he 
comes to the functions of the teeth, and their sympathetic con- 
nections, Bichat is himself again, he seizes his subject and mas- 
ters it, searching out with his eagle glance, its most hidden re- 
lations. "There is often," says he, "a sympathy existing between 
the corresponding teeth of the same or of the opposite jaws. I 
have a great molaris of the left side a little carious, which some- 
times causes much pain, and I have always observed that the 
first molaris of the right side, at such times, although it was 
perfectly sound, became painful." In other cases, where the 
disease existed in the lower jaw, the sympathetic pain manifest- 
ed itself in the superior jaw, and reciprocally. He compares the 
sac which envelopes the pulp to a serous membrane. He be- 
lieved that, in the eruption of the teeth, there is something more 
than a simple elevation of the gum, but he acknowledges that 
he does not comprehend the true mechanism. 
In an article upon the phenomena which take place subse- 
quent to the appearance of the second teeth, Bichat says, that 
after their eruption, they increase manifestly, both in length and 
thickness. The root only grows in length after the eruption of 
the teeth, the crown always preserving the same external 
dimensions, and if in old persons they present the appearance 
of being elongated, it is only on account of the absorption of the 
gums. The same phenomenon is also observed in those who 
are emaciated, and in persons who have made an excessive use ANATOMY OF THE TEETH. 
31 
of mercury. Bichat adds : "The increase of the tooth in thick- 
ness does not take place externally, but is caused by the filling 
up of the dental canal, which gradually growing smaller, is at 
last entirely obliterated. When this occurs, the teeth no longer 
supplied with blood and nervous fluid, are deprived of life and 
fall out; but this death is also caused by the excessive accumu- 
lation of phosphate of lime, which becomes so predominant over 
the gelatinous constituent of the teeth, that the principle of life 
is, as it were, suffocated; under this relation, the fall of the teeth 
presents phenomena analogous to the shedding of the horns of 
herbiverous animals, and the calcareous covering of the crus- 
taceae." He asks, why nature has accorded to the teeth a term 
of life, shorter than that of the other bones, which cease to exist 
only with life, and here he acknowledges himself unable to 
make a satisfactory reply. 
I should have done with this historical period, what I did for 
the preceding, have noticed, successively, the works which had 
been published upon the subject, or at least the most important 
of them, and have given in a few words the views of each author, 
or what he had contributed to the science, but as it is particu- 
larly from these authors, that I shall draw principally the ma- 
terial of the following dissertation, I shall not speak of them 
here, to avoid waste of time, and a tedious repetition. I will say 
only a few words of Lavagna, an Italian author, of whose work 
I have made a translation, as it appears to me, that he had made 
some curious experiments, and has opened the way to researches 
of the highest importance. And, indeed, in his treatise entitled 
"Experiments and Reflections upon Caries of the Human Teeth, 
and upon the reproduction of the teeth of the rodentia" La- 
vagna described caries of the teeth, and advanced a new theory, 
founded upon experiments, to explain the cause of its occurrence, 
and pointed out its most frequent seat. He mentions a series of 
experiments, which he made upon the teeth of the rodentia, and 
from which he drew the conclusion that they grew indefinitely, 
having broken off, indeed, considerable portions of their teeth, 
he saw them reproduced. His experiments are happily conceiv- 
ed, the conclusions which he draws from them, appear natural, 
and his whole work justly merits the unanimous encomiums of 32 
HISTORICAL SKETCH OF THE ANATOMY OF THE TEETH. 
the Medical Society of Emulation of Geneva, which it received. 
Having established a learned analogy, he draws conclusions, of 
which the following are the most important. "We see, in the 
first place, that the human nails, the hoof of quadrupeds, the 
beaks and claws of birds, the scales of fishes, &c., increase con- 
tinually, as do, also, the teeth of the rodentia, if no external cause 
occurs to prevent it: (si osserva in primo luogo, che le unghie 
umane, le scarpe dei quadrupedi, il becco et gli artigle degli 
uccelli, i capelli, le pinne dei pesci, ec, si allungano, si destendono 
continuamente, siccome i denti dei rosicanti,se qualche exteriore 
cagione non si oppone alia loro perenne vegetazione, etc.) PART II. 
ANATOMY OF THE DENTAL SYSTEM. 
CLASS 1. 
OF THE TEETH IN GENERAL. 
In entering upon an anatomical history of the teeth, consider- 
ed in relation to the whole of the animal kingdom, it seems 
desirable that a certain degree of generalization should be ob- 
served, the field which presents itself, indeed, is so vast, and the 
divisions are so various, that without adopting a method of this 
kind, which at once simplifies the subject, there is great risk of 
confusion, or of overlooking some points of importance. 
The most general idea which can be given of the teeth, at 
this stage of our work, is, certainly, that which represents them 
as resisting bodies placed at or near the entrance of the digestive 
canal, destined to seize and divide alimentary substances, and 
to serve sometimes, as means of attack and defence. 
The teeth are a production of the internal tegumentary system; 
they are true appendages of the digestive membrane, in a depres- 
sion of which they are lodged by their adherent extremities. 
Independently of the constant relation of the teeth to the tegu- 
mentary system, they present another, which, although it is not 
so common, is of acknowledged importance, I mean that which 
they bear to the osseous system. Sometimes there is no man- 
ner of connection between them, but more frequently the osseous 
system furnishes a point of support for the teeth, either upon a 
surface or in special cavities, which bear the name of alveoli. 
Generally, the teeth are arranged in series; they are all, at 
least, opposed by their free extremities forming pincers, more or 34 
ANATOMY OF THE DENTAL SYSTEM. 
less pointed, cutting or flattened ; without this last conformation, 
indeed, they would have been unable to perforin those functions 
for which they were intended. 
The dental organs, the nature of which is well known, are 
essentially composed of two elements, the. secreting portion, and 
the portion secreted. 
The secreting portion, the matrix, follicle, bulb or germ, is an 
immediate dependence of the tegumentary system, it is a little 
sac,analagous to the sebaceous glands, with this difference, that 
it gives origin in its interior, to a little body of variable form, 
which constitutes the papilla ox noyau pulpeux. Its base is united 
to the adjoining parts, by a plexus of vessels and nerves, whilst 
its opposite extremity presents an opening, the throat of the fol- 
licle, through which the tooth is carried to the exterior; which, 
however, remains closed, until the eruption of the tooth takes 
place. 
The secreted portion is the tooth, properly so called; under 
its organic relation, it is the secondary, but, considered in regard 
to its utility, the principal part. The variations of form, are so 
numerous, that it is impossible to describe them here; we will 
say only, that the tooth is composed of two parts, the crown, 
which is free at its extremity, and the root, which is implanted 
in the follicle, and generally hollowed for the reception of the 
papilla. 
The matrix of the tooth, has the membranous organization of 
the teguments in general; the only thing peculiar that it pre- 
sents, is the considerable growth of the papillary body, in one 
point. The tooth proper, is, on the contrary, composed of bony 
laminae, imbedded one within the other, and which are entirely 
deprived of the vessels and nerves of the germ. To describe, in 
a few words, these two elementary portions of the teeth, it will 
be sufficient to say, that one is endowed with a vitality superior 
to that of some other organs of the body, whilst the other is en- 
tirely unorganized ; the first is, a kind of gland, the second is 
the production. 
It will be perceived from the above, that the two portions of 
the teeth are always formed successively, the secreting portion 
first, the secreted portion afterwards. The secreted portion ap- ANATOMY OF THE DENTAL SYSTEM. 
35 
pears in the interior of the follicle, and is developed upon the 
pulp by their laminae, which are secreted internally to each 
other, and which are in simple juxtaposition with the pulp. It 
remains in the follicle, until, from its increase of size, it is no 
longer able to be contained within it, at which time it is carried 
towards the exterior. It effects its eruption, either by dilating 
the throat of the follicle, or by forcing a route through some 
other portion. 
After its eruption, the tooth continues for a time of greater or 
less duration to increase, but always by the addition of succes- 
sive layers, internally to those already existing; but then com- 
mences a work of destruction, which proceeds from the exterior 
to the interior, in consequence of the friction to which the tooth 
is exposed, in performing its proper functions. 
Some teeth, the incisors of the rodentia, for instance, are ca- 
pable of being reproduced, in proportion as they are worn away; 
but others less fortunately disposed, are delivered up, as it were, 
to the destructive agents, which surround them, without being 
furnished with any means of defence, and are destroyed after a 
time more or less long. 
Thus has nature, by the boundaries more or less narrow, 
which she has placed to the growth of most of the teeth, marked 
the period of the existence of animals ; for a time comes, when 
deprived of these organs, they are no longer able to seize their 
prey, or to effect those modifications in their food, which are ne- 
cessary to prepare it for the action of the digestive fluids. 
The dental system, however, possesses some means of coun- 
teracting the destructive effects of these agents, and of prolong- 
ing their duration. I have already mentioned the fact, that some 
teeth increase continually, by the deposition of new matter at 
their base, in proportion as the work of attrition goes on at the 
opposite extremity. But another means, not less remarkable 
exists, by which the teeth that have become worn, and almost 
useless, are replaced by others, which are much more suitable to 
fulfil the necessary functions. It is principally the work of re- 
placement, which, though, differing in mode, in the great series 
of animals, always takes place, that we designate by the name 
of dentition. 36 
ANATOMY OF THE DENTAL SYSTEM. 
The teeth are not only important, on account of the functions 
they perform in the economy, they furnish to the physician and 
zoologist, marks for the determination of the age, the tempera- 
ment, the nature and habits of animals ; hence is seen the im- 
portance of carefully studying them. 
CLASS II. 
THE TEETH IN PARTICULAR. 
CHAPTER I.- The. Human Teeth. 
Few portions of the human organism have attracted as much 
of the attention of anatomists as the teeth, the most hidden cir- 
cumstances of their external form, of their organization, of their 
development, and the part they perform in the economy, have 
been the subject, of the most minute and satisfactory research ; 
the varieties they present, according to the ages, races, and indi- 
viduals, have also been studied with the greatest care. Thus it 
will be seen, that the task before me, is one remarkable for its 
extent and difficulties. 
ORDER I. 
CONFORMATION OF THE TEETH. 
The teeth, as I have already remarked, are composed of two 
distinct portions, the part produced, and the follicle. The pro- 
duction of the dental follicle is ossiform, for which reason it has 
been called the bony portion. We have, then, to describe the 
bony portion and the follicle, successively in a general, and then 
in a particular manner. ANATOMY OF THE DENTAL SYSTEM. 
37 
ARTICLE I. 
CONFORMATION OF THE BONY PORTION, AND THE DENTAL FOLLICLE. 
Sec. 1.- Of the Bony Portion of the Tooth. 
The bony portion of the tooth has, generally, the form of a 
hollow cone, free at its base, and adherent by its apex. A por- 
tion projects from the alveolus, and presents an appearance re- 
sembling, so nearly, the other bones, that it has for a long time 
deceived anatomists, and is, even at this day, the source of an 
error of the same nature. Its external surface is clearly divided 
into the crown, the root,and the neck. 
The crown is placed without the alveolus, in continual con- 
tact with the air, the saliva, and other external agents. It differs 
but little with respect to length; the varieties of form, on the 
contrary, are according to the different classes of the teeth. The 
summit, turned upward or downward, according to its situation 
in either jaw, presents an even surface, after it has been some- 
what worn by the friction of mastication only ; in a new tooth 
it is relieved by many points. Its circumference is more round- 
ed and projecting towards the exterior than the interior of the 
mouth, and the whole surface presents a fine white tint, of a 
very remarkable vitreous appearance. 
The root is the portion which is received into the alveolus. 
It is longer than the crown ; is sometimes simple, and sometimes 
divided into two or more portions; this division is frequently 
only traced upon the root, and is not completely effected. Its 
form is that of an irregular cone, the base of which is attached 
to the adherent part of the crown; the apex or apices are pierced 
with an opening or openings, which transmit the vessels and 
nerves to the central cavity of the tooth. Its surface presents a 
yellowish tint, in contrast with that of the crown. In the recent 
state, it is united, in an intimate manner, to the alveolar wall, 
by means of the membrane of the dental follicle. 
The neck is represented by the point of junction between 
the crown and the root, and is the place where the vitreous 
substance of the crown ceases. The neck is often marked with 38 
ANATOMY OF THE DENTAL SYSTEM. 
two curved lines, the convexity of which is turned towards the 
root, and which unite at an angle upon the sides. It is inti- 
mately united, in the recent state, to the throat of the dental 
follicle, and the tissue of the gum, which is continuous with the 
latter. 
The interior of the bony portion of the tooth is hollowed into 
a cavity, which extends from a level with the neck to the centre 
of the crown. This cavity takes very nearly the form of the 
tooth itself; it is closed towards the crown, but is prolonged into 
the root, gradually growing more and more narrow as it ap- 
proaches the extremity, where it terminates in the little foramen 
mentioned above. The dental cavity prolongs itself into each 
root, when there are more than one, and serves to afford a lodg- 
ment to the papilla. 
Sec. 2.- The. Dental Pellicle. 
The dental follicle, the soft or pulpy portion of the tooth, (pulpe 
centrale, Cuvier,) is the part by which the tooth is produced, 
and is one of the means of its union with the alveolus. It is a 
sac, very analogous to the follicles which serve as matrices for 
the production of the hair and feathers of birds. 
The dental follicles are placed in the alveoli, and are equal 
in number to the teeth; they are little sacs, formed by depres- 
sions of the mucous membrane from the level of the neck of the 
tooth. Exteriorly, they are united intimately to the alveolar 
periosteum, and are adapted to all the anfractuosities of these 
cavities. At the bottom of the alveolus, the external coat of the 
dental follicle receives its vessels and nerves. 
Interiorly, the follicle of the fully developed tooth, to a descrip- 
tion of which I shall now confine myself, is filled by the root of 
the tooth, to which it adheres intimately ; its throat, or buccal 
opening, embraces and is firmly attached to the neck of the tooth ; 
its base gives origin to the papilla, or central pulp, [noyau 
pulpeux.) 
The papilla is analogous to those of the hair and feathers; it 
is a mucous papilla, which, at this particular point, has taken a ANATOMY OF THE DENTAL SYSTEM. 
39 
considerable development, to become an organ of secretion; it is 
lodged in the cavity of the tooth. Its volume is in inverse pro- 
portion to the age of the individual; its form is exactly that of 
the tooth, from a level with the neck of which it swells out into 
the crown, where it terminates in as many points as the latter 
presents externally. It is inserted upon the bottom of the folli- 
cle, of which it makes a part, by means of one or more thin 
pedicles, which traverse the root or roots, and the foramina 
which they present at their extremities. It is of a grayish color, 
has all the softness of mucous fungosities, and is endowed with 
an exquisite degree of sensibility. 
M. Serres described, twenty years since, a series of little 
bodies, which he called dental glands, that are disposed in a 
circle upon the edge of the alveolus, around the throat of the 
follicle. These bodies are themselves little follicles, which se- 
crete a substance destined to lubricate the surfaces of the alveoli, 
previously to the eruption of the teeth, and which, according to 
the anatomist I have cited, afterwards form the tartar upon them. 
M. Serres compares them to the Meibomian glands ; but they 
appear to me, rather, analogous to the follicles which are found 
around the throats of the matrices of the hair. 
The dental glands have been observed by M. Rousseau; but 
this anatomist assures us, that they disappear after the eruption 
of the teeth, and that, consequently, it is impossible to attribute 
to them the secretion of the tartar, which continues during 
life. This point of dental anatomy is very obscure, and more 
light is needed to enable us to come to any positive conclusions; 
I believe myself able to affirm, however, from my own observa- 
tion, that follicles do exist around the necks of the teeth of adult 
individuals. 
It is plain, from what has just been shown, that a close 
analogy exists between the dental follicle and that of the hair 
and feathers. Both organs are formed by a reflection of the 
mucous membrane; both are united to the adjoining parts by a 
nervous and vascular pedicle; both have a narrow throat, ad- 
hering to the body which they produce, and surrounded by a 
follicular circle ; both give origin to a papilla at their base ; both, 
finally, enclose, the former the tooth, and the latter the hair or 40 
ANATOMY OF THE DENTAL SYSTEM. 
the feather. The only very sensible differences which exist 
between these two parts, consist in these: the dental follicle is 
mucous, whilst piliferous and penniferous follicles are generally 
cutaneous ; the first is enclosed in the alveolus, whilst the .latter 
are plunged in the general cellular tissue ; and the dental folli- 
cle is pediculated, whilst the piliferous follicle, particularly, is 
sessile. It will be seen, presently, that this last difference im- 
plicates the limited growth of the teeth and the indefinite 
increase of the hair. 
ARTICLE II. 
PARTICULAR CONFORMATION OF THE TEETH. 
At the time of the complete development of the organization, 
a period which I have taken as the type of my description, we 
find thirty-two teeth, sixteen in each jaw, placed upon a para- 
bolic line, the convexity of which presents anteriorly, the con- 
cavity posteriorly, and which constitutes the dental arch. 
The teeth are disposed, symmetrically, in each jaw, upon the 
right and left of the median line; those of the superior differ 
from those of the inferior jaw, being generally more fully de- 
veloped. The anterior teeth do not resemble either those situ- 
ated laterally or posteriorly to them. 
The differences which are observed between the anterior, 
the lateral and posterior teeth, are very important, for they are 
founded, not only upon their conformation and position, but 
upon the uses which they perform. They are properly divided 
into three species, the incisor, the canine, and the molar teeth. 
Let us examine, successively, their bony portion, their follicle, 
and the alveoli which receive them. 
Sec. 1.- The Bony Portion of the Tooth. 
Considered with regard to their external appearance only, the 
three classes of teeth present very marked differences in their 
conformation. ANATOMY OF THE DENTAL SYSTEM. 
41 
The incisors are eight in number, four in each jaw, in the 
anterior part of which they are situated, and, as their name indi- 
cates, serve, principally, to cut or divide the food. 
The crowns of the incisor teeth are wedge-shaped, and com- 
pressed antero-posteriorly. Their anterior face is convex, their 
posterior concave; the lateral faces are plane and triangular. 
The free extremities form cutting edges, and present three 
unequal elevations, the middle of which are greatest. The 
roots are simple, compressed laterally, and sometimes marked 
with a longitudinal furrow upon their sides. The extremities 
are sometimes bifid. The internal cavities are generally simple. 
It is unnecessary to repeat, that the superior are larger than the 
inferior incisors; it is a fact 1 have already indicated, and which, 
indeed, is not peculiar to the incisor teeth of the superior max- 
illa. I will mention, here, however, that the superior central, 
are larger than the lateral incisors ; the reverse of which is the 
case in the inferior jaw. 
The canine teeth are four in number, two in each jaw, and 
situated next to the lateral incisors. 
These teeth, as their name indicates, are destined to tear the 
food ; they have a conical crown, convex outwardly, and a little 
compressed within; it terminates in a sharp point, somewhat 
elevated above the level of the other teeth. Their root is long, 
large, always simple, and less flattened, laterally, than those of 
the incisors ; the cavity is simple. 
The molar teeth are more numerous, and situated more pos- 
teriorly, than the others; there are twenty, ten in each jaw. 
They are destined to grind the food, as their name implies. 
These teeth are remarkable for the flat surface presented by 
the summit of their crown. This part is little elevated, rounded 
or square, and terminates by points, which are never found 
singly upon these teeth, from which cause they take their name 
multicuspides. Their roots are generally compound, the divi- 
sions of which are either entirely separated, or joined together 
by a deposition of bony matter between them. Their internal 
cavity, simple in the crown, is divided, in the root, into as many 
portions as there are divisions of the latter. The conformation 42 
ANATOMY OF THE DENTAL SYSTEM. 
of the bony portion of these teeth makes a division into two 
species necessary, the large and small molars. 
The small, or bicuspides, are situated before the large mol ares, 
and next to the canine teeth. Their crowns are a little compressed 
antero-posteriorly, of small size compared with the multicuspides, 
and are terminated by two points, one placed towards the inside 
of the mouth, the other, which is more elevated, towards the 
outside. Their roots are sometimes simple, and sometimes more 
or less deeply divided. 
The large molars, or the multicuspides, are the largest and 
strongest of all the teeth. Their crowns are quadrilateral, very 
large, comparatively, and surmounted by three, four or five tuber- 
cles. Their roots are always compound, but there is consid- 
erable variation in the degree of convergence and divergence of 
the different divisions. The first great molars, proceeding from 
before backwards, is the largest; the second and third diminish 
gradually in size. The third great molars is called the wisdom 
tooth, in consequence of the advanced period of life at which it 
makes its appearance. 
An exception to the general rule, I mentioned above, obtains 
here: the superior great molars are not so large as the molars of 
the inferior jaw; it holds good, however, with regard to their 
roots. 
Sec. 2.- The Dental Follicle. 
The follicle, as may be supposed, is not similar in all the spe- 
cies of teeth, as this part is the matrix of the tooth, properly so 
called, which is, as it were, moulded upon the papilla. 
Independently of differences of size, which are always in pro- 
portion to the volume of the tooth, the dental follicle presents 
others of more importance. 
The sac of the follicle of the incisors and canine teeth is sim- 
ple, like the alveoli in which they are enclosed ; that of the fol- 
licle of the molars, on the contrary, is sub-divided into a number 
of secondary follicles. 
The papilla is uni-pediculated in the anterior and lateral teeth 
and multi-pediculated in the molars. Its upper extremity is sur- ANATOMY OF THE DENTAL SYSTEM. 
43 
mounted by as many eminences as there are tubercles to the 
crown of the multicuspid tooth. 
Sec. 3.- Of the Alveoli and the Dental Arches. 
The teeth are placed in special cavities, hollowed in the cor- 
responding borders of the maxillary bones, which belong to a 
particular portion of the jaws, called alveolar processes. 
The alveoli are conical and more or less sub-divided, as the 
roots of the teeth, which they receive, are more or less com- 
pound. Their openings are directed upward in the inferior and 
downward in the superior jaw; their bases are pierced with small 
foramina which give passage to the nerves and vessels destined 
to supply the dental follicles. 
The alveoli are exactly embraced by the two plates of the al- 
veolar processes, insomuch that they stand out in sensible re- 
lief, anterior and without the surface of the jaw. They are, in 
size, proportionate to the teeth which fdl them; small, for the 
incisors, a little larger for the canine, and largest for the great 
molars. 
'The teeth are received into the alveoli like a nail driven into 
a piece of wood ; this species of union received the name of gom- 
phosis at a time when the teeth were regarded as bones, and 
their articulation with the jaw as analogous to that of the joints. 
The walls of the dental follicle are confounded externally with 
the alveolar periosteum; this forms their only means of union 
with the alveolar processes in a normal condition. 
It is sometimes the case, however, that the teeth are more 
firmly retained in their sockets than by this union, in conse- 
quence of the curved form of their roots; thus the molars some- 
times divide, and making an outward curve, are fixed strongly 
in the bone: offering a great degree of resistance. Sometimes, 
on the contrary, the roots of the same teeth converge, and we 
find an osseous body between them, which is so closely attached 
as to be almost inseparable from the tooth. 
The teeth and their alveoli form, upon the two jaws, an un- 
interrupted series, which constitute the dental or alveolar arches. 44 
ANATOMY OF THE DENTAL SYSTEM. 
These arches have an elliptical form; their convexity presents 
outwardly in the direction of the lips and cheeks, their concavity 
inwardly towards the tongue; their direction is sensibly hori- 
zontal. 
The superior is a little greater in its extent than the inferior 
dental arch; it projects in such a manner that the superior in- 
cisors and canine teeth close over those of the under jaw like 
the blades of a pair of scissors. The depressions and elevations 
upon the crowns of the molar teeth of the two jaws are perfectly 
adapted to each other. 
ORDER II. 
ORGANIZATION OF THE TEETH. 
The necessity of examining, separately, the osseous and fol- 
licular portions of the teeth, is felt more sensibly at this point of 
our progress than in the preceding pages; indeed, without an- 
ticipating the important question of the degree of vitality of the 
former, it is very evident that a great difference exists between 
the two parts, a difference which will be better appreciated when 
we come to understand their relative situation. 
ARTICLE I. 
ORGANIZATION OF THE OSSEOUS PORTION OF THE TEETH. 
The bony portion of the teeth is formed by the union of two 
very distinct substances-the ivory and the enamel. Bertin and 
M. Rousseau, pr'eparateur to the Museum of Natural History, 
have described a third substance which is deposited in the den- 
tal cavity, which it at last fills up, destroying, gradually, the pa- 
pilla. Bertin made his observations upon the human subject 
and M. Rousseau upon numerous animals. M. Rousseau found 
it co-existent with the papilla of a perfectly healthy molar, which 
had become painful on account of the pressure exercised by this 
substance. It is said to present itself in the form of little grains 45 
ANATOMY OF THE DENTAL SYSTEM. 
placed confusedly in a sort of mortar or stalagmite. But, not- 
withstanding the authority of these anatomists, I do not think 
the admission of this third substance is justified by the facts 
known. I have myself observed the formation spoken of by 
Bertin; but it did not appear to me to be any thing else, in some 
instances, than an altered secretion of the papilla, and in others, 
but an ossification or petrifaction of the papilla itself. 
Be this as it may, the two essential elements of the osseous 
portion of the tooth are the ivory and enamel. 
The ivory alone constitutes nearly the whole of the tooth; it 
forms, exclusively, the root and the central part of the crown. 
Its fracture presents a white color, similar in appearance to satin ; 
neither fibres nor cells can be distinguished. It is made up of 
lamellae, one within another, and parallel to the external surface 
of the tooth. 
The ivory is of considerable density; treated with dilute ni- 
tric acid, it undergoes the same changes produced upon the 
bones when exposed to this agent. The calcareous portion is 
taken up, and a flexible mass, of a homogeneous appearance, re- 
mains, which may be reduced by digestion to gelatin. When 
exposed to the action of the fire, it blackens, burns, and leaves a 
friable residue. 
According to Berzelius, this substance is composed, in 100 
parts, of- 
Phosphate of lime, . . . 61.95 
Fluate of lime, .... 2.10 
Phosphate of magnesia, . . 1.05 
Carbonate of magnesia, . . 5.30 
Soda and chloride of soda, . . 1.40 
Animal matter and water, . . 28.00* 
* The analysis of Berzelius, which follows, as given in the work of Mr. 
Thomas Bell, differs from the above, which is evidently erroneous. 
Phosphate of lime, . . . 62.0 
Fluate of lime, .... 2.0 
Carbonate of lime, . . . 5.5 
Phosphate of magnesia, . . 1.0 
Soda and muriate of soda, . . 1.5 
Gelatine and water, . . . 28.0 
100.0 
Translator. 46 
ANATOMY OF THE DENTAL SYSTEM. 
According to Pepys, the roots of the teeth afford, in 100 parts- 
Phosphate of lime, ... 58. 
Carbonate of lime, ... 4. 
Animal matter, .... 28. 
Water and loss, .... 10. 
Morichini announced, in 1802, the presence of fluate of lime in 
the ivory of the teeth, but Berzelius is the only chemist that 
agrees with him. Fourcroy, Vauqelin, Wollaston, and Brandt 
have sought, without success, for this salt. 
The enamel, the vitreous, or cortical substance, is limited to 
the crown of the tooth, according to most anatomists. Bertin, 
only, contends that an extremely thin lamina is, also, extended 
over all the surface of the root. It is thickest upon the extrem- 
ity of the crown, and particularly upon the points which sur- 
mount it; it becomes thinner at the neck of the tooth, where it 
terminates in an undulated line; this fact, however, has been 
questioned. 
The enamel is of a milky whiteness, and presents a vitreous 
appearance. It is extremely hard, and will produce fire when 
struck against steel. Its fracture is fibrous, and its fibres rise 
perpendicularly, or a little obliquely, from the exterior surface of 
the ivory, and resemble the pile of velvet. It dissolves almost 
entirely in nitric acid; in the fire it blackens and becomes fria- 
ble. 
According to Berzelius, it is composed, in 100 parts, of- 
Phosphate of lime, . . . 85.3 
Carbonate of lime, . . . 8.0 
Phosphate of magnesia, . . 1.5 
Animal matter and water, . . 20.0* 
* This statement, also, is strangely inaccurate. The analysis of the ena- 
mel by Berzelius, as given in Sands' work, mentioned above, is- 
Phosphate of lime, . . . 85.3 
Fluate of lime, .... 3.2 
Carbonate of lime, . . . 8.0 
Phosphate of magnesia, . . 1-5 
Soda and muriate of soda, . . 1.0 
Animal matter and water, . . 1.0 
100.0 
Translator. ANATOMY OF THE DENTAL SYSTEM. 
47 
Pepys has found it to consist of- 
Phosphate of lime, . . - 78. 
Carbonate of lime, ... 6. 
Water and loss, . . . . 16. 
The enamel, as will be perceived from the above analyses, 
differs very much from the ivory; it is almost entirely calcare- 
ous, whilst the latter contains some animal matter analogous to 
that of the bones. 
Between the enamel and the ivory there is a greyish line 
which has been perfectly described by Cuvier, and upon the im- 
portance of which, Doctor Duval has lately, with much reason, 
insisted. This line, at the neck of the tooth, is continuous with 
the internal lamina of the follicle which adheres to the root of 
the tooth. Cuvier, in his magnificent work upon fossil bones, 
with regard to this substance, says: " Beside the osseous sub- 
stance and the enamel, there is still a very fine membrane which 
1 believe I have discovered. Before any portion of the bony 
substance is secreted, this membrane makes an immediate envel- 
ope for the papilla, which it embraces very closely. In propor- 
tion as the pulp is separated from this substance, it shortens, re- 
tires within, and is separated from the membrane, which serves 
always as a tunic, but as a tunic common to it and the matter 
secreted underneath. The enamel produced by the internal 
lamina is now of the follicle deposited upon this tunic, which it 
compresses to such a degree against the internal or osseous sub- 
stance, that it soon becomes imperceptible, except when the tooth 
is broken at a very fine thin greyish line, which separates the 
enamel from the bony substance. It must be perceived that this 
membrane is the only means of connection between the hard 
parts and the follicle, for without it there would be a solution of 
continuity." 
The relative arrangement of the enamel and the ivory may be 
compared to that of the extremities of the bones and the carti- 
lages of the articulations ; parts which have been equally disposed 
to support pressure and frequently repeated frictions. Not only 
are the fibres of the enamel implanted perpendicularly upon the 
ivory as the cartilage upon the bones, but their membrane is 48 
ANATOMY OF THE DENTAL SYSTEM. 
placed between them similar to the synovial membrane, which 
is interposed between the bones and the cartilage; this, at least, 
is the result of researches to which I have for some time devoted 
myself, and which I announced in my last anatomical course. 
The analogy with regard to structure is equally apparent be- 
tween horny substances, that of the hair for example, and the 
ivory of the teeth. This analogy, besides, as has been seen, was 
recognised by Aristotle, in whose works we find the germ of 
almost all the great ideas which have been developed since his 
time. The ivory is formed of concentric laminae, as the horny 
portions of the hair, it rests upon a papilla, as the latter is placed 
upon a papilla which belongs to it, and finally it grows in the 
same manner, as will be presently seen. 
ARTICLE II. 
ORGANIZATION OF THE FOLLICLE OF THE FULLY DEVELOPED TOOTH. 
Closely embraced between the root of the tooth and the wall 
of the alveolus, in the adult, the dental follicle becomes so thin 
and adheres so closely to both parts that it is traced with diffi- 
culty in all its extent. 
At this time, however, its continuity with the mucous mem- 
brane of the mouth is perfectly apparent. It is formed of two 
membranous lamellae; the external of which is fibrous, and con- 
nected intimately with the proper periosteum of the alveolus; 
the internal is more vascular than the other, and adheres to the 
root of the tooth from the extremity to the neck, inclusively. 
These two lamella), united, constitute the alveolo-dental perios- 
teum of anatomists. They are sometimes separated in the ex- 
traction of the tooth, the internal lamella continuing to adhere 
to the root, is drawn out with it. 
The organization of the papilla is not known precisely; all 
the positive knowledge we have with regard to it, is, that it is 
composed of the terminations of the dental vessels and nerves; 
which two organic elements exist in sensibly equal proportions. 
The teeth receive their vessels from two distinct sources, ac- 
cording as they go to the wall of the follicle or to the papilla. ANATOMY OF THE DENTAL SYSTEM. 
49 
The vessels of the dental follicle come from those of the mu- 
cous membrane of the gums. Their principal trunks are placed 
on the side of the throat of the follicle, at the neck of the tooth, 
whilst their anastomosing branches are directed towards the base. 
The vessels of the papilla are those which form the pedicle of 
the follicle. They have their origin from special trunks lodged 
in canals of the maxillary bones. These vessels do not anasto- 
mose with the others; they are disposed in an inverse manner; 
their trunks correspond to the base of the follicle, and their ulti- 
mate ramifications to the extremity of the pulp, and they, conse- 
quently, reach a point above the level of the neck of the tooth. 
The dental arteries and veins are easily found and injected; 
but I do not know that any one has ever demonstrated the lym- 
phatics of these organs. The assertions of Mascagni, relative 
to the lymphatics of the enamel, prove only that the most learned 
men who have observed nature herself, and who, of all others, 
should confine themselves to facts, are not always exempt from 
the tendency of light and superficial minds to take for truth the 
fruits of their imagination. 
The dental nerves, like the vessels, are of two classes. Those 
of the wall of the follicle are very small and are derived from the 
nerves of the mucous membrane of the mouth. The others go 
only to the papilla, and assist in forming its pedicle. 
It will be perceived that the dental vessels and nerves form 
two distinct systems: one to supply the exterior portion of the 
follicle, the other that part enclosed in the bony cavity of the 
tooth. The first is immediately continuous with the vascular and 
nervous system of the buccal membrane, the second comes from 
a special source. The verification of this statement may be 
found, daily, in the various pathological conditions of the teeth, 
and it seems to me to be an arrangement which has never been 
sufficiently insisted upon by anatomists. 
The same arterial and nervous trunks supply the teeth of both 
jaws: the internal maxillary artery and trifacial nerve. There 
is only this difference with regard to the superior and inferior 
teeth: to the first, special branches go to the anterior and poste- 
rior, whilst to the last the same branches go to all the teeth. 
The trunks of the vessels and nerves of the teeth are situated 50 
ANATOMY OF THE DENTAL SYSTEM. 
above or below the alveoli, according as they are in the upper 
or lower jaw, on a level with each of these cavities. They send 
to the teeth one or more branches which pass through the open- 
ings at the bottom of the alveoli, form the pedicle of the follicle, 
and traverse the foramen, at the extremity of the root, to reach 
the papilla, in the substance of which they ramify. 
At this point we encounter a more important question than 
any which has yet arisen. Do the vessels and nerves terminate 
in the follicle, or do they pass through it, and penetrate the bony 
substance of the tooth? 
We will call to mind here, a fact which bears with overwhelm- 
ing weight upon the discussion. It is this: no one has yet been 
able to distinguish either vessels or nerves in the bony sub- 
stance, and all that has been advanced up to this time is mere 
hypothesis.* 
When the teeth were regarded as entirely analogous to the 
bones, they were believed to be vascular, in the same degree; 
but, even then, more than one anatomist, who drew their con- 
clusions from a strict observation of nature, only, held a differ- 
ent opinion. But anatomists, in consequence of an imperfect 
knowledge of the dental follicle, and the distinction which exists 
between it and the bony portion of the tooth, have frequently 
been led to take opposite positions when no difference really 
existed between them. Some attributing to the whole tooth 
what should have been considered only in relation to the folli- 
cle ; others generalizing circumstances which should have been 
confined to the bony portion of the tooth. 
At present, happily, these two anatomical elements of the 
teeth, the bony portion and the follicle, are so perfectly under- 
stood, that a similar confusion cannot arise ; and the time appears 
to have come when it is proper to propose the question of the 
vitality of the former, to decide between the contrary theories 
which have been advanced and defended, with equal talent, by 
* The existence of vessels in tooth-bone is no longer a matter of doubt. 
Subsequently to the publication of this work. Dr. C. A. Harris has, in two 
or three cases, by the aid of a microscope, detected them, in human teeth, 
charged with red blood. A microscopic view of one of which is contained 
in the Maryland Medical and Surgical Journal, and in the American Jour- 
nal of Dental Science.- Translator. ANATOMY OF THE DENTAL SYSTEM. 
51 
Blake, Mascagni, &c., on the one hand, by Hunter and Cuvier 
on the other. 
Those who contend for the vitality of the osseous substance 
of the teeth, allege- 
1st. That a healthy tooth is sensitive when penetrated by an 
instrument to a certain depth; 
2d. That acids applied to the teeth develope a peculiar sensi- 
bility : the setting of the teeth on edge ; 
3d. That they become colored in an animal fed with madder; 
4th. That superficial caries cause a very lively degree of sen- 
sibility in the diseased tooth; 
5th. That fractures or solutions of continuity of the teeth are 
perfectly repaired; 
6th. That teeth which do not possess the elements of organi- 
zation, as, for instance, human artificial teeth, are rapidly de- 
stroyed ; 
7th. That in certain diseases, as, for instance, the cholera, the 
teeth assume a red tinge. 
But those who contend with Eustachius, Hunter, Cuvier, &c., 
against this doctrine, justly respond- 
1st. That if, in deep wounds of the teeth, blood follows the 
instrument, and sharp pain is produced, it is only because the 
papilla has been implicated in the injury with the osseous por- 
tion, and no more proves their vitality than the bleeding of the 
feather of a young bird when cut across, near the skin, proves 
that the horny substance of the feather is vascular. 
2d. That the peculiar sensation produced by the action of 
acids upon the teeth (setting them on edge, as it is called) may, 
perhaps, be explained, in accordance with the opinion of Fallo- 
pius : the acid acting directly upon the papilla, in consequence 
of its imbibition by the ivory. 
3d. That the fact of the teeth, under certain circumstances, 
becoming colored, proves much more against than for their vas- 
cularity, for, if Hunter has established the fact that the teeth of 
an animal fed upon madder takes its red tinge, during the pro- 
gress of the experiment, he has shown, also, that these parts re- 
tain their red tinge during the life of the animal, which is not 
the case with the bones, between which and the teeth, those 52 
ANATOMY OF THE DENTAL SYSTEM. 
who contend for the vascularity of the latter, wish to establish 
an analogy. 
4th. That if in slight injuries and superficial caries of the 
teeth, pain is developed, it is only in consequence of the partial 
destruction of the osseous portion which is rendered less able to 
protect the papilla against the action of external agents to which 
it is exposed, and by which, in these cases, it is painfully af- 
fected. 
5th. That if fractures and other solutions of continuity are re- 
paired, it is always effected by a secretion of the papilla, precisely 
in the same manner to similar injuries of the nails. And that if 
balls have been found in the centre of the tusks of the elephant, 
without any trace of the holes by which they entered, it does 
not prove that these holes were obliterated by a new deposition 
of bone from the vessels of the osseous portion of the tooth; but 
that the ball did not enter at or near the place where it was 
found lodged, but had traversed the alveolus, and found its way 
to its situation in the centre of the tusk through the opening at 
its alveolar extremity, and, coming down into the cavity of the 
tooth, was enclosed in osseous matter, secreted by the papilla. 
(Dr. Duval showed me a pathological specimen of this charac- 
ter, which belongs to his rich collection, and I am convinced 
from the examination, that the ball, in this instance, found its 
way into the central cavity to the base of the papilla, which, irri- 
tated by the presence of the foreign body, surrounded it with a 
deposition of osseous matter.) 
6th. The reason why the natural teeth are not so rapidly de- 
stroyed as some kinds of artificial teeth, is, because they are (like 
the nails which never dry up when attached to the matrix as 
they do when separated from it) surrounded by parts that sup- 
ply them with fluids, which keep them in their normal condition. 
7th. That the red tinge which the teeth take, in certain dis- 
eases, is in consequence of a simple imbibition from within out- 
ward of the materials, which are then carried to the dental cavity 
by the vessels of the pulp. 
I should, perhaps, confine myself, rigorously, to the facts which 
present themselves, and allow the reader to draw his own con- 
clusions ; but, that I may not lay myself open to the accusation ANATOMY OF THE DENTAL SYSTEM. 
53 
of endeavoring to avoid a difficulty by citing only the opposing 
arguments of the partisans of these two doctrines, I will throw 
myself into the discussion, and advance my own particular opin- 
ions with regard to this difficult point of odontology. 
1st. It is my opinion, that the ivory and enamel of the osseous 
portion of the teeth are entirely destitute of vessels; 
2d. I admit, with Blake, Fox, Duval, Oudet, Toirac, etc., that 
the osseous portion of the teeth possesses a peculiar sensibility in 
its superficial laminae, which is most apparent in a certain kind 
of decay that commences, as Dr. Duval has very plainly demon- 
strated, between the enamel and the ivory, when the layer of 
enamel has been removed by the file or any other means; 
3d. Is it not possible that this sensibility exists in the greyish 
line, intermediate to the ivory and enamel, which Cuvier sup- 
posed to be a prolongation of the internal lamella of the follicle, 
and in which might still be remaining some of the nerves it con- 
tained before entering between the two substances of the tooth 
at the time of its formation ? 
4th. If the explanation which I have hazarded be founded 
upon truth, the rapidity with which the phenomena of agacement 
(setting of the teeth on edge) take place, will be comprehended 
more easily ; the acid, which produces this sensation, can readily 
penetrate the thin coating of the enamel, and have an immediate 
action upon this membrane. 
The whole of the question relative to the presence or absence 
of vessels and nerves in the osseous portion of the teeth, may 
be summed up thus : the tooth is composed of two portions, the 
producing organ, and the part produced; the former, which is 
the follicle, is essentially nervous and vascular; the latter, the 
ivory and enamel, are calcareous substances, in which we dis- 
cover very little organic matter, and which has not been endow- 
ed with nerves and blood vessels. 
It is, certainly, not impossible that vessels may be developed 
in certain teeth that adhere to the alveolus, as they make a part 
of the maxillary bones; but this is an abnormal condition, and 
only goes to prove the general fact, that organic matter, secreted 
in a portion of one body, may become identified with it in some 
manner, and be endowed with a true organization ; this fact 
does not, of course, affect the general conclusion. 54 
ANATOMY OF THE DENTAL SYSTEM. 
ORDER III. 
DEVELOPMENT OF THE TEETH. 
The formation of the teeth is the most interesting, and, at the 
same time, the most complicated portion of the natural history 
of these organs. 
That nothing of importance may be omitted in this part of my 
treatise, I shall, first, consider the development of the teeth in 
general, and then, in a second chapter, treat of their particular 
development. 
ARTICLE I. 
DEVELOPMENT OF THE TEETH IN GENERAL. 
A perfect acquaintance with the development of the teeth, 
supposes a knowledge of the formation of the follicle and bony 
portion, and the issue of the tooth from the alveolus. 
Sec. 1.-Formation of the Dental Follicle. 
If the parts which represent the alveolar arches of the foetus 
of two months, be carefully examined, a great number of dental 
follicles will be found lodged in the membranous folds of the 
gum. These follicles are very small, and are lodged in a groove, 
which is the rudiment of the alveoli; they are covered by the 
lowest lamina of the tissue of the gum. Their form is globular; 
superiorly and inferiorly they adhere to the gumsand the alveo- 
lar groove, and the vessels and nerves which traverse it; late- 
rally, they are contiguous to the adjoining follicles ; anteriorly 
and posteriorly, they correspond to the gums. 
After about four months, according to M. Serres, fibrous par- 
titions, which are subsequently ossified, are developed between 
the follicles, changing their relations to each other. 
At the period of birth, the follicles are, already, completely 
isolated from each other, and form their vessels and nerves ; the 
canal of the latter, at first a simple groove, is now completed. ANATOMY OF THE DENTAL SYSTEM. 
55 
If the dental follicle of a young embryo is opened, it will be 
found filled with a yellowish fluid, viscous like the synovial se- 
cretion ; acid in some, and alkaline in others ; having, also, an 
unctious appearance, in some cases, by which Ungebaur was 
deceived. This fluid continues to diminish in quantity, from 
the first moment it becomes perceptible, until the eruption of the 
tooth, at which time it disappear altogether. 
The bottom of the dental follicle of the embryo is occupied by 
a very large papilla, which varies in form, according to the 
character of the tooth which it is destined to produce. It is 
continuous with the gum at the opposite extremity, by means 
of a prolongation, which constitutes the iter dentis, gubernacu- 
lum det dis. 
The gubernaculum dentis is the throat of the dental follicle. 
In the first stages of its formation, it is contracted upon itself, 
and, it is believed, presents an opening, which is afterwards 
dilated for the passage of the tooth; anatomists, however, are 
not all agreed with regard to the permeability of this part. 
Fallopius, who appears to me to have been the first to describe 
it, represented it as a cord. Herissant asserts that this prolonga- 
tion is perforated, and that the opening through it closed by 
what he calls the second or temporary gum, but that it opens to 
the surface of the permanent gum. M. Serres and M. Delabarre 
contend, that it is really perforated; an opinion in which 
they are not sustained by M. Rousseau and M. Cruveilhier. 
M. Rousseau states, that he succeeded in injecting it, as M. Dela- 
barre had done, but attributed the opening made, rather to the 
means used, than to the existence of any natural perforation. 
Finally, Herissant asserts, that the gubernaculum dentis is 
encountered in all the follicles, (a fact which appears now to be 
generally admitted,) whilst Fallopius and M. Serres attribute it, 
exclusively, to the teeth of second dentition. 
Be this as it may, the structure of the dental follicle of the 
foetus should be studied with so much greater care, as a know- 
ledge of this difficult point of anatomy is absolutely necessary 
to the comprehension of the development of the osseous portion 
of the tooth. I will state, therefore, all that is positively known 
with regard to it. 56 
ANATOMY OF THE DENTAL SYSTEM. 
There are two points in the history of this structure, about 
which, amongst anatomists, there is no difference of opinion : 
the formation of the papilla, which occupies the bottom of the 
follicle, by the extremities of the vessels and nerves which 
reach it, by means of its pedicle; and the constitution of the 
wall of the follicle, by means of a membrane joined to the gum. 
All that remains to be determined, consequently, are the dispo- 
sition and structure of this membrane. 
Jourdain, Herissant, Desmoulins, M. Serres and Professor 
Cruveilhier, supposed the wall of the follicle to be formed of a 
single membrane, which lines the alveolus down to the pedicle 
of the papilla, where, according to the first two, it terminates ; 
but which was then, according to the others, reflected upon the 
papilla, and could be traced up to the summit of that body. 
Herissant added, that this membrane is gathered in at its middle 
portion, and adheres closely to the neck of the tooth. 
Hunter and Blake supposed the wall of the follicle to be 
formed by the juxtaposition of two lamellae, which terminate 
upon the pedicle of the papilla, without being reflected upon it. 
Bichat and Cuvier admitted that the wall of the follicle was 
composed of two laminae ; but believed that the external one 
terminated upon the pedicle, whilst the internal, like a serous 
membrane, was reflected over the whole surface of the papilla. 
Delabarre describes, also, a double laminas, as composing the 
wall of the follicle; the external comes off, according to this au- 
thor, from the fibro-cartilaginous tissue which covers the alveoli, 
and which assists in forming the gum, and descends with- 
out presenting any thing remarkable to the pedicle of the papilla, 
near which it terminates. The internal, on the contrary, is di- 
rectly continuous with the mucous membrane of the mouth; it 
goes downwards, directed towards the lateral part of the papilla, 
and terminates at the point which corresponds to the neck of the 
tooth. Thus the dental follicle, according to Delabarre, pre- 
sents two cavities-one which takes in the summit of the pa- 
pilla, another which corresponds to the pedicle of this part; in 
the first the crown is afterwards formed, in the second the root of 
the tooth. 
Although at first sight some differences appear between the ANATOMY OF THE DENTAL SYSTEM. 
57 
preceding accounts of the dental follicle, it will be found, on a 
closer examination, that, in fact, no real differences exist. It 
will be readily seen, indeed, that the account which represents 
the wall of the follicle as simple, is not essentially different from 
that which recognises two distinct membranes; this apparent 
discord depends upon the latter describing the alveolar perios- 
teum as belonging to the follicle, and the former carefully dis- 
tinguishing it. 
We are enabled, then, to reduce to three, the opinions of the 
principal authors, with regard to the organization of the dental 
follicle: the first in which the membranes, constituting the 
follicle, are represented as terminating upon the pedicle of the 
papilla, and being more or less reflected upon it; the second, in 
which the pulp is represented as being covered by the internal 
membrane; the third, which is founded upon the insertion of 
this internal membrane upon the lateral part of the papilla. 
This last opinion has in its favor fewer probabilities than the 
two former, which, as I have shown, very nearly resemble each 
other. In the first place it is unfavorable to the analogy which 
exists between the follicles of the hair and the nails, and those of 
the teeth; and, secondly, what appears to me more conclusive 
evidence against this opinion, no one, as far as my own knowledge 
extends, has proved its truth by actual disse'ctions; for myself, 
I have always sought in vain for this peculiar formation. 
Hunter considered the internal membrane of the follicle as 
essentially vascular; Blake differs with him in opinion, and 
Fox asserts that the whole thickness of the follicle is abundantly 
provided with vessels. 
Herissant has described upon the external membrane of the 
follicle a curious and very important arrangement: "If this mem- 
brane," says he, " be detached with precaution from the crown, 
and its interior surface examined, immediately, with a magnify- 
ing glass of three or four lines focus, the beholder will be struck 
with wonder at the appearance of an infinite multitude of very 
small vesicles, that, by their transparency, resemble those with 
which the ice plant (glaciate) is covered. They are disposed, 
with much order, in ranges one above the other, which are, for 
the most part, parallel with the base of the tooth. These vesi- 58 
ANATOMY OF THE DENTAL SYSTEM. 
cles, at first, contain a very clear and limpid fluid, which after- 
wards becomes thickened, and resembles milk in appearance. 
Now we cannot be mistaken in determining the purpose for 
which this fluid is intended, and cannot hesitate to conclude, 
that, when it is shed upon the crown of the tooth, and acquires 
all its consistence, that the tooth will be ornamented with the 
enamel which is so pleasing to the eye." 
M. Rousseau, Desmoulins, and Professor Cruveilhier have 
made observations similar to those of M. Herissant on the vesic- 
ular elevations which exist upon the free surface of the internal 
membrane of the follicle. 
Sec. 2.-Development of the Osseous Portion of the Teeth. 
A short time after the first appearance of the follicle, towards 
the third month of foetal life, ossification commences upon those 
teeth which subsequently first make their appearance through 
the gum. 
It is well known that this formation is accomplished in the 
interior of the follicle, but authors are not all agreed relatively to 
the precise point upon which the first portions of calcareous mat- 
ter are deposited. Cuvier asserts, that it is between the papilla 
and the part of the internal membrane which covers it; others 
contend that it is in the cavity of the internal membrane. 
Be this as it may, we know that the crown, and particularly 
the points upon the crown, are first ossified. The deposition of 
calcareous matter is preceded by a manifest reddening of the 
pulp. This deposition commences by as many points as the 
crown of the tooth is to present after its complete formation, in 
the form of scales, or rather little caps, which cover the eleva- 
tions of the pulp; thus, on the incisors, ossification commences 
by three points, according to Hunter and M. Oudet; by one, 
only, according to Meckel, Blake, and Albinus; upon the canine 
teeth by one, and upon the molars by as many points as the 
tooth afterwards presents. 
The dimensions of each of these rudimentary parts are, ac- 
cording to M. Rousseau, about a half line in breadth, and a six- 59 
ANATOMY OF THE DENTAL SYSTEM. 
teenth of a line in thickness; they are always in a greater state 
of development towards the outer than the lingual side. Their 
respective volume diminishes, also, in proportion as they ap- 
proach the condyles. 
The enamel, according to Auzebi, Jourdain, and M. Rousseau, 
is secreted before the ivory. Desmoulins entertained the same 
opinion; and he assures us, that this manner of formation takes 
place in the cyprinus; the crowns of their teeth, according to 
his account, being as complicated as the incisors of the roden- 
tia. In the teeth of these animals, he says, the shell of enamel 
remains for a long time soft and flexible ; that it is sometime be- 
fore it takes its proper consistence, and is moulded upon the 
elevations and indentations of the papilla. 
Most anatomists maintain, on the contrary, that the ivory is 
secreted first, and that the enamel is formed after the surface of 
the crown of the tooth is ossified. Cuvier states, that he has 
seen the two substances appear almost simultaneously. 
Many different hypotheses have been advanced relative to the 
mechanism of the formation of the teeth. Seduced by a false 
analogy, admitted a priori, between the bones and the teeth, anat- 
omists believed, for a long time, that the ivory was formed by an 
osseous transformation of the pulp. It must be admitted, that 
the gradual lessening and final obliteration of the dental cavity, 
in old persons, appears, in some degree, to sustain this theory, 
which has lately been adopted by M. Leveille. The most sim- 
ple direct examination will suffice to show, however, that this is 
not true; the rudimentary formation is only superimposed upon 
the pulp, without adhering to it, which would not be the case, 
even if the most superficial part of the pulp underwent an osse- 
ous transformation. 
Bunon, in 1743, Hunter, and Cuvier, strongly opposed this 
doctrine. They have shown that the ivory is secreted by the 
pulp in the same manner as the nail by the matrix, and the epi- 
dermis by the skin. Bunon compared this formation to the shell 
of certain crustacae. 
The history of the enamel is much more complicated than 
that of the ivory; and it must be admitted, that upon the well 
attested facts, in our possession, the theory of its formation is 60 
ANATOMY OF THE DENTAL SYSTEM. 
much more difficult to establish. The secretion of the enamel 
differs in every way from that of the ivory, and as such a short 
period elapses from the commencement of its formation to its 
completion, it is much more difficult to observe it in all the stages. 
Bertin, Hunter, and many others, have asserted that the enamel 
is secreted by the internal membrane of the follicle, and perhaps, 
also, by the pulp, from the first moment of the appearance of the 
germ; that it remains in solution in the fluid of the follicle up 
to the time of the formation of the crown, when it is deposited 
in crystals upon its external surface. Hunter compared this 
deposition of the enamel upon the crown of the tooth to the 
crystalization of the salts of the urine around a foreign body in 
the cavity of the bladder. One fact appears to give some sup- 
port to this theory; the fluid of the follicle, abundant at first, 
diminishes in proportion to the development of the tooth, and 
disappears entirely; "taken up, doubtless, by the absorbents,'' 
they say, when the enamel is completed. Hunter averred, that 
these phenomena take place in the horse, the ass, and the sheep, 
and thought there was no reason why they should not also occur 
in man. Cuvier and M. Serres are opposed to this doctrine of 
Hunter. The fluid of the follicle, according to these authors, 
takes no part in the formation of the tooth ; is poured out of the 
opening of the follicle at the moment of its eruption, and disap- 
pears entirely when this is effected. 
It is generally admitted, at present, with Herissant, Meckel, 
Cuvier, &c., that the enamel is very soft at the time of its forma- 
tion, and that it is deposited directly upon the tooth by a secre- 
tion of the internal membrane of the follicle, for which purpose, 
the little vesicles, said to exist in this membrane, by Herissant, 
appear to be destined. 
According to Cuvier, the enamel is not deposited immediately 
upon the crown of the tooth, but upon that portion of the internal 
membrane which covers the crown. In this manner, as I have 
before remarked, the lamina is pressed between the two sub- 
stances, and remains a greyish line during life, a proof of this 
arrangement. 
As regards the opinion of M. Delabarre, who believed the 
enamel to be formed by the papilla, and, transuding through 61 
the external laminaa of the ivory, was deposited upon the surface 
of the crown, it appears to me, notwithstanding the authority of 
the author, to be altogether inadmissible. 
One consideration seems, at first sight, to embarrass this point 
of the natural history of the teeth: why is it that the enamel is 
deposited upon the crowns only, and never upon the roots of the 
teeth? This question is of importance, and merits attention. 
In the first place, it is evident that this difficulty will not af- 
fect the theory of Cuvier, according to which the ivory is not 
formed in the same cavity of the follicle in which the enamel is 
secreted, and which contains the crown of the tooth only. The 
supporters of the almost abandoned theory of the crystalization 
of the enamel, asserted that the fluid of the follicle disappeared 
when the crown was fully formed, consequently there could be 
no vitreous deposition upon the root. 
Herissant, and those who observed the little glands destined, 
according to this anatomist, to the secretion of the enamel, sup- 
posed that these little organs disappeared after the completion of 
the crown of the tooth, and that thus the root, which is after- 
wards formed, has no deposition of enamel. 
ANATOMY OF THE DENTAL SYSTEM. 
Sec. 3.- Growth of the Teeth. 
The deposition of bone, once commenced, by the papilla, con- 
tinues as long as this organ receives the materials necessary for 
its formation. New laminae, similar to the first, are formed, 
always interiorly and upon the surface of the papilla. These 
laminae are greater in extent in proportion as the development of 
the tooth advances, up to a certain period, when an inverse dis- 
position will be observed. As the inner laminae are formed, the 
external layers become more and more distant from the papilla, 
which is soon embraced by the bony deposition, on all sides, 
down to its base. The crown of the tooth entirely formed, the 
enamel is deposited, and the work of evolution commences ; 
previously to which, however, the tooth, in some persons, re- 
mains for a time stationary, at this stage of the formation. The 
papilla is raised from the bottom of the alveolus ; the new por- 
tions of ivory, now secreted by it, take the form of rings, less 62 
ANATOMY OF THE DENTAL SYSTEM. 
and less wide inferiorly, which, surrounding the pedicle of the 
pulp, descend to its extremity, and form the root of the tooth. 
At the period to which we have come, the tooth ceases to grow" 
in length ; the new lamin®, which are now formed, can only 
serve to augment the thickness of the osseous substance, and, 
as it is always by an internal juxtaposition that this increase 
takes place, the dental cavity must, necessarily, become more 
and more narrowed. The pulp is then compressed, and the 
circulation being obstructed in its vessels, the secretion lessens 
in quantity, and, at length, ceases altogether. 
We have here described the manner in which a tooth, with 
only one root, the canine, for instance, is formed; this was 
chosen, as being more simple and easily understood. We will 
now take up the consideration of one of the multicuspides with 
a compound root. 
The ossification of the tooth commences, as I have stated, by 
many separate points; corresponding to elevations upon the 
papilla; the little caps, first formed, representing the tubercles 
which the fully developed tooth will present. These little caps 
are, from the beginning, convergent towards each other at their 
bases ; and, by the deposition of new lamin® interiorly, which 
are always greater in extent than the first, they are, at last, en- 
tirely united. There is now formed, upon the superior surface of 
the pulp, a large inner cap, and the ossification proceeds as if it 
had commenced by a single point. When the newly formed 
osseous portion of the tooth reaches the union of the pulp with 
its pedicles, the calcareous matter is secreted at once around 
both portions. Each of the pedicles is, separately, surrounded 
by a tubular deposition of bone, continuous with the circum- 
ference of the rest of the pulp. The growth then continues to 
the end, in a manner precisely similar to that of a simple tooth, 
with this difference, that, instead of a single hollow cone, a 
number, corresponding to the roots of the tooth, are formed. 
Thus the teeth are formed, from the extremity of the crown 
to that of the root, and from the exterior to the interior; they 
acquire, at once, length and thickness, and are moulded, as it 
were, upon the papilla, which they enclose more and more 
narrowly. 63 
ANATOMY OF THE DENTAL SYSTEM. 
The growth of the osseous portion of the tooth is, necessarily, 
confined within very narrow limits, and the exact conformation 
of the future tooth, as it always takes the form of this rudimen- 
tary part, may be easily ascertained from the size and length of 
the papilla. In proportion as the tooth advances in its forma- 
tion, as we have seen, the pulp is more and more closely em- 
braced by the osseous laminae, until its functions, at first ob- 
structed, cease entirely; at this moment its growth is completed. 
As the tooth is developed, the secretion of osseous matter becomes 
more and more difficult, for the very deposition of this substance 
cuts off a supply, which at first seemed inexhaustible; the pulp, 
thus containing, within itself, the elements of its own destruction. 
From this description, it will be at once perceived, that the 
definite growth of the teeth is attributable to the form given to 
the calcareous deposition by the papilla; yet this consequence, 
which so naturally flows from the facts in our possession, was 
not, until very lately, properly appreciated. We are indebted to 
M. Oudet for the precise knowledge we now have of the subject; 
he satisfactorily explained it, in his paper upon the dentition of 
the rodentia. M. Oudet established, in this remarkable produc- 
tion, that it is owing to the pediculated form of the dental papilla 
in man, that the growth of the tooth is limited. He then showed 
that, in the incisors of the rodentia, which increase indefinitely, 
the dental papilla is of a form directly the reverse of that of the 
human tooth. This papilla has, indeed, no pedicle; it is conical, 
and is attached to the bottom of the follicle and alveolus by the 
base of the cone which it represents. In consequence of this 
formation, the papilla of the incisors of these animals continues 
to secrete the calcareous matter, without being exposed to the 
danger of obstruction on the side from which it receives its ves- 
sels and nerves. Thus, never being in the least degree com- 
pressed, nor interrupted in its functions, it continues to deposite 
new matter, and the tooth is pushed towards the exterior,till the 
end of life, unless, from some external cause, it is materially 
injured or destroyed. 
This indefinite growth of some of the teeth of certain animals 
must give to them, in time, a considerable length, as is observed 
in the tusks of the elephant. In the rodentia, also, when the 64 
ANATOMY OF THE DENTAL SYSTEM. 
incisors are not worn away at their free extremity, in proportion 
to the deposition which takes place at their base, they sometimes 
acquire enormous dimensions, and are the cause of serious 
accidents. 
M. Devergie, in 1825, presented to the Academy of Medicine, 
the head of an old rat, killed at the Ecole-Militaire, which fur- 
nished a fine example of this kind. The right superior incisor, 
on issuing from its alveolus, curved immediately downwards 
and backwards, into the interior of the mouth ; penetrated the 
left nasal fossa, entering at its posterior opening, traversed this 
cavity from behind forwards, and issued again from the left alveo- 
lus next to its own, by the side of the left incisor, which it did 
not displace; it then recurves downwards and backwards, and 
terminated under the left oibit. This tooth described a double 
spiral, of which the two circles, successively decreasing in dia- 
meter, were directed from before backwards, and from right to left. 
The left superior incisor, the alveolus of which was traversed 
by the tooth I have just described, was equally curved, but the 
circle it formed did not take the same direction as that of its 
fellow. 
The incisor teeth of the inferior jaw formed two long tusks, 
curved upwards and outwards, of which the right, thrown more 
backwards, described a circle of about eight lines in diameter. 
In passing before the orbit, it destroyed the lower border, (the 
eye of this side was atrophied,) in which it had hollowed a 
groove; its point recurved upon the cranium, which, had the 
animal lived, would, in a short time, have been inevitably pene- 
trated. The molar teeth of the right side had partially changed 
their direction, and were inclined inwards, so as to come into 
contact with those of the superior jaw. 
True phaneres, according to the expression of M. de Blainville, 
the teeth are developed and increase in size like them. Their 
growth is not indefinite, like the hair and the nails, as their 
papilla is neither conical nor sessile; it is, on the contrary, 
limited, like that of the feathers of birds, in consequence of the 
formation of their papillae, which are alike elongated and sup- 
ported by a narrow pedicle. 
A careless observer may be deceived by the apparent lengthen- ANATOMY OF THE DENTAL SYSTEM. 
65 
ing of the teeth of old persons, in consequence of a contraction 
of the alveoli; but a close examination of the enamel will show 
that, instead of being increased in length, they are actually worn 
away by the friction to which their extremities have been ex- 
posed. It is, undoubtedly, this mistake which has led many 
anatomists, and particularly Fallopius, to attribute to the teeth 
an unlimited growth. 
The formation of the calcareous portion of the teeth differs 
altogether from that of the other parts of our body; it takes 
place by simple juxtaposition, like inorganic formations, and not 
by intro-susception. Hunter's fine experiments have established 
this fact in the most positive manner; since, as we have seen, 
when a young animal is fed upon madder, those parts of the 
teeth only which are forming at the time it is submitted to the 
experiment, become reddened. 
Many disorders of dentition go, equally, to prove this theory. 
It is well known, that it may be ascertained by an experienced 
observer, even in conversing with persons who show their teeth 
when speaking, whether they have been, at the period of the 
formation of these organs, affected with any serious disease. 
We observe, upon the crowns of the teeth, elevated undulating 
lines, irregular rough grooves, or little depressed points, which 
constitute what is called erosion, but which Duval preferred to 
designate atrophy of the teeth. These organs, in the adult, pre- 
sent a faithful image of the condition of the whole organization 
at the time they were being formed. If a serious malady com- 
mitted its ravages at the commencement of dentition, when the 
follicle first began to secrete the crown, then the superior portion, 
only, of this part of the tooth will appear changed, the rest being 
in a normal condition. The close observer is enabled, as was 
remarked by the illustrious Chaussier, to indicate, when the 
alteration of the parts is disposed in bands, with intervening 
sound portions, the periods of health and disease, which have, in 
the infancy of such persons, succeeded each other. 66 
ANATOMY OE THE DENTAL SYSTEM. 
Sec. 4.-Eruption of the Teeth in General. 
When the teeth have attained a certain degree of development, 
the sac in which they were first formed is incapable of holding 
them any longer ; they are consequently carried outwardly, and 
the crowns soon make their appearance, devoid of covering, in 
the mouth. 
Generally, the eruption of the teeth does not commence till 
after the period of birth; the time, however, at which they make 
their appearance through the gum, varies in different individuals, 
but particularly, as will be presently shown, in regard to the 
species of teeth. Dentition may also be advanced or retarded 
by disease, as was remarked by Alphonse Leroy. "I have often 
seen," said he, "an infant cut two teeth before the ordinary pe- 
riod, when the nurse had had an attack of fever or inflammatory 
congestion; her milk, surcharged with caloric, accelerated den- 
tition, in the same manner that plants are made to grow rapidly, 
and to bloom early, by exposing them to the influence of artifi- 
cial heat, and watering them frequently and copiously: but, as 
the frail flowers, thus hurried forward before their time, fall 
without producing fruit, so do the precocious teeth of children 
waste away and fall soon after their eruption." 
The order in which the teeth make their appearance through 
the gums, is more exactly determined than the period at which 
their formation commences. The teeth of the inferior generally 
make their appearance before those of the superior jaw; not. the 
whole range, however; they are cut in pairs, and each pair which 
appears in the lower is succeeded by that corresponding in the 
upper jaw. 
Generally, the eruption of the teeth progresses regularly, from 
the anterior to the posterior part of the jaw; the canine, which 
do not make their appearance until after the first molaris, is an 
exception to this rule. Anatomists are not all, however, as will 
be seen from the following extracts, agreed upon this point. 
The celebrated Sabatier, in his treatise upon anatomy, says, 
"Some time after birth, the teeth make their appearance, succes- 
sively, in each jaw; their eruption taking place sooner in some ANATOMY OF THE DENTAL SYSTEM. 
67 
and later in others. The first rarely make their appearance 
earlier than the seventh or eighth month, or later than the 
twelfth or fourteenth. The inferior middle incisors cut the gum 
first, and frequently at an interval of from five days to three 
weeks ; they are followed by the superior central incisors ; then 
succeed the lower lateral incisors, followed by those above; the 
inferior canine teeth next make their appearance, and are folloxved 
by those in the upper jaw ; and, lastly, the two molars on each 
side of both jaws appear. 
M. Boyer, in his account, differs but little with M. Sabatier: 
"The two middle incisors of the lower jaw," says he, "first 
pierce the gums; sometimes they appear together, but more fre- 
quently at an interval of three weeks or a month. The eruption 
of the two middle incisors of the inferior is followed by that of 
corresponding teeth of the superior jaw ; then the lateral incisors 
of the inferior jaw appear, and are soon after followed by the su- 
perior lateral incisors ; to the latter succeed the lower, and then the 
upper canine teeth. The molars rarely appear before the age of 
nineteen months or two years; the two first inferior molars first 
show themselves, and are followed by the corresponding supe- 
rior molar teeth: to these succeed the second lower molars, 
which are sometimes accompanied by those of the upper jaw." 
According to Sabatier and Boyer, the eruption of the canine 
teeth takes place immediately after the lateral incisors, and be- 
fore the molars. Bichat adopts the same order in his general 
anatomy: "We soon see appear," says he, "sometimes singly, 
sometimes simultaneously, the two middle incisors of the inferior 
jaw; soon after, the corresponding incisors of the superior jaw 
are seen ; a month or two after, the four other incisors pierce the 
gum; at the end of the first year, usually, the eruption of the 
canine teeth takes place; about the end of the second year, or, 
as is often the case, somewhat later, two molars in each jaw are 
seen to issue, and these are soon followed by the two others." 
A great number of reasons have been assigned to account for 
the eruption of the teeth, which, as in many other instances, are 
mostly wide of the truth; who would believe, for instance, that 
this phenomenon has been attributed to the gravitation of the 
teeth ; to the pulsations of the dental arteries, or to a contest 68 
ANATOMY OF THE DENTAL SYSTEM. 
which takes place between the tooth and the gum, in which the 
latter are always victorious! Such theories as these do not, of 
course, merit a serious refutation. The opinions of Herissant, 
of Serres, and Delabarre,must not, however, be treated so lightly. 
According to Herissant and Delabarre, the tooth is drawn out- 
wardly by the contraction of the internal lamina of the mem- 
brane of the follicle, which, as we have seen, is attached to its 
neck; the neck of the tooth is, by this means, drawn towards 
the surface of the gum, and, when it reaches that point, it does 
not go farther, because the contractile power of the membrane is 
then exhausted. This theory is very simple, besides being very 
ingenious, but, unfortunately, it is very difficult to sustain. How 
can it be supposed, indeed, that the almost arachnoidean mem- 
brane, which lines the internal face of the follicle, possesses the 
power to draw out such a body as the osseous portion of the 
tooth? But it is useless to perplex ourselves to explain a phe- 
nomenon which is so easily understood. The cause of the erup- 
tion of the teeth is very simple and very apparent; they issue 
from their alveoli because they have attained to such a size that 
they can be no longer contained in them; in a manner precisely 
analogous to that in which the hair and nails pass from their 
particular matrices. It is a great mistake to suppose that the 
contraction of the alveoli, and the elevation of their basis, assist 
in the eruption of the teeth; for, in the first place, the alveoli 
become narrowed very little, transversely; and secondly, they 
become deeper and deeper, in proportion to the development of 
the teeth. The alveoli, indeed, are double the height of the 
body of the bone, as in the inferior jaw. 
Be this as it may, the following phenomena characterise the 
eruption of the teeth ; the tissue of the gum is elevated, the mu- 
cous membrane is swollen, reddens, becomes inflamed and pain- 
ful. Soon after, the red color disappears, and they become white; 
one or more openings are seen upon the surface, according to 
the number of points the rising tooth presents, and the tooth 
comes forth. If it be simple, it comes outwardly by dilating the 
only way prepared for it, but if the crown is broad, several open- 
ings are cut through the gum, which soon, however, unite into 
one. ANATOMY OF THE DENTAL SYSTEM. 
69 
A difficulty naturally presents itself here: is the opening which 
the tooth makes for itself merely a dilatation of the throat of the 
follicle, or is it the result of destruction of the gum at the point 
where it passes? M. Delabarre, without hesitation, adopts the 
first theory? " The fibro-mucous canal of the iter-dentis" says 
he, "is neither cut nor torn by the points which the tooth pre- 
sents ; the way is traced out, and all that remains to be done is 
to dilate it." Without disputing, positively, this position, it is 
evident that a distinction is necessary. It may, possibly, be ad- 
mitted that the canine teeth, and even the incisors, merely dilate 
the throat of the follicle, without cutting or tearing the gum ; but 
the same explanation will not apply to the molars, as the gum, 
when these teeth rise, presents several openings which cannot 
certainly be attributed to the iter-dentis. This view is, however, 
eminently philosophical; it includes all that occurs in the normal 
condition of the eruption of the teeth; the several openings ap- 
parent in the gum in the case of the molars may constitute but 
an exception, an anomaly. New observations appear to be re- 
quired to establish this point. 
M. Delabarre, besides, was not the first who supposed that the 
teeth issued from the alveolus by the natural opening of the fol- 
licle. Herissant has expressed himself very clearly with regard 
to this subject. After having established an important distinc- 
tion between the gum, properly called, which he designates, as 
has been already seen, the permanent, and the cartilage that 
covers it, which he calls the temporary gum, he adds: "The 
true or permanent gum is neither pierced nor torn by the teeth, 
as appears up to this time to have been believed. In order to 
have an adequate idea of the manner in which the teeth pass 
from the alveoli into the mouth, the fact must be recalled, that 
they are, each, enclosed in a little sac or thin membranous folli- 
cle, the orifice of which looks toward the opening of the alveo- 
lus. Those sacs are prolongations of the temporary gum, and 
ought to be well understood; as each one resembles a little closed 
purse, we will give them that name. This purse is closely ad- 
herent, interiorly, to all the surface of the crown of the tooth 
which it contains; but their adherence is more intimate at the 
place where the enamelled portion of the tooth is distinguished 70 
ANATOMY OF THE DENTAL SYSTEM. 
from the root, and the latter is shut up in the lower part of the 
purse, which adheres to it but very slightly. 
" Let us now take up the consideration of a tooth which has 
acquired its consistence and growth in this purse; the opening 
is then insensibly dilated ; its lower portion is carried little by 
little toward the alveolar opening, till the neck of the tooth is 
brought to a level with the edge of the socket, upon which the 
purse is turned from within outward to form the permanent gum. 
It is by this sort of reversing of the purse that the forming tooth 
is carried out of the alveolus, where, finding in its way the tem- 
porary gum, it at last, after repeated efforts, tears through it." 
Before the teeth cut the gums, they frequently give rise to dis- 
orders which jeopardize the life of the child; these are caused 
by the pressure exercised upon the adjoining parts, and the irri- 
tation which results from it. Some of the disorders, attendant 
upon dentition, have been attributed, but without good reason I 
think, to pressure made upon the nervous trunks by the roots of 
the teeth. At this period, indeed, they are shut up in perfectly 
formed canals, and are placed beyond the reach of irritation from 
this cause. With regard to the filaments which come off from 
these trunks to form the pedicles of the papilla, this, however, 
is not the case, as 1 will presently show. 
ARTICLE II. 
DEVELOPMENT OF THE TEETH IN PARTICULAR. 
The history of the particular development of the teeth is nat- 
urally divided into three parts: the consideration of the tempo- 
rary, permanent, and a third set of anomalous teeth, with which 
nature has sometimes endowed old persons, and which, for this 
reason, has been termed a senile dentition. ANATOMY OF THE DENTAL SYSTEM. 
71 
Sec. 1.-Development of the Temporary Teeth. 
FIRST DENTITION. 
The first twenty teeth of the child, including the eight inci- 
sors, the four canine, and the eight molar teeth, are destined to 
have but a very short existence. They do not ordinarily remain 
beyond the first years of life-for which reason they have been 
called temporary, deciduous, infant, and milk teeth ; and all the 
details which relate to their history are recorded under the name 
of first dentition. 
What has been already said with regard to the period at which 
the dental follicles first make their appearance, relates to the tem- 
porary teeth; and a repetition of these details is, of course, un- 
necessary ; neither will I anticipate any thing in this place that 
relates to the origin of the secondary teeth, of which I shall treat 
in the following section. 
The germs of the teeth make their appearance in exactly the 
same order in which they afterwards pass through the gums. 
M. Serres detected the germs of the incisors and molars at the 
second month after conception ; those of the canine teeth about 
two weeks later. Their disposition, under the gum, offers no- 
thing which 1 have not already noticed ; it is only necessary to 
add, here, that the point above them is harder, now, than it is at 
a later period, and that it is covered by a cartilaginous produc- 
tion, which is called the dental cartilage, and which has been, 
very justly, compared, with regard to its consistence, to the beak 
of birds. This cartilage, according to M. Oudet, may be sepa- 
rated from the gum by maceration; it forms a sort of crust, which 
is, frequently, marked with elevations and indentations; its bor- 
ders cause a slight swelling of the mucous membrane of the gum. 
This is the cartilage which was considered by Herissant as the 
temporary gum: " Raise it up," said he, " and you will find un- 
der it the permanent gum, in which will be perceived the open- 
ings of the dental follicles." 
The ossification, or, to speak more exactly, the calcareous se- 
cretion commences very early, towards the second month of ute- 
rine life. Every fifteen days from this time up to the seventh 72 
ANATOMY OF THE DENTAL SYSTEM. 
month of gestation, according to M. Rousseau, some portion of 
a new tooth is formed ; the whole of the twenty crowns of the 
temporary teeth may be observed in some stage of development 
at about this period. 
The calcareous deposite of the papilla appears, with regard to 
time, in the exact order that the follicles are formed, and the 
eruption of the teeth takes place. It commences first upon the 
inferior central incisors, then the superior, and successively, up- 
on the lateral incisors, the first molaris, the canine, and the se- 
cond molaris. 
In the foetus of eight months, each superior central incisor is? 
ordinarily, about two lines in breadth and two lines in height. 
The small lateral incisors, which at this time still preserve a 
triangular form, are each, according to M. Rousseau, about a line 
and three quarters in breadth and about a line and two-thirds in 
height. The canine tooth presents a conical cap about a line in 
breadth and a line in height. 
The first molaris is three lines in breadth at its base, and two 
lines and a half in thickness antero-posteriorly. This tooth is 
now divided into two parts, an anterior and a posterior, which, 
however, are united by a transparent lamella, upon which a lit- 
tle opaque point may be observed. At this stage, each of the 
parts of the tooth is about a line and a half in breadth at its base 
and a line in height. 
At nine months, the sac of the first large molaris, which be- 
longs to the second dentition, is plainly distinguishable; a very 
small point of ossification only can be perceived at this period. 
The second molaris which completes the temporary set of 
teeth, is now formed of four little enamelled caps, disposed in a 
circle, but not yet united. The first of these caps presents itself 
at the anterior part; it is a line and three quarters in the greatest 
diameter of the opening at its base; a line, only, in its antero- 
posterior diameter, and a line in height. The second cap, sit- 
uated on the posterior or lingual side, differs, but little, from the 
first in its dimensions. The third, smaller than the two preced- 
ing, is more conoidal, and but a line in diameter at its base. 
The fourth and last of these caps is the smallest of all, and is 
placed upon a circular base a quarter of a line in diameter. ANATOMY OF THE DENTAL SYSTEM. 
73 
The temporary teeth soon begin to issue from their alveoli. 
Pliny, Columbus, Van Swieten, Donatus, &c., relate examples 
of the premature eruption of the first teeth. Haller mentions 
nineteen children who cut their teeth before the usual time, and 
Polydorus Virgilius relates the case of an infant who had six 
teeth at its birth. Charles Rayger, on the other hand, makes 
mention of a woman whose canine teeth did not make their ap- 
pearance until her thirtieth year. Usually, however, the first 
teeth appear from the fourth to the eighth month after birth. 
The cases cited by Fauchard and Bourdet, of some individuals, 
who never had any teeth,or those who did not cut the full num- 
ber, are altogether exceptions. 
About the eighth month, the two central incisors make their 
appearance ; from the tenth to the twelfth, the two laterals ; from 
the twelfth to the fourteenth the four first molars; the canine 
teeth at eighteen months, and the four second molars at about 
two years. 
The temporary teeth present very marked differences from 
those which succeed them. They are but twenty in number, 
and the supposition that there are twenty-four is altogether a 
mistake. The four teeth which appear about the fourth year are 
never shed; they do not, consequently, belong to the temporary 
set, but are the first permanent large molars. The necks of the 
temporary teeth are surmounted without by a slight elevation, 
which gives to them a particular rounded appearance; their 
crowns are whiter and fuller than those of the permanent set. 
The incisor and canine teeth are smaller, whilst the molars, on 
the contrary, are larger than those of the second dentition. The 
incisor and canine teeth of this set differ but little in form from 
those which succeed them, but it is not so with the molars ; the 
latter, which have the form of the permanent great molars, are 
replaced by the bicuspides of the second set. 
The reason of this remarkable difference may be inferred from 
the use which the great molars subserve in the economy. These 
teeth are much more important for the purpose of grinding the 
food than the small molars, which may, almost, be considered as 
of little service in mastication; and, as the jaws of the child are 74 
ANATOMY OF THE DENTAL SYSTEM. 
too small to give room to all the molars found in the adult, the 
most useful are chosen. 
The first molaris of the superior jaw is quadricuspidated ; its 
root has three divisions, two of which are joined together, the 
other isolated. The second molaris, which is larger than the 
preceding, has five points and is sustained by three divergent 
roots. The two inferior molars resemble very nearly those of 
the superior jaw, except that they are not quite so large. 
The roots of the temporary are generally shorter and more 
slender than those of the permanent teeth. That they are en- 
tirely deprived of roots, according to Van Swieten and Auzebi, 
is an opinion it is hardly necessary to disprove. This error took 
rise from the fact that the root of this set of teeth is most com- 
monly destroyed at the time of their spontaneous fall. Auzebi, 
however, believed so firmly that this was the fact, that he criti- 
cised, very pleasantly, those who thought it necessary to discuss 
the question, whether the roots of the temporary teeth were de- 
stroyed or not by the pressure of the rising teeth of the second 
set. 
The substance of the deciduous teeth is very analogous to 
that of the second set; it is not, however, so hard. They crack 
with a particular facility, when exposed to desiccation; a fact 
which I have not seen mentioned by any author. 
These teeth are rapidly destroyed by friction. M. Murat has 
related the case of a young physician, whose first teeth, never 
having been shed, were worn down almost to the roots, like 
those of an old person. M. Deneux, and some others, have ob- 
served similar cases. 
The temporary teeth receive their arteries from a special branch 
of the dental trunk which occupies a distinct conduit in the den- 
tal canal itself. This conduit has been known for a long time; 
Jourdain has described it in the two following passages: 
"The disposition of these bees produce agroove and a foramen. 
By the superior groove passes the foramen of the principal dental 
trunk; and by the inferior foramen various ramifications of this 
trunk enter, to be distributed in the substance of the base of the 
jaw, to furnish the fluids and branches necessary to the forma- 
tion of the germs of the permanent teeth, and to close their sacs 
or matrices." 75 
ANATOMY OF THE DENTAL SYSTEM. 
"The fluids which the permanent teeth receive, are carried by 
this branch, which, as I have stated, passes by the inferior fora- 
men, and which I have observed in a jaw of seven or eight 
months' formation. At this time, this branch alone occupies the 
maxillary canal, as that which had supplied the temporary teeth 
has been confounded with it." 
This description of Jourdain had been entirely forgotten, when 
M. Serres, in his researches upon the teeth, discovered the con- 
duit in question, of which he has given a more exact description 
than Jourdain; he showed, also, that it was represented by an 
analogous canal in the superior maxillary bone. 
This canal commences behind the superior opening of the 
inferior maxillary conduit, under which it goes a little towards 
the outside and terminates under the alveoli of the milk teeth, 
after having been partly confounded with the diploe of the bone, 
and opening in a special hole situated under the mental foramen. 
It is very large in the foetus, and still remains quite large in the 
infant; but it becomes more and more narrow as it is affected 
by the pressure of the secondary teeth. Finally, it disappears, 
except in some cases after second dentition is effected. 
The temporary teeth do notremain longer than from the sixth 
to the twelfth or thirteenth year. Towards this period of life they 
become, successively, loose and fall, very nearly in the order of 
their formation and eruption. 
But a certain combination of circumstances is necessary to the 
shedding of the temporary teeth, which does not always exist, 
and the absence of which, either retards or prevents altogether 
this phenomenon from having place; authors relate many in- 
stances illustrative of this fact. 
At the moment of their falling, the teeth have undergone a 
certain number of modifications which should be understood; 
their root is, to a greater or less extent, destroyed ; this is almost 
invariably the case with the molars, but less constantly with the 
incisors and canine teeth. This alteration is not confined to the 
extremity of the root, for these parts become thinner, more irreg- 
ular in their whole length, their canal is enlarged, and, accord- 
ing to M. Duval, the internal portion of the crown itself is ero- 
ded. 76 
ANATOMY OF THE DENTAL SYSTEM. 
Phenomena as curious as these, and of as constant occurrence, 
could not fail to attract the attention of physiologists, and expla- 
nations of the subject have crowded upon us from all sides. 
Some authors, Delecluse, Ungebaur, and Serres, have attribu- 
ted the destruction of the roots to the compression exercised 
upon the dental artery and its obliteration ; some to the mechan- 
ical action of the secondary teeth ; Hunter to a peculiar action, 
and Delabarre to the production of a special absorbent organ. 
In whatever manner we examine this question, we are com- 
pelled to recognise the fact, that absorption, as Hunter has well 
expressed it, plays the principal part; but the question arises, 
why does this absorption take place? Under what influence 
does it commence and terminate at a certain period? Here lies 
the difficulty. The fall of the teeth is, undoubtedly, determined 
by some other cause, than the influence of pressure, for Hunter, 
and other anatomists, have observed it to take place under cir- 
cumstances which precluded the possibility of pressure. 
" Vidi duas tresve maxillas, in quibus secundi molares lactei 
deciderint communi metho do, absque ullo supposito dente, et in 
una maxilla ubi ambo molares decide/ int, eamdem inveni circum- 
stantiam" 
The temporary teeth sometimes remain after the eruption of 
the corresponding teeth of the second set; but this circumstance 
must be attributed to some other cause than a defect of pressure. 
The milk tooth, at the time it is shed, appears to have under- 
gone a change, as if it had been, for some time, reduced to the 
condition of a foreign body; it is eroded in the same manner as 
pessaries, which have remained too long in the vagina. Is it 
not very probable, consequently, as was thought by Delecluse 
and Ungebaur, and was latterly maintained by M. Serres, that 
the vessels which go to the pulps of the temporary teeth are 
destroyed by the pressure of the secondary teeth? Indeed, 
this fact appears to me well established. If the jaw of a child, 
at the age when the alveoli of both dentitions and the canals, 
for the passage of the dental vessels of both sets of teeth, exist, 
be examined, we will be struck with the complicated course the 
vessels which supply the deciduous teeth are compelled to take, 
after leaving the main trunk, in the dental canal to reach their ANATOMY OF THE DENTAL SYSTEM. 
77 
alveoli. The canal in which the trunk of the vessel of the de- 
ciduous teeth passes, occupies the lowest portion of the maxillary 
bone, under the alveoli of the teeth of the second dentition, and 
the branches sent off" are compelled to pass over the sides of the 
alveoli of the permanent teeth, to reach their destination. This 
being the case, it is physically impossible that these vessels can 
escape obliteration under the pressure, daily becoming greater, 
which the growing secondary teeth and alveoli exercise upon the 
adjoining parts. 
Sec. 2.-Development of the Permanent Teeth. 
SECOND DENTITION. 
When we reflect upon the difficulty with which we have ob- 
tained the teeth intended for ordinary usage, and which should, 
unless destroyed by disease, serve us to the end of life, it seems 
as if nature, in this instance, had rambled a little from her usual 
simple and provident course. Would it not have been better, 
we are at first inclined to ask, to have at once provided us with 
permanent teeth, without undergoing the labor of supplying two 
sets? But we may well answer, without fear of being exposed 
to the accusation of optimism, that nature here, as always, has 
done that which was necessary and no more. 
The child, indeed, requires teeth in his earlier years, but his 
jaws are too slender and too weak to support teeth of such size 
as those of the permanent set. The very limited extent, antero- 
posteriorly, of the maxillary arches, rendering them incapable of 
receiving all the molars, it was necessary, first, to place in them 
those which would render the greatest service, the large molars. 
As the jaws would have been obstructed, however, in their ac- 
tion, after the child became older, by the presence of so many 
large teeth, it became necessary to furnish those which were 
more in relation to the changes which take place: consequently 
the large molars were replaced with the bicuspides. 
The permanent teeth, as has been shown, are thirty-two in 
number. They are, naturally, divided into two series; the first, 78 
ANATOMY OF THE DENTAL SYSTEM. 
the true teeth of replacement, comprises the twenty anterior, 
which succeed the temporary teeth; the second, the twelve 
teeth which are primitively permanent, and which represent the 
large molars of the adult. 
We are acquainted with the characteristics of the permanent 
teeth, as they are those found in the adult subject, and have 
served as a type for the general description given at the com- 
mencement of this treatise. All that is necessary here, is to bring 
them into comparison with the temporary teeth. The six 
central permanent teeth occupy a greater space in the jaw than 
the four small molars ; this is the reverse of the first dentition, 
the incisor and canine teeth of this set not forming so large an 
extent as the molars. The two first permanent molars are bicus- 
pides, but they succeed large molars. "This, indeed," says Cu- 
vier, "is a general rule; the first molars of replacement have, 
always, a crown less complicated than those which preceded 
them ; this complicated crown is, however, observed in those 
teeth posterior to those which represent the first set. 
The permanent teeth receive their vessels from the trunk of 
the dental artery, which passes immediately under their alveoli. 
We begin to perceive the germs of the permanent teeth at 
about the third month of uterine life, almost as soon as those of 
the temporary teeth are distinguishable. At this period they are 
very small, are suspended from the gum by a mucous cord about 
a line in length, and are placed behind the germs of the tempo- 
rary teeth. The germs first perceived are those belonging to 
the series which replaces the deciduous teeth. The order in 
which they are formed, and become apparent to the eye of the 
anatomist, is the same as that attributed to the temporary teeth. 
M. Serres has placed the appearance of the germ of the first 
great molaris in the last period of foetal life; those of the two 
last are never seen till after birth. 
In the foetus, the germs of the permanent teeth are much 
smaller than the others. When first distinguishable, they are 
both placed upon the same plane, but the maxillary bone, soon 
acquiring greater height, the former are carried downwards, 
passing by the germs of the first teeth, and placing themselves 
beneath, in consequence of a remarkable elongation of the throat, 
ductus dent is. 79 
ANATOMY OF THE DENTAL SYSTEM. 
At first, the germs of the two dentitions are placed together, 
in the same alveolar furrow, but afterwards partition walls sepa- 
rate them, and constitute distinct alveoli. 
After birth, in the inferior jaw, the central incisors are placed 
against the posterior face of the roots of those they are destined 
to replace; and, as they are larger, they overlap a little their 
alveolar walls. The permanent lateral incisors, larger still than 
the preceding, are placed behind the partition which separates 
the lateral incisors and the canine teeth of the first set; the 
canine is more deeply buried in the thickness of the jaw than 
the others ; it is placed out of the alveolar range, and under the 
anterior lamina of the alveolar process, which it sometimes 
raises in a remarkable manner. The first small molaris is placed 
under and behind the tooth it is to follow, whilst the second 
small molaris is exactly subjacent to the second temporary 
molaris. 
The reason why the canine is thrown out of the range of the 
arch formed by the other teeth, as we have stated above, is very 
obvious: the molars of replacement correspond exactly to those 
of the first dentition ; the incisors of the second set occupy as 
great a space as the temporary incisors and canine teeth together, 
thus the rudimentary permanent canine teeth are compelled to 
seek a position out of the circle. 
About a year after birth, the germs of the teeth of the second 
dentition are separated from each other and from the milk 
teeth, by bony walls, which form for them special cavities. 
The cavities or alveoli are pierced with a canal at each of their 
extremities, to give passage, below, to the vessels and nerves 
which form the pedicle of the dental pulp, and above, to the 
throat of the follicle, or ductus dentis. The canals situated at 
the upper surface of the alveoli were, at first, observed in the 
anterior part of the jaw only, and for that reason were called in- 
cisors ; but they are much more general than was then supposed. 
They do not open into the alveoli of the temporary teeth, as was 
believed by Fallopius, but terminate upon the alveolar arch, be- 
hind the alveoli of these teeth. 
The follicle of the permanent tooth is a dependence of the 
mucous membrane of the mouth, like that of the temporary tooth. 80 
ANATOMY OF THE DENTAL SYSTEM. 
It is continuous with that membrane, by means of a long ductus, 
which has been well described by Fallopius, who called it a 
second pedicle of the papilla. This ductus passes through the 
bony canal in the superior part of the alveolus, and reaches the 
mucous membrane. Albinus erroneously believed that the 
ductus of the molaris terminated in the alveolus of the deciduous 
tooth. 
Meckel believed that the follicles of the temporary and perma- 
nent teeth were connected by their fibrous membranes. He 
supposed, also, that those of the permanent proceeded from those 
of the temporary teeth; "at first," says he, "they rest imme- 
diately upon them, but afterwards they are only joined by long 
and slender cords." In my observations, however, I have dis- 
covered that this communication exists between the external 
laminae of the dental follicles only, and that the internal, so 
essential, are entirely isolated from each other. If this commu- 
nication ever exists, it must be at a very early period, for I have 
never been able to discover it, although I have examined the 
follicles of the permanent teeth, from the first moment they 
became perceptible. 
The permanent teeth of replacement are developed in their 
follicles, in the same order, and subject to the same laws 
which govern all the teeth in their increase, which I have 
mentioned in the general description I gave, and to which 
it is useless to return. When these teeth have undergone a 
certain degree of development, they exercise a force upon all 
parts of the walls of their cavities ; behind they press upon the 
lingual lamina of the alveoli ; forward they compress the vessels 
that come from the accessory dental canal to supply the tempo- 
rary teeth, and first obstructing their canal, at last destroy them 
altogether; forward and above, they press upon the partitions 
which separate their alveoli from those of the first set; and, 
finally, below or above, according to their position in the jaws, 
they press upon the trunks of the dental vessels and nerves. 
At the end of a short time, as I have already explained, when 
treating of the deciduous teeth, the pedicles of the papillae of 
these last are destroyed, their follicles are obliterated, and the 
teeth themselves, reduced to the condition of foreign bodies, ANATOMY OF THE DENTAL SYSTEM. 
81 
undergo all the changes which affect unorganized substances 
in the middle of organized tissues. They become softened, are 
destroyed at the base, and fall more or less promptly, according 
to the rapidity with which these phenomena succeed each other. 
In this successive elevation of the tooth of replacement, by 
the sacrifice of the one which precedes it, the septum which 
separates the two alveolar cavities is destroyed, and they are con- 
founded together, the crown of the second tooth pressing imme- 
diately upon the root of the one which precedes it. Sometimes, 
however, the secondary tooth makes a passage through the 
alveolar border, without affecting the wall of the alveolus of the 
temporary tooth. In the first case, the pressure of the perma- 
nent tooth adds a new element of destruction to those which 
already surround the temporary tooth; its fall becomes more 
certain, and the period less distant when it will be shed; the 
permanent tooth, then placed in the widened alveolus, finds its 
way outward without any difficulty. In the other, which Hunter 
has erroneously represented as the normal condition, the perma- 
nent are carried behind the alveoli of the milk teeth, directed in 
this course by the ductus; they make a special opening, by 
dilating the bony canal described above, and the alveoli of the 
temporary teeth are pressed upon and destroyed. 
It is, perhaps, useless to remark, that the phenomena here 
described relate only to the twenty anterior permanent teeth, 
as there are but twenty of the temporary set. 
The permanent, like the milk teeth, issue from their alveoli 
in the following order: the first large molaris, the central inci- 
sor, the lateral incisor, the first small molaris, the canine, the 
second small molaris, the second and third large molars. The 
first tooth of the second series commences the great change; the 
whole of the first series then replaces the temporary teeth, and 
finally, the second and third large molars complete the second 
dentition. 
The first large molaris makes its appearance about the fourth 
or fifth year, immediately behind the second temporary molaris. 
Its eruption follows so nearly that of the last deciduous molaris, 
that some persons have erroneously classed it among the tem- 
porary teeth. 82 
ANATOMY OF THE DENTAL SYSTEM. 
The central incisor shows itself from the sixth to the eighth 
year ; the lateral incisor soon follows. 
The first small molaris appears about the ninth year; the 
canine from the tenth to the eleventh ; the second small molaris 
from the eleventh to the thirteenth ; the second large molaris 
from the twelfth to the fourteenth ; and, finally, the last great 
molaris, the dens sapientice, at a period which varies from the 
eighteenth to the thirtieth year. 
Blake and Bichat maintained that the first temporary molaris 
was replaced by the two small permanent molars ; that this is 
an error, the most simple inspection of the teeth will prove; 
an error which I have corrected in my edition of "Bichat's 
General Anatomy," and which had already been rejected by 
every anatomist. 
All the great molars, when they first make their appearance, 
are directed obliquely forward, but afterwards take their straight 
position, when the alveolar arch is more crowded with them. 
My subject does not embrace the disorders caused by the 
eruption of the teeth, particularly those of second dentition ; but 
I will mention a phenomenon which often accompanies the 
issue of the last great molaris : placed at the base of the coronoid 
process, at its anterior part, this tooth frequently finds so much 
difficulty in extricating itself from the bony lamina which covers 
it, that it frequently remains shut up in the cavity, or takes a 
direction towards the tongue, after having given rise to various 
unpleasant symptoms. I was lately called to remove one of 
these teeth, which, forced to remain in its alveolus, had become 
anchylosed to the bone, and given rise to fistulous openings, 
against which all the resources of art had been ineffectually 
exhausted. 
Second dentition is not always accomplished with such ex- 
actitude ; many circumstances, as I have already indicated, may 
occur to interrupt it. The permanent teeth sometimes are not 
formed at the usual time, and those of the temporary set continue 
to occupy their places. This is a species of irregularity which 
most frequently occurs, and which may include either the whole 
series or a lesser number of the teeth. M. Maingault reported 
to the academy the case of a young man, whose first teeth had ANATOMY OF THE DENTAL SYSTEM. 
83 
never been shed; and M. Murat met with a case of similar 
character. All the treatises upon anatomy, indeed, are full of 
examples of the absence of formation of some of the teeth of the 
second set. 
I know, at this time, a person thirty-eight years of age, who 
did not lose the second right inferior temporary molaris, till the 
age of thirty, and which has not yet been replaced. 
It is not less common to observe the issue of the secondary, 
without the fall of the primitive teeth ; and this vice of confor- 
mation, like the preceding, may occur in any part, more or less 
extended, of the dental arch. Pfaff has often observed, he says, 
thirty-three or four teeth; Soemmering has seen as many as 
thirty-six. In some individuals, there appears to be a predispo- 
sition to the formation of these supernumerary teeth. Various 
reasons have been given to explain the origin of this variety of 
irregularity: some have attributed it to the absence of a commu- 
nication between the alveoli of the first and second teeth, and 
the defect of pressure, in consequence, by the latter. Without 
attempting, for a moment, to deny the influence which this cir- 
cumstance might have, I am inclined to believe that the irregu- 
larity sometimes depends upon the absence of the special tem- 
porary artery, as M. Serres has observed, and the origin, by a 
common trunk, of the arteries which supply both sets of teeth. 
Sometimes the teeth do not appear in the order and at the 
periods indicated above. The eruption of the second molaris 
often occurs before the canine tooth ; sometimes the issue of the 
latter is retarded; indeed,! know an individual in whom it has 
never appeared. 
Sec. 3.-Development of the Senile Teeth. 
THIRD DENTITION. 
If any one fact more than another throws light upon the his- 
tory of the formation of the teeth, it is assuredly this : that the 
two dentitions have been calculated according to the ordinary 
duration of life, and that they will suffice, unless influenced by 84 
ANATOMY OF THE DENTAL SYSTEM. 
circumstances to which our manner of life too frequently gives 
rise, to assure teeth to each individual during his term of exist- 
ence. It should, also, be recognised that these two dentitions 
are all that were originally intended for our use, and that excep- 
tions to this law are extremely rare, appearing like those freaks 
of nature in which she sometimes indulges, as if to display her 
power. 
Joubert relates the case of a lady of quality, who, having lost 
all her teeth, cut twenty new ones at the age of sixty years. 
Sennert mentions a similar case, of a lady of Silesia, who, about 
the same age, cut twenty teeth, the eruption of which was ac- 
companied by all the phenomena attendant upon first denti- 
tion. Eustachius mentions a young man, twenty years of age, 
whose incisor teeth were replaced, in the course of a year, after 
they had been extracted. Dufay, a physician of 1'Orient, saw, 
in that city, a man, eighty-four years of age, to whom nature had 
given, at this late period, two incisors and two canine teeth. 
Gehlet mentions a canine tooth which was twice renewed. 
Hunter, also, speaks of teeth which were renewed at the age of 
seventy years. I found, myself, in the jaw of an adult, imme- 
diately under the first small molaris, a new tooth, of which the 
crown was half formed-both the small molars were in place on 
this side of the jaw. 
Authors, however, are not agreed as to whether we should in- 
terpret such cases as evidences of a third dentition. Some be- 
lieve that they are simply cases of the retarded eruption of teeth 
of the first or second dentitions; others find it more simple to 
deny the facts altogether, and to delay forming any conclusion 
until more light is thrown upon the subject. 
On both sides there is error. Can we admit in the case men- 
tioned by Gehlet, where the canine tooth was renewed the third 
time, the possibility of the retarded dentition? Can any doubt 
be entertained in the case which fell under my own observation ? 
It cannot be urged that this was not the rudiments of a tooth of 
a third dentition, for it was placed under the bicuspides, which 
class of teeth belong to the second set alone. 
Why, indeed, does the possibility of a third dental formation 
seem so remote? Is this anatomical truth more difficult to con- ANATOMY OF THE DENTAL SYSTEM. 
85 
ceive than the thousand anomalies encountered daily in organs 
much more important than the teeth ? Assuredly not. Let us 
show ourselves less incredulous, without believing with Fallo- 
pius, that the body renews itself to the sixth septenary, and 
that, consequently, the teeth may be renewed at that period; 
let us hold ourselves rigorously to the observation of facts. 
It will have been observed, that in all the cases of third den- 
tition, mentioned by credible authors, that they have been ex- 
tremely incomplete: one or two isolated teeth only making their 
appearance. Accounts of a renewal of the whole dental range 
are very rare, and even those cases on record of doubtful au- 
thenticity. This third dentition, as Hunter justly remarks, 
when it occurs in persons who have lost all their teeth, instead 
of being a benefit, is really a serious inconvenience to the indi- 
vidual. Isolated, most frequently, upon the dental arches, and 
wanting points of support against opposing teeth, they cause irri- 
tation, inflammation, and ulceration of the gums, till their remo- 
val becomes necessary. 
Sec. 4.-Application of the Development of the Teeth to the De- 
termination of Ages. 
The consideration of the teeth with regard to the determina- 
tion of the ages of individuals, is not only interesting in an ana- 
tomical and physiological point of view, but it has a practical appli- 
cation of much importance. It serves, in legal medicine, to re- 
cognise the age of an individual, in the absence of the ordinary 
proofs. This application of the phenomena presented by the 
development of the teeth, has enabled Cuvier to fix the opinion 
of the learned, with regard to two heads of extraordinary size, 
which were disinterred, one in the environs of Rheims, the other 
at Billerbeek, in the bishopric of Munster, which were, generally, 
thought to prove the existence of a gigantic race, at present ex- 
tinct. An examination of the teeth and alveolar arches enabled 
this celebrated anatomist to overturn the opinion generally enter- 
tained, and to show that the heads not only did not belong to a 
race of men different from our own, but that they were those of 86 
ANATOMY OF THE DENTAL SYSTEM. 
very young children. We will give, however, the account in his 
own words: 
"The age of a head, however deformed it may have become 
in consequence of diseases of the osseous system, may always 
be very nearly ascertained by the number and configuration of 
the teeth. 
"The reason of this, is, that the teeth are not developed like 
the bones by introsusception, but grow like shells, by simple jux- 
taposition, and their parts once formed, being no longer subject to 
inflammation from an internal principle, those diseases to which 
the bones may be subject do not affect them in the slightest de- 
gree ; neither are the bones immediately affected by diseases 
which attack the teeth. Guided by these views in the examina- 
tion of the heads in question, I found in that of Darmstadt the 
half-filled alveoli of six teeth on each side, two incisors, a canine 
and three molars. In the inferior jaw, the left side of which only 
remained, the alveolus of the third molaris was wanting. 
"This first led me to the conclusion that the individual was 
about six or seven years of age at the time of his death, and that 
the alveoli remaining were those of the temporary teeth. 
"Towards the sixth or seventh year, the first permanent mo- 
laris makes its appearance, and at the same time the temporary 
teeth in the anterior part of the jaw begin to fall, to give place 
to the teeth which are to succeed them. 
"What the alveoli of the Darmstadt head appeared to indicate, 
the teeth themselves of the head, in the possession of M. Jussieu, 
seemed to confirm. 
"This head, also, had but six alveoli on each side of both 
jaws; the sixth of the left side of the superior jaw was also ab- 
sent. This sufficiently proved that it was near the age of that 
of Darmstadt; but, by great good fortune, two molars, the second 
of the left side of the superior jaw, and the second of right side 
of the inferior, were preserved. 
"Now nothing was more easy than to determine whether these 
teeth belonged to the first or second dentition, as the second tem- 
porary molaris differs, entirely, in form, from that which suc- 
ceeds it. 
"In man, as in most quadrupeds, indeed, the milk molars have 87 
ANATOMY OF THE DENTAL SYSTEM. 
a more complicated form and resemble the large permanent mo- 
lars more than those which replace them, and the object of this 
difference is easily comprehended : as a long time elapses before 
the appearance of the great molars, and as those teeth are essen- 
tial to perfect mastication, their form was given to the tempo- 
rary molars, in order that they might fulfil the requisite forma- 
tions. Thus, in man, the first temporary molaris has towards the 
inside of the mouth a large tubercle, and a crest divided into two 
lobes without; the second has four tubercles disposed obliquely. 
In the inferior jaw, the first milk molaris has four tubercles a little 
elevated above the surface of the tooth, and the second five, of 
which there are three without and two within ; each of the latter 
being a little bilobed. In other words, the second temporary in 
each jaw resembles the first permanent molaris which rises be- 
hind it, and not the one which succeeds it. 
"The molars of replacement are the bicuspides of the adult; 
their crown presents two great tubercles, one within and one 
without; the tubercles of those of the inferior are a little more 
indented than those of the superior jaw. 
"The roots of these two species of teeth are also very different, 
and are always shorter and more complicated in the temporary 
than in the teeth of replacement. 
"Guided by these facts, I examined the teeth, and their dimin- 
ished roots of the head, in the possession of Jussieu. 
"The second molaris remaining in the superior jaw had four 
tubercles and an uneven crown, and, by examining the corres- 
ponding alveolus of the opposite side, it was ascertained that it 
had three short roots. Thus complicated, and occupying the 
second alveolus from the canine, the conclusion that this is a 
temporary molaris is inevitable. 
"The tooth which had occupied the next anterior alveolus to 
this, was of the same form, for it left the marks of its three roots 
in the alveolus. Behind it, was a third molaris, now broken off, 
but which had left three roots; this could not have been any 
other than the first large permanent molaris, which appears about 
the seventh year. It is only about the seventh year, indeed, that 
three teeth are observed together in the superior jaw, each having 
three roots; for before this age, the first permanent molaris has 88 
ANATOMY OF THE DENTAL SYSTEM. 
not made its appearance, and a little while after the temporary 
molars are replaced by the bicuspides, which have but one, or at 
most, two roots. It is true that the second permanent molaris, 
which has three roots, then passes through the gum, but the 
third or wisdom tooth never has so many. Then, as I have 
said, a little while after the age of seven years, there are but two 
molars in contact with each other which have three roots. 
"The inferior molaris of the head in question had five tuber- 
cles upon its crown like a second temporary molaris of this jaw, 
a little worn away; which fact proved that they had served the 
individual for mastication during some time. It is true, that if 
this tooth had been found isolated, it would have been difficult 
to have determined whether it was the second temporary or the 
first permanent molaris; these teeth,as I have mentioned above, 
having very nearly the same form. But under the present cir- 
cumstances, this supposition would be inadmissible, as there 
would not then be the ordinary number of teeth in front of it. 
The two cavities, anteriorly to the tooth, in place, are not two 
alveoli, but places for the two roots of the same tooth; and the 
existence of the two roots, separated from the neck of the tooth, 
proves that these cavities were filled by one temporary molaris, 
and not two bicuspides. 
"The canine, on this side is broken out, and not driven into 
the substance of the bone, as was thought by M. Jadelot. As 
regards the incisors, this idea is still less applicable. 
"The alveoli of all the incisors are marked, and at their ordi- 
nary place, they are half filled, which proves that the teeth which 
occupied them had been shed. 
"The tooth remaining in the substance of the bone, near its 
inferior face, has its cutting edge very entire, and the points of 
the crown resemble those of an incisor of replacement. It has, 
evidently, never been used : for in that case it would have been 
somewhat worn like the molaris which remained in place. 
"From the perfection of the cutting edge of this tooth, and the 
existence of an alveolus, which is a certain mark that another 
incisor had preceded it, 1 am convinced that far from having 
been driven back into a softened bone by the pressure of masti- 
cation, this has been unable to pass outwardly, in consequence ANATOMY OF THE DENTAL SYSTEM. 
89 
of the hardness and thickness of the bone,'which opposed an in- 
vincible obstacle to its eruption. 
"Near to this tooth, on the interior, another larger cell is situa- 
ted, which will doubtless be found to contain a tooth if the jaw 
be broken at this place. 
"I am persuaded if the bone were opened in this vicinity more 
teeth would be found, which were unable to reach the exterior. 
"The surface of the jaws, examined in detail, confirm what is 
indicated by the teeth and alveoli. Behind the alveoli of the 
incisors are the vestiges of the little holes, which, in the normal 
condition of the parts, offers passage to the incisors of replace- 
ment; these little holes are, however, entirely closed by the 
swelling of the bone. 
"In the superior jaw, very distinct traces, only a vestige of 
which remains in man, are observable, of the suture which, in 
animals, separates the incisor from the maxillary bone. The re- 
mains of this fissure is of value in determining the situation of 
the canine tooth; and in enabling us to see that the tooth placed 
behind it, or the first molaris, had three roots, and was, conse- 
quently, a temporary molar. 
"If I do not deceive myself, all these circumstances concur to 
prove, that the heads under examination are those of children 
who died about the period when the shedding of the teeth takes 
place, and that this change in their case could not be effected." 
ORDER IV. 
IMPORTANCE OF THE TEETH IN THE ORGANISM. 
The influence of the teeth upon the rest of the organism is 
two-fold: by the functions which they perform, and by the mod- 
ifications they effect in their development upon the parts with 
which they are more immediately in relation. Let us examine, 
first, the second point, which comes more particularly within the 
scope of our subject. 90 
ANATOMY OF THE DENTAL SYSTEM. 
ARTICLE I. 
INFLUENCE OF DENTITION UPON THE FACE. 
It is unnecessary to insist very strongly, upon showing, a 
priori, how great should be the modifications effected upon the 
face by the teeth. It will be sufficient to state, that these organs 
protect the cavities of reception, and hold the jaWs separated at 
a proper distance. 
The action of the teeth upon the soft parts of the face, reduces 
itself, in our examination of the subject, to the greater or less 
tension of these parts, for it does not come within the range of 
this work to consider the sympathetic affections caused by the 
development of the teeth. In the foetus the cheeks are flaccid 
and make a kind of projection outwards, in consequence of their 
excess of length, which they hold in reserve to give room to the 
teeth when they issue from their alveoli. It is this condition of 
the parts which gives to the face of a new-born infant the disa- 
greeable and almost senile appearance which it presents. The 
cheeks continue to present this excess of length until the com- 
mencement of the eruption of the teeth ; and if, before this pe- 
riod, the physiognomy loses its disagreeable character, and as- 
sumes that almost angelic expression so apparent in the face of 
an infant, it is in consequence of a deposition of fat in the sub- 
cutaneous tissue, and is not the result of any increase of the 
teeth. 
After the eruption of the temporary teeth the cheeks are less 
full; the face is more elongated vertically than before, and has 
a much more agreeable expression. 
Up to the time of the completion of second dentition, the cheeks 
possess a much greater extent from above downwards before, 
than posteriorly, which gives them a triangular form. After this 
period they become more square, in consequence of the depres- 
sion of the angle, and increase of the rami of the inferior jaw. 
Finally, in old persons, when the teeth are fallen, the cheeks 
again become flaccid as in the foetus, and the face assumes a 
much less agreeable expression as the fat disappears ; the cheeks 
no longer having, as in the child, their full rounded appearance. ANATOMY OF THE DENTAL SYSTEM. 
91 
The influence exercised by the teeth upon the maxillary bones 
is very great, and it is necessary to give particular attention to 
this part of their history: 
The action of the teeth upon the jaws is two-fold: directly, 
they affect the dental arches; indirectly, the lower border of the 
inferior maxillary bone-the inferior dental canal-the angle of 
the jaw-the mental process-the mental foramen-the relations 
of the condyle and coronoid process-the pterygoid process-the 
malar tuberosity and the suborbital foramen. 
1st. Changesproducedby the Teethupon the Dental Arches.- 
These changes are effected in the form and dimensions of the 
arches. 
The maxillary bones are, really, formed into two distinct por- 
tions: that which has an immediate connection with the teeth, 
and the properly called dental portion. The dental part, to 
which, only, we will direct our attention at this place, is of less 
extent than the other. With regard to development, it is always 
in exact relation to that of the teeth; and, like the teeth, it un- 
dergoes a series of modifications in early life, which are very ex- 
actly repeated at an advanced age. 
The dental portion of the maxillary bone presents itself in the 
form of a simple trench, almost imperceptible at the period when 
the development of the germs of the teeth first becomes sensible. 
A little while after, it is separated into a certain number of alve- 
oli, common to the teeth of the first and second dentitions. 
Somewhat later, two distinct sets of alveoli for the temporary and 
permanent teeth are formed. After the eruption of the perma- 
nent teeth, it presents but a single range of alveoli for these 
teeth. Finally after the loss of the teeth, the alveolar portion of 
the maxillary bones is obliterated, and gradually takes the form 
presented in the embryo. 
The alveolar arches undergo a series of remarkable modifica- 
tions, with regard to their dimensions, in consequence of the 
development of the teeth. In height, they follow very exactly 
the development of the roots of the teeth, as may be inferred 
from what has preceded. They are, at their maximum of devel- 
opment, in relation to their volume, about the age of five or six 
years, at which period they give place to the teeth of the first 92 
ANATOMY OF THE DENTAL SYSTEM. 
and second dentitions; before and after this epoch, in inverse 
proportion, with regard to age, they diminish gradually. Con- 
sidered in relation to their length, the changes are more compli- 
cated; the circumstances of which, it is of importance fully to 
appreciate. 
The extent, in length, of the alveoli, is, necessarily, in propor- 
tion, to the number and volume of the teeth, to which they give 
place. It may be asserted, indeed, without fear of contradiction, 
that, under this relation, the alveolar arches continue to increase 
from the beginning of life to the full development of the wisdom 
teeth; and if they do not decrease from that period in length, it 
is only because they are maintained by the non-dental portion of 
the bone, which cannot diminish. 
In the adult, the alveolar arches are divided into two portions 
of equal length, which may be represented by a line drawn in 
front of the first great molaris on each side. Up to the period of 
the eruption of the first permanent molaris, at about the fifth 
year, the alveoli are reduced to their anterior portion; at this pe- 
riod the posterior part exists, but it is much inferior to the ante- 
rior portion. At about the tenth year, the posterior portion of the 
alveolar border is extended backwards to give place to the second 
large molaris, which, then, makes its appearance. Finally, after 
the eruption of the wisdom tooth, the two portions are, as I have 
said, equal in extent. 
This simple account of the changes which occur in the alveo- 
lar border, in proportion to the development of the teeth, suffices 
to show that the teeth are the cause of these modifications, and 
that the changes affect the posterior portion only. 
But another question presents itself here, which is a little more 
complex, and a little more difficult to resolve-it is this : Do the 
twenty anterior teeth of the second set occupy more or less than, 
or only the same amount of space, as the teeth which they re- 
place? Or, in other words, when the first great molaris is de- 
veloped, and takes its place in the dental arch, does that portion 
of the alveolar border, which is anterior to this tooth, undergo 
any modifications with regard to length? Hunter first proposed 
this question, and he decided that the anterior portion of the al- 
veolar border remained unchanged; but his theory, so wisely ANATOMY OF THE DENTAL SYSTEM. 
93 
adopted, has not met with the assent of all; Blake and Leveille 
have advanced a different opinion. This point of odontology 
deserves to be examined with much attention, as it has a directly 
practical bearing in regard to the artificial direction of the erup- 
tion of the permanent teeth. 
The best means, evidently, of deciding this question, is, to 
measure, carefully, as Delabarre has done, before and after the 
shedding of the teeth, the distance between the large molars, and 
the central incisors; and this process gives the same result in 
both cases. M. Miel, who gave much attention to this subject, 
and who warmly defended the opinion of Hunter, adds: "The 
appearance of the second teeth is but a substitution of those 
which are longer and more capable of effecting the uses of a more 
vigorous age; their total volume is the same as that of the tem- 
porary teeth, the only difference is in their respective size." An- 
other circumstance, upon which M. Miel lays great stress and 
with much reason, is, that the teeth of those persons in whom 
the second dentition is premature, are not placed regularly in the 
arch, but are pressed up against each other, and sometimes pre- 
sent their exterior surfaces obliquely during life, which could 
not be the case if the anterior portion of the alveolar border were 
capable of elongation. 
The anterior portion of the dental arch, indeed, does not only 
not undergo any increase at the period when the teeth are shed, 
but no alteration takes place after first dentition is completed. 
The drawings, taken from M. Oudet, of the dental arch, of sub- 
jects from five to six years, do not show the slightest variation, 
although this measurement was made in a great number of in- 
stances. 
The fact of the equality of length of the anterior portion of 
the dental arch, before and after the shedding of the teeth, has 
been effectively proved by Hunter and M. Miel; although its 
invariability, during all the process of second dentition, was not 
made out by these authors. This, however, has been perfectly 
established by M. Oudet, in a paper which he read to the Acade- 
my, in 1824. M. Oudet proved, first, that when the secondary 
incisors appeared, they, being larger than those which preceded 
them, caused an elongation of the alveolar border, proportionate 94 
ANATOMY OF THE DENTAL SYSTEM. 
to their excess of volume, and that the first large molaris is 
pressed a little backwards; he showed, secondly, that after the 
eruption of the fourth great rnolaris, the first is again pressed 
forwards to its proper place, as there is more room, in consequence 
of the eruption of the second small molaris, which is much less 
in volume than that which preceded it. 
Finally, to terminate this subject, let us present a considera- 
tion which does not appear to have been yet properly appreciated : 
nature shows, by the manner in which she proceeds in the 
development of the second teeth, that there is to be no increase 
of this anterior portion of the alveolar arch, for the canine tooth 
does not make its appearance until the issue of the first and 
sometimes the second small molaris, and it is, meanwhile, placed 
out of the dental arch. If it be admitted, that there is an in- 
crease in length of the anterior portion of the alveolar arch, as is 
believed by Blake, then the cause of this particular arrangement 
is inexplicable. If the opinion of Hunter be admitted, nothing 
can be more simple. The secondary incisors, larger than those 
of the first dentition, having taken the place of the canine, the 
eruption of this tooth is delayed until sufficient space is gained 
by the change of the temporary molars for the bicuspides, which 
are smaller. 
After the loss of the teeth, the alveolar arches diminish in 
length, from behind forwards, and take again the first form they 
presented. In the child of five years of age they are semi-circu- 
lar; they are parabolic in the adult, and assume again the 
semi-circular form in old persons. 
Changes produced by the Teeth upon the Lower Border of 
the Inferior Maxillary Bone.-M. Miel first directed the atten- 
tion of anatomists to this subject. He has shown that the lower- 
border of the inferior maxillary bone is slightly arched upwards, 
particularly backwards, in the child and old person, but that it 
is perfectly horizontal in the adult. 
Changes produced by the Teeth upon the Inferior Dental 
Canal.-In the earlier stages of the formation of the inferior 
maxillary bone, this canal does not exist; the vessels and nerves 
to which it afterwards gives lodgment, now occupy the bottom 
of the groove, which is the rudiment of the canal. This canal ANATOMY OF THE DENTAL SYSTEM. 
95 
is developed, together with the conduit destined to give place 
to the vessels of the temporary teeth, when the alveoli are sepa- 
rated from each other In the adult, this canal is placed about 
the middle of the bone, between the dental and basilar portions. 
In old persons, after the obliteration of the alveoli, the dental 
canal occupies the superior border of the bone, but it never dis- 
appears entirely. In early life, it corresponds, exactly, to the 
lower portion of the alveoli; in the adult it is placed a little 
within them, pressed towards this point, according to Cuvier, 
by the prolongation of the roots of the teeth. During uterine 
life, and until some time after birth, the dental canal of first 
dentition is very large; but from this time it diminishes gradu- 
ally, and finally disappears entirely, when the fall of the tempo- 
rary teeth is accomplished. 
Changes produced upon the Angle of the Inferior Jaw.-In the 
earliest periods of life the inferior maxillary is nearly or almost 
entirely straight; the angle is gradually developed, until the 
adult age ; in old persons it again diminishes. Very obtuse at 
first, it forms a right angle in the adult, and finally, in old per- 
sons, again assumes the obtuse form it presented in the foetus. 
Changes produced upon the Mental Process.-The changes 
of this part are intimately related to the preceding; when the 
angle of the jaw is obtuse, as in the child and old person, the 
mental process projects considerably, and is turned much up- 
wards ; when, on the contrary, the former approaches the right 
angle in the adult, the latter is less projecting, and almost en- 
tirely turned upwards. 
Changes produced upon the Condyle and Coronoid Pro- 
cess.-The surface of the condyle and the summit of the coronoid 
process are directed backwards and upwards, in the child and 
old person ; in the adult they present directly upwards. But 
the most remarkable modifications which these eminences pre- 
sent, are those which result from the changes they undergo in 
regard to their relative height. In the foetus, the coronoid pro- 
cess is elevated in all its height above the condyle; in the child, 
the two parts tend more and more to the same plane; finally, in 
old persons, they again assume their first relations. 
Changes produced by the Development of the Teeth upon the 96 
ANATOMY OF THE DENTAL SYSTEM. 
Mental Foramen.-M. Duval first observed these changes. He 
has shown that the mental foramen is situated very near to the 
symphysis, at birth, and is gradually carried backwards, in pro- 
portion to the development of the temporary teeth. At birth, 
this opening corresponds to the inter-alveolar wall of the canine 
and first molaris. When the temporary teeth are fully develop- 
ed, it is placed more posteriorly. When the first large molaris 
makes its appearance, it corresponds to the partition between 
the two temporary molars ; and, finally, when the wisdom tooth 
has issued, the mental foramen is almost always found very 
near to the place under the alveoli which separate the first and 
second molars. 
Changes produced by the Development of the Teeth upon the 
Pterygoid Process.-The pterygoid process is, to the superior, 
what the posterior border and angle of the jaw are to the inferior 
dental arch. Both serve as a point of support to the posterior 
portion of the alveolar arch ; both are free posteriorly, and, con- 
sequently in a condition to follow all the changes of the alveolar 
border. That the analogy which is shown to exist between 
these parts is not founded upon theory alone, the observation 
and comparison of the changes which they undergo under the 
influence of the development of the teeth give the most positive 
confirmation. 
In early life, at the period of birth, especially, the pterygoid 
process, like the posterior border of the inferior jaw, is directed 
obliquely downwards and forwards. When the thirty-two teeth 
are fully developed, the angle it forms with the horizon is sen- 
sibly right. Finally, after the loss of the teeth of the superior 
jaw, the pterygoid process takes again its original oblique 
direction. 
Changes produced by the Development of the Teeth upon the 
Suborbital Foramen.-These changes are analogous to those 
which the mental foramen of the inferior jaw undergo. At 
birth, the suborbital foramen is placed above the wall which 
separates the alveoli of the canine and first molar tooth. When 
the first dentition is completed, it is placed a little more poste- 
riorly. It is situated above the wall of separation between the 
two temporary molars, when the first large molaris makes ANATOMY OF THE DENTAL SYSTEM. 
97 
its appearance, after which time its relative position undergoes 
no sensible change. 
Changes in the molar tuberosity.-The molar tuberosity and 
the base of the coronoid process of the inferior jaw undergo 
some important changes under the influence of the development 
of the teeth. For a considerable time before their eruption, 
these parts afford a lodgment to the forming molar teeth, which 
give to them a considerable volume. At birth the molar tuber- 
osity is entirely rudimentary, but, in a short time after, it be- 
gins to enlarge, as the first large molar is gradually developed. 
After the eruption of this tooth the tuberosity still remains 
enlarged, as it encloses the second and third large molar. 
After the eruption of the wisdom tooth, the molar tuberosity no 
longer exists; the alveolar border has no greater extent trans- 
versely here than in any other part of the arch; and it is less ele- 
vated at this point than in the vicinity of the first large molar. 
Changes in the facial angle under the influence of the develop- 
ment of the teeth.-Supported, posteriorly, by the pterygoid 
processes, the alveolar arch of the superior jaw cannot be deve- 
loped in any great degree in that direction ; and as the elonga- 
tion it undergoes it is necessary to express by a greater projec- 
tion forward, which gives a more oblique direction to the facial 
line of Camper. This takes place in proportion to the eruption 
of the teeth, and this change removes from the face of the child 
something of the sprightliness and intelligence which, at first, 
characterised it. 
In the adult, the middle molars of the superior jaw exercise, 
by their roots, a remarkable influence upon the floor of the max- 
illary sinus, they raise and render it in some degree flexuous. 
Some authors have believed that the roots of these teeth were 
made divergent for the purpose of diminishing, as much as pos- 
sible, this action upon the sinus. Be this as it may, the short- 
ness of the roots of the teeth on one side and the rudimentary 
condition of the sinus render its action unimportant in the child. 
In the adult, on the contrary, every thing in this connection 
concurs to give it a great degree of importance; the sinus is very 
large, the roots of the teeth have acquired all their length and 
are plunged deeply into their alveoli. In old persons, doubtless, 98 
ANATOMY OF THE DENTAL SYSTEM. 
the sinus takes a new development, and its floor is carried back 
from contact with the roots of the teeth ; the action of the latter, 
however, upon the floor of the sinus is already diminished by 
the contraction of the alveoli so that the phenomena is less mark- 
ed at this time than about the middle period of life. 
This action of the roots of the superior molar teeth is some- 
times so great, that they penetrate the sinus itself, and give rise 
in consequence to a number of disorders. 
ARTICLE II. 
IMPORTANCE OF THE TEETH IN THEIR FUNCTIONAL RELATIONS. 
The teeth perforin, in the human economy, a part of great and 
varied importance. They concur in forming a barrier which 
retains the saliva in the interior of the mouth; they act in the 
prehension and mastication of aliments and assist in pronuncia- 
tion ; they are susceptible of receiving and transmitting certain 
impressions, and serve under certain circumstances as means of 
attack and defence. 
All the teeth may be employed in the prehension of solid sub- 
stances, but this is peculiarly the office of the incisors; these 
teeth act in an opposite direction upon the body presented to 
their action, and separate from it a portion more or less consid- 
erable. The arrangement of the incisors are remarkably well 
adapted for the accomplishment of this end; they have cutting 
edges at their free extremities, which cross each other like the 
blades of a pair of scissors. But, on the other hand, placed at 
the extremity of the lever of the jaws, they cannot exercise any 
great degree of force upon the bodies presented to them; and 
when the latter offer much resistance they are necessarily pre- 
sented to these teeth in small portions, for when the jaws are 
widely separated, the levator muscles act with diminished power. 
The canine teeth serve better to tear, than to divide aliments 
simply; their pointed crowns penetrate deeply into the sub- 
stances offered to them, and, in consequence of the great length 
of their roots, they are enabled to sustain a great degree of force. 99 
ANATOMY OF THE DENTAL SYSTEM. 
As they are placed nearer the fulcrum of the maxillary lever than 
the incisors, they act with more power than these teeth. 
The molar teeth are rarely used in the prehension of aliments, 
and their form renders them entirely unfitted for cutting or tear- 
ing the food; their assistance is, however, of importance for this 
purpose, in conjunction with the hands and extensor muscles of 
the head. But in this act the molar teeth only serve to fix the 
substance we wish to separate-whilst the two powers, the 
hands and the muscles of the back of the neck, acting in con- 
trary directions, effect the object. Although the molars do not 
answer well for cutting or tearing substances presented to them, 
they are capable of acting with great power, and making strong 
pressure. For this purpose they are admirably adapted, not only 
in consequence of their position near its fulcrum of the lever of 
the jaw, but of the points and depressions of the opposing teeth, 
which are so arranged that they close exactly within each other, 
and make it impossible for a body to escape them. To wholly 
carnivorous animals they are more useful as instruments of pre- 
hension than to man ; his incisors and canine teeth serving his 
purpose fully. 
But if the molar teeth are of little use for the prehension of 
aliments, they are not so with regard to mastication ; they are 
indeed most advantageously constructed for bruising and divid- 
ing into very small particles such substances as are submitted to 
their action. Their crowns are large ; the summits are furnish- 
ed with inequalities as was stated above, which alternate and 
close together in the two jaws, in such a manner that substances 
taken between them are retained a sufficient length of time to 
insure their perfect trituration. In addition to this, the molar 
teeth are provided with roots subdivided into several branches; 
each of which is received into a special alveolar cavity. 
The precautions for the accomplishment of complete mastica- 
tion have not been confined to the disposition and arrangement 
of the teeth ; the most perfect harmony has been established be- 
tween the opposing power of the superior and the action of the 
inferior jaws. As the superior incisor teeth are not required to 
sustain any great amount of pressure, it was not necessary that 
the alveolar processes at this point should be very strongly sup- 100 
ANATOMY OF THE DENTAL SYSTEM. 
ported ; thus we find them corresponding to the anterior nasal 
opening. The canine teeth are sometimes required to with- 
stand great force, especially in carnivorous animals, which with 
these teeth, daily tear their food ; and we consequently find that 
their alveoli are solidly supported against the external orbital 
process of the frontal bone through the intermediate fronts-na- 
sal column of the superior maxillary. The molar teeth which 
bear nearly all the brunt of mastication, and are required to 
sustain the powerful force of the lower jaw, we find strongly 
supported by the base of the cranium, through the zygomalico, 
jugal and pterygordian columns. 
It is almost unnecessary to remark that the food undergoes 
the requisite degree of modification only by passing many times 
under the action of the molar teeth, and that the tongue and lips 
are engaged in carrying back the aliments which are constantly 
disposed to escape. 
The great advantage which results from the conical form of 
the roots of the teeth is very apparent; the force that would 
otherwise tend to bring them in their alveoli, is, by this con- 
struction, entirely decomposed. Instead of acting upon the ex- 
tremities of the roots where the vessels and nerves form the pe- 
dicle, the pressure is distributed upon all their surface. It will 
be remarked, besides, that in proportion to the greater amount 
of pressure the different classes of teeth are required to sustain, 
are they provided with roots in greater number and better adapt- 
ed to the purpose. 
The precautions which nature has taken to render perfect the 
action of the teeth upon alimentary substances are, doubtless, 
very numerous; but it will be found that none were unnecessa- 
ry, when the influence of mastication upon digestion in the 
stomach is considered. When a great number of the teeth have 
been lost, or when mastication has not been perfect, chymifica- 
tion, accomplished with difficulty, the stomach, irritated by 
aliments not sufficiently triturated, suffers, becomes inflamed, 
and disease is developed. Old persons who have lost their teeth 
are obliged to observe a particular regimen in order to avoid dis- 
orders of this kind. 
It is only necessary to mention here, to be comprehended by ANATOMY OF THE DENTAL SYSTEM. 
101 
every one, the influence of the teeth upon the pure and clear ar- 
ticulation of some sounds. All the teeth, however, are not 
equally important in this relation; the incisors occupy the first 
place, the canine teeth the next, and the first molars the last. 
The large molars exercise but little if any influence upon the 
pronunciation. 
The teeth, and particularly those situated anteriorly, not only 
serve to give clearness and precision to the pronunciation ; but 
they, besides, prevent the expulsion of the saliva from the mouth 
during conversation. Thus it will be seen that the use of arti- 
ficial teeth is not always to be considered a luxury or a mere 
gratification of vanity; in this case they correct a real infirmity, 
unpleasant to those who are the subjects of it, and unsuppor- 
table to all who approach them. 
The teeth are also susceptible of receiving certain impressions 
and transmitting them to the brain; the ticking of a watch may 
be perceived when placed between them with the case closed; 
heat and cold, to a certain extent, affect them disagreeably and 
we are enabled to judge of the qualities of bodies accidentally 
coming in contact with them. These facts, at first sight, appear 
to clash with the opinions I have advanced in a former part of 
this work ; but, upon a little reflection, it will be perceived, that 
this is only an apparent difference. 
The phenomena of sensibility in the cases mentioned, are not 
to be attributed to the osseous substance of the tooth, but to the 
follicle, the papilla and to the nerves which are distributed upon 
them. The long portion of the tooth serves only as a means of 
exciting these nerves, which receive the impressions and trans- 
mit them to the brain. In this manner should be understood, 
almost exclusively, the phenomena of the sensibility of the teeth; 
phenomena which, it has been said, are never disturbed by the 
causes which produce paralysis in other organs, ( Robert Graves, 
Dublin Journal,) an assertion which appears to me nothing less 
than established. 
It might be supposed that in the ticking of a watch placed 
between the teeth, the auditive impression is received and trans- 
mitted by the dental nerves. But this is not the case ; the so- 
norous vibrations have been communicated by the teeth to the 102 
ANATOMY OF THE DENTAL SYSTEM. 
jaws ; by them to the cranium and to the labyrinth, from which 
the impression is conveyed to the brain by the proper auditory 
nerve. 
Although the teeth in their development exercise considerable 
influence upon the surrounding parts, they are in their turn af- 
fected by them. It appears paradoxical to assert, that the cheeks, 
the lips and tongue concur to give the teeth their proper direc- 
tion ; this is, however, true. When the lips are destroyed, the 
teeth take an outward inclination, whilst they incline inwardly, 
when the tongue is diminished in size. I have had an oppor- 
tunity of seeing the truth of this latter position established, in 
the case of a young man who had lost the anterior portion of his 
tongue. 
We may say, tlien, that the teeth, to a certain extent, are na- 
turally placed between two opposing forces, one acting from 
without inwardly, the other from within outwardly, and that 
from this equilibrium results the vertical direction of these or- 
gans in the human subject. 
The salivary organs, the mucous membrane of the mouth, and 
the dental glands all exert an influence upon the teeth by their 
particular secretions, which penetrate, and remains adherent to 
their surfaces, protecting them from the injurious action of the 
atmosphere, acids, Ac. 
ORDER V. 
VARIETIES OF THE TEETH. 
The varieties of the teeth are very numerous, and like most 
other organs, the differences all exist according to ages, indivi- 
duals, and races. With regard to the sexes no variety exists. 
ARTICLE I. 
VARIETIES OF THE TEETH ACCORDING TO THE AGES. 
After the details given, in describing the two partitions, and 
after what has been said of the progressive development of the 
teeth, little remains to be added here. ANATOMY OF THE DENTAL SYSTEM. 
103 
The root of the tooth is always developed in inverse propor- 
tion to the crown. In the very young child, the crown is form- 
ed before the ossification of the root commences. At an age a 
little more advanced, the crown of the tooth, is beginning to 
wear away before the root is entirely completed. In the adult, 
the crown has lost its points and the root soon attained its full 
development. Finally, in old persons, the crown is sometimes 
completely worn away whilst the root still remains almost in a 
perfect state. The ossification of the tooth commences with the 
crown and proceeds towards the root, and in the same manner 
they are destroyed by friction. The wearing away of the teeth 
commences upon the crown, and as may be readily supposed, 
first upon the points. The incisors are affected first as they 
are first developed and come into service before the others. 
From what has been said, the reason why the free surface of 
the teeth, and, particularly, the summits of the crown, have 
been furnished with a very hard vitreous covering will be readily 
conceived. 
At a certain period, which varies according to the habits of 
the individual, the condition of the teeth, after their formation 
and some other causes, the points have disappeared, and the 
enamel which covered the summit of the crown has been worn 
away. At this time, the upper surface offers a remarkable ap- 
pearance ; the centre presents a yellowish tint; and the circum- 
ference a line of unpolished white; these constitute the ivory 
and enamel of the crown; the relative disposition of which may 
now be studied. Before the wearing away has proceeded so 
far, if the crown of a large molaris is examined, a more compli- 
cated appearance will be observed. The enamel is worn away 
at the elevations upon the tooth only, and a number of white 
points, corresponding to the indentations of the crown, will be 
found upon the yellowish bed of the ivory. 
The wearing away of the teeth continues to advance with 
age; and in some old persons, the crown is entirely destroyed. 
Here a remarkable fact presents itself, which, however, will be 
readily comprehended, after what has been said with regard to 
the development of the teeth; although the crown is gradually 
destroyed, no pain or irritation of the pulp is developed, nor is 
any opening made into the dental cavity. 104 
ANATOMY OF THE DENTAL SYSTEM. 
It follows, necessarily, from what has preceded, that the de- 
gree of destruction which the teeth have undergone, will furnish 
accurate data for the determination of the ages of individuals. 
The conclusions drawn from the examinations of the teeth of 
animals, which exist on one kind of food, are very accurate. 
In man, however, whose food is as varied as his tastes, and 
whose teeth are materially affected by the diseases to which he 
is subject, and which are the cause of modifications that render 
the action of frictions more prompt, there are but few certain 
conclusions, with regard to his age, to be drawn from the exam- 
ination of his teeth after the completion of second dentition. We 
are enabled, however, to obtain approximative results, as Serres 
has done, of much importance. He was required to ascertain 
the ages of the individuals to whom the fossil bones, found in 
the cave of Dufart, in the department of Gard, had belonged. 
After having studied them carefully, he says: 
"The principal bones I have had to examine, were first, a large 
number of crania, more or less entire, and, more or less en- 
crusted with calcareous tufo or sandstone; second, a superior 
maxillary with the right cheek bone, to which a part of the or- 
bital arches were attached; a considerable number of teeth, of 
all classes, in a most perfect state of preservation. The enamel 
of these teeth is as brilliant and clear as if they were interred but 
yesterday; the roots only of the teeth found isolated, the bony 
sockets having been entirely decomposed, are covered with a very 
fine yellowish dust, which effervesces strongly under the influ- 
ence of mineral acids, and which is carbonate of lime. Where 
the teeth were entirely absent in the jaw, the sockets were filled 
with earthy and ferraginous carbonate of lime. The teeth were, 
generally, but little worn; from which fact, we may conclude 
that the individual to whom this superior jaw belonged, could 
not have been more than thirty years of age at most; and 
although the facial line cannot be measured with precision, it is 
not far from eighty degrees. This fragment then belonged to a 
young man of the white or Caucasian race. ANATOMY OF THE DENTAL SYSTEM. 
105 
ARTICLE II. 
VARIETIES OF THE TEETH, ACCORDING TO THE DIFFERENT RACES. 
The teeth show but little variation with regard to the different 
races. Negroes have them a little larger, longer and more 
obliquely directed than ours. Buffon said that the teeth of the 
Calmoucks are remarkable for their length, and the spaces which 
separate them; but the more recent observations of Blumenbach 
have contradicted this assertion. 
Care must be taken to guard against the error of considering, 
as varieties of this kind, those modifications produced simply by 
the age of the individual, or his particular mode of life. Some 
have fallen into this mistake in a report upon the examination 
of the teeth of certain Egyptian mummies, but later develop- 
ments have rectified these erroneous ideas. The error of class- 
ing, as characteristics of the teeth, those modifications which 
are the result of the customs of certain people only, must also be 
avoided, as, for instance, that of staining them or filing away a 
portion of their crowns. 
ARTICLE III. 
VARIETIES OF THE TEETH OF INDIVIDUALS. 
The varieties of the teeth of individuals are very numerous, 
and may be arranged under four principal heads-according to 
their number, form, direction, position and structure. 
1st. Varieties of Number.-We sometimes find less, some- 
times more than the ordinary number of teeth. There are 
fewer when some among them have not been primitively devel- 
oped, nor afterwards renewed, or when several are joined to- 
gether. It is rarely that there is an entire absence of all the 
teeth during life, yet this circumstance has been observed. 
Baumes says, he saw an adult man, named Vaison, who had 
never had any teeth. Borelli saw a woman, sixty years of age, 
in the same condition. In some cases, a portion only of the 
whole number of teeth have appeared; of which irregularity, 
Schmitt and Fauchard relate instances. In the "Ephemerides 
des Curieuz de la nature f the case of a magistrate is mentioned 106 
ANATOMY OF THE DENTAL SYSTEM. 
who had never had any except molar teeth. More frequently, 
however, but one or two of the teeth are absent: a vice of con- 
formation which appears to be hereditary in some families; the 
absent tooth may belong to any of the three classes. 
A deficiency in the ordinary number of the teeth, in conse- 
quence of the union of two or more, is an anomaly more rare 
than the absolute absence of some of the teeth, and the union 
of all the teeth in the same jaw is still more rare. According to 
the account of Plutarch, the teeth of Pyrrhus were united in this 
manner; and Pliny mentions a similar anomaly which was ob- 
served in the son of Prusias, king of Bithynia. Other authors, 
according to Diemerbroeck, relate, that Eriphoeus of Cyrene, 
Pherecrates the poet, and Sicinius, were distinguished from other 
men by a similar conformation of the teeth. Bartholin says he 
met with a similar anomaly; and Melanthon, finally asserts, 
that he saw at Lunenburg, in the court of prince Ernest, a girl 
who, like Pyrrhus, had but a single tooth, which occupied the 
whole arch of one of her jaws. 
But are these statements entirely authentic 1 it will be asked. 
I will not say that such a vice of conformation as the above men- 
tioned is impossible, since similar cases have been observed in 
our day, although upon a much less extended scale. The in- 
cisor and canine teeth more frequently present this species of 
union by the crown than any other portion of their body. The 
molars, on the contrary, as M. Oudet has correctly remarked, are 
more frequently adherent by their roots. M. Toirac recently 
showed me two cases of a lateral incisor united to the adjoining 
canine tooth. It is said that the temporary teeth present more 
frequently than any others this abnormal union. Be this as it 
may, the teeth seem to offer two varieties of union, judging, at 
least, from the specimens I have recently examined. Sometimes 
there is an intimate fusion of the two teeth, the bony substance 
being common in them; and sometimes they are only joined 
together by an ossification of the alveolar-dental periosteum. 
The first variety is peculiar to the crowns, the second to the 
roots of the teeth. In the first case, the fusion of the two teeth 
takes place when the tooth is in an embryo state; the two germs 
are close to each other; the alveolar partition is not placed be- ANATOMY OF THE DENTAL SYSTEM. 
107 
tween them, or not formed at all; the two germs remain in the 
same cavity; their two cavities are joined together, and the two 
papillas are confounded with each other. From this time the 
two germs have all the characteristics of one of the molar teeth, 
and the calcareous laminse, after having been extended over the 
whole of this double papillae, are separated into two parts to form 
the roots of the united teeth. 
The second variety of union is very different from the first, 
and is not formed till sometime after birth. It is a simple an- 
chylosis, formed by the union of the two teeth with the inter- 
alveolar partition, in consequence of inflammation of the alveoli- 
dental periosteum. 
The union of the canine with a lateral incisor tooth appears to 
be of more frequent occurrence than any other; and the reason 
appears to be very plain, for these teeth are formed very close 
together, and, from the moment of its formation, the canine tooth, 
thrown out of the range by the lateral incisor, is strongly pressed 
by it. 
The excess, in number, of the teeth, depends more frequently, 
as I have observed, upon the persistence of the deciduous teeth. 
Supernumerary teeth also constitute this species of irregularity; 
they appear either isolated or in a complete series, and almost 
always behind the permanent teeth. Boudet has observed the 
two last superior molars doubled; and Plouquet, Camper and 
Soemmering have observed five molars well ranged in the inferior 
jaw; the first in his own case, the second in an inhabitant of 
Java, and the third in an European. 
2d. Varieties of Form.-The varieties of this kind, not de- 
pendent upon a morbid cause, are much less frequently met 
with than the preceding; they occur either in the crown or the 
roots of the teeth. They depend, very commonly, however, 
upon the persistence of the temporary teeth. One of my friends 
retained deciduous molar teeth, of the right side, until his thir- 
tieth year; at which age, he had, in the lower jaw, seven large 
molars, and but three small ones. 
3d. Varieties of Direction.-Anomalies of this class are suffi- 
ciently rare; the teeth sometimes take an oblique direction ; are 
sometimes placed horizontally, and more rarely they are com- 108 
ANATOMY OF THE DENTAL SYSTEM. 
pletely inverted. The obliquity of direction is sometimes so 
great, according to Soemmering, that the existence of a double 
range of teeth has been supposed. 
Soemmering saw an incisor tooth occupying a horizontal posi- 
tion, the crown presenting forwards. Albinus observed an 
anomaly of the same character, with the crown presenting back- 
wards. 
Albinus and Sandifort have mentioned instances of the com- 
plete inversion of teeth; the former of a superior incisor, the 
latter of a second molars, which remained enclosed in the max- 
illary bone. 
4th. Varieties of Position.-The teeth are sometimes found, in 
consequence of a vice in their direction, removed from their po- 
sition in the alveolar border, and carried either towards the palate, 
towards the maxillary sinus, or some other point; a fact which 
surgeons should always take into consideration, when called 
upon to make a diagnosis of a tumor developed in the vicinity 
of the dental arches. Professor Marjol in and M. Duval removed 
a tumor of this description, which was situated upon the infe- 
rior maxillary bone entirely without the alveolar arch; and I 
have had occasion myself to operate upon a female who had a 
dental tumor in the palatine region. 
Case.-A country woman, forty-three years of age, entered the 
hospital Beaujon ; there were two fungous ulcerations, one upon 
the nose and the other on the right cheek, with hard surfaces 
turned outwards, which caused troublesome, lancinating pains. 
She said she had first suffered pain from this affection about eigh- 
teen months previously. In examining this patient, attentively, I 
remarked a peculiar modification of the voice, (she spoke as if 
a piece of money were lying upon her tongue,) which directed 
my attention to her mouth. I immediately discovered on the 
left side of the roof of the mouth, a tumor of the form and size 
of half of a very large walnut, bounded externally by the alveo- 
lar arch, passing the median line by its internal part, extending 
from before backward, from a point placed at the extremity of 
the corresponding canine tooth, almost to the velum pendulum 
palati. It was moderately hard, indolent and prevented the pa- 
tient from articulating clearly. The mucous membrane was ANATOMY OF THE DENTAL SYSTEM. 
109 
healthy at the level of the tumor. I learned afterwards, that one 
of the molars had been extracted and that the others had never 
made their appearance; this conclusion at least was drawn from 
the very unsatisfactory history of the case given by the patient. 
The carcinomalous nature of the ulcers upon the nose and 
cheek, compelled me to make an unfavorable diagnosis upon 
the tumor, which I believed to be of a malignant character. 
Professor Marjolin agreed with me in opinion, and it was deter- 
mined that the tumor should be removed and the ulcerations of 
the face cauterized. I informed the patient of this decision, and 
as she raised no objection, a day was appointed for.the opera- 
tion. 
Not knowing precisely the superior limits of the tumor, I de- 
termined to attack it from before backward with the gouge and 
mallet, intending to carry the stroke through the whole thick- 
ness of the palate, if during the operation it appeared to be ne- 
cessary. Bistouries, saws of suitable form, and cauterizing in- 
struments were provided. The patient was placed upon a bed, a 
little lower than ordinary, with the head thrown slightly back- 
ward, and the mouth kept open by means of a wedge of cork 
placed between the last teeth of the right side. I made a cru- 
cial incision upon the tumor, and dissected out, as rapidly as 
possible, the flaps I had made. It was then my intention to re- 
move the osseous portion with the gouge, but in sponging out 
the tumor, I discovered in its centre a white and shining body. 
In examining it with my finger, I found it was moveable, and 
taking hold of it with the forceps drew out, not without some 
difficulty, a molar tooth with three short roots, the crown of 
which was of the form and size of the first large molars. I 
examined the wound again with my finger and discovered an- 
other tooth which I also drew out. This was not so large as 
the other, but was multicuspidated like the temporary molars. 
The great surprise of myself and assistants may be readily im- 
agined. I interrogated the patient, and it was then that she gave 
me the information of which I have spoken, through the obscu- 
rity of which I believed myself able to perceive that the second 
molar and the canine teeth had never appeared. For any thing 
more it was unnecessary to torment the patient with questions; 110 
ANATOMY OF THE DENTAL SYSTEM. 
the teeth I had extracted spoke a language more clear than any 
which she could hold; they had all the characteristics, one of 
the second molar of the first dentition, the other of the first per- 
manent large molars. It was then, incontestible, that these 
teeth, taking an inward oblique direction, had pierced the inter- 
nal alveolar wall, and being placed between the mucous mem- 
brane and the bone, had given rise to the tumor. 
When the operation was completed, I cauterized the bottom 
of the wound, both for the purpose of suppressing the haemorr- 
hage, which was considerable, and of preventing the recurrence 
of the fungous growth, the character of which I doubted, in con- 
sequence of the evidently cancerous appearance of the ulcers 
upon the face. 
In a short time the wound of the palate was completely 
healed; frequent cauterization with the nitrate of mercury 
promptly produced a healthy action in the ulcers upon the face, 
and the patient left the hospital perfectly cured two months 
after her entrance. 
The teeth have been sometimes found in parts of the body 
very remote from the mouth, in the ovaries, or in other portions 
of the genital organs. Blumenbach, Ruisch, and Mochsen 
have cited instances, and a case of this kind has fallen under 
my own observation. Generally, such teeth have been found 
with hair and fatty matter in fibrous or fibro-cartilaginous cysts. 
Sometimes they have been seen implanted in true alveoli upon 
the portions of bone, and such was the condition of the forma- 
tion in a case I observed, which is so very curious, that I will 
transcribe it. 
A woman, aged twenty-eight years, scrofulous in her infancy, 
but afterwards healthy, and regular in her periods, married at 
eighteen; was affected after her fourth accouchment, with 
leucorrhoea, which varied in abundance. The general and 
local remedies were administered, but as they did not produce 
the usual effects, an examination of the genital part was made, 
and a tumor, which broke by the pressure and discharged a 
puriform liquid, was discovered in the vagina. The leucorr- 
hcea being complicated with pain and spasmodic action, we 
examined the vagina anew, and ascertained, upon the left su- 111 
ANATOMY OF THE DENTAL SYSTEM. 
perior part a hard body which caused pain to the husband 
during coition. The woman, notwitstanding the existence of 
this tumor, had been delivered of her fifth infant, which, at 
birth, bore upon its left cheek a recent excoriation. The patient 
was brought to Varsovie, and a more careful examination en- 
abled M. Jasinski, and a number of other physicians, to ascer- 
tain, that the hard body felt in the vagina was situated between 
the rectum and vagina, and the projection it made into the latter 
was in consequence of the destruction of a portion of its wall. 
The disorders caused by the contact of the sharp surface of this 
body with the matrix, caused M. Jasinski to determine upon 
its removal. He took hold of the hard body with the ordinary 
polypus forceps, but they slipped off at every attempt he made 
to extract it. Five days after, with a stronger and more suitable 
pair of forceps, he extracted a well formed molar tooth, which 
had three roots and a slightly squared crown. Three other 
incisor and molar teeth were extracted without the loss of much 
blood, or causing violent pain. These teeth appeared to have 
been implanted in a bone which could be felt with the finger, 
but which was so firmly fixed, that, as it did not come into con- 
tact with the vagina or uterus, it was allowed to remain.- 
Grafe and Walters' Journal. 
It is evident in all these cases that the anomalous formation is 
a fragment of an extra uterine foetus; but it is curious to observe 
the growth of the teeth continue after the death and atrophy of 
the foetus; the materials being furnished by the mother to 
whom the cyst is attached. 
Other varieties of position of the teeth consist, essentially, in 
the transposition of these organs, and a true error of place. Dr. 
Oudet saw many times the canine tooth occupying the place of 
the lateral incisor, and the reverse. He also observed a similar 
transposition of the first molar and canine teeth. 
The teeth have sometimes been found entirely unconnected 
with the alveoli, and retained in the thickness of the mucous 
membrane of the mouth. Hunter relates a case of this species 
of anomaly. 
"I have seen," said he, "in a young subject, two central in- 
cisors of the superior jaw, the roots of which were only suf- 112 
ANATOMY OF THE DENTAL SYSTEM. 
ficiently long to be held in their position by the gum to which 
they adhered. In examining the jaw, I could discover, at this 
place, neither alveolar process nor alveolus. It is not easy to 
explain this phenomenon; these teeth perhaps were not formed 
in the jaw but in the gum, and perhaps the roots were destroyed. 
The structure of the teeth appeared to favor the former hypothesis; 
they were not of the temporary class, and since they did not 
penetrate beyond the gum, it is reasonable to conclude that they 
never had roots. The extremity towards the gum was furnished 
with little round and uniform eminences, each having in it a 
little hole, a narrow canal of communication with the crown of 
the tooth, which was quite well formed." 
Miel, also, relates many instances of the same kind : "Some 
years ago," says he, "I extracted from the right side of the su- 
perior jaw, between the second molar and the wisdom tooth, 
at the place where the gum prolongs itself into a point, a little 
dental body, which was not, however, shaped like the ordinary 
teeth. As it was too short to have reached the maxillary bone, 
this tooth was contained in the tissue of the gum where it was 
formed out of the alveolar system. This tooth issued from the 
thickness of the gum, presenting towards the mouth its longer 
portion, whilst the smaller or more pointed part penetrated the 
membrane itself, to which it adhered. It incommoded the in- 
dividual, and was on that account extracted." 
CHAPTER II.- Comparative Anatomy of the Teeth. 
The invertebrata are almost the only animals whose teeth can 
be compared to those of man. The parts which serve the pur- 
pose of teeth in the mollusca and constacea, and other inverte- 
brata, are rather horny or calcareous indurations of the mucous 
membrane, than true teeth. 
This observation, however, is rendered almost unnecessary 
by the definition given of the teeth at the commencement of this 
work, and I only make it here to give the fact a new confirma- 
tion. It is my intention, after having examined the four great 
classes of the animalia vertebrate^ for the purpose of showing ANATOMY OF THE DENTAL SYSTEM. 
113 
the characters of their dental systems and indicating the differ- 
ences existing between them and man, in this relation to make 
some mention of the masticatory organs of the invertibrated ani- 
mals. 
ORDER I. 
TEETH OF THE MAMMALIA. 
The minute details given in examining the teeth of man, the 
first of the mammalia, will render unnecessary an extended 
general description of the teeth of these animals. 
The mammalia, with a very few exceptions, are provided with 
teeth. The four millie, pangolin and echidna, are the only ani- 
mals of this class entirely deprived of them. The order eden- 
tata, to which these animals belong, is far from meriting this 
name, for if they are not all well supplied they are not entirely 
deprived of teeth, as, for instance the ai, the ornithorynchus, and 
the orycterope. Some animals, which appear to be entirely de- 
prived of teeth, have them during a part of their life-time ; M. 
Geoffroy St. Hilaire, discovered them in the foetus of the haloena 
an animal which, before his time, was supposed to be unprovided 
with teeth during life. 
The number of teeth in the mammalia varies considerably, 
but less than the other vertebrata. More than 190 are never 
found, and this great number only in the dolphin; the Peruvian 
dolphin has 190; the dolphin of the Ganges 120; the delphinus 
frontatus 92. 
The teeth of the mammalia are always sustained upon the 
maxillary or inter-maxillary bones, and are received into proper 
alveolar cavities. Some zootomists have stated that the ornith- 
orynchus and hyperoodon are furnished with palatine teeth, but 
it seems to me that they have mistaken for dental bodies, those 
callous eminences found upon the palatine membrane of these 
animals. 
The mammalia are particularly distinguished from each other 
by the form of their teeth, and it is under this relation that it is 
most important, perhaps, to study them closely. 114 
ANATOMY OF THE DENTAL SYSTEM. 
The human teeth, as has been seen, were naturally divided 
into three parts ; the crown, the root, and the neck; but this 
division is not applicable to the teeth of all the mammalia; the 
rodentia and probescidia have certain teeth which are covered 
with enamel over their whole extent, for which reason they 
have been said to be without roots; this is a bad distinction, 
however, since these teeth have a part implanted in alveolies 
which constitutes a true root. Be this as it may, the teeth of 
the mammalia have been divided into those with and those 
without roots. 
Those teeth deprived of roots, as the incisors of the rodentia, 
the tusks of the hippopotamus, elephant, &c. have a conical 
form, and are much greater in length than the other teeth. The 
cavity is also conical and the base of the cone which it repre- 
sents is the part most deeply buried in the follicle. This cavity 
does not, as in the human teeth, close around the base of the 
pulp, which is not pressed, and the functions of which go on, 
unimpeded at any time. 
The teeth provided with true roots, similar to those of the 
human dental organs, have, like them, a cavity expanded in the 
crown, but more or less narrowed in the roots and terminating 
at their extremities by a small opening. This cavity, in animals, 
as in man, shuts up and embraces closely the pulp in such a 
manner as to throw gradually increasing shackles upon its ac- 
tion. 
The teeth of the mammalia have been again divided, very 
properly, into simple compound, and semi-compound or mixed. 
Those classed as simple, like the human teeth, offer no an- 
fractuosity of the external surface, and have their crown formed 
of a regular shell of ivory covered with a plain and even lamina 
of emanel. 
The external surfaces of the compound teeth, on the contrary, 
present so many sinuosities that they appear to be formed of 
several teeth joined together, and it will be found that in sawing 
them across, the several substances of which they are composed 
will be passed through many times. The anfractuosities of the 
surfaces of the compound teeth are filled with a substance pecu- 
liar to the teeth of mammiferous animals, called cement, which 
I shall, presently, examine more particularly. ANATOMY OF THE DENTAL SYSTEM. 
115 
The cavity of the compound tooth is sub-divided as many 
times as the tooth itself presents parts joined together by the 
cement. Their pulp has the same configuration as that of the 
human teeth, but there seems to be a certain number of secon- 
dary pulps joined together by a common base. For the rest, we 
will give Cuvier's description of the grinding tooth of an ele- 
phant. 
"It has (the germ) in each animal a peculiar figure. To ob- 
tain a correct idea of that of the elephant, let the bottom of the 
capsule, representing the base, send off little parallel walls toward 
the part of the sac, next the buccal extremity of the alveolus. 
"These little walls are adherent to the bottom of the capsule, 
whilst their opposite extremity or summit is free. 
"This free summit is much thinner than the base, and it may 
be called the cutting edge. It is, moreover, deeply cleft into 
many points or sharp denticulations. 
"The substance of these little walls is soft, transparent, very 
vascular, and appears to partake very much of the nature of 
gelatin. It becomes hardened, white and opaque from the action 
of alcohol. 
"The semi-compound teeth are those in which the interme- 
diate substances penetrates only to a certain depth, the base be- 
ing simple. 
"A good idea of the compound teeth of animals may be drawn 
from the human molar teeth, which have a simple crown and 
compound root, whilst the former have generally a simple root 
and compound crown. Suppose the roots large human molars, 
covered with enamel, and joined together by cement, and you 
have a type of the compound teeth of other mammalia." 
The teeth of the mammiferous animals differ as much from 
the teeth of man in the conformation of their crown as their spe- 
cies of food differs from his. Studied under this relation, they 
furnish very numerous zoological characteristics, upon the im- 
portance of which, modern zoologists, particularly M. Blainville, 
have justly insisted. It will be sufficient to say at present that, 
in proportion as the animals are carnivorous and ferocious, the 
teeth are remarkable for their greater projections, their pointed 
and cutting edges; and that, on the contrary, as the dispositions 116 
ANATOMY OF THE DENTAL SYSTEM. 
of the animals are more peaceable, and their food of the vegetable 
kind, their teeth become proportionately enlarged and flattened 
upon the upper surface. The human teeth occupy a middle 
place between these two opposite organizations, as he is con- 
fined to neither a vegetable nor animal diet. The differences of 
conformation of the grinding surfaces of the teeth of these animals 
are in relation to their species of food. In the horse, for instance, 
who is removed as far as possible, in his nature and habits, from 
the carnivorous animals, instead of points, depressions will be 
found upon the grinding surfaces of some of the teeth. 
All the species of the teeth of man are found also in the other 
mammalia, but they arc not all relatively disposed in the same 
manner. In number they vary according to the families. I can 
only give a very general view of the subject here, afterwards it 
will be seen how much is confirmed by particular details. The 
determination of the teeth of the mammalia is often a difficult 
point, and one which demands the close attention of zoologists. 
The teeth of the mammalia, like those of man, are essentially 
composed of two substances, the ivory and enamel. The ivory, 
as in man, forms the principal and central part, the enamel the 
cortical part of the crown. The ivory is formed of concentric 
lamellae, and the enamel of perpendicular or oblique fibres, pro- 
ceeding from the external surface of the ivory by one extremity. 
But to these two essential substances, composing the teeth of 
the mammalia, another is added, the cement, called by Tenon 
the osseous cortical substance. There is, besides, in the teeth 
of these animals that confused calcareous crystallization; a kind 
of internal tartar which Rousseau and Desmoulins, from its re- 
semblance to the pudding stone, called poudingoido. 
The cement is found only in the compound or semi-com- 
pound, and never in the simple teeth of the mammalia. It is 
placed between the divisions of these teeth, and fills the inter- 
stices to the surface of the tooth. The cement is the least hard 
of the three dental substances; it is dissolved less readily in al- 
cohol, and blackens sooner when exposed to the action of the 
fire than the enamel. 
The cement exists in such quantities in some of the teeth, as 
for instance, in the grinders of the elephant, that it forms about ANATOMY OF THE DENTAL SYSTEM. 
117 
half of their whole mass. It is unorganized, and seems to be a 
kind of tartar crystallization. According to Tenon, it is pro- 
duced by the ossification of the internal membrane of the follicle, 
which, according to Cuvier and Bichat, as I have before stated, 
is reflected upon the pulp, and under which the tooth is primi- 
tively formed. According to Cuvier and Blake, on the contrary, 
this substance is produced by the same organ, which secretes the 
enamel after the latter is formed. 
Be this as it may, the analysis of this substance, taken from 
the tooth of a capybard, has furnished the following results: 
animal matter, 43.01; phosphate of lime, 52.94; carbonate of 
lime, 4.05. 
The follicle of the teeth of mammiferous animals is disposed 
like that of man. Indeed, it must be admitted, that the descrip- 
tion given of the follicle of the human teeth was drawn from a 
particular examination of those of larger animals, as the ox and 
elephant. 
There is little to be added here to what has been said of the 
embryo formation of the human teeth. The teeth of animals 
are developed in a manner precisely similar; a third substance 
is formed, however, over the other two, which make up their 
body to guard them from the friction to which they would other- 
wise be exposed. 
The teeth of these animals do not all resemble each other 
with respect to the period of their growth. In all, it is true, the 
development goes on by the formation of successive concentric 
laminae; but in some, as in man, this increase is limited, whilst 
in others it continues during life. Those which are limited in 
their growth are more common, the others really constitute an 
exception. 
This indefinite growth of the teeth is almost always confined 
to the incisor or canine teeth. We rarely observe a molar pre- 
senting this remarkable character. The reason of this is easily 
understood; as the molar teeth are intended for the trituration 
of the food, it is consequently necessary that the distance be- 
tween the antagonist teeth of this class should correspond to the 
separation of the jaws. "As the functions canine and incisor 
teeth are to divide the aliments, they may attain to great size 118 
ANATOMY OF THE DENTAL SYSTEM. 
without becoming a source of inconvenience; indeed, this in- 
crease of dimension renders them more useful in fulfilling ano- 
ther function. 
It is evident that those teeth, of which the growth contin- 
ues during life, have the means of furnishing a constant supply 
of enamel, and in this respect differ from the human teeth; they 
are reduced, indeed, to the part which represents the crown of 
the latter. In order that this continual elongation might go on, 
without a change of character, it was necessary that the parts 
should be kept in constant relation with the organs which se- 
crete the two substances of the tooth, and such is the case. As 
in the description of the human teeth the causes which limit 
their growth was explained, we will now consider the causes of 
the indefinite increase of some of the teeth of mammiferous 
animals. 
The rodentia, pacydermatu and cetacea, are almost the only 
animals of this class which have teeth possessing the property of 
increasing during life. These teeth are classed with those which 
have no roots; their internal cavity is conical in form. The 
pulp, conical also, rests, by a large base, upon the bottom of the 
alveolus, whence it receives its vessels and nerves, and not 
through the medium of a pedicle. In consequence of this ar- 
rangement, it is evident that the bony matter can never surround 
the pulp in such a manner as to interrupt its functions, and 
there is no reason why it should not continue to secrete this 
substance during life. 
When the teeth have acquired a certain degree of develop- 
ment in their follicles, in mammiferous animals as well as in 
man, their eruption takes place, and dentition is accomplished. 
The period at which this eruption takes place, and the manner 
in which the teeth of these animals are shed, is not perfectly 
known; and here, particularly, the importance is felt of having 
a fixed knowledge of the changes which take place in human 
teeth. 
The order in which the teeth of the mammalia appear like 
those of man, is from before to the posterior part of the mouth. 
They are divided with regard to their duration into deciduous 
and permanent teeth, as in man few remain during life. But AN A TOMY OF THE DENTAL SYSTEM. 
119 
how do the first and second teeth in these animals succeed each 
other? This is an important point to determine. In most of 
the mammalia, the change takes place from below upward, as in 
man; in others, from behind forwards, as Pallas has demon- 
strated in the elephant. 
Let the order in which the teeth are shed be what it may, the 
primitive tooth is atrophied in proportion to the growth of the 
second tooth. Anthropotanists have, principally, attributed the 
destruction of the roots of the temporary teeth to the pressure of 
the secondary teeth. I have advanced the opinion in a preceding 
part of this work, that it is caused by the destruction of the ves- 
sels which go to the temporary teeth. This view is the only one 
confirmed by comparative anatomy. In the elephant, indeed, 
as the teeth succeed each other from behind forwards, no pres- 
sure can be exercised upon the root of the tooth, which soon 
after falls. Yet, as Cuvier remarked, the same phenomena 
which occurred in man, occur also in the gigantic animal. 
The number of dentitions is not limited in some of the mam- 
malia as it is in man. Some of them, in which these changes 
have been well observed, the elephant among others, according 
to Corse, have their molars renewed as many as eight times. 
We may conclude, however, a priori, that the renewal of the 
teeth will be proportioned according to the life, more or less long 
of the animal. Nature, indeed, has but two methods of assu- 
ring the teeth of animals, either to replace them by others when 
they are worn away, or by a continual deposition of new matter 
at the base, in proportion as they are destroyed by friction at the 
opposite extremity. 
Whatever precautions nature may have taken to render the 
teeth hard and resisting, whatever the care with which she has 
deposited the enamel upon the grinding surfaces of the teeth, 
they must yield to time, and be destroyed, more or less com- 
pletely destroyed by the frictions to which they are exposed. 
The influence of the peculiar regimen of animals is particularly 
apparent upon the teeth; that kind of food which requires their 
action in a contrary direction, to effect perfect trituration from with- 
out inwards, as in ruminating animals, from before backwards, 
as in the rodentia^ destroys them in the greatest degree. The 120 
ANATOMY OF THE DENTAL SYSTEM. 
percussion of the crowns of the teeth, such as occurs in ordi- 
nary mastication, affect them but little. In laborious or graniv- 
orous animals, the grinding action necessary for the trituration 
of their food wears their teeth rapidly away, whilst carnivorous 
animals preserve the points and cutting edges of their teeth to 
the end of life. The influence of friction in the wearing away 
of the teeth is very apparent in the sloth ; in this animal, accord- 
ing to Desmoulins, the teeth in the two jaws are of unequal 
size, and, as they grind their food like the rodentia, the smaller 
dental range traces a furrow upon the larger one. The lines 
upon the teeth of animals which grind their food, indicate the 
direction in which the friction is habitually exercised; in the 
ruminantia they are transverse; in the rodentia antero-poste- 
riorly. 
Another phenomenon, not less curious, with regard to the phy- 
siology of the teeth, is now apparent. We know that it is ne- 
cessary for the surface of a mill-stone, in order that it may sub- 
serve the purpose for which it is intended, should be rough and 
unequal; and that, after having been used for some time and 
worn smooth the miller is compelled to repick it to supply it 
anew with its asperities. This same process takes place spon- 
taneously in the molar teeth, the true buccal mill-stones of the 
large mammalia. The crowns of the teeth are formed of sub- 
stances of unequal hardness, which are not equally capable of 
resisting frictions, the first effect of which is to wear away the 
original asperities presented. But when this is effected, the 
ivory of the tooth, less resisting than the cement, and still less 
than the enamel is worn away sooner than the other parts and 
new inequalities are formed,the teeth in this manner, repicking 
themselves. Under this relation, we at once apprehend the im- 
portance of the mixture of the three substances of the compound 
teeth, and why, also, the compound teeth are always molars. 
The incisors of the rodentia are always much more worn 
away behind than before, and always present a cutting edge; 
as the enamel is thicker anteriorly than posteriorly, this is a na- 
tural consequence. 
The teeth of certain animals are worn away unequally; pos- 
terior teeth of the elephant are less worn than those more for- 
ward. ANATOMY OF THE DENTAL SYSTEM. 
121 
But of all among the practical applications which have been 
made of this fact, there is none more beautiful, and at the same 
time more useful than that by means of which we are enabled to 
ascertain the age of the horse. We are particularly indebted to 
Tenon for the knowledge we at present possess with regard to 
this subject. 
"In this animal," says Cuvier, "the milk incisors make their 
appearance about the fifteenth day; four of middle teeth or ga- 
therers fall at thirty months, the four adjoining at forty-two, 
and the four external or conis, at fifty-four. 
The permanent conis do not grow as rapidly as the other inci- 
sors, and it is by them principally, that we are enabled to ascer- 
tain the age of the animal. 
"In the centre of these teeth, filled with blackish tartar, is a 
hollow, the edges of which, in proportion as the tooth issues from 
the gum,are worn away by contact with the antagonist tooth; 
it continues to diminish in size from the fifty-fourth month to 
the eighth year, when it is entirely effaced. 
"The hollows in the other incisors are much sooner effaced, 
so that we are enabled, with regard to the incisors to judge of the 
age of the animal only by their length, as they increase indefi- 
nitely. 
"The first back molar appears at eleven, the second at twenty 
months ; at thirty-two months the first temporary molars fall; 
the third at three years, and it is not till the fifth or sixth year 
that the last back molar appears. 
"The two first molars of each jaw, and on each side about the 
eighth day; the following at twenty; the small or anterior mo- 
lar at five or six months. 
"The deciduous molars are longer antero-posteriorly than 
those which succeed them, and the latter lose their dimension 
in this sense as the back molars issue and press upon them; 
thus, crowns of the teeth of a young horse are oblong, whilst in 
the old horse they are square." 
To return, the horse as most of the ruminant animals, has 
three milk and three back molars; the temporary teeth are more 
narrow than those which replace them, but have the same form, 
save that the last inferior resembles the last back molar 122 
ANATOMY OF THE DENTAL SYSTEM. 
As regards the order in which they make their appearance, it 
will be observed, that the third permanent molar makes it ap- 
pearance after the two first back molars, and, indeed, judging 
from the proportion in which they have been worn, after the 
third. 
In the quadrumana the teeth are arranged very much like 
those of man, the number is exactly the same with a rare excep- 
tion, observed upon some species ; the mycetes and ateles, have 
a small molar more. The teeth of the quadrumana are arrang- 
ed precisely like the human teeth, with perhaps but a single ex- 
ception ; in the ouistiti the dental arch is terminated by a small 
molar. 
We begin to perceive the teeth, already, in the ape, lose some 
of the most marked characters of the human teeth; their points 
are, particularly in certain species of makis, which are somewhat 
carnivorous, more developed, the canine is more pointed than, 
and a little more elevated above, the rest of the teeth. 
The order insectivora forms, with regard to the teeth, the na- 
tural transition from the quadrumana to the carnivora. The 
individuals composing this order have teeth varying in number 
from 28 to 44. The Peruvian cephalote has 28, and the mole 
44; between these two extremes there are numerous varieties. 
These variations affect always the molar or incisor, never the 
canine teeth of which there are always two in each jaw. 
The points of the teeth are more fully developed in the insec- 
tivora than in the quadrumana; the shrew mouse, the fourth 
false molar of which has a cutting point like the carnassiere of 
the following order, is a remarkable illustration of this fact. 
The incisors are well developed in some of the insectivoras, 
in the shrew mouse there are three, but the megadermes and ta- 
phiens have none at all. 
Amongst the carnivorous mammalia much analogy exists un- 
der the relation of their teeth. The molars only present any 
difference, all have twelve incisors and four canine teeth. The 
molars of the carnivora are divided into two classes, the false 
and the tuberculous carnassiers. The false molars are large and 
have several roots. The superior carnassiers have three lobes 
and a blunt heel within; the inferior carnassiers have two 
pointed and cutting lobes without the heel. 123 
The genus felis furnish a type of this order as regards the 
teeth. The bear is not so well distinguished as a carnivorous 
animal, as it feeds upon flesh only from necessity. The carnas- 
sier is small and its anterior lobe is almost effaced. The tuber- 
cles are situated like those of the rodentia. The seal has from four 
to six incisors above and four below, their canine teeth are very 
pointed, and their jaw teeth which are twenty, twenty-two, or 
twenty-four in number, are cutting or conical, which last disposi- 
tion may be considered as a transition to the teeth of the cetacea. 
Amongst the marsupials, some, the didelphi and dasyuria, 
have small incisors in each jaw, canine teeth very long, back 
molars covered with points; they partake indeed of all the char- 
acteristics of carnivorous insectivorae, and live upon the same 
kind of food. Others, the phalangers have below, two pointed 
incisors, and six smaller ones above ; their superior canine teeth 
are very long, but those in the inferior jaw are so small as often 
to be hidden by the gum, and sometimes disappear altogether. 
The kangaroo have no superior canine teeth, and have the mid- 
dle incisors equal to the others. The koala have in the inferior 
jaw two long incisors without canine teeth, and in the superior 
jaw two long middle incisors, some small lateral and four small 
canine teeth. The wombat under the relation of its teeth is a 
true rodentia. 
The canine teeth are absent in the rodentia. The incisors 
are four in number, generally two in each jaw, and separated 
from the molars by a considerable space. These teeth are long, 
strong, of the species, which increase indefinitely, and are more 
thickly covered with enamel before them posteriorly. In con- 
sequence of this peculiar arrangement, the incisor teeth of the 
rodentia preserve a sharp cutting edge during life, notwithstand- 
ing the great degree of friction to which they are exposed. The 
molar teeth have very irregular surfaces, and the terminal ine- 
qualities generally form transverse lines, such as we observe in 
the same class of teeth in the elephant. 
The individuals of the mammiferous order, called edentata, 
are not entirely deprived of teeth, as their name would indicate; 
they have no incisors, and all except the sloth want the canine 
teeth. The fourmellier, panzolen and echidne are the only ani- 
mals of this order entirely deprived of dental organs. 
ANATOMY OF THE DENTAL SYSTEM. 124 
ANATOMY OF THE DENTAL SYSTExM. 
The canine teeth of the sloth are longer and more pointed 
than his molars. 
The molars of the animals of this order vary in number very 
considerably; the priodontes have from forty-eight to fifty above, 
and forty-eight below. It is remarkable that all the edentata 
have a larger number of molar teeth in the superior than in the 
inferior jaw, with the exception of the taton, which has sixteen 
in each jaw. 
The grinding teeth of the edentata are nearly cylindrical. 
They are cylinders more or less perfect, simple, or joined two 
and two together, and sometimes formed of a single substance. 
Their growth, like the incisors of the rodentia, is indefinite; 
and, indeed, it is easily conceived how this must, of necessity, 
be, as the cylindrical tube is as unable to enclose and press upon 
the pulp as the conical cavities of the teeth of the rodentia. 
The ornithorynchus has no true teeth, but their place is sup- 
plied by a horny substance. The form, according to M. Blain- 
ville, is square, and there are four of the same kind in each jaw. 
They are flattened, and the base is irregular and moulded upon 
the bottoms of the alveoli. 
The probescidia have no incisors, properly so called; their 
place in the superior jaw is occupied by their enormous tusks, 
which are classed amongst teeth without roots, and are capable 
of an indefinite growth. Their molars are not very numerous ; 
sometimes there are four, sometimes eight, and sometimes twelve. 
Cuvier says, that in all the elephants he had an opportunity of 
examining, he found three molar teeth, an anterior one upon the 
point of falling, a middle one in perfect condition, and a poste- 
rior rudimentary one; so that the elephant has but two perfect 
molar teeth in each jaw atone time. These enormous teeth are 
of a quadrilateral form, and have upon their grinding surfaces 
transverse parallel crests united by cement. These crests are 
notched in teeth which are not much worn. In the old probes- 
cidia, they present variable lozenge shaped figures in the Afri- 
can, and narrow and festooned ribands in the Indian elephant. 
All the other pachydermata have teeth of a much more varied 
character than the probescidia. Their incisors are generally 
simple and cutting. Their canine teeth sometimes resemble the ANATOMY OF THE DENTAL SYSTEM. 
125 
ordinary teeth of this class; sometimes they make formidable 
tusks, and are sometimes altogether absent. Their molar teeth 
have a large irregular surface, and well formed for the purpose 
of grinding their food. 
The horse, particularly, has six incisors above and six below; 
four canine and twenty-six molar teeth, fourteen above and 
twelve below. The incisors are remarkable in forming a very 
regular semi-circular curve in young horses. Those in the cen- 
tre are called the gatherers, the adjoining one the middle, and 
the external one the coins. Their crowns are all hollowed into 
a funnel shaped cavity, the base of which presents towards the 
free extremity of the teeth, and in which there is an accumula- 
tion of blackish tartar. This cavity is gradually effaced, as I have 
already mentioned, by the influence of frictions. The canine 
teeth are called tusks ; they become blunted as the animal grows 
old. It is a remarkable fact, that in the mare the canine teeth 
are generally absent. The molars have a prismatic form, and 
present irregular elevations which cross their grinding surfaces. 
The ruminantia have incisor teeth only in the lower jaw; 
they are eight in number. The canine teeth are generally ab- 
sent; the camel, lama and kid are, however, furnished with 
them; the stag has them only in the superior jaw. The molar 
teeth are formed of double parallel crescents, their grinding sur- 
faces presenting longitudinally, which are rapidly destroyed by 
friction. 
Finally, the cetacea are, of all the mammalia, the best provi- 
ded with teeth, at least with regard to number. Some dolphins 
have as many as one hundred and eighty or ninety. It is that, 
on the contrary, the hyperoodon has but two, the narwal but 
two, sometimes only one, and the balcena none at all. 
The incisors are generally absent in this order of mammals ; 
the dugong is almost the only individual furnished with them, 
they have them, however, well developed. The canine teeth 
are entirely wanting. The molars are mostly conical and 
pointed. Those of the manatus, however, are flattened on their 
grinding surfaces, and are surmounted by two transverse ridges, 
resembling the grinding teeth of some of the pachydermatae, par- 
ticularly the tapir. 126 
ANATOMY OF THE DENTAL SYSTEM. 
The balana has no true teeth, but they are replaced by horny 
productions, which constitute the/azzonsor barbs. The fanons 
are inserted upon the concavity of the palate, and are directed 
perpendicularly downwards. They are very numerous; as 
many as a thousand have been counted in the free whole of 
fifteen feet in height. Each is formed interiorly of a layer of horny 
fibres, which are covered by two laminae, finer and closer in their 
structure, and in which the horny fibres are not so apparent. 
The fibres come out from between the laminae, and form a free 
fringe upon all the inferior and internal border of the fanon; 
so that all lateral parts of the palate, which are above the tongue, 
are covered with a hairy fringe. The fanons are inserted in the 
follicle of the gum, in which the mucous membrane is very vas- 
cular. 
The fanons, as will be at once perceived, are more analogous 
to the hair than the teeth. But if the balaena is not furnished 
with teeth in the superior jaw, the observations of M. Geoffroy 
St. Hilaire have demonstrated that they exist in the foetus in 
the furrow which represents the inferior jaw. These teeth, ac- 
cording to M. Blainville, are simple and conical like those of the 
cachalot. 
ORDER II. 
OF THE TEETH OF BIRDS. 
The definition of the teeth which I adopted at the outset, 
taken from the new edition of Cuvier's Comparative Anatomy, 
should exempt me from treating of the beak of the bird ; from 
the labors of M. Geoffroy St. Hilaire, with regard to this sub- 
ject, and the desire to present a complete view of the teeth of 
vertebrated animals, or the organs which represent them, how- 
ever, I am determined not to pass them by. 
Rigorously speaking, the beak is, to the bird, an organ of pre- 
hension and mastication, and may become a powerful offensive 
and defensive weapon ; but with relation to form and structure, 
they resemble much more the claws and nails than the teeth. ANATOMY OF THE DENTAL SYSTEM. 
127 
It is only a horny body which nature has substituted for the 
teeth. 
The consistence of the beak is variable. In birds of prey, it 
is remarkably hard, whilst in aquatic fowls it is very weak. 
With regard to form, the beak presents yet more numerous 
varieties, and as it is in exact relation with the habits and 
species of food of birds, zoologists have studied these diverse 
modifications with particular attention. The beak of some 
birds of prey is compressed, curved into a hook with sharp cut- 
ting edges ; some have them entirely straight, as the stork and 
heron ; others are curved downwards, as in the tantales^ or up- 
wards, as in thejaiin. The beak of the penguin is compressed 
transversely; some are remarkable for their flatness, as the 
ducks are ; and some are much elongated, as the spatule of the 
vanneau. 
The horny covering of the two mandibles is sometimes cov- 
ered with little elevations, or notches, which represent a species 
of teeth. A little within, at the point where the mucous mem- 
brane of the mouth is united to the substance of the beak, inden- 
tations are found, particularly in the duck, very regularly ar- 
ranged, and formed by a horny membrane, continuous on one 
side with the substance of the beak, and on the other with the 
mucous membrane of the mouth. A number of filiments of the 
inferior maxillary nerve come from the lower jaw-bone, go to- 
wards the points which represent the alveoli, and are lost in the 
notches above described. 
Carus compares the horny substance of the beak to the nails, 
and in the adult, at least, there is most analogy between these 
two parts. It would appear, however, from the researches ofM. 
Geoffroy St. Hilaire, that in young birds there is to be found upon 
the two edges of the beak, elevations, which he considered as 
true rudimentary teeth, the number and form of which he care- 
fully indicated. 
M. Geoffroy found also in the souchet^ horny laminae coming 
from the external part of the palate, which he compared to the 
fanons of the whale. I have observed an arrangement similar 
to this in the ordinary duck. 128 
ANATOMY OF THE DENTAL SYSTEM. 
ORDER III. 
THE TEETH OF REPTILES. 
Nature appears to have desired to mark clearly the position of 
reptiles in the zoological scale by the characters which she has 
given to the dental system of these animals. Occupying a place 
between birds and fishes, reptiles partake equally of the dental 
characteristics of both great classes. The tortoise has a beak 
like birds, and other reptiles closely resemble fishes in the form, 
number and principal characters of their teeth. 
I have little to say of the beak of the tortoise, after the descrip- 
tion I have given of that of the bird, as the parts are closely ana- 
logous to each other. As in birds the beak of the tortoise pre- 
sents little elevations, which have been regarded by some as the 
rudiments of separate teeth. The only important distinctive 
character of the beak of the tortoise is the existence of an osse- 
ous plate attached to but not implanted upon the jaws under the 
horny lamina. In consequence of this formation, an analogy 
may be drawn between this beak and the human teeth ; the cal- 
careous plate representing a range of teeth united together, of 
which the horny layer may be considered the enamel. Accord- 
ing to M. Blainville, true teeth are found in the trionyx^ a family 
very analogous to the crocodile, implanted in the jaws, which in 
these animals are pierced with regular holes. The last re- 
searches of M. Geoffroy St. Hilaire gives great weight to this 
view. 
With the exception of the chelonians all reptiles have true 
teeth which are analogous to those of man, and the study of 
which may, in more than one point of view, throw light upon the 
natural history of the human teeth. 
The teeth of reptiles are pointed and conical, answering very 
imperfectly, if at all, the purpose of grinding; they constitute, 
however, very effective weapons of attack and defence, and for 
the prehension of aliments may be classed with those of carniv- 
orous animals. 
From the preceding, the reason why the teeth of reptiles are ANATOMY OF THE DENTAL SYSTEM. 
129 
generally curved backward in the form of a hook, with the con- 
cavity posteriorly, will be at once apprehended. In consequence 
of this disposition, they are much better fitted to seize, draw in 
and retain their prey the resistance they offer to the escape of 
any body from their mouth is such that they will break sooner 
than relinquish their hold. 
Reptiles have a greater number of teeth than man ; it is con- 
siderable, but has not yet been exactly determined, however, it 
is but of little importance. Their teeth are generally like 
the human teeth implanted in the jaws, but sometimes as in most 
serpents they are attached to the palate. 
The teeth of reptiles belongs to the class comprising those 
without roots, of some of the mammalia, and as those they are 
hollowed into a similar cavity for the lodgment of the pulp. The 
teeth are placed, at least those attached to the jaws, in alveoli, 
which are more narrow at their external opening than towards 
the bottom, and as their base is in exact proportion to the vo- 
lume of the bottom of the alveoli, it will be readily conceived 
that their attachment must be very firm. 
The teeth of the animals so nearly resemble each other that 
it is impossible to separate them into distinct classes, as we do 
the human teeth. They resemble the canine teeth more than 
either the incisors or molars, it may be said,indeed, that they be- 
long to this class. There are sometimes indentations upon the 
free extremities ; the maxillary teeth of lizards are three pointed. 
The teeth of reptiles are generally developed at a very early 
age; this is particularly the case with the crocodile. These 
animals, says Cuvier, always have the same number of teeth; 
those which have just issued from the egg have as many as the 
animal twenty feet long. They grow like the human teeth by 
the addition of concustriclamellEe, and as their pulp is conical, 
they would increase indefinitely if they were not retained in the 
alveoli from its peculiar shape, being narrower at the opening 
than towards the base. 
Reptiles appear to be endowed, in a greater degree than most 
other animals with regard to the facility and frequency with 
which their teeth are shed. At whatever age a tooth of the cro- 
codile is extracted, another one will always be found under it, 130 
ANATOMY OF THE DENTAL SYSTEM. 
either in the alveolus or in the cavity of the tooth itself; some- 
times under the form of a little shell, very thin and short; some 
times more advanced and ready to take the place of the old tooth 
when it is shed. This succession takes place so frequently that 
young or old, these animals are always furnished with new, 
sharp and effective teeth. 
With age the teeth of these animals become longer and larger. 
In this respect no comparison can be drawn between the young 
and old crocodile. Their dimensions are always proportioned 
to the size of the animal, and particularly to the dimensions of 
the maxillary bones. In proportion to the development of these 
bones, the openings of the alveoli are enlarged, and the tooth, 
the growth of which, in length, appeared to have been prevent- 
ed by the narrowness of this opening, now receives new calca- 
reous depositions internally, by which they are thrown outwards. 
The manner in which the work of replacement is accomplish- 
ed in reptiles, varies a little, which will be the only question in 
detail. We will only say, that the same regularity in the shed- 
ding of the teeth which is observable in the mammalia, and par- 
ticularly in man, is not to be looked for here. 
In the samiens, with the exception of the iguana and lucurta 
tribes, teeth are found only upon the maxillary or inter-maxillary 
bones ; their number varies from seventy-eight to one hundred 
and forty. Tenon first described the mechanism of their fall 
and replacement. The question very naturally arises here, how 
these teeth,closely embraced as they are by the narrow opening 
of their alveoli, can be shed. This is effected by the following 
process : the tooth of replacement in developing itself in the ca- 
vity of the tooth about to be shed, presses it against the alveolus, 
in consequence of which the latter loses its consistence and is 
soon broken up. The fragments remain in the alveolus, whence 
they are afterwards expelled by the vital forces. In crocodiles, 
rings are often found formed in the alveoli by the remains of the 
old teeth, through which the new tooth first showed itself. 
The lizard tribe, accordingly, present remarkable peculiarities 
with respect to the manner of shedding their teeth. "The new 
teeth," says he, "are not formed in the cavities of old, nor do 
they make their way through the bodies of the latter, as in ANATOMY OF THE DENTAL SYSTEM. 
131 
the crocodile ; they are formed near the internal face of the 
base of the teeth, or in certain species in the thickness of the bone 
itself, either above or below, according to the jaw. In the latter 
case, examples of which are to be found in the safe-guard and 
dragon, a cavity is formed in which the development of the pulp 
and bony shell begins. This cavity gradually opens to the in- 
ternal face of the maxillary bone. When the new tooth is 
formed near the base of the preceding tooth, the pulp is de- 
veloped under the gum, simply; but in proportion to the 
development of the dental shell, a groove is formed in the near- 
est part of the old tooth, by which it is partially covered. Then 
it appears as if the new tooth is in the old one, but it is never 
entirely enveloped by it. 
"In whatever manner the new tooth is formed, it comes at a 
moment when by its increase the old tooth is entirely supplanted, 
which falls in consequence of the necrosis of its ossified base, 
whereby its connection with the jaw is broken up. This is not 
a spontaneous rupture like that which takes place in the old 
horns of the stag, which fall before they are pressed upon by 
the new ones. It has always appeared to me, that the new 
tooth was of some importance in assisting the mechanism of 
dentition." 
The ophidia have teeth both upon the jaws and palate. They 
all have, with the exception of the amphibcena, two parallel 
ranges of teeth on each side of the superior jaw. 
In venomous serpents, the teeth particularly curved back- 
wards in a semi-circular form, with the concavity posteriorly, 
and adherent to the superior maxillary bone, constitute the 
venomous fangs. The fangs generally occupy the anterior of 
the jaw; some serpents, however, make an exception to this 
rule, having them placed posteriorly. The fangs are not mov- 
able, as has been generally believed, but are fast soldered to the 
bone ; the movement which they appear to make, is communi- 
cated to them by the jaw itself, which has a peculiar mobility. 
They are much longer than any of the other teeth. Their 
free extremity is blunted and pierced by a hole, which is the 
external termination of a canal that traverses the tooth in its 
whole length, and which receives the excretory duct of the 132 
ANATOMY OF THE DENTAL SYSTEM. 
gland that secretes the venom. In the membranous sac which 
surrounds the base of the fang, a certain number of rudimentary 
fangs are placed; as many as eleven have been found disposed 
so as to take the place of the one in use, when it is shed. 
These rudimentary fangs are formed in membranous capsules, 
arranged parallel to each other, in the substance of the palatine 
membrane. Their order, with regard to dimension, depends 
upon their proximity to the tooth in service. When the latter 
has fallen, the adjoining fang takes its place, the base of which 
remaining membranous, is attached so accurately in the position 
of the one just shed, that the opening of the canal is exactly 
opposite to the duct of the venomous gland. 
The teeth of the batrachians are much less important as re- 
gards their utility, than those of other reptiles, but in a zoological 
point of view, they furnish data, which should not be overlooked. 
All the batrachia, the toad, \X\e pipa, and perhaps the syren ex- 
cepted, have teeth in both jaws. All except the^yja have teeth 
in the roof of the palate. The pipa is entirely deprived of teeth ; 
the toad, and perhaps the syren, has only palatine teeth, whilst 
all the other tribes belonging to this order have both maxillary 
and palatine teeth. 
ORDER IV. 
THE TEETH OF FISHES. 
In the dental system of fishes a great variety is found, both in 
respect to the number and arrangement of the parts of which it 
it is composed. It is impossible, and fortunately, unnecessary, 
to determine the number of these parts. All that is of import- 
ance, at present, is to ascertain their position and form. 
Fishes are furnished with teeth upon all parts of the internal 
face of the mouth proper, and of the pharynx, besides other pro- 
ductions of the skin of the vicinity which M. Blainville wished 
to consider as true teeth. The teeth of fishes have been distin- 
guished into inter-maxillary, mandibulary, palatine, vomerial, 
lingual., branchial, and phayngeal. ANATOMY OF THE DENTAL SYSTEM. 
133 
But it is not sufficient merely to know, in a general manner, 
that the teeth of fishes occupy such and such portions of the 
entrance to the dental canal, it is necessary also to ascertain the 
special manner of their implantation. The teeth of the animals, 
now under consideration, may be in this relation divided into 
two species, those which are lodged in particular alveoli, 
(poissons osseux gnatodontes of M. Blainville,) and those which 
are placed at a distance from the maxillary bones which do not 
furnish cavities for them, as in all the truly cartilaginous fishes, 
with the exception of the saw-fish. The former are perfectly 
firm and immovable, whilst the latter are movable, and suscep- 
tible of erection and depression, as is evident in the shark. 
The circumstance of the teeth being attached to the mucous 
membrane, without any connection with the bone, is a conclu- 
sive fact in favor of the theory which represents the teeth as 
simple productions of this membrane. In certain anomalous 
cases, as I have already mentioned, similar teeth have been pro- 
duced in'the human subject, marking the analogy existing be- 
tween him and more inferior animals. 
The teeth of fishes vary more, if possible, in form than in any 
other respect. Some are pointed and others have flattened sur- 
faces, for which reason they are called dents en pave. The 
pointed teeth, which are the most numerous, have sometimes 
but a single point, and sometimes two or three, as in the squalus 
and roussette ; these teeth are directed inwards and backwards, 
the better to enable them to retain their prey and to offer no 
obstacle to deglutition. 
The dents enpave, of the ray are flattened or a little raised in 
the centre, in the form of transverse bands, whilst the sides are 
square; the greater number, however, have an even surface. 
They appear to be formed, according to Desmoulins, of a bundle 
of little tubes, united at the summit by a common layer of 
enamel. In a fish, classed with the scarius, by Cuvier, the 
teeth form five or six ranges, each composed of five or six teeth, 
which are all united by a kind of cement. 
The teeth of the osseous fishes, which are implanted in 
alveoli, are, after their complete development, closely soldered 
to the circumference of the cavity in which they are placed. 134 
ANATOMY OF THE DENTAL SYSTEM. 
According to Desmoulins the base of the pharyngeal teeth of 
the cyprenus, present, a foramen which performs a very impor- 
tant part in the work of replacement of the teeth. He says: "the 
pedicle of the tooth of replacement is carried towards this hole, 
and as it becomes more elastic as the formation of the tooth ad- 
vances, the latter, I conceive, is drawn toward the place it is to 
occupy." 
"All the alveolar teeth of fishes are fixed upon their alveolar 
border, at a certain stage of their development, and after the 
lapse of a time, which varies, they are replaced by new teeth, in 
a manner, not, however, perfectly understood. "Sometimes," 
says M. Blainville, "the teeth of replacement take the position of 
the teeth which they succeed, as in the mammalia; again they 
appear at the side of the other in a very irregular manner, as for 
instance in the pike. In the ray, the squalus, and fishes of 
which the teeth are compound, as the diodins, the tetraodons, 
the scarce, new ranges of teeth appear on the posterior or inte- 
rior border of the old." 
From such facts the habits and species of food of the fish may 
be easily ascertained. The fishes armed with numerous sharp 
teeth inclined strongly backward, as in the pike, or denticulated 
and cutting, as in the shark and squalce, should be classed 
among the most voracious, the most carnivorous of the inhabi- 
tants of the waters. Those on the contrary which are furnished 
with simple or flattened teeth, as the dorado, and many other 
sparoids, and those which have only pharyngeal teeth, should 
be considered as the least carnivorous of all. Finally, the fishes 
I have described as having complicated teeth, formed like 
grinders or paves, so well formed for grinding or crushing hard 
substances, feed upon shell-fish, and frequent those waters 
where they abound. APPENDIX. 
OF THE PARTS WHICH REPRESENT THE TEETH IN INVERTE- 
BRATED ANIMALS. 
The parts we are about to describe in a very general manner, 
as the teeth of the invertebrata, have certainly this analogy with 
the teeth of vertebrated animals; they are placed at or near the 
entrance of the alimentary canal; they serve to seize, retain and 
comminute the alimentary substances. But this analogy, in a 
functional point of view, does not, necessarily, imply a corres- 
ponding analogy of organization. Nature is able, doubtless, to 
attain to the same end by the employment of different means, 
and it appears to me that she has done so in this case. 
The dental organs of these animals are dependencies of the teg- 
umentary membrane, and are productions ofa calcareous or horny 
nature. But between these and the teeth, that is, those organs 
furnished with a special follicle, in which is secreted the bony 
substance of the tooth, which, after a certain time, makes its 
appearance through the gum, there are very great differences, 
differences which have, with reason in my opinion, prevented 
Cuvier from classing them together. 
Taking all the facts into consideration, I think a much greater 
analogy exists between the teeth and the hair, than between 
them and the so-called teeth of invertebrated animals. Doubt- 
less, in the classification of the masticatory organs, we should 
necessarily take in both, but it would be always necessary to 
divide them into two distinct classes, one of which should com- 
prehend the teeth, the other the odontoid organs of the inverte- 
brata. 136 
ANATOMY OF THE DENTAL SYSTEM. 
There is a fact which deserves particular attention in this in- 
ventory of the dental organs of invertebrated animals; it is this : 
these animals have those parts representing the teeth placed in 
the stomach. It will be observed that the masticatory organs 
of the invertebrata are submitted to a rule to which nature ap- 
pears to have confined herself in the constitution of the masti- 
catory organs. The higher the animal is elevated in the scale, 
the higher are the dental organs elevated in the alimentary canal. 
In the crustaceae and mollusca, they are placed principally in the 
stomach; in fishes, they reach the pharynx; in reptiles, the 
posterior part of the mouth, whilst in the mammalia they are 
confined to the anterior and lateral parts of the mouth. 
In the mollusca the true masticatory organs are situated, with- 
out exception, in the stomach; the detached stony shells of the 
tarets and the unios; the tenaculae which surrounds the mouth 
in the balaines and huitres, are undoubted organs intended for 
the prehension of aliments, but do not appear to be in any other 
manner assimilated to the teeth. 
The aplysia of all the mollusca has the most complete masti- 
catory apparatus. According to Cuvier's description, the crop is 
furnished with a gizzard of a short cylindrical form; the walls 
of which are muscular and very strong. "They are furnished, 
interiorly, with a kind of armor, which is very extraordinary, and 
to which I can find nothing exactly analogous, although the 
osseous pieces of the stomach of the bullies may have some rela- 
tion to them. They represent pyramids, with rhomboidal bases, 
the irregular faces of which are joined together at the summit by 
two or three blunt points. Their substance is semi-cartilaginous, 
composed of laminae parallel to the base. Their number in in- 
dividuals, from which I have carefully collected them, is about 
twelve large ones, placed in three ranges in a quincunx order, 
and some small ones arranged in the superior border of the giz- 
zard. The attachment of these pyramids to the villons coat of 
the organ, is so slight that they are broken away by the slightest 
effort, without leaving any trace of their membranous or other 
means of union. Their places of adherence are well marked, 
however, by smooth and elevated surfaces, whilst the intervals 
between them are a little depressed and slightly wrinkled. The 137 
ANATOMY OF THE DENTAL SYSTEM. 
free extremities of these pyramids are so arranged that their 
points touch in the middle of the cavity of the gizzard, and as 
there remains but little space for the passage of aliments, they 
are, consequently, broken up with much force. 
The third stomach, as large as the first, though not so long, is 
furnished with an apparatus as singular as the second. A num- 
ber of little pointed hooks attached to the internal surface of the 
stomach, but almost as slightly as the pyramids of the gizzard; 
their points are directed towards the gizzard, and I cannot con- 
ceive of any other use they perform than to arrest the passage of 
the food which has not been sufficiently triturated in that organ. 
The form of the alimentary substance is entirely lost in the third 
stomach. 
The crustaceas of all the invertebrated animals have the most 
remarkable gastrico-dental organs; they are calcareous produc- 
tions, carried upon a kind of skeleton with which the stomach of 
the animal is armed. According to Cuvier, we find first a trans- 
verse ridge which occupies the middle of the stomach. This 
ridge is furnished with a tooth or oblong osseous plate, which 
is attached to the superior wall of the stomach, and is directed 
backward towards the pylorus terminating in a tubercle. Upon 
this posterior extremity is articulated a second ridge directed 
backwards, and bifurcated in the form of the letter Y upon each 
of the lateral processes, of which is articulated another which 
goes forwards and outwards to be united to the lateral extremity 
of the first transverse ridge. 
Upon these two lateral ridges are placed the two larger teeth. 
They are oblong; have a flat crown, which is furrowed across 
the elevations, and furrows differing according to the species. 
In the crab poupart the crown is striated, and has upon its infe- 
rior border large denticulations, and forwards, a projecting part 
which is not striated. In the great lobster, there are nine trans- 
verse rib-like elevations, of which the three anterior are much 
the largest. 
From the point of union of the transverse and lateral ridges 
comes off another lateral one which extends lower than the first, 
and has upon its extremity a lateral tooth, placed a little before 138 
ANATOMY OF THE DENTAL SYSTEM. 
and under its anterior extremity, and furnished with three and 
sometimes five small sharp curved and pointed elevations. 
The two teeth furnished with hooked points, seize the food 
taken into the mouth, and carry it between the two teeth with 
flattened crowns, and the first plate I described. 
After having undergone this process, the food passes by the 
straight part of the stomach where its progress is again impeded, 
first by an oval fleshy projection, which corresponds to the inter- 
val of the two great lateral teeth, and then by a sharp crest, 
which divides the pyloras into two semi-canals. 
Insects and worms have no organs which can be, with any 
appearance of reason, compared to the teeth of the superior ani- 
mals. Some of the orthopterce, the acheta, the locusta, and the 
blattes only have their stomachs furnished with scales or horny 
hooks, which have been supposed to be destined to perform a 
kind of mastication. At the entrance of the mouth of all insects 
the skin is harder than in any other part of the body, the epider- 
mis appearing to have undergone a horny modification; but, as 
has been seen, this arrangement does not enable us to class it as 
a special dental apparatus. In the radiata, finally, without 
speaking of the tenaculae which surround the mouths of these 
animals, and which have been compared, without much appear- 
ance of reason, to the teeth; some of them echonis, which are 
admitted to have special dental organs. In this class, in the oral 
opening of the shell, which looks downwards, there is, according 
to Carus, an apparatus of five branches, lantern of Aristotle, in 
each of which a long tooth is situated, and moved by many 
muscles. INDEX. 
PAGE. 
Introduction, ........ 3 
PART I. 
HISTORICAL SKETCH OF THE ANATOMY OF THE TEETH. 
Period I.-From an indefinite time in the Discoveries of Egypt, 
China and Greece, to Aristotle, .... 6 
Period II.-From Aristotle to Galen, . . . .8 
Period III.-From Galen to Vesalius, . . . .11 
Period IV-From Vesalius to Harvey, . . • .13 
Period V-From Harvey to Bichat, .... 17 
Period VI.-From Bichat to the present time, . . .29 
PART II. 
ANATOMY OF THE PENTAL SYSTEM. 
Class I.-Of the Teeth in General, . . • . .33 
Class II.-The Teeth in particular, .... 36 
Chap. I.-The Human Teeth, . . . . .36 
Order I.-Conformation of the Teeth, . • .36 
Art. I.-Conformation of the Bony Portion, and the Dental Follicle, 37 
Sec. 1-Of the Bony Portion of the Tooth, ... 37 
Sec. II-The Dental Follicle, - . • . .38 
Art. II.-Particular Conformation of the Teeth, . . 40 
Sec. I.-The Bony Portion of the Tooth, . • -40 
Sec. II-The Dental Follicle, . . • . 42 
Sec. III.-Of the Alveoli and the Dental Arches, . . 43 
Order II.-Organization of the Teeth, .... 44 
Art. I.-Organization of the Osseous Portion of the Teeth, . 44 
Art. II.-Organization of the Follicle of the fully Developed Tooth, 48 
Order III.-Development of the Teeth, . . . .54 140 
INDEX. 
PAGE. 
Art. I.-Development of the Teeth in General, . . 54 
Sec I-Formation of the Dental Follicle, . . .54 
Sbc. II.-Development of the Osseous Portion of the Teeth, 58 
Sec. III.-Growth of the Teeth, . . . .61 
Sec. IV.-Eruption of the Teeth in General, . . 66 
Art. II.-Development of the Teeth in Particular, . . 70 
Sec. I-Development of the Temporary Teeth-First Dentition, 71 
Sec. II-Development of the PermanentTeeth-Second Dentition, 77 
Sec. Ill-Development of the Senile Teeth-Third Dentition, 83 
Sec. IV-Application of the Development of the Teeth to the 
Determination of Ages, ..... 85 
Order IV.-Importance of the Teeth in the Organism, . . 89 
Art- I.-Influence of Dentition upon the Face, • . 90 
Art. II-Importance of the Teeth in their Functional Relations, 98 
Order V-Varieties of the Teeth, . . . .102 
Art. I.-Varieties of the Teeth according to the Ages, . . 102 
Art. II.-Varieties of the Teeth, according to the Different Races, 105 
Art. III.-Varieties of the Teeth of Individuals, . . . 105 
Chap. II.-Comparative Anatomy of the Teeth, . ' . 112 
Order I.-Teeth of the Mammalia, . . . . .113 
Order II.-Of the Teeth of Birds, .... 126 
Order III.-The Teeth of Reptiles, ..... 128 
Order IV.-The Teeth of Fishes, . . . . • 132 
Appendix.-Of the parts which represent the Teeth in Invertebrated 
Animals, . . . . . . .135