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TUFTS UNIVERSITY LIBRARIES
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Webster Famiiv Library of Veterinary Medicine.
VETERINARY SURGERY
Bv Louis A. Merillat, V. S. Volume I
ANIMAL DENTLSTRY AND DISEASES OF THE MOUTH
VETERINARY SURGERY
By LOUIS A. MERILLAT, V. S.
Volume I ANIMAL DENTLSTRY AND DISEASES OF THE MOUTH
Volume H THE PRINCH'LES OF VETERINARY SURGERY
VOLUM3 HI
VETERINARY SURGICAL OPERATIONS
lDetcrinar\> ©uroeri^
Voi-UME I.
ANIMAL DENTISTRY
AND
DISEASES OF THE MOUTH
\ BY
Louis A. Merillat^ V. S.
PROFESSOR OF VETERINARY SURGERY IN THE CHICAGO VETERINARY COLLEGE ; LATE SECRE- TARY AND PROFESSOR OF DENTISTRY IN THE MKILLIP VETERINARY COLLEGE : LATE PRESIDENT OF THE CHICAGO VETERINARY SOCIETY ; SECRETARY OF THE ASSO- CIATION OF VETERINARY FACULTIES AND EXAMINING BOARDS OF NORTH AMERICA ; MEMBER OF THE AMERICAN VETERINARY MEDICAL ASSOCIATION; MEMBER OF THE ILLINOIS STATE VETERINARY MEDICAL SOCIETY, ETC.
Ifllustratc^
CHICAGO:
ALEXANDER EGE: 1908
Entered according to Act of Congress, in the year 1905, by
ALEXANDER EGER aD ♦he office of the Librarian of Congress at Washington.
Daniels Company Press, Chicago
To Mr. MYRON H. TICHENOR and Mr. LOUIS M. NEWCAS, of Chicago, U. S. A., for their appreciation of the varw^ ^.i animal dentistry on valuable coach and saddle horses, this volume is re- spectfully dedicated by
The Author.
PREFACE.
The domain of animal dentistry is too limited to fill a large volume without entering into the details of embryol- ogy, anatomy and physiology, and since these sciences are today ably covered by v/riters possessing special merit in each, it would appear ridiculous for a veterinary practitioner to "venture where angels fear to tread." A comprehensive understanding of the teeth in their normal state at the dif- ferent periods of life, as a foundation for the intelligent treat- ment of their abnormalities is, however, so essential that it has been thought advisable to include an epitome of these sciences so far as they appertain to the teeth.
This Volume, with Volumes II and III, is written at the earnest solicitation of the students I have had the privilege of teaching during the past twelve years, which circumstance is the only excuse for its publication. The fact that animal dentistry is given but limited space in the surgical litera- ture of the profession has not entered into the proposition, because the task of writing books belongs to those having the time and inclination to ponder leisurely over each single topic, and not to the busy practitioner, whose few idle moments are usually interrupted by "a call to action."
It has been the aim to cover the subject in a matter-of- fact manner, excluding all obscure, rare and imaginary con- ditions and including all the conditions encountered in the routine of practice. For compiling the index and for the illustrations, which are made from copies and original draw-
^ PREFACE.
inj^s. I am particularly indebted to Mr. .\le.\. Ki;er. I have also to thank my friend, Dr. \\'. L. Williams. Professor of Surgery in the New York State Veterinary College, for his valuable suggestions as to the origin of teratoniata of the mastoid region, and my brother Professor, Edw. Alerillat, for his many original ideas which are entered throughout the text with but a single credit, viz., the operation for clos- ing skull perforations.
With a full knowledge that the manuscript would crum- ble from the assault of a literary critic, I forthwith apologize to the censors of English veterinary literature.
L. A. AlERILLAT.
CONTENTS.
PAGE
Preface ix
Introduction 13
Chapter I 18-43
Nomenclature of Teeth 18
Divisions of a Tooth 19
Structures of the Teeth 20
Chapter II 44-67
Evolution of the Teeth 44
Embryonic Evolution , 44
Evolution of the Temporary Teeth 49
Evolution of the Permanent Teeth 58
Chapter III , 68-126
Retrogression of the Temporary Teeth 68
Retrogression of the Permanent Teeth 68
Determination of Age 74
Routine of Examination of a Horse's Mouth to Determine Age 113
Anomalies of the Teeth, Natural and Artificial 117
Chapter IV 127-132
Function of the Teeth 127
Chapter V 133-151
Dental Diagnosis 133
Dental Instruments — Their Uses 135
Restraint 148
Chapter VI 152-256
Diseases and Irregularities of the Teeth 152
Necrosis of the Teeth of Herbivora 152
Caries 172
Abnormal Eruptions of the Teeth 175
Dental Cysts 177
Odontomata 178
Brachygnathism 179
Prognathism 181
Parvignathism 182
Projections on First Superior and Sixth Inferior Molars 184
Projections on the Superior Corners 185
Acquired Elongations of the Molars 185
Enamel Points 187
Wolf Teeth 202
xii CONTENTS.
PAGE
Supernumerary Teeth 204
Elongation of Incisors 207
Erosion of Enamel 208
Tartar 208
Fracture of the Teeth 209
Splitting of the Molars 209
Foreign Bodies in the Mouth 210
Fracture of the Inferior Maxilla 211
Fractures of the Pre-Maxilla and Superior Maxilla 213
Dislocation of the Temporo-Maxillary Articulation 213
Bit Gnathitis 214
Osteomata of the Superior Maxilla 216
Carcinomata of the Palate 217
Sarcomata of the Mouth 217
Actinomycosis 218
Dental Teratomata 222
Dental Fistulae 224
Traumatic Stomatitis 226
Stomatitis — Infectious 227
Ulcerative Gingivitis of Dogs 229
Retention Cysts 230
Lampas 230
Secondary Chronic Nasal Catarrh 231
Chronic Perforation of the Skull 236
Application of Gutta Percha Plugs 238
Cribbing and Wind-Sucking 239
Habitual Ptyalism 241
Side-Reining 242
Habitual Protrusion of the Tongue 244
Bit Lugging 245
Facial Paralysis 248
Lacerations of the Lips 249
Ranula 250
Foreign Bodies in the Tongue 250
Frost Bites, Laceration of the Cheeks and Tumors of Lips and
Cheeks 251
Laceration and Inflammation of Tongue 252
Aberrations of the Function of Mastication 253
INTRODUCTION.
Dentistry is the art of repairing the teeth or improving their utiHty. Human dentistry embraces the art of supply- ing artificial substitutes for the teeth when the original ones are lost, while animal dentistr}- includes the therapeutics of the secondary pathological processes and lesions in the mouth and nasal cavities, caused by the teeth. It is, however, essentially a mechanical rather than a surgical departure, and a preventive rather than a curative effort. Its province ends with the teeth and their immediate environs. Dis- orders of the digestion or impairment of the general health, although directly traceable to the teeth, cannot be included within the domain of dentistry. The principal ol)ject of dentistry is to promote the general health by improving the mastication and by relieving pain. It also aims at the pre- servation of the juvenile appearance, to which the animal dentist adds the amelioration of the driving defects of horses.
Human dentistr}^ owes its existence to a single disease process, caries, while animal dentistry depends upon a single physical defect, enamel points. Without these two abnor- malities dentistry wouhl never have existed as an advanced art ; no*^ because there are no other serious abnormalities within the domain of dentistry, Init because other abnormali- ties are infrequent. Few mature human beings escape caries, and few mature herbivora escape enamel points. Hence the wide requirement for dental operations in the human family, and in the chief domestic animal — the horse. As the extrac- tion, replacement and repair of the decayed tooth is the chief occupation of the human dentist, so is cutting and floating
13
14 ANIMAL DENTISTRY.
enamel jioints the j)i'incipal work of the animal dentist. No student of zoology will deny that the domestic herbivora, especially the horse, suffers from frightful physical defects that are inimical to their o-eneral health and usefulness. The other defects and diseases, although frequently of s'erious import, demand only a small share of the animal dentist's attention because they are relatively rare. The porcine, ovine, and l)Ovine species do not suffer to the same extent as the domestic horse on account of their different occupa- tion and short life. Except for breeding purposes these genera seldom live beyond their maturity, and even then they are not submitted to the same artificial influences as the horse. In the canine and feline species the anatomical con- stitution of the teeth prevents projecting defects and their short life precludes caries, so here again the animal dentist meets only an occasional condition demanding attention. It is evident, therefore, that animal dentistry naturally cen- ters upon the horse, the commercial value of which depends as much upon its utility as upon its general appearance. And again, mastication and insalivation are two essential digestive processes in herbivora, and of more relative impor- tance than in carnivora and or.uiivora. The coarse amy- laceous food of herbivora, especially the non-ruminating her- bivora, requires immediate and perfect comminution and incorporation with saliva to insure perfect gastric digestion and subsequent absorption, while the artificially prepared food of man may without special detriment be passed di- rectly to the stomach with but little mastication. The same may be said of the dog, the cat and the hog, all of which consume their food -vvithout a semblance of persistent mas- tication.
Then again, animal dentistry must respect the horse's mouth as the "seat of the l)it" as well as the mechanism of mastication. The manner in which the horse accepts the bit
ANIMAL DENTISTRY. X5
must always be a determining factor in its value. The dental defects which irritate or wound the buccal surfaces under the pressure of the complicated riggings of harness and saddle horses constitute an important feature of animal dentistry.
A summary of the exact scope of animal dentistry is as follows :
1st. The cutting and floating of the enamel points of the horse and ox.
2nd. The removal of projections which prevent perfect apposition of the dental arcades of the horse, ox and hog.
3rd, The treatment of secondary nasal catarrh resulting from diseased teeth.
4th. The extraction of all diseased teeth of all animals.
5th. The removal of tumors related to the teeth, in all animals.
6th. The treatment of stomatitis caused by the bit or by dental projections.
7th. The amelioration of driving defects resulting from dental irregularities in the horse.
8th. The treatment of faulty eruptions of the perma- nent or temporary dentures in the dog, the horse, the ox and the cat.
9th. Improving the appearance of the incisors of the horse.
When dentistry in animals is more generally recognized as an important if not essential feature of animal therapeu- tics, and when dental operations by reason of greater skill are made easier, the veterinarian will then treat the art of dentistry with the same dignity as the other branches of surgery. One object of this volume is to popularize the art of animal dentistry by describing easy methods of perform- ing dental operations ; by drawing attention to the value and necessity of dentistry, and by pointing out the advisability
16 ANIMAL DEXTISTRV.
of sacredly ijnardinc;- dentistry from becominj:^ obsolete in the veterinary profession, and from passinc^ to the willing specialist, who, through deficient fundamental technical edu- cation cannot keep pace with the advancement continually being made in the other branches of veterinary surgery. Animal dentistry is unpopular, not so much because it is difficult, tedious and even dangerous, Imt because it is re- garded as of minor importance in the veterinary colleges and by the better class of veterinary practitioners, who will- ingly stigmatize animal dentistry as an unimportant "side issue" by relegating dental operations to the student, the assistant, the stable-helper, the horse-shoer or the horse- dentist.
Only a few years ago, at the urgent rec|uest of a suffering patient, the family physician would condescend to pull an aching tooth, but he was never specially provoked if such a patient had consulted the watchmaker or the locksmith, who in many localities had earned enviable reputations as expert tooth-pullers, and who finally became the first recruits in the new i)rofession of human dentistry. The duty of the veteri- narian of today toward the tooth-rasping horse-shoer or the professional horse-dentist 1)ears a striking resemblance to the relations between the physician and tooth-pulling lock- smith of a few years ago. The able physician in those davs willingly consigned the tooth-ache patient to the locksmith, or the barber, or the watchmaker, l)ecause dental operations were then considered as an unimportant "side issue," rather beneath the dignity of the learned therapeutist. But, in spite of this apathy, dentistry asserted its importance and soon became a part of the curriculum of the foremost uni- versities of the world.
This is precisely the status of animal dcntistrv today. The veterinarian consigns dental operations to others, be- cause it is rather beneath the dignity of the learned veteri-
ANIMAL DENTISTRY. I7
narian to float the teeth of horses: not because it is difficult, tedious or dangerous, but because animal dentistry is re- garded as a trifling accomplishment that the uneducated can master. The intimate relation of the condition of the teeth to the general health is becoming more and more recognized, and when the value and importance of veterinary dentistry is universally recognized l)y the veterinary profession and lay public, and when it becomes more generally admitted on all sides that the veterinary patient receives the same relative benefits from dental operations as the human subject, animal dentistry will then take its place among the useful branches of veterinary science. The limited number of patients will probably always prevent the evolution of animal dentistrv into a special profession. The veterinarian will, therefore, be required to perfect himself in the practice of this art.
There were tv/o potent factors concerned in the evolu- tion of human dentistry — the college and the practitioner. The same influences are essential to the healthy evolution of animal dentistry. The college must devote more time to the art and the practitioner must become more proficient, even though the increasing importance of animal dentistry cannot be met by the birth of a new profession. The subject deserves to be brought out more prominently in the litera- ture on surgical subjects, in order to foster and maintain its sesqui-special relations to veterinar}^ surgery as a whole.
CPiAPTER I.
NOMENCLATURE OF THE TEETH.
The teeth are called. Incisors, Canines, or Molars, ac- cording to their location, form and function; they are supe- rior or inferior according- to the jaw into which they are im- planted; and right or left according to the side of the n^icdian line of the body they occnpy. The incisors, naming from the median line outward, are called centrals, laterals and cor- ners. The molars are numbered, ist, 2nd, 3rd, etc., from
Fk;. I. Complete Denture of a Horse.
1. The Canine denture.
2. Incisor denture.
3. Molar denture.
before b-ackward. The sul)division of the molars int(~) molars and n^.ola.rs is useless in the herbivora, as thcv sess no distinguishing characteristics that woitld wai such classihcation. and in the other animals the subdi\- is more confusing than instructive.
Each tooth in the head n^.ay then be identified by r
18
prc- pos- •rant ision
(ifer-
ANIMAL DENTISTRY. 19
ring to it as the "right-first-superior molar," the "left- fourth-siiperior molar," the 'Meft-infcrior-lateral," or the "left-inferior canine." etc., throughout the dental arcades.
DIVISIONS OF A TOOTH.
Anatomically a tooth is divided into the crown, neck, fang, roots, table, infundibulum and cup. The crown refers to the projecting portion, or in other words that part of a nor- mal tooth that is visible. The neck is the part covered with gums, or the part between the crown and alveolar margin. The fang is the imbedded portion or the part between the al- veolar margin and the projecting roots. The roots are the small projections at the imbedded extremity of the fang. The table refers to the grinding or contact surface. The infundibulum is the cavity on the table produced by the in- folding of the enamel, while the cup refers to the unfilled portion of the infundibula of the incisors.
The surfaces of the teeth are frequently referred to as the "buccal surface," the "labial surface," or the "lingual sur- face." In the case of the molars the buccal surface is the external and the lingual, the internal, while in the incisors the lingual refers to the posterior surface, and the labial to the anterior.
Other names frequently used in the study of dentistry are "alveolar margin," referring to the outer border of the alveo- lar cavity; the "gingival margin," which refers to the outer border of the gums, and "contact margin," which implies the cutting Ijorder of a tooth such as an incisor of carnivora.
STRUCTURES OF THE TEETH.
A tooth is composed of hard and soft tissues, of which the former predominates in volume and importance. The hard tissues comprise a body of dentine, capped with enamel.
20
ANIMAL DlCXTIS'lkV.
aiid encrusted over the rcmainiiif^ portion witli crusta pe- trosa, or cement. Tlie soft structures are the pulp, which occupies a cavity within the 1)ody of the tooth, the aveolo- dental periosteum which surrounds tlie external surface of the fano-, the .churns or gingivae, which cover the neck, the blood vessels which supply its nutrition, and the nerves whicli furnish its sensil)ility and tactile sense.
DENTINE. The dentine is a hard, yel]o\\-ish, sensitive substance con-
"f'j
mm,'/
'iHiriilh'l iM„lllul!.illlUI|ht|!,;l||((||K||||
Fig. ta.
Enamel and Dentine as .Arranged at the Crown.
1. F.naniel.
2. Spaces of Czcrmak.
3. T'cntiiK?.
(Magnified.)
Fig. 2. Dentinal Tnlndes. Ma'Jjnified.
stitutino- the major ])ortion of the tooth's volume. It ex- tends from the j)ulp cavity within to the enamel and crusta petrosa without. Chcnu'cally it shows the followiu"- compo- sition :
Carbonate of lime 7-97
Phosphate of lime ^^'7-54
Phosphate of magnesia 2.49
Fluoride of lime a trace
ANIMAL DENTISTRY. 21
Fats 58
Cartilage 20.42
Soluble salts i.
Microscopically it reveals a homogeneous substance per- forated throughout with small canals (the dentinal tubules) which anastomose freely with each other and extend out- ward from the pulp cavity to the surface where they termi- nate in large lacunae (the spaces of Czermak), which in turn communicate with the canaliculi of the crusta petrosa at the fang, and cuticle of the enamel at the crown. The tubules are from four to five microns in diameter at the pulp cavity, and one to t\\o microns at the surface of the dentine.
ENAMEL.
The enamel is the hardest of the dental tissues contain- ing more than 96 per cent of inorganic matter. It is ar- ranged upon the dentine in the form of a thin cap over the crown and extending beyond the alveolar margin over a part of the fang. In the herbivorous animals it is deeply
Fig. 3. Enamel (Magnified).
Fig. 4.
The Enamel Organ Dissected from
the First Molar of a Small
Ruminant.
folded into the table to form the well known depression characteristic of these teeth, the infundibulum. In the virgin tooth it covers the entire table surface, but soon wears ofT at that point from the mastication of food, leaving only its edges projecting at the grinding surface. In the incisor teeth it is the outer covering of both the lal)ial and lingual surfaces, throughout the life of the animal, but in the molars
22 ANLMAL DICXTISTRY.
it soon hc'conics lliicl<l_\- encrusted witli crnsta pctrosa on l)otli the liuccal and lingual surfaces. The molar teeth have no outer enamel co\'erin^" after they ha\-e been in wear for a short time. The enamel surrounding^ the infundibula of the incisors is arranged in the form of an oblong or elliptical ring at the table surface, ^^■hilc that of the molars is folded into a very irregular boundary. The external enamel con- sists of an undulated i)late following the course of the longi- tudinal ridges and groo\-es of the molar teeth. At the table end of the longitudinal ridges it terminates in a sharp point, constituting the "sharp teeth" of herbivora. Chemically, it consists of :
Carbonate of lime 4-37
Phosphate of lime 89.82
Fluoride of lime a trace
Phosphate of magnesia 1.34
Soluble salts 88
Organic matter 3.59
Microscopically it presents a thin cutic'e or skin called the cuticle of the enamel, which is separable when a section of enaniel is treated with hydrochloric acid, and hexagonal prisms projecting at a right angle from the surface of the dentine, giving the appearance of a mosiac floor.
CRUSTA PETROSA OR CEMENT.
The crusta petrosa is the softest of the three hard bodies composing the teeth. It is an external osseous incrustation of the fang by which the tooth is cemented to the alveolar cavity. Tn the \-irgin footh it is but a thin layer, but as the tooth ages it becomes thick from the deposition of osseous tissue. Crusta peti'osa covers the entire outer surfaces of the mature molars, the fangs of the incisors, the grooves in the crowns of the incisors of old animals and parllv fills the
ANIMAL DENTISTRY
23
iiifiindiljula. In animals having siniple teeth it is limited to the fangs. Chemically, it is composed of:
Carbonate of lime '].22
Phosphate of lime 48.73
Fluoride of lime a trace
Phosphate of magnesia 99
Soluble salts 82
Cartilage 4i-3i
Fats 93
Microscopically it presents the typical characteristics of
Fig. s. Dentine and Crusta Petrosa as Ar- ranged at the Fang (Magnified).
1. Crusta petrosa.
2. Spaces of Czermak.
3. Dentine.
Fig. 6. Natural Cavities of a Molar.
A. Pulp cavity.
B. Infundibulum.
the compact tissue of bone, the canaliculi of which communi- cate with those of the dentine. It is intimately associated with the alveolo-dental periosteum, which membrane is con- cerned in its formation.
24
ANLMAL IMvNTISTRV
THE PULP.
The pulp is a piiltaceons sul).stance molded to tlie sliape of the pnlp cavity, consisting of loosely arranged connective tissue, blood vessels, nerves and a limiting membrane (odontogenic membrane) which sends processes through- out the entire length and course of the dentinal tubules, and communicates with the alveolo-dental periosteum at the
''<&/,"','M^
Fu;. 7. Arrangement of t!ie Dental Tissues in an Incisor.
1. Internal enamel surrounding the infundibulum.
2. Pulp.
3. Dentine.
4. External enamel.
apical foramen. The pulp itself acts as a support for the blood vessels and nerves while the odontogenic membrane is concerned in tooth construction. In the teeth of herbivora it is constantly depositing dentinal substance in the tubules ])eneath the table surface to destroy the sensibility of the wearing dentine.
ALVEOLO-DENTAL PERIOSTEUM.
The alveolo-dental periosteum is a dense, tough mem- brane consisting chiefly of white fibrous tissue and osteo- blasts. It covers the entire fang, communicates with the limiting membrane of the pulp at the apical foramen, and in- termingles intimately with the gun^s at the neck of the
ANIMAL DENTISTRY. 25
tooth. Its fibers are continuous with the stroma of the crusta petrosa and that of the alveolar wall, forming a firm connecting medium betw^een the two. In the virgin tooth it has all the characteristics of a membrane, but it soon loses this feature and becomes confused with the crusta petrosa, which tissue it develops.
THE GUMS.
The gums, or gingivae, may be considered in the sense of a hypertrophy, either of the buccal mucous membrane or of the alveolo-dental periosteum, to both of which they are intimately connected. They consist of dense fibrous tissue, the fibers of which intermingle with the alveolo-dental peri- osteum and crusta petrosa, with the purpose of hermetically sealing the alveolar cavities from external influences.
BLOOD VESSELS.
The blood supply of the teeth is derived from the su- perior and inferior dental arteries, branches of the external carotid. The superior dental is given ofif the internal maxil- lary, passes into the superior dental foramen of the maxi!- lary hiatus, through the superior dental canal as far as the infra-orbita! foramen, along the roots of the third, second and first molars, and then through the premaxilla to the ca- nines and incisors. Along the course of the dental arcades it gives off branches, for each tooth, which pass into the pulp cavity through the apical foramina. The inferior den- tal artery has the same general distribution via the inferior dental canal. In addition to this principal blood supply teeth receive nourishment from surrounding blood vessels by way of the alveolo-dental periosteum to the extent of pre- serving the integrity of the tooth should its principal supply be interrupted.
26
AN'IMAL I)1-:\T1STRV
THE NERVES.
The nerves arc sensory aiul tactile, and are derived from the snperior and tlie inferior maxillary 1)ranches of the tri-
Fu;. g. Lncisor and Canine Teeth of a Mature Horse.
28
ANIMAL DENTISTRY.
facial. They have the same g-eneral distribution as the ar- teries, the courses of whicli they follow into the pulp cavity.
jiMii!l!ii!;i|[|tj|||||jj||[jii|;ilj,j|lffllpiii'Ji
Fk;. 10. Incisor Teeth of a Mature Horse. Anterior View.
PERMANENT INCISOR TEETH OF A HORSE.
The incisor tooth of a horse presents the form of a curved pyramid with the q-reatcr curvature forward, the base out- ward and the apex implanted deeply into the alveolar cavity
ANIMAL DENTISTRY
29
of the same shape. The base of the pyramid, which repre- sents the crown, is elHptical, and measuring toward the apex it becomes first oblong, then triangular, then rounded and finally biangular in the antero-posterior direction. At the table it presents the external enamel dentine, internal enamel, and infundibulum. * Tlie labial and lingual surfaces
Fig. II. Fig. 12.
Canine Teeth of a Horse, Buccal Sur- C-anine Teeth of a Horse, Lingual
face.
Surfac
Fig. 13. Longitudinal Sections Through Incisor Teeth.
are covered with enamel which in youth is uninterrupted with encrustations of either tartar or crusta petrosa, and is of a bluish-white color. At the apex it presents a wide ope.n-
30
ANIMAL DENTISTRY
iyg — the apical foramen — for the entrance- of l^lood vessels and nerves.
In sitn they are arranged in perfect juxtaposition in the form of a symmetrical curve with the convexity forward, and their contact with the opposing arcade is at an obtuse angle. Xear the gingival margin they are separated by processes of the gums. (See Fig. lo.)
The function of the incisor teeth is that of detaching food that has been gathered by the lips, and to serve as weapons of defense. Thev are not concerned in mastication. For changes in the teeth, see Chapter TTT.
THE CANINE TEETH OF THE HORSE.
The canine teeth exist only in males and occur only as permanent teeth. They occur occasionally as rudimentary structures in the mare, but never develop the typical canine characteristics. They represent a curved tube about one centimeter in diameter, and flattened at one end — the crown. The crown is flat and presents internally two shallow per- pendicular grooves divided by a rounded ridge. The fang is cylindrical and the apical foramen round and large.
The canines, so far as digestion is concerned, are use- less members which the horse could well do without. They are prol)al)ly intended as weapons of defense, and may serve to assist in passing coarse filjrous food from the incisors to the molars.
THE MOLARS.
The superior molars rcsemlfle an elongated square block tapering slightly toward one extremity. They present for description four surfaces, the table and apex. The external or buccal surface presents three prominent longitudinal ridges separated by two grooves, all of which traverse the entire length of the tooth, and terminate at the table in a
ANIMAL DENTISTRY.
31
sharp point. The anterior and posterior surfaces are iiat and smooth and come in contact with contiguous surfaces at the crown only. The internal surface is quite smooth and some- what convex from before backward. The table presents the external crusta petrosa, the external enamel, the den- tine, uhe internal enamel, and the internal crusta petrosa. The edges of the enamel are arranged in the form of the letter "B." (See Figs. i6, 17.) In the center of the internal
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Fig. 14. A Superior l\Iolar, Buccal Surface.
Fig. 15.
.■\ Superior Molar, Lingual Surface,
with Measurement.
crusta petrosa is a small black spot marking the only open- ings of the infundibula, which are two in number on all the superior molar teeth. The apex presents three to four roots, each having a round opening — the apical foramen. The first molar is triangular in shape, has a sharp anterior face and presents but three roots at the apex. The sixth is also somewhat triangular with its acutest angle posteriorly, and like the first, has but tliree roots.
32
AXI.MAl. DK.v'riSTRV
The I'lrst superior molar a\era<4es 48 milliiiietcrs 1<mi<^. the second 55 milHineters, the third yi^ millimeters, the fourth 68 millimeters, the hfth 65 millimeters, and the sixtii 60 to 63 millimeters.
The inferior molars are somewhat longer and much more flattened than the superior ones. In volume, tooth for tooth, the superior ones greatly exceed them. Their surfaces are smoother, their borders less distinct, and the longitudinal ridges less j^romincnt. The longitu(hnal ridges of the
WW SZ
Z5 M.M.
Fig. 16.
Tabic Surface of a Supcrifir Alolar,
witli Measurement.
Fig. 17
Arrangement of tlic Dental Tissues
on tlie Talile of a .Superior
Alolar.
I, 2. Infundibula.
3. Crusta petrosa.
4. l^entine.
5. Enamel.
internal or lingual surface are three in number and termi- nate at the tables in sharp enamel points similar to the external ones of the superior molars. The tables present the same dental substances as the superior, but the enamel is arranged in the form of an irregular figure, and not in the shape of the letter "B," as on the superior tables. The enamel is but a single organ and is not divided into internal and external enamel, as in the incisors and superior molars. This arrangement leaves the inferior molars without per- fectl}' inclosed infundibula and allows all the crusta petrosa
ANIMAL DENTISTRY.
33
to communicate freely. This arrangement of the enamel org-an is due to the fact that its infolds are lateral and not superior. That is, the enamel does not dip deeply into the table end, but folds inwards into great ruffles along each side. They each have two roots, each of which is pierced at the apex with the foramen for the entrance of the vessels and nerves.
Fig. i8.
Longitudinal Section
Through a Molar.
1. I. Infundibuluni.
2. Dentine.
3. Crusta petrosa and enamel.
4. Internal enamel.
Fig. 19.
An Inferior Molar,
Buccal Surface.
Fig. 20. An Inferior Molar, Lin- gual Surface, with Measurement.
The superior arcades are prominently convex on the external or buccal surface, and concave on the internal or lingual surface. The width of the arcade is. uniform through- out the entire length, with the exception of the extremities which taper to a narrow border anteriorly and a blunted one
34
ANLMi\L J)Jv\TISTRV
posteriorly, 'llic width between the arcades is 83 milli- meters at the sixth molars, 75 millimeters at the fourth, and 57 millimeters at the first. They are from 18 to 20 centi- meters lont^: and average 25 to 28 millimeters wide.
The inferior arcades are more on a straight line than the superior ones. They are but slightly curved outward at the fourth and fifth molars, while at the second and third they may even present a slight inward curvature. Like the su- perior, they have a uniform width with the exception of the pointed extremities. The width between the arcades is 75 millimeters at the sixth molars, 60 millimeters at the fourth and about 50 millimeters at the first. They are from 18 to 20 centimeters long and average 17 to 20 millimeters wide.
;7 N M.
Fig. 20.\. Table Surface of an Inferior Molar, with Measurement.
In situ the molars present four arcades — right and left superior and right and left inferior — each containing six teeth, juxtaposited so closely as to give the impression of being a single body. The juxtaposition of the molars is one of the important features of tlie dental mechanism of her- bivorous animals. This feature adds materiall}'- to the for- mation of a perfect, as well as a stable, grinding apparatus.
Each arcade is from t8 to 20 centimeters in length.
THE PERMANENT INCISORS OF RUMINANTS.
Ruminants have but one incisor arcade — the inferior — the superior l>eing replaced by a dense pad of connective tissue. The incisors are eight in number, identified, count-
Fig. 21.
Fig. 22.
A Superior Molar Arcade of a Horse, Inferior Molar Arcade of a Horse, with Measurement. wifJi Measurement.
35
36
ANIMAL DEXTISTKV
\nv; from the median line outward, as : centrals, laterals, inter- mediates, and comers. They resemble a scoop or shovel with a tapering handle, are not juxtaposed and are always loose. The fangs are imbedded into shallow alveolar cavaties and the long necks are firmly attached to the gums. They are very white in color. The labial surface is convex and the lingual one concave to fit the dental pad on the premaxilla. They diminish in size from the centrals outward, the cor- ners being (juite small.
Fig. 23. Incisor Denture of the Ox.
THE PERMANENT MOLARS OF RUMINANTS.
The superior molars of the large ruminants resemble those of the horse. They are arranged in two arcades of six molars each as in solipeds. The tables present the enamel, internal and external, the crusta petrosa, dentine and the infundibu'a. In the three posterior molars the enamel is arranged in the shape of the letter "B," as in the horse,
ANIMAL DENTISTRY.
37
while the three anterior ones present more the shape of a "U" turned bottom against the tongue. The first three molars have but one infundibulum, while the last three have two. The longitudinal ridges are prominent features of the buccal surface and terminate at the table in sharp points.
A
Fig. 24. Incisor Teeth of the Ox.
A. Lingual surface of lateral incisor.
B. Labial surface of central incisor.
C. Lingual surface of corner incisor.
D. Labial surface of intermediate incisor.
The length of the posterior molars is about 8J2 centimeters, and that of the anterior about 5V2 centimeters. Each tooth presents three roots, two of which project externally and one internally.
In situ they consist of a continuous arcade, narrow an- teriorly and becoming gradually wider toward the posterior
38
ANIMAL DENTISTRY
Fig. 26.
Inferior ^lolar of an Ox
(Labial Surface).
Fig. 25. A Superior Molar Ar- cade of an Ox.
Fic. 27.
Inferior Molar of an Ox
(Linp;ual Surface).
Animal dentistry. ^^
extremity. They cannot be said to be as perfectly juxta- posited as in the horse, as the internal surface of the arcades has deep depressions at the interdentia. The arcade will average 12 centimeters long and from 15 to 22 millimeters wide.
The inferior molars are very narrow and closely juxta- posited, as in the inferiors of the horse, but in shape and arrangement of the enamel each tooth differs from the oth- ers. The first is triangular in shape and contains but a single ring of enamel. The second and third are rectangular and their enamel is arranged into the form of an irregular figure havinp- five to six indentations. The fourth and fifth con-
Fu;. 28. Tabic of a Superior Molar of the Ox.
sist of two lobes, each having a central enamel ring and infundibulum, while the sixth has three lobes w-ith central enamel infundibula on the two anterior lobes. The arcades measure from 11 to 15 millimeters wide. The first three are from 52 to 54 millimeters long- and the posterior three meas- ure from 88 to 93 millimeters in length.
TEETH OF THE DOG.
The dog has in ail forty-two teeth — six incisors, two canines and six molars in the superior jaw and six incisors, two canines and seven molars in the inferior jaw. All of the teeth of the dog are simple teeth, i. e., they are covered with enamel on the table through life. The incisors are small as compared with the other teeth, and they do not contact each other until the dog is more than a year old.
40
AN'l.MAL I)1<:XTIS'1M<Y.
^ :
^
ANIMAL DENTISTRY.
41
The canines are the prominent features of the dog's den- ture. They are large, white members having deep implan- tations and elongated conical crowns curved backwards. which pass each other in a manner to grasp and hold firmly
.r-
I I
I'TG. 30.
Inferior Denture of a Dog. (Cornevin et Lesbre.)
any object caught between them. The molar denture is very irregular, as is also each individual tooth. The first inferior molar of dogs is properly classified as a temporary tooth that persists in the mature animal, although it is fre- quently referred to as a permanent tooth having no tern-
42
ANIMAL DEXTISTRV
porary predecessor. 'J'hc first and second inferior molars have small conical crowns, slightly ctit out internally and
Fig. 31. Superior Denture of an Aged Dog. (Cornevin ct Lcshre.)
but a single root. The third and fourth present on the crown one large cone anteriorly and two smaller ones posteriorly; and each fang has two roots. The fifth has two small an-
ANIMATv DENTISTRY. 43
terior cones, three small posterior ones on the crown, and three roots. The sixth inferior has two roots projecting backwards and presents a large crown with a number of conical projections and a deep infundibulum. The seventh is small but has three projections on the table and two roots.
The superior molars are six in number and will answer the same general description as the inferior ones, located behind the first, but their crowns are wider and more beveled from within outward.
CHAPTER II.
EVOLUTION OF THE TEETH.
The teeth arc not a part of the skeleton and never, like other juxtapositcd hard tissues, unite to each other or to the bones that surround them. They originate from the mucous membranes of the mouth and develop independently of the bones. They are appendages of the buccal mucosa precisely as horn, hair and hoof are appendages of the skin.
The evolution (growth) of the teeth and their subse- quent retrogression (wear) occurs in such distinct succes- sive stages from embryo to old age that the age of animals can be accurately determined at any period of life. The stages of evolution and the stages of retrogression, however, vary with each species — the horse, the dog, the ox and the cat each showing individual characteristics. The stages of evolution are distinct in all species, while those of retro- gression are onb/ apparent in the horse, the ox, the sheep and the pig. The dog, the cat and man show no visible distinct stages of wear, owing to the different anatomical construction of the teeth.
Dental evolution naturally divides itself into three periods :
I St. The embryonic evolution.
2nd. Evolution of the temporary teeth.
3rd. Evolution of the permanent teeth.
EMBRYONIC EVOLUTION.
In the embryo of the domestic mammal tooth formation begins at the seventh week of foetal life. The dental ap-
44
ANIMAL DENTISTRY,
45
paratus at that time is represented by a whitened ridge of mucous membrane extending around the maxillary margin. This ridge (gingival cushion) is the matrix from which the teeth develop. At the earliest period it consists chiefly of two layers of epithelial cells and basement membrane of connective tissue. The outer layer consists of loosely ar- ranged cells while the deep one is dense and lies in close relation to the jaw, being only divided from the latter by the thin connective tissue of the mucous membrane.
1- Z- 3
4 5-
»>-^y'T
'^
'-^^^^^^^wtm->f
(Cornevin et Lesbre.)
Fig. ,72. Section Through a Part of a Dental Follicle.
1. Crusta petrosa.
2. External enamel.
3. 4, 5. Internal enamel.
6. Dentine.
7. Odontoblasts.
8. Pulp.
The following changes which the gingival cushion under- goes constitute the process of tooth development: The first step in the direction of tooth formation is observed at about
46
ANIMAL DENTISTRY.
I'ic. 33- Perpendicular Section Tlirousli a Dental Papilla.
1. Epithelium of tlie gingival cushion.
2. Stalk for the future permanent tooth.
3. First dentinal formation.
4. The jaw bone.
5. The alveolar periosteum.
The crescent-shaped ring rei)resents the enamel organ.
ANIMAL DENTISTRY. 47
the eighth week of foetal life, when the deep celhilar layer of the gingival cushion begins to grow inward into the sub- stance of the jaw, which at that period is represented by cartilage. The cartilaginous jaw at the same time grows upward around the descending epithelium until it presents a deep trough-like groove which the gingival cushion now occupies. The outer or loose layer remains without and persists through life as the gums, while the deep or dense layer pushes deeper and deeper into the jaw, becomes better organized to form the common enamel germ. The common enamel germ which is no more than the deep epithelial layer of the gingival cushion, is continued evenly through the whole trough, but at the ninth or tenth week of foetal life it becomes tumefied at regular intervals to form the first real representatives of the future teeth (the enamel germs). As the enamel germs devlop into larger bodies the sub- stance between them gradually disappears, leaving only a sniall mound for each temporary tooth. Simultaneously the basement layer of the gingival cushion tumefies beneath this mound and forces it upwards into a permanent body (the dental papilla). The dental papilla consists, therefore, of a body of connective tissue, capped with epithelium.
At the third month of foetal life the epithelial layer un- dergoes petrification to form the future enamel organ. The connective tissue calcifies to form dentinal substance, while the base of the papilla remains unchanged to form the pulp. While this process is going on the papilla is gradually as- suming the shape and form of a tooth crown, the first di- vision of a tooth to form. The neck and fang occur by the deposition of dentinal substance at the base of the papilla. The aperture into the pulp cavity is at first a wide one, but soon becomes narrow and takes its place at the end of the fang as an apical foramen, the opening through which the vessels and nerves enter the tooth. In the case of the molar
48 ANLMAL DENTISTRY.
teeth several openings are formed, one for each root. The cement is ossified connective tissue, and is the last of the three hard tissues to form. It develops Ijetween the perios- teum of the tooth cavity and the dental substance and is influenced in its evolution through life by both these ele- ments.
During these evolutionary changes each tooth is en- closed within a separate sac ordinarily designated as a den- tal follicle. During the same period the jaw is undergoing great changes. It is growing upward to further enclose the follicles within itself, and is gradually separating them one from another by the formation of bony partitions (the inter- dental cancellated tissue) until each tooth occupies a deep individual compartirxnt — the alveolar cavity — which the tooth fills completely at every stage of its evolution and ex- istence and which entirely encloses both until by sheer force of its expansion it forces its way into the mouth and takes its place at the level of the dental arcade. This event marks the beginning of the second period of dental evolu- tion.
The permanent teeth are developed much in the same manner. About the sixteenth week of foetal life a stalk or neck becomes disconnected from the common enamel germ and takes its place first on the side, and secondly, at the root of the temporary tooth. It undergoes the same steps of de- velopment, and b}' its upward growth absorbs the fang of the temporary tooth until only a mere shell remains. The permanent teeth that arc not represented by temporary predecessors are formed by the backward extension of the common enamel germ. The first permanent tooth of this class — the fourth molar — has its origin in embryo, while the others which erupt later in life may not begin to form until some time after birth. The enamel germ, therefore, is not entirelv a foetal structure, but exists until the last tooth is
ANIMAL DENTISTRY. 49
set on its way toward maturity. (Thus far dental evolution does not vary materially in the different species).
^>^
EVOLUTION OF THE TEMPORARY TEETH.
This period of dental evolution begins when the milk teeth make their first appearance on the buccal surface, and ends when they are entirely replaced by their permanent successors. In some animals the temporary teeth erupt be- fore birth. It is, however, at the time of birth or within a few days after that the first evidence of temporary dentition appears in all domestic animals. The end of the period varies with each species. In the horse the last temporary teeth disappear at four and a half years of age. Thus the period in the horse lasts from birth to four and a half years of age, in the ox from birth to four and a half years, in the sheep from birth to three and a half years, in the dog from birth to six months, and in the pig from birth to three years. In all the domestic animals except the dog the temporary incisors persist longer than the mo'ars.
THE HORSE.
The central incisors erupt before birth or, in some in- stances, within a few days after. They are large, white teeth, occupying the entire incisor arcade and contact their opposing teeth by their anterior borders only. The pos- terior border is still hidden beneath the gums and only comes to the level of the anterior l)order after three months' wear, at which time they present the typical table of an herbivorous incisor. The cup is deep and distinct, and in its whole appearance cannot be readily recognized from that of a permanent incisor. At the earliest period after eruption two influences are at w^ork for their destruction — -the perma- nent tooth is gradually encroaching upon its fang while the crown is becoming shorter and shorter under the influence
50
ANIMAL DENTISTRY.
of wear until at the age of two and a half years there remains only a loosened shell.
LATERAL INCISORS.
The lateral incisors make their appearance at from four
to six weeks, gain the level of the arcade at four months,
and are replaced by permanent incisors at three and a half
years.
CORNER INCISORS.
The corner incisors appear on the buccal surface at about
Fig. 34. Temporary Incisor Teeth of a Horse. A. B, C. Labial surface of centra!, lateral and corner. D', E, F. Lingual surface of same.
seven months, gain the level of the arcade at ten months and are shed at four and a half years.
FIRST, SECOND AND THIRD MOLARS.
These teeth api)car about the time of birth. They are large organs and occupy the whole maxillary margin behind the interdental space. At the time of eruption their tables arc covered with enamel, whicli soon wears off to expose the dentinal tissue and cement. Their fangs are g-radually lost by absorption from pressure of the growing- permanent molars beneath. The first and second are shed at two and one-half years and the third at three to three and a half, leaving the molar arcades free from temporary teeth
ANIMAL DENTISTRY.
51
CANINES.
The canine teeth are frequently referred to as being rep- resented in youth by temporary predecessors. This claim cannot be accepted as entirely correct. The needle-like ca- nines, occasionally observed in three-year-old colts, must be regarded as a freak of perverted dental evolution rather than as a part of the normal economy.
3
sr"^'
y
t^il-i I
^\
'^•^•-r.
'-^S^
;■'
A
....J
Fig. 35- Temporal"}' Incisors of the Colt.
3. Inferior incisors at birth.
4. Inferior incisors at ten weeks. 2. Inferior incisors at four months. I. Inferior incisors at seven months.
THE OX.
Central Incisors* — Erupt at birth, become prominent at one month and shed at one and a half years of age.
Lateral Incisors — Erupt at birth, gain the level of the arcade at one month and shed at two and a half years.
*Lower jaw only.
52
ANIMAL DENTISTRY.
Intermediate Incisors — The intermediates erupt at two weeks, gain the level of the arcade at two months and shed at three and a half years.
Corner Incisors — The corners erupt at three weeks to one month, gain the level of the arcade at three months and shed at four and a half years.
First, Second and Third Molars — As in the horse, these
Fig. 36. Tompornry Molar Tectli of a Horse.
molars erupt at birth. 1"lic hrst is cast off at one and a half years, the second at two and a half years and the third at three and a half years.
THE PIG. Central Incisors — F.rupt at three to four months and 'are shed at three years.
I'
Fic. 37.
Superior and Inferior [Molar Arcades of the Horse under the Age of lo
^Months. A, B. Opening fur the 4th Molar.
53
54 ANIMAL DKN'riSTKY.
Lateral Incisors — l'".ni])t at four niontlis and arc shed at tlircc }-cars.
Corner Incisors — l^-upt at birth and are shed at six months.
Canines — Erupt at l)irth and are shed at one year (The temporary canines of the pi": are common to both sexes, l)ut are more prominent in the n.iale).
First Molar — Tlic tirst molar of the hoi;- has no temporary predecessor.
Second and Third Molars — Irrupt at birth and are shed at two \-ears.
Fourth Molar — Erupts at six months and is sh.ed at two years.
THE DOG.
Central Incisors — I'^rui)t at four weeks and are shed at four montlis.
Lateral Incisors — Erupt at four weeks and are shed at for.r months.
Corner Incisors — Erupt at four weeks and are shed at five months.
( The incisor teeth do not come in contact witli one an- other until the ag-e of lifteen months).
Canines — Eru]")t at four weeks and are shed at six months. The}' are commcin to botli sexes.
First Molar — There is no temporary first molar in the dog.
Second, third and fourth molars erupt at five to six weeks and shed at six nu^nths. The fourth ma\- be delayed until six and one-half to seven months.
At the age of se\'en months the tem])orar\- denture (jf the dog is entirely re])laced by its ])ermanent successor.
Fig. 38. Superior Denture of a 2- Year-old Hog. (Cornevin et Lesbre.)
55
56
ANIMAL DENTISTRY.
THE SHEEP.
Central Incisors — Erupt (lurino- ilic I'lrst month after birth and arc shed at fifteen to eit^htecn montlis.
Lateral Incisors — Erupt (hirino- the first month, a few
u
u.
H
(hiys after the eentrals. and are shed at twenty to twenty-four months.
ANIMAL DENTISTRY.
57
Intermediate Incisors — Erupt during the second to the fourth week, a few days after the laterals, and are shed at twenty-four to thirty-three months.
Corner Incisors — Erupt about the fifth week after birth and are shed at four to four and a half years.
_i
u
t H
Q
H
First Molar — Erupts during the first month and is shed at one and a half years.
Second Molar — Erupts with the first molar and is shed at two and a half years.
Third Molar — Erupts with the first and second and is shed at three and a half years.
5g
ANIMAL DENTISTRY.
EVOLUTION OF THE PERMANENT TEETH.
The clc\cl()i)Hient of the pennaiient teetli of animals be- s^ins diirins;' the foetal life. Dnring- this period they are rep- resented only 1)}' a stalk or neck extending- from the enamel o-erm of their temporary analogues, located first on the side
Fig. 41. Mnhir Denture at Birth. A. Infcri^■^ 4tli irolar. P>. Superior 4th molar.
and afterwards at the root. At the time of birth the germ of the central incisors and the first, second and third molars are alreadx- ])rominently formed at the root of the temporary teeth, and the fourth molar — the hrst ]H'rn\'inent tootli to develop — consists of a roimded hy];ertrophy of the common enamel germ located just posterior to the third temporary molar. (Fig". 41 A. B.) The temporary molars occupy the
ANIMAL DENTISTRY.
59
entire jaw behind the interdental space until the age of ten months. In the herbivora the fourth molar forces its way to the surface in the same relative position that the sixth molar occupies in the mature animal. The jaw is therefore always filled with molars, the fourth, fifth and sixth forcing their way behind their successive neighbors.
Fig. 42. Molars of a Horse Approaching 5 to 6 Months.
During the first year the only prominent visible event in the evolution of the permanent teeth is the eruption of the fourth molar. The invisible events occurring in the germs located at the roots of the temporary are, however, of no less importance. They are developing rapidly into teeth of normal shape and size, gradually transgressing upon and shortening by absorption the fangs of the temporary teeth,
60
ANIMAL DENTISTRY
molars and incisors alike. The first, second and third mo- lars make the most rapid prog-ress during the first year, pre- paratory to their subse(|uent eruption one to two years hence. The incisors are less developed, the centrals are somewhat prominent preparatory to their eruption two years hence, but the lateral, intermediates — in ruminants — and the corners are merely represented by an undeveloped tooth o-erm. Such is the condition of development of the denture
Fig. 43. Molars of a Horse Approaching 10 Months.
of an herbivorous animal at the age of one year from whence the evolution proper begins. (See Fig. 43.)
THE HORSE.
Central Incisor — Begins to develop in embryo, assumes the shape of a tooth during the first year, reaches the level of the alveolar border at two years, expels the temporary shell at two and a half years and takes its place at the nor- mal level of the arcade at three years of age.
Lateral Incisor — Begins to develop during the first six
ANIMAL DENTISTRY.
61
months, assumes the shape of a tooth during the second year, reaches the alveolar border at three years, expels the tem- porary shell at three and a half years and takes its place at the level of the arcade at four years.
Corner Incisor — Is very rudimentary at one year, begins to develop at two years, assumes the shape of a tooth at three years, reaches the alveolar border at four years, expels the temporary shell at four and a half years and takes its
Fig. 44. Molars of a Horse Approaching the Age of 2 Years.
place at the level of the arcade at five to five and a half years.
Canines — Erupt at the age of four to four and a half years, but may be delayed in their outward course by the hardness of the jaw. Occasionally their growth, especially of the superiors, is arrested beneath the gums until the sev- enth year of the animal's life. The inferior canines always erupt slightly in advance of the superior.
First, second and third molars begin to develop in the foetal life of the colt. At birth they are small, rudimentary
52 ANIMAL DENTISTRY.
objects, but become tooth-like very rapidly during the first twelve months, at which time they are all morphologically and anatomically similar. During the ensuing year their growth is about equal, each growing to the level of the alveolar border. At two and a half years the first and sec- ond expel the temporary shell and become concerned ac- tively in mastication at about three years of age. The third at two and a half years seems to be mysteriously retarded in its growth as if 1)locked in its outward course by the unyielding fourth molar, which has now been in active serv- ice for the past one and a half years. (See osteoma of the maxilla.) At tw^o to two and a half years old the develop- ment of the third molar is at a standstill, until the age of three to three and a half years, when it finally expels its shell and then grows tardily outward to the level of the arcade. It is not unusual to find this molar below the level of its neighbors at four and even five years old.
Fourth Molar — The fourth molar is the most interesting of the horse's teeth. Its development begins during the last months of foetal life. At birth it consists of a small, rounded mass of rudimentary tooth substance, developing from a backward projection of the common enamel germ, and lo- cated in close contiguity to the fang of the third temporary molar. During the first ten months after birth it grows very rapidly into a shapely tooth and points to the surface at about the end of the tenth month. At twelve months it is already actively concerned in mastication, although it is morphologically defective, assuming its maximum stability only during the next two years.
Fifth Molar — The common enamel germ at the age of six months, after having formed the fourth molar projects backward to form the fifth molar. At one year old the for- mation is almost perfect, at one and a half years it erupts.
Animal dentistry
63
and at two and a half years it is found on a level with the fourth.
Sixth Molar — The sixth molar is the last of the molars to erupt, which event occurs at any time between four and five years of age. Its formation, like that of the other per- manent molars, having no temporary predecessors, depends upon the backward growth of the common enamel germ. The first evidence of this molar is seen at two to two and
Fig. 45. Molar Denture of the Ox at 10 Months.
a half years in the form of a rounded mass similar to that of the fourth and fifth. At this age the jaw is more un- yielding and its eruption may be delayed by the resistance offered therefrom.
RUMINANTS.
Central Incisor — Reaches the alveolar margin at one year and erupts at one and a half years.
64 ANIMAL DENTISTRY.
Lateral Incisor — Reaches the alveolar margin at two years and erupts at two and a half years.
Intermediate Incisor — Reaches the alveolar margin at three years and erupts at three and a half years.
Corner Incisor — Reaches the alveolar margin at four years and erupts at four and a half to five years.
First Molar — Reaches the alveolar margin at one year, expels the temporary shell at one and a half years and be- comes concerned in mastication soon after.
Second Molar — Reaches the alveolar margin at two years, expels the temporary shell at two and a half years and gains the level of the first molar a month or two later.
Third Molar — Reaches the level of the alveolar margin at three years, expels the temporary shell at three and a half years and gains the table level at about four years.
Fourth Molar — Erupts at nine months and becomes con- cerned in mastication at ten to eleven months.
Fifth Molar — Erupts at two and a half years and gains the table level several months later.
Sixth Molar — Erupts between the ages of four and five vears. As in the horse, its outward progress is hindered by the hardness of the jaws at that age.
CARNIVORA.
Central Incisor — Erupts at three to four months.
Lateral Incisor — Erupts at three to four months.
Corner Incisor — Erupts at five to live and a half months. Canines — Erupt at five to six months, common to both sexes.
First Molar — Erupts at three months, and has no tem- ])orary predecessor.
Second Molar — Eruj^ts at five to six months.
Third Molar — Erupts at five to six months.
Fourth Molar — Erupts at five to six months.
Fifth Molar — Erupts at four to five months.
ANIMAL DENTISTRY. 65-
Sixth Molar — Erupts at five to six months. Seventh Molar — Erupts at seven months.
OMNIVORA.
Central Incisor — Erupts at two and a half years.
Lateral Incisor — Erupts at three years.
Corner Incisor — Erupts at six months.
Canine — Erupts at one year and is common to both sexes.
First Molar — Erupts at birth and is a permanent tooth.
Second Molar — Erupts at two years.
Third Molar — Erupts at two to two and a half years
Fourth Molar — Erupts at six months.
Fifth Molar — Erupts at one year.
Sixth Molar — Erupts at one and a half to two years.
Seventh Molar — Erupts at three years.
NUMBER OF PERMANENT TEETH.
Incisors. Canines. Molars. Total.
Horse 12 4 24 40
Mare 12 o 24 36
Ox 8 o 24 T^2
Pig 12 4 28 44
Dog 12 4 26 42
Cat 12 4 14 30
Rabbit 6 o 22 28
NUMBER OF TEMPORARY TEETH.
Incisors. Canines. Molars. Total.
Horse 12 o 12 24
Ox 8 o 12 20
Pig 12 4 12 28
Dog 12 4 24 30
Cat 12 4 10 26
Rabbit 8 o 24 32
66 ANIMAL DP:NTIS'rRV.
FORMULAE OF THE TEMPORARY AND PERMA- NENT DENTURES OF DOMESTIC ANIMALS.
|
HORSE. |
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|
Temporary, |
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|
3-- |
•••3 0 |
, .0 |
3--- |
0 • • • 0 |
||
|
Incisors :■ |
— |
Canines : — |
Molars: |
— |
||
|
3--- |
•••3 0 Permanent. |
. .0 |
-> 0 • • • |
• ■ • 0 |
||
|
3--- |
...3 I.... |
. . I |
6... |
...G |
||
|
Incisors :• |
— |
Canines : — |
Molars : |
— |
||
|
• |
3--- |
...3 I.... OX. Temporary. |
. . I |
6... |
...6 |
|
|
4... |
...4 0.... |
. .0 |
3--- |
|||
|
Incisors : |
— |
Canines : — |
Molars: |
— |
||
|
0. . . |
. . .0 0. . . . Permanent. |
. .0 |
3--- |
•••3 |
||
|
4.. . |
. ..4 0.. . . |
. .0 |
6... |
...6 |
||
|
Incisors : |
— |
Canines : — |
?\Iolars : |
— |
||
|
0. . . |
. . .0 0. . . . DOG. Temporary. |
. .0 |
6... |
...6 |
||
|
3-- |
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. . I |
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||
|
Incisors : |
:— |
Canines : — |
Molars : |
: — |
||
|
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...3 1.... |
. . I |
3--- |
•••3 |
ANIMAL DENTISTRY. 67
|
Permanent. |
||||||
|
3"- |
•••3 I |
. . I |
6... |
...6 |
||
|
Incisors : |
— |
Canines : — |
Molars : |
— |
||
|
3--- |
•••3 I CAT. Temporary. |
. . I |
7... |
...7 |
||
|
3--- |
...3 I.... |
. . I |
3-- |
•••3 |
||
|
Incisors : |
— |
Canines : — |
Molars: |
— |
||
|
3--- |
...3 I.. .. Permanent. |
. . I |
2. . . |
. . .2 |
||
|
3--- |
...3 I.... |
. . I |
4... |
...4 |
||
|
Incisors : |
— |
Canines : — |
Molars : |
— |
||
|
3--- |
...3 I.... PIG. Temporary. |
. .1 |
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•••3 |
||
|
3-.- |
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. . I |
3-.- |
•••3 |
||
|
Incisors : |
— |
Canines : — |
Molars : |
— |
||
|
3--- |
...3 I.... Permanent. |
. . I |
3--- |
•••3 |
||
|
3--- |
... 3 I . . . . |
. . I |
7... |
...7 |
||
|
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— |
Canines : — |
Molars: |
— |
||
|
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...3 I.... |
. . I |
7... |
...7 |
CHAPTER III.
RETROGRESSION OF THE TEMPORARY TEETH.
The temporary teeth attain their greatest capacity and length at the time of eruption, after which event they at once begin to retrogress under the influences of pressure ab- sorption at the root and of wear from mastication at the ta1)le extremity, until only a shell remains to be expelled into the mouth. The first event of this character (shed- ding) occurs to the first and second molars at two and a half years, and the last to the corner incisors at four and a half years, after which time the denture is entirely free from temporary teeth. The order of shedding of the tem- porary teeth in solipeds is as follows:
(i) Two and a half years, the first and second molars and the central incisors.
(2) Three to three and a half years, the third molars and the lateral incisors.
(3) Four and a half years, the corner incisors.
This order may be made to apply to all ruminants and solipeds. In the carnivora the destruction of the temporary denture is remarkably rapid, as at the age of seven months no temporary teeth remain.
RETROGRESSION OF THE PERMANENT TEETH.
The retrogression of the permanent teeth is the most im- portant feature of dentistry of animals. It includes the wear and eventual destruction of the teeth. The teeth of solipeds and ruminants attain their maximum length and volume the second year after eruption. During the first year they
ANIMAL DENTISTRY.
69
g-ain in length and volume by expansion of the fang, but lose slightly by wear. The growth, however, exceeds the wear during the first year. During the second year the wear and growth are about equal. The greatest length of the teeth is therefore attained during the second twelve months of their existence within the mouth. During the succeed-
FlG. 46. The Destruction of a Temporary Tooth by the Permanent.
A. Temporary shell.
B. Permanent tooth.
ing years the teeth do not grow,- but instead undergo a gradual and regular process of destruction under two in- fluences :
(i) Wear from mastication, which slowly shortens th^ length of the tooth.
(2) Receding of the alveolar margin, which gradually shortens the depth of the alveolar cavity.
In the herbivorous animals both of these influences are
70 ANIMAL DENTISTRY.
at work to a remarkable degree, while in the carnivora and omnivora only the second influence is concerned in the de- structive process. In the herbivora the length of the teeth varies from the long-, three or four-inch tooth of the young subject, to the short, half-inch tooth of extreme old age (from the wear of mastication), while the alveolar cavity varies from the exceedingly deep excavation of youth to the shallow, flattened cavity of old age. The diminution in the depth of the alveolar cavity occurs in all the animals, and is solely responsible for senile self-extraction in the animals having simple teeth. In the animals having simple teeth the table retains its enamel covering through life, and the tooth does not diminish in length from wear.
I. Wear from mastication. — When the teeth of the ru- minant and soliped first enter into the process of mastica- tion they are covered with enamel over the grinding sur- face. The enamel in addition dips deeply into the body of the tooth around the infundibula. As soon as wear begins the surface enamel of the table at once wears off, exposing the dentine and leaving only the edges of the enamel organ on the grinding surface. The dentine, ordinarily a sensitive substance, becomes hard and insensitive along the table surface, by the deposit of dentinal cells within its tubules. The area of insensitiveness extends throughout the entire table and to the depth of one to two millimeters during the first year of wear, but in the subsequent three or four years it descends to the depth of one centimeter or even more. At the age of ten to twelve years it has descended to more than one-third of the entire tooth in the molars, and to the depth of about two centimeters in the incisors. When the animal has passed the age of eighteen the tooth is practically a dead organ so far as the sensibility of the dentine is concerned. That the stimulus to the proliferation of dentinal cells (os- teo-dentine) is wear is demonstrated in the fact that teeth
ANIMAL DENTISTRY.
71
that do not contact opposing teeth (e. g., brachygnathism) are sensitive to the very tips.
During youth and through the prime of life the active tooth wears at the rate of about two milHmeters each year. In the asred animal the loss is slower. In the case of the
^30yrs.
Fig. 47.
An Illustration of the Change in Sliape of the Incisor Tahles as a Result of
Wear, from 6 Years to 30 Years.
visible teeth (the incisors) the wear brings to the surface of the table a constantly changing picture, by exposing to view the different consecutive parts of the tooth, from the flattened table of youth to the triangular table of old age. The most striking change in the teeth from wear occurs
72 AXLMAI. DENTISTRY.
to the incisor teeth, especially tlie inferiors, which furnish the best evidence of the a^^e after the fifth year. First, by chanq-es in the infnn(hl)n]uni and then by change in tlie shape of the table surface. The infundibuhim of the tooth is produced by the infolding of the enamel into the body of the tooth to a depth of one and a half to two and a half centimeters. The bottom of the cavity thus formed is filled with crusta petrosa, Init the outer end is empty and consti- tutes the cup. which becomes blackened by the chemical action of foods and saliva. The infundibula of the incisors are shaped like a flattened cone with the apex inward and the elliptical opening outward. When the tooth is but a virgin, the cup, made more apparent by its dark color, pre- sents an elliptical opening at the table surface, but as the crown w^ears aw^ay it becomes shorter and more rounded and disappears entirely when the crown has worn as far as the crusta petrosa that fills the bottom of the infundibula. Thereafter the infundibula are not dark but are recognized by their surrounding enamel, at first still elliptical, but final- ly becoming small circular rings located well toward the posterior border of the tal)les. Tn the study of dental wear the cup must not be mistaken for the infundibuhim, as "cup" refers only to the unfilled portion of the infun(lil)ulum. The cups of the incisor teeth disappear three years after erup- tion, and the infundibuhim about ten years to fifteen years after.
The molar teeth have two infundibula extending deeply into the fang. They are entirely filled with crusta petrosa and would entirely escape notice but for the presence of a small dark spot in the center.
In shape the tables change even more than in their infundibula. In the young tooth the table is fiattened from before backw^ard, but as the crowns wear away the other parts of the tooth come to the surface. The table becomes
ANIMAL DENTISTRY. 73
first triangular, then round and finally in extreme age flat- tened from side to side. The triangular shape makes its ap- pearance almost as soon as the cups disappear in the central and lateral incisors, while the corners maintain their ob- long shape until after the age of twelve, and even never become as distinctly triangular as the former. (See Fig. 47.)
2. Receding of the alveolar margin is more prominent in the herbivora than in the other species, although it con- stitutes a feature of dental retrogression in all animals. Through its influence the teeth lose their implantation by gradual stages until in extreme old age they are held in position only by the gums and small pits in the jaw, which retain the remaining roots.
In the incisor arcades the alveolar margin recedes much faster than the teeth wear at the table, which circumstance results in the elongation of the crowns as the animal be- comes older. In rare cases the reverse occurs and the crowns become shorter A\'ith age, but this incident results only when the teeth are defective in cpiality. The long crowns of the incisor teeth of old horses due to the re- ceding jaw, is responsible for the general impression that the teeth grow in length and that they are longer in old than in young horses.
The receding process is also responsible for the gradual change in the inclination (angle) of the incisor teeth. The angle formed by the incisor teeth at the contact point is obtuse in the young, but changes gradually into a very acute one in the aged animal. This change is the result of the great curvature in the incisor tooth, which in the young animal is implanted into a deep curved cavity. As the tooth wears the part projecting forwards becomes exposed and the increased inclination results. The incisor teeth, like all teeth of herbivora, are longest in the young animal, but
74 ANIMAL DENTISTRY.
have a longer exposed portion (crown) in the aged subject, owing to the receding of the alveolar margin.
A SUMMARY OF DENTAL EVOLUTION AND RET- ROGRESSION APPLIED TO THE DE- TERMINATION OF AGE.
The age of the horse is determined by the examination of the incisor teeth, and in certain instances tlic molars, as follows :
(i) From birth to one year by the evolution of the temporary incisors.
(2) From one year to two and a half years by the
eruption of the fourth and fifth molars and the evolution of the temporar}- incisors.
(3) From two and one-half years to five years by
the retrogression of the temporary incisors, the evolution of the canines and the evolu- tion of the sixth molar.
(4) From five and a half years to nine years by the
retrogression of the infundibula of the in- ferior incisors.
(5) From nine years to old age by:
(i) Changes in the shape of the tables of the in- ferior incisors.
(2) Changes in the anterior face of the superior
incisor arcades.
(3) Changes in the inclination of the incisor ar-
cades.
(4) Changes in the crown of the canines.
(5) Changes in the molars.
FROM BIRTH TO ONE YEAR.
The colt at birth, or within a day or two after, has four incisor teeth — the superior and inferior nippers, and three
Animal dentistry. 75
molars in each arcade, the first second, and third. The crowns of the incisors are short and contact only at the anterior margin. The infundibula are wide, elliptical and deep, and their posterior boundaries are buried within the gums. At one month the posterior edges of the infundibula are exposed and the lateral incisors are breaking through the gums. Two weeks later their crowns answer the same description as the centrals at birth. During the next eight or nine months there is no great change in the arcades ex- cept the elongation of the crowns, which resemble a cone broken off at its apex. The tenth month is marked by the
"1 \
1: \
Fig. 47a. Inferior Incisors at Birth.
eruption of the corner incisors and the fourth permanent molars.
FROM ONE TO TWO AND A HALF YEARS.
The absence of any prominent event during this period makes the determination of age rather ditTicult. The incisor teeth become large and prominent in all the features of teeth, and are not easily recognized from permanent teeth. If unassisted by the colt-appearance of the subject the mouth during the last part of this period is readily mistaken for a full mouth of permanent incisors. When any doubt ex- ists the examination of the molars will reveal the presence of but four teeth in each arcade. At the age of two to two and a half years the fifth molar will be found breaking through the gums. The incisors are white, have a some-
t(^
ANLMAL DKXTISTRV
Figs. 48 and 49.
Anterior View of llie Incisor Denture at 12 Months.
Incisors ('{"able View) at 12 Months.
ANIMAL DENTISTRY
77
Fig. 50. Incisor Denture at 15 Months (Table View).
78
ANIMAL DENTISTRY.
Fig. 51. Incisor Denture of a Colt at t8 ]\Tonths (Tabic- View").
ANIMAL DENTISTKY
79
Fig. 52. Incisor Denture at 2 Years (Table View).
80
ANIMAL DENTIS'I^KV.
what proiiiiiK'iil neck and are separated with ^unis shaped as an inverted cone. 'J'lie crowns do not contact one another throughout their entire length, as in the horse five and a half to six years old, for which the two-year-old might be mistaken. The absence of canines (in the male) will also assist in making the differentiation. The confusion is most likely to occur in the examination of a thoroughbred or trot- ter with a well developed muscular system, and the habits of an older horse from training.
FROM TWO AND A HALF TO FIVE YEARS.
The determination of age during this period is more simple and more certain than at any other period of the horse's life, owing to the three successive prominent events occurring during this period. At two and a half years the central temporary incisors are readily recognized 1)y being loose preparatory to shedding. At three years old they are cast of¥ and the permanent successors, broad and shiny, are seen protruding beneath, leaving an interrupted surface in the arcade. y\t three and a half to four years the laterals undergo the same transformation, and at four and a half to five, the corners. The five-year-old mouth is recognized by the deep, oblong infundibula of the centrals and laterals and the imdeveloped condition of the corners. The latter are bluish-white, have a short crown and do not contact their opponents. The posterior edge of the table is still Iniricd within the gums. The canines are already visible in both the jaws, but especially in the inferior, and the molar arcades are completed. At two and a half years the first and sec- ond molars cast ofT the temporary shells, at three the third molar casts off its predecessor, and at four to four and a half the sixth molar erupts, leaving at the end of this period a full mouth of permanent teeth.
ANIMAL DENTISTRY.
■?1
Fig. 53. Incisor Denture Approaching 2j^ Years (Table View).
tl
ANIMAL DENTISTRY.
Fig. 54. \ncisor Denture at 25/2 Years (Table View).
ANIMAL DENTISTRY.
83
Fig. 55- Incisor Denture at 3 Years (Table View).
84
ANIMAL DEXTISTRV.
Fig. 56. ^ncisor Denture at 3 Years (Anterior View).
ANIMAL DENTISTRY.
£5
Fig. 57. Incisor Denture at 3;/. Years (Table View).
56
AMIMAL DENTISTRY.
Fic. 58. Incisor Denture at 4 Years (Table View).
ANIMAL DENTISTRY.
87
Fig. 59. Incisor Denture at 4 Years (Anterior View).
88
ANIMAL DENTISTRY.
Fig. 6o. Incisor and Canine Dentures at 41I Years (Table View).
ANIMAL DENTISTRY. 89
FROM FIVE TO EIGHT YEARS.
The age during this period is determined by changes in the infundibula of the inferior incisors, the cups of which disappear in regular succession, beginning with the centrals. In some instances a small round spot remains for several years in the center of the infundibulum, but this event must be regarded as equivalent to the disappearance. The disap- pearance of the blackened cup is marked by the appearance of the crusta petrosa filling the bottom of the infundibulum. At six years old the central cup disappears, at seven the lateral cup. and at eight the corner one has become shallow and rounded. The cup of the corner inferior incisor is more persistent than that of the centrals and laterals, and may remain quite prominent even at the age of ten to eleven years. Its change in shape from elliptical to round is equal- ly valuable in the determination of the age at that period.
FROM NINE YEARS TO OLD AGE.
After the age of nine years the retrogressive changes continue incessantly, but without any prominent event to mark the exact age. The age of the horse is henceforth only estimated.
Nine years — The age of nine years is easily determined by the appearance of the crusta petrosa groove at the gingi- val margin of the superior corner incisor and the slight downward curvature of the gums at that point. The infun- dibula of the inferior incisors are nearer to the posterior bor- der of the taldes of the centrals, which are now quite triangular. The inferior corner incisors are still oblong, present a rounded black cup and are beginning to show the first sign of increased inclination of the incisor arcades. The anterior surfaces of the teeth are becoming yellow.
00
ANIMAL DEXTIS'I'RV
Fic. 6i. Incisor Denture Arprnaching 5 Years (Table View).
ANIMAL DENTISTRY.
91
Fig. 62. Incisor Denture at 5 Years (Table View),
92
ANIMAL DENTISTRY.
P^IG. 63.
Incisor Denture at Sl< Years (Tahlc View).
ANIMAL DENTISTRY.
93
Fig. 64. Incisor Denture at 6 Years (Table View).
94
AN I iM AL l)E X Tl STR Y
"^-•^'**aMtHili'!'ii|i;i|;i;i;!ll:i|i!lj Fjg. 65. Incisor Denture at 6 Years (Anterior View).
ANIMAL DENTISTRY.
95
Fig. 65.'\. Incisor Denture at 6 Years (Lateral View), with Dark Lines Showing In- clination
96
ANIMAL DENTISTRY
Fig. 66. Incisor Denture at 6j/' Years (Table View).
ANIMAL DENTISTRY.
97
Fig. 66a. Incisor Denture of a Mare at 6K Years (Table View) ,
98
ANIMAL DENTISTRY.
Fig. 67. Incisor Denture at 7 Years f Table View).
ANIMAL DENTISTRY.
99
Fig. 68. Incisor Denture at 7 Years, Dark Lines Showing Inclination.
100
ANIMAL DENTISTRY.
Fig. 69. Incisor Denture of a Mare at 7 Years (Table View).
ANIMAL DENTISTRY.
101
Fig. 70. Incisor Denture at 8 Years (Table View).
102
Fir,. 71. Incisor and Canine Dentures at 9 Years (Table View).
ANIMAL DENTISTRY.
103
Fig. 72. Incisor Denture at 9 Years, with Dark Lines Showing the Inclination.
104
ANIMAL DENTISTRY.
Fi.;. 73. Incisor Denture of a Mare at 9 Years (Table View).
ANIMAL DENTISTRY. 105
Ten to twelve years — The inferior centrals and laterals are more triangular, the cups of the inferior corners are disappearing entirely, the enamel around the infundibula of the centrals and laterals is changing from oblong to round, the crusta petrosa groove on the superior corners is two to three millimeters long and is appearing on the laterals and centrals, and finally the length of the crowns of the superior incisors is markedly increased. The crowns of the canines are large and are becoming rounded at the gingival margin. The inclination of the incisor arcades is now a marked feature of the mouth and is recognized by a mere glance at the lateral aspect of the arcades. (Figs. 74, 75, y6.)
Thirteen to fifteen years — The crusta petrosa groove on the superior corner incisor is nearing the middle of the crown, the tables are markedly triangular, the crowns of the superior incisors are becoming widely separated from the gums, and are l)ecoming narrow near the gingival mar- gin, the infundibula of the central and lateral inferior in- cisors are now but small circles of enamel — the enamel island — projecting above the level of the dentine and located well toward the posterior aspect of the table, and the gingi- val margin of the superior central incisors is much lower than that of the laterals. The crowns of the canines are round at the gingival margin (Fig. yy.)
Sixteen to twenty years — The inclination of the incisor arcades is so pronounced that the inferior incisors pro- ject forward almost on a straight line with the jaw, the superior corner incisor is grooved almost to the contact border, the crusta petrosa grooves extend well downward over the crowns of all the incisors, the crown of the cen- trals is shorter than that of the laterals, the infundibula have either disappeared entirely or exist only in the form of small projections of enamel near the posterior border of the tables of the inferior incisors, the crowns of all the superior
106
ANIMAL DENTISTRY.
Fig. 74. Incisor and Canine Dentures at 10 Years (Table View).
ANIMAL DENTISTRY.
107
Fig. 75. Incisor Denture at 12 Years (Table View).
108
ANIMAT. DENTISTRY
Fk;. 'jCx
Incisor Denture Between the Ages of lo and u, Inclusive, wilii Dark Lines
Showini'- the Inclination.
ANIlvrAL DENTISTRY.
109
Fig. ^7. Incisor and Canine Dentures at 13 and 15 Years (Table View).
no
ANIMAL DENTISTRY.
Fig. 7«. Incisor and Canine Dentures at i6 to 20 Years (Table View).
ANIMAL DENTISTRY.
Ill
Fig. 78a. Incisor Denture of a Mare from 16 to 20 Years (Table View),
J 12
ANIMAL DKNTISTRV
Fig. 79. Incisor Denture -at 16 to 20 Years, with Dark Line Showing Average In-
chnatinn.
ANIMAL DENTISTRY. II3
incisors, with the possible exception of the corners, are long and completely conceal the inferior incisors from an an- terior view when the mouth is closed, the contact edge of the superior incisor arcade overlaps that of the inferior, and finally the tables of the central inferior incisors are becoming circular and even flattened from side to side. (Figs. 78, 79.)
Twenty to twenty-five years — The mouth presents all the features of the foregoing paragraph with the exception that the enamel island, representing the last vestige of the infundibulum, has entirely disappeared and is replaced by either a light or dark spot — -the dental star — which repre- sents the obliterated pulp cavity. The tables are round and the external enamel around them projects beyond the sur- face of the dentine v\'ithin, and the crowns of the superior incisors are widely separated with gums and are very nar- row at the gingival end. (Fig. 79.)
Old age — The mouth of an old horse may present either very long or very short (worn out) incisor teeth. If long, the implantation can be disturbed on manipulation and can almost be extracted wnth the fingers. If short, the crowns at the tables are separated one from another by the gums, the crowns are round and the tables of the inferior centrals are flattened from side to side. The canines are round and the molars are uneven, easily extracted, and their roots can be felt along the gingival margin. Often a number of molars are absent from self-extraction.
ROUTINE OF THE EXAMINATION OF A HORSE'S MOUTH TO DETERMINE THE AGE.
I. The horse is approached on the left side and the lips are opened laterally, the left hand elevating the upper lip as the right depresses the under one, thus exposing the lateral aspect of the incisor arcades. A glance at the inclination
.14
ANIMAL DENTISTRY.
Fi<;. 79.\. Incisor a:ul Canine Dentures at _'0 lo 25 Years (Table View),
ANIMAL DENTISTRY,
115
Fig. So. Incisor Denture of an Old Horse, with Dark Lines Showing the IncHnation.
116
ANIMAL J )i: XT IS TRY
will determine whclher the horse is old or young. If young a second glance is taken to determine whether the exposed teeth are permanent or temporary.
Fu;. Si. Anterior View of the Incisor Denture of an Extremely Old Horse.
2. Without releasing the hold the inspector steps to the front of the horse, elevates the upper lip with the left hand and slips the second and third finger of the right into
ANIMAL DENTISTRY. 117
the interdental space, the tirst to expose the superior ar- cade and the latter to cause the horse to open the mouth slightly. From this position the length, color, crusta pe- trosa grooves, contiguity of the crowns, and the gingival margin of the superior arcade are inspected.
3. Without changing positions the left hand is now placed gently into the interdental space as the right one depresses the lower lip to expose the tables of the incisor teeth to determine the shape of the tables, the absence, ex- istence or size of the cups, and the shape of the internal enamel surrounding the infundibula.
4. If deemed necessary, without changing the position the left hand is slipped upward along the left molar arcades, to determine the number and condition of the molar teeth.
ANOMALIES OF THE TEETH, NATURAL AND ARTIFICIAL.
Nature's anomalies in dental evolution and retrogression are of such common occurrence that any set rules for the determination of age will frequently mislead the diagnos- tician. This is especially the case when one or two features of dental growth and wear are depended upon. The com- mon anomalies of the teeth are :
(i) Anomalies of eruption.
(2) Anomalies of the texture of the dental tissues.
(3) Anomalies of the infundibula.
(4) Anomalies of the cups of the infundibula.
(5) Anomalies due to the character of the food.
(i) Eruption of the teeth will vary slightly in dif- ferent breeds and from climate and artificial influences. In the well-bred horse, the thoroughbred, hackneys and Ameri- can trotters, in which the development is forced from colt- hood, the temporary teeth erupt several months earlier than in the horse reared under more natural conditions, and the
118 ANIMAL DKX'I'ISTRV.
same precocity will he observed in the sheddini;- of the tem- porary teeth, from the increased amount of hard food in- gested at an age when the teeth are still defective in tex- ture. In the one-year-old race horse that is trained and fed to force the development of the muscular system the teeth will share in the development providing the unnatural requirement does not impair the general health.
(2) The texture of the teeth varies in difTerent animals of the same class reared under the same conditions, from causes too obscure to recognize. Deficiency in the inorganic proximate principles of food in certain districts has been observed to yield horses with soft teeth. The variation in the texture of the teeth will either hasten or retard the retrogression of the teeth. AMicn the teeth arc hard the events by which age is determined will be retarded, and as a consequence the animal will appear young. When the teeth are soft the reverse occurs and the animal appears older. The anomalies caused by the varied density of the tooth substance are precocious or retarded changes in the cups, infundibula, shape of the tables and length of the crowns. One of the most pronounced results of soft teeth is the shortening instead of elongation of the incisor crowns as the animal becomes old.
(3) The infundibula of the incisor teeth may vary greatly as to their depth. They may be very shallow in some animals and very deep in others, and thus prove mis- leading when depended upon alone in the determination of age.
(4) The cups of the infundibula are equally subject to variations, due to the amount of crusta petrosa in the bot- tom of the infundibula. In some teeth the infundibula are almost full of crusta petrosa, while others contain but a small amount. When full the cup disappears early, and when empty it persists longer. This anomaly is not con-
ANIMAL DENTISTRY.
119
fusing if the shape of the infundibula is taken into account. (5) Character of the food will hasten or retard the wear of the teeth to a remarkable degree. Grazing, which re- quires the use of the incisor teeth to detach the food, has a
Fig. 81A. Gouge.
Fig. 81B. Bishoping Drills.
precocious influence, while stable feeding, which exacts but little work from the incisors, retards the wear.
Artificial anomalies refer to alterations in the appearance of the incisor teeth by the use of instruments. Deviation from the normal may result from :
(i) Shortening of the crowns of the incisors, espe-
120 AXIMAL DENTISTRY.
cially the superior, with the incisor nipper and file.
(2) I'ohshing the anterior surface of the superior incisors.
(3) Renewal of the cups by drilling and staining.
1. Shortening of the crowns of the superior incisors will deceive only the novice or the careless expert. The ar- tificially shortened crown is promptly recognized by the in- terrupted contact of the anterior margin of the arcades, if not by the other retrogressive changes which cannot be ef- faced. The operation is performed with an ordinary incisor nipper and file. The first step is to cut ofT the anterior end of the superior corners where they contact the laterals, and then file them to the length decided upon. Then using this length as a guide, a groove is filed across the entire arcade, over the laterals and centrals. The teeth are then cut off along the groove and filed to a regular, smooth edge, and beveled backw^ards to give the appearance of a normal su- perior table. If the nipper alone is used without first groov- ing the arcade, the enamel may chip upward and ruin the appearance of the whole arcade.
2. Polishing the crowns — After shortening the arcade the anterior face is scraped of all its tartar and crusta pe- trosa with a curette, and then whitened wnth emery paper to give the appearance of young teeth. This operation is also performed with a small revolving emery wheel applied to the flexible shaft of a dental engine. By this means the grooves, as w'ell as the incrustations, can be removed. The typical bluish-white color of young enamel can, however, not be imitated, and besides, the yellow color will soon re- turn.
3. Renewal of the cups (Bishoping) is the most impor- tant of tlie artificial attempts to make horses appear younger, and if performed intelligently upon horses that are not too old, together with, the above operations, even the vaunted
ANIMAL DENTISTRY
121
expert may blunder. The operation consists of cutting large cups in the inferior corners, smaller ones in the laterals and mere dots in the centrals and then staining them with
Fu;. 82A. Wheel Drill.
Fig. 82. Dental Engine.
Fig. 82B. The Polishing Wheel.
silver nitrate. The cupping process is performed with an engraver's gouge, revolving hand drill, or by the modern ingenious implement in vogue in the Chicago horse market,
122
AXLMAI. I)i:X'IMS'rRY.
consisting of the foot cnL^ine used by human dentists, equipped with a circular cutting wheel, by which cups of per- fectly normal shape and size can be made.
Modus operandi: The horse is backed into a single stall
Fic. 83. An 8-Ycar-Oli! Alouth Aladc '-6" by "Bishoping."
and secured in the dental halter. An assistant works the dental engine with the foot. The operator holding the hand- piece of the flexible shaft in the right hand and the jaw in
Fic. 84. A 9 or io-Ycar-01(l Mouth Made "7" l>y "Rislioping."
the Other, cuts first a large elliptical cup with sharp commis- sures in the table of the corner incisors, then smaller ones in the laterals and small dots in the centrals. As the wheel revolves with great velocity, the cupping is the work of but
ANIMAL DENTLSTRY. j[23
a moment, if the horse stands complacently. When the cor- ner tooth has but a small table it is enlarged by filing and the cup is cut across its entire length. The cup in the cor- ners is frequently made with a rounded belly internally and a sharp commissure externally to give a more confusing if
Fig. 85.
not more natural appearance. When the cupping process is complete the arcade is dried and kept free from saliva by wrapping the jaw behind the teeth with a cloth or towel. The cups are then stained by applying a saturated solution of silver nitrate with a stick and then drying it immediately
Fig. 86. Effect of "Bishoping" Teeth of 9 to 12- Year-Old Horses.
by plunging the head of a burning match into it. The drying process immediately blackens the cavity. If the stain flows over the table of the tooth it is filed off.
Shortening, polishing, cupping and staining the incisor teeth of a nine or ten-year-old horse may be so cleverly per-
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126 ANIMAL DENTISTRY.
formed that tlic most circumspect study of the mouth may fail to detect the alteration. In these cases the cupping is limited to the removal of the crusta petrosa within the in- fundibula, thus leaving the cup with a perfect enamel bound- ary. At that age the other retrogressive changes are not pronounced and afford but little evidence to guide the diag- nostician. (See Figs. 8^, 84, 85, 86.)
Fig. 87. The Ridiculous Effect of "Bishoping" Aged Horses.
When horses are past the age of twelve years the results of these operations are readily detected by the interrupted contact of the incisor arcades and especially ])y the angle of inclination, which is never altered by any natural anomaly and which cannot be artificially changed. The shape of the tables and the absence of enamel around the cup will also lead readily to detection of the fraudulent attempts to make very old horses appear younger. (See Fig. 87.)
CHAPTER IV.
FUNCTION OF THE TEETH.
The teeth have but a passive function to perform as ac- cessory organs of prehension, mastication and insaliva- tion, and as organs of defense. Their uses are similar in all species, varying but slightly in detail.
The incisors serve the general purpose of holding food, after the lips or tongue have gathered it between them, and as a jerk of the head detaches it. In the ingestion of de- tached food they serve no useful purpose in any of the do- mestic animals. In all the domestic mammals except rumi- nants they are important organs of defense, and as such they are most useful in the soliped. The incisors of carnivora are so much shorter than the canines that the latter inflict the greatest harm to an enemy.
The canines of solipeds are common only to males, in which animals they have no special function to perform. In the carnivora and omnivora they serve the useful purpose of tearing attached food preparatory to mastication, besides constituting the principal organs of defense. In these ani- mals they are common to both sexes and they lock over each other in a manner to hold fast to any object into which they are imbedded.
The molars of herbivora are the mill-stones of the mechanism of mastication. The wide, roughened tables of the superior molars, and the series of strong muscles which move the inferior ones upon them, constitutes the principal features of a perfect grinding apparatus necessary to the welfare of animals ingesting coarse, fibrous food. In these animals the molars grind the food perfectly, carefully and
127
128 ANIMAL DENTISTRY.
persistently, and at the same time incorporate it with the abundant saliva essential to the proper digestion of amyla- ceous food. In ruminants the food is first passed by the molars with only nominal conmiinution, but when it is re- gurgitated during rumination it is as carefully masticated as in the non-ruminating animal. Besides the function of mas- tication and insalivation, the molars might correctly be class- ified as tactile organs, as they readily detect the presence of undesirable particles of food.
In the carnivora the molars serve to crack hard objects, as bones, into smaller particles and to divide large pieces of flesh into smaller ones simultaneously with surrounding the particles with a slimy coat of saliva to facilitate deglutition. In these animals they are not essential organs, as the food may be bolted without material impairment of the general health, while in the herbivora the molars are as essential to the life of the animal as any of the internal digestive organs.
PREHENSION.
The function of prehension is performed by the lips, in- cisor teeth, canine teeth and tongue. When the food has passed the incisors and canines, and the mouth is closed, it is drawn backward to the molars by suction. The organs of prehension named in the order of their importance in the dif- ferent animals are as follows:
Horse: (i), the lips; (2), the incisor teeth; (3), the tongue.
Ruminants: (i), the tongue; (2), the incisor teeth and dental pad; (3), the lips.
Carnivora: (i). the canine teeth; (2), the tongue; (3), the incisor teeth; (4), the lips. In the ingestion of liquids the tongue alone performs the function by dashing the liquid well backward into the mouth.
ANIMAL DENTISTRY. 129
Omnivora: (i), the incisor teeth; (2), the canine teeth; (3), the lips; (4), the tongue.
(In sheep and goats the hps are very motile and serve to gather attached food as in the horse.)
MECHANISM OF MASTICATION.
The organs of mastication comprise : The superior max- illary, the inferior maxillary, the premaxilla, the molar teeth, the tongue, the hard palate, the cheeks, and the masseter, the internal pterygoid, the temporalis, the digastricus, the external pterygoid, the stylo-maxillaris and the sterno- maxillaris muscles.
The superior maxillary is an immovable bone, closely united by sutures to its contiguous facial and cranial bones, and to its fellow by a wide, flat process extending across the mouth to form its bony roof. It receives into six deep cavi- ties the imbedded portions of the superior molar arcade, and with its fellow and premaxilla constitutes the upper jaw. Its function is to hold taut the superior molars and to form the roof of the mouth.
The inferior maxillary is a movable bone articulating with the squamous temporal by a diarthrosis having imper- fect rotatory and perfect ginglymoid motion. It is a single bone consisting of a small body anteriorly with two large branches extending posteriorly to the temporo-maxillary articulation. xA.t the anterior extremity of the body it re- ceives the six incisor teeth and along the superior margin of each branch the six inferior molars. Its function in masti- cation is to serve as a carriage for the inferior molars, a medium for the attachment of the muscles which move it and to assist in forming the bony Imundary of the mouth.
The premaxilla is an irregular bone, which, with its fel- low completes the upper jaw anteriorly and contains the
130
ANIMAL DENTISTRY.
alveolar cavities for superior incisor teeth. It consists of a body and two branches extending- 1>ack\vard. The upper branch passes apward and backward along the superior maxilla to the base of the nasal peak, where it enters into the formation of the maxillo-nasal notch. The lower branch is a thin plate loosely attached to its fellow and the superior maxilla to complete the roof of the mouth anteriorly.
The tongue of animals is a very strong, motile, musculo- membranous organ, having a fixed attachment to the spur process of the hyoid bone posteriorly, and a free extremity anteriorly. It is held to the floor of the mouth by its mucous membrane. Its upper surface is thickly paved with epi- thelium. It is a tactile, gustatory, prehensile and masticating organ. In mastication it serves the useful purpose of keep- ing the food between the molars while grinding-, and to assist in its backward passage when mastication is complete.
The hard palate is a dense fibrous cushion covering the entire roof of the mouth from the incisor teeth to the soft palate. It presents a number of transverse bars which meet in a longitudinal raphe. It serves the purpose of preventing food from slipping freely outward, and to assist the tongue in passing food backward.
The cheeks arc composed of the buccinator muscle cov- ered externally with the skin and internally with the buccal mucous membrane. It is a loose curtain attached just be- yond the alveolar border of each molar arcade. In masti- cation it serves to keep the food between the teeth and to complete the lateral boundaries of the mouth.
The masseter muscle is a thick, wide and short muscle located on the lateral aspect of the lower jaw. Its fixed at- tachment is the maxillary spine and zygoma and its movable insertion the external face of the lower jaw. Its function is that of closing the jaws and drawing the inferior maxillary slightly forward.
ANIMAL DENTISTRY. 131
The pterygoid internus muscle occupies the same relative position on the internal aspect of the ramus as the masseter does externally. Its fixed attachment is the palatine crest and the movable insertion the internal face of the lower jaw. Its function is that of producing lateral motion and as- sisting the masseter to close the jaws, as follows: The left muscle acting alone draws the jaw to the right and the right one to the left, and when acting together they assist the masseter in closing the mouth.
The temporahs muscle occupies the space over the parie- tal bones, and is inserted to the coronoid process and anterior border of the ramus of the jaw. Its function is that of clos- ing the jaw, and when acting singly it produces lateral mo- tion.
The pterygoid extemus is a short, thick muscle situated internally and in front of the temporo-maxillary articulation. It originates on the sphenoid bone and is inserted at the neck of the jaw just below the condyle. Acting together they pull the jaw forward and singly they produce a lateral mo- tion.
The stylo-maxillaris originates at the styloid process of the occipital and is inserted to the posterior border of the ramus of the jaw. Its function is that of drawing the jaw backward and depressing it.
The digastricus muscle is located in the maxillary space, originating on the styloid process with the stylo-maxillaris and is inserted along the inner border of the ramus toward the symphysis. Its function is that of retracting and de- pressing the jaw.
The sterno-maxillaris muscle originates on the cariniform cartilage of the sternum and is inserted at the angle of the jaw. Its function is that of depressing the jaw.
The lower jaw is moved in every direction by the muscles of mastication; it is advanced, retracted, elevated, depressed
132 ANIMAL DENTISTRY.
and drawn to either side at will. In ruminants the lateral motion is pronounced while in the carnivora it is prevented by the interlocking^ of the canine teeth, the beveled molars and the ginglymoid character of the articulation. In soli- peds the lateral motion is nominal. The antero-posterior motion is prominent in rodents and is possible to a normal degree in herbivora. The upward movement, which is the most forcible, is of course a prominent movement in all animals, but is an exceptionally powerful one in the solipeds and ruminants.
^lastication is effected in about the following manner. The mouth is opened by gravity, aided by the stylo-maxil- laris and digastricus muscles; it is then swung to the side and slightly forward by the pterygoids, temporalis and mas- seter, and then diagonally upward by the combined effort of the masseter, internal pterygoid and temporalis. During these movements the tongue and buccinator are engaged in keeping the bolus in position to be caught between the teeth as they come together.
Mastication is unilateral, only one side of the mouth is used at a time. Herbivora will chew on one side for a few minutes and then shift the next bolus to the other, at their will.
CHAPTER V.
DENTAL DIAGNOSIS.
Examination of the incisors (see page 113).
Examination of the horse's mouth preceding the usual dental operations is done in the standing position, by palpa- tion and inspection.
Palpation of the mouth. — As the horse's mouth is a dark, deep cavern its examination for the detection of the common irregularities must depend chiefly upon manual ex- ploration. For this purpose the mouth speculum or a gag may be used. The expert, however, requires neither, but passes the hand v,nth the greatest freedom, ease and leisure to any and all parts of the mouth, without inconvenience to the horse or injury or danger to himself. To accomplish that valuable attainment the halter is removed and the head is held from being thrown upward by an assistant holding one hand on the nose and the other on the poll. The diag- nostician stands directly facing the horse, and passes the right hand into the left commissure of the mouth, across the interdental space into the space between the tongue and molar teeth on the opposite (left) side. The palm of the hand faces the teeth and the dorsum the tongue. In this position the tongue of the horse is not forced into any un- comfortable attitude and the mouth is not forcibly opened. The hand may then be passed gently backward to the fauces and the fingers may be extended over the tables of the teeth without danger or injury. The secret of success is in not opening the mouth too wide and in engaging the horse by keeping the hand constantly moving. When the hand is
.133
134
ANIMAL DENTISTRY.
kept stationary in the mouth resistance is immediately of- fered.
The right side is palpated with the left hand and vice versa. Prior to the molar examination or immediately after,
, ,, ,p.
" Search Lights."
the interdental space, first below and then above, is palpated with the palmar surface of the thumbs to locate possible bit lesions or wolf teeth.
The novice may use the mouth speculum, which will ad- mit of free palpation of the teeth with the exception of the
ANIMAL DENTISTRY.
135
external borders of the molar arcades. The hand cannot be admitted freely into the mouth unless the speculum is opened wide enough to provoke resistance, and besides the cheek is drawn taut against the teeth and prevents palpation of the borders of the molars.
Inspection of the mouth. — Beyond the first two molars the mouth cannot be satisfactorily inspected in the standing position. Only gross abnormalities can be seen, and these only to an unsatisfactory degree. With the aid of a mouth speculum and artificial light, — a reflector or incandescent light, — with the head raised and the operator standing on an elevation it is possible to inspect the teeth, but in this pro- cedure the tongue and the resistance to such forcible manip- ulations offered by the horse, materially interfere. A perfect inspection of the mouth can only be made in the recumbent posture with the head turned upward and the speculum ad- justed, and then only by the aid of good light, — a reflector if necessary. By pulling the tongue to first one side and then the other, every part of the mouth can be seen and felt, and in addition abnormalities can be searched for with steel picks.
DENTAL INSTRUMENTS— THEIR USES.
FLOATS AND FLOAT BLADES.
Floats are the principal instruments of the animal dentist. They are to the animal dentist what the drill and dental engine are to the human dentist. The float is a simple con- trivance consisting of a handle, shaft and head to receive the blade which may be either a rasp or file. The entire length should not exceed nineteen inches, divided as follows: Handle, 5% inches ; shaft, 10V2 inches, and head, 3 inches. The head is open to receive the blade at either end and is perforated with two openings to receive the screws with which the blade is kept taut. There are many patent affairs
136
ANIMAL DENTISTRY
on the market, some simple and others complex, which hold the blade solid by various means. Some are equipped with a mechanism by which the head can be placed at different angles with the aim of combining two instruments in one, i. e., the straight and the angular float. All these inventions to date are but poor imitations of the old reliable simple screw-head float, and are neither durable nor practical, and few will hold the blade as solid as the old pattern.
These instruments are generally designated as the House floats ; they have been in use for more than thirty years, and as they ofTcr but little chance for improvement they will probably always retain the prestige of being the most satis-
FiG. 89a. Straight and Angular Floats, with Lines showing the Proper Angle of
Each.
factory instrument of their kind. Two styles are recom- mended— the straight float and the angular float.
The Straight Float is used to file the lower arcades and the posterior two-thirds of the superior arcades, and to facilitate its passage to the remotest teeth its head must be on a straight line with the handle, i. e., when the handle lies flat upon a plane the head, — face downward, — must do like- wise throughout its entire length. The posterior end of the; arcades, especially the inferior, cannot be reached with a float of any other shape without opening the horses's mouth wide enough to provoke resistance.
The Angular Float is used to file the anterior third or half of the superior arcades, which, owing to the inward cur-
ANIMAL DENTISTRY.
137
vature of their external borders, cannot be conveniently reached with an instrument of any other shape. The angular float should be of the same size and length as the straight one. When its head lies, face downward, upon a plane, the center of the handle should be elevated two and one-half inches above the plane. The short-handled floats of greater angles are much less convenient.
The Float Blades should be of the rasp variety, tempered hard enough to wear well and yet not so hard as to chip from filing the hard enamel points of the molars. In the straight float the cutting edges of the rasp must point back- ward,— toward the handle, — and in the angular they must point forward. This arrangement is intended to train the hands to make the float cut on its outward course instead of its inward course, and thereby prevent prodding the back of the mouth.
Fu;. 90.
THE FLAT FILE AND RASP.
The flat file and rasp should be twelve inches long, rounded at the extremities and have a file on one side and a rasp on the other. It is used to round the first superior and first inferior molars, and to shorten the canines and in- cisors.
THE CLOSED MOLAR-TRIMMER OR CUTTER.
The closed trimmers are nineteen to twenty inches long, including the handles, and have a head consisting of a box
138 ANIMAL DENTISTRY.
joint and two cutting jaws, one to one and a quarter inches long, which come together in perfect apposition. The cut- ting surface is dropped three-eighths of an inch below the level of the instrument better to enable the grasping of small points. It should be made with a box joint, the center of which is no more than two and a quarter inches from the end of the cutting jaws. The forks and handles should be of no less than five-sixteenths inch steel.
This instrument was primarily intended to trim the enamel points along the arcades, both superior and inferior, and it is still being used for this purpose by some veterinary practitioners. Its use for this purpose cannot, however, be sanctioned, owing to the difficulty of placing them accurately upon the small enamel points located posteriorly on the ar-
FiG. gi.
Closed Molar Trimmer.
cades. The smallness of the points, the motility of the head and the great distance between the hands and the cutting end of the instrument, makes their applicability difficult in the hands of the unskilled. Even in the hands of the skilled den- tist their use amounts to the cutting of whatever happens to be caught between the jaws.
The closed trimmer should be used only in cutting the projections at the extremities of the arcades — the first su- perior and sixth inferior molars — for which purpose they are
indispensable.
THE OPEN MOLAR-CUTTER.
The open molar-cutter of the double-lever variety is also an indispensable part of the dental outfit, and owing to the laborious work it must perform it should be powerful enough to cut any projecting tooth promptly. The style recom-
ANIMAL DENTISTRY.
139
mended is twenty-four to twenty-five inches long and has a head consisting of a box joint and two cutting jaws no more than one inch long which approximate within one-quarter of an inch when the instrument is closed. Six inches from the center of the box joint is a second one. to increase the lever-
FiG. 92. The Cpen Molar Lever Cutter.
age. The fork between the joints is of three-quarter inch (square) bar steel, while that from the last joint and handles is of five-sixteenth steel.
This instrument must possess strength at the expense of its neatness. It can be opened wide enough to receive any
TH, CHICAGO,
Fig. 92A. Plain Open Molar Cutter.
elongation of the horse's molars and will promptly cut, with only nominal effort, any tooth its jaws may grasp.
The single joint open molar-cutters, unless made much stronger and longer, will frequently disappoint the operator and will always require a number of strenuous efforts before a large tooth will yield.
140 ANIMAL DENTISTRY.
THE WOLF-TOOTH SEPARATOR AND FORCEPS.
The wolf-tooth separator is a nine-inch instrument hav- ing a box joint and l)ayonct-'point head, which contains two cutting or wedging jaws approximating cacli other closely at the end but open slightly along the cutting surface. This instrument is made use of to extract wolf teeth by wedging them between the wolf tooth and molar to disturb the alveo-
FiG. 93. Wolf-Tootli Separator.
lar implantation and then pry them out. Their use to dis- turb the tooth may precede the use of the ordinary wolf tooth extractor which, in view of the utility of the separator, may be entirely dispensed with in veterinary dentistry. The separator may, in addition, be used to extract the sheddin^
Jhic. g3A. Wolf-Tool li Forceps.
incisors, shedding molar caps, incisors and canines of dogs and fractured incisors of horses.
THE MOLAR SEPARATOR.
The molar separator is twenty inches long and has a head consisting of a box joint and two wedge-shaped jaws, projecting at a right angle, the edges of which come together when the instrument is closed. It is used for the purpose of loosening the decayed molar prior to the application of out-
ANIMAL DENTISTRY.
141
ward force with the extracting forceps. Its jaws are wedged alternately, into the interdentia on either side of the de- cayed tooth until the implantation is disturbed.
Fig. 94. Open Molar Separator, for Superior .Arcades.
THE CLOSED MOLAR EXTRACTOR.
The closed molar extractor is twenty inches long and has jaws no more than one inch long and five-eighths of an inch wide, projecting at a right angle from the head. The forks
Fic^. r;4.'\. Closed Molar Separator, for Inferior Arcades.
and handles are strong enough to prevent springing when pressed forcibly together. The jaws approximate within one- eighth of an inch and are furrowed internally to prevent slipping from the tooth. This instrument is indispensable in
I'lc. 95. Closed Molar E.xtractor.
the extraction of molars, most of which are split into narrow plates that cannot be held with an open forceps. It is used chiefly to extract split molars, but may be utilized to ad- vantage even when the crown is whole. The dental equip-
142
ANIMAL DENTISTRY.
merit containing only one extractor should, therefore, con- lain the closed variety instead of the open, which can only be applied in the extraction of molars having full crowns.
Fu;. 96. Closed Molar Extractor, with Curved Handles.
THE OPEN MOLAR EXTRACTOR.
The open molar extractor answers the same general de- scription as the closed, with the exception that the jaws are five-eighths of an inch apart when the instrument is closed, and that the forks form an abrupt drop of one inch, five inches from the head. The object of the curved or drop forks is to prevent the handles from striking the incisor teeth before the tooth is lifted from its cavity. The closed extrac-
Fi;:. 97. Open Molar Extractor.
tor may be similarly curved, but owing to the fact that when
they are applied to the entire crown the handles are wide
enough apart to pass the incisors between them, the curve
is not as essential as in the open ones.
THE ANGULAR MOLAR-CUTTER.
The angular molar-cutter is twenty inches long, and is of the same size and pattern as the closed molar trimmer. Its jaws extend from the head at an angle of about forty-five degrees, and open in the shape of a V to fit the triangular crown of the first inferior molar.
This instrument is used solely for the purpose of beveling
ANIMAL DENTISTRY.
143
the first inferior molars and to cut projections of nominal size on the first superior molars. It is a useful instrument, but not an essential one. The same work on the superior
Fig. 98. Angular Molar Cutter.
molars can be accomplished with the closed cutter and file, and the first inferior can be beveled with the file to the de- sired point without cutting.
Fig. 98a. Handles for Figs. 92, 92a, 94, 94a, 95, 97 and 98.
THE INCISOR NIPPERS.
The incisor nippers is a simple instrument about ten inches long, with a screw joint to bring the power nearer the cutting edge. It has cutting jaws which curve claw-like from
Fig. 99. Incisor Nipper.
the head and come in perfect apposition when the instru- ment is closed. The cutting surface should be no less than five-eighths of an inch wide. This instrument is used to shorten the incisors and canines. It may also be used to
144 ANIMAL DENTISTRY. /
/'
cut the sharp elong-ation at the extremity of the first superior molar.
THE MOLAR CROWN CUTTER.
The molar crown cutter or claw cutter, as it is occasion- ally called, answers the same general description as the open molar-cutter, with the exception that the cutting- jaws drop at a right angle from the head and curve toward each other like a pair of claws. The jaws have a cutting edge of no less than three-quarters of an inch, and part three-sixteenths of an inch when the instrument is closed. They are used ••-■.■
Fig. ioo. Molar Crown Cutter.
remove the crown opposing a decayed tooth, or that of a decayed one when extraction is not deemed advisable.
THE MOUTH SPECULUM.
The mouth speculum is indispensable in a dental prac- tice. It may consist of a simple oblong loop of one-quarter inch iron bar, a wooden gag to insert between the molar teeth, or a double bar that is made to open as wide as neces- sary with a screw. These simple affairs may be made to answer the purpose of the more costly and complicated ratchet speculum, which has recently come into quite general use. The ratchet speculum consists of two cups to fit the incisor arcades, upper and lower, connected to the ratchet mechanism by means of curved bars following the line of the lips to a point behind the commissure of the mouth, thus
ANIMAL DENTISTRY.
145
leaving the fissure oris free from obstruction. They have the advantage also of opening the mouth to any width de-
Fic. loi.
sired, and the disadvantages of being none too reliable. The ratchet may break or slip when the jaws of a powerful horse
Fig. 102.
are set against its strength. Slipping of the ratchet is a very frequent accident after the catches have become worn from constant use.
146
ANIMAL DENTISTRY.
I'IG. LO3B.
l-ic. 103c.
ANIMAL DENTISTRY. I47
The mouth speculum is used only for operation in the recumbent position, and especially when an animal is under the influence of an anaesthetic. In the standing posture it is useful only to the plebe and novice. It obstructs the free use of large instruments in the standing position, and is unnecessary for the minor operations.
THE TOOTH CHISEL.
The tooth chisel is a recent invention, the artifice of an Iowa veterinarian. It consists of a strong band of iron shaped as a horseshoe. At one heel is a chisel inserted as a lag screw, while on the other heel is a head to receive the blows of the hammer. The chisel end is passed into the mouth while the other heel is kept outside. Its object is to break or loosen teeth that cannot be grasped with forceps. It is undoubtedly an instrument of some value, especially in the extraction of broken fangs, as it can be equipped with chisels of different dimensions and shapes to meet each re- quirement.
OTHER INSTRUMENTS.
The above is a description of the more essential instru- ments of a dental outfit for a veterinary practitioner. It is, however, undeniable that many others might be added to the advantage of the dental branch of veterinary surgery. There is room for the addition of many instruments of vari- ous shapes, styles and patterns suitable for special purposes. For example, extractors for the superior arcades should be wider than those for the inferior; those for the right side might be curved toward the left, and those for the left side toward the right, so as to bring the instrument out of the mouth at the median line; those for the last molars might be longer and have smaller heads and shorter jaws, to pass more freely between the teeth ; and finally all cutters, separa- tors and extractors might be made specially for superior,
148 ANIMAL DENTISTRY.
inferior, posterior, anterior, right or left work to the advan- tage of tlie dental surgeon.
At the present time there is no standard dental instru- ment. Each manufacturer and each practitioner has his particular idea as to what constitutes the appropriate style of instrument for each particular purpose, and as a result an unfortunate state of chaos exists in the veterinary dental instrument shop. This unfortunate condition makes the veterinary dental instrument costly, as the manufacturer cannot reduce the cost by making them in large quantities.
A change for the better in this connection will come when the dental operations are regarded as being of sufficient im- ]K:)rtance to warrant the adoption of standard methods of operating, which in turn will create a demand for standard instruments.
Trephines, chisels, punches, curettes, and the dissecting instruments used in animal dentistry are too well known to demand description here.
RESTRAINT.
Floating, filing and trimming the teeth of horses can be accomplished without provoking resistance — enough to de- mand any forcible means of restraint. The minor dental operations are accepted with remarkable complacency in the great majority of horses. The only necessary restraint is to prevent the horse from backing away from the operator and from elevating the muzzle out of the reach of the hands and instruments. This is done by backing the horse into a single stall and securing the head at a comfortable height on the pillar reins with the dental halter. The ordinary leather halter is not satisfactory for this purpose because one side or the other will press against the cheek and pre- vent the free passage of instruments along the teeth.
The dental halter consists of a leather-covered iron loop
ANIMAL DENTISTRY.
140
fifteen inches long and nine inclies wide, with a single poll strap and a ring on each side for the tie ropes. The poll strap is of two-inch heavy leather with numerous buckle- holes to make it adjustable to any sized head. The tie ropes are ordinary half-inch hemp, long- enough to encircle the pillar or to reach the pillars of a stall of any ordinary width. Whenever the tie ropes, owing to the construction of the stall, cannot be tied low enough on the pillars to hold the
Fig. 104. Horse Properly Secured for the Simple Dental Operations.
head down to the proper height, a third rope or strap is tied to the lower end of the halter, passed between the fore legs around the withers and back again between the fore legs to the halter. By this addition a horse can be secured in an open room, field or box stall with only the assistance of one person to steady the head. (Fig. 105.)
In the absence of the dental halter dental operations should be performed with the aid of an assistant, to hold
1 50
ANIMAL DEXTISTRV.
tlic head with one hand on the poll and the other over the nasal bones.
Fig. 105.
A Satisfactory Method of Securing a Horse for Simple Dental Operations,
Without the Use of Pillar Reins.
Major operations, i. e., repulsion of teeth, etc., and minor operations upon vicious horses, require the recumbent posi-
FiG. io5.\. Lucas' Dental Halter.
tion and the use of the mouth speculum. The operating- table is par excellence the best restraining apparatus for such
ANIMAL DENTISTRY. 151
operations because it brings the head to a comfortable height for inspection and operation.
Anaesthetics are seldom necessary to perform dental operations and frequently they are harmful in that they favor the aspiration of blood and saliva into the trachea. Local anaesthetics are not applicable in any form to the den- tal operations upon animals.
Floating, filing, trimming and cutting the teeth should be performed in the standing position. The extraction of teeth may require the recumbent, but only occasionally. Tre- phining the skull can be performed in the standing posture with the aid of the twitch and dental halter, but the repul- sion of teeth must never be attempted without recumbent restraint.
Chiseling, punching and sawing operations require per- fect restraint in the recumbent position.
CHAPTER VI,
DISEASES AND IRREGULARITIES OF THE TEETH.
NECROSIS OF THE TEETH OF HERBIVORA.
Synonyms: — Alve()lar-]:)criostitis. Pcridentitis. Perice- mentitis. Pulpitis. Dentitis : Caries (erroneous). Decayed teeth.
Fig. io6.
Molars Predisposed to Decay by an Open Clianncl Through the Crusta Petrosa of the Infundibula.
1, I. The infundibula.
2, 2. Openings of channel at table.
3, 3. Pulp cavity. (Tn the slmrt [old] tooth the pulp cavity is already closed.)
Definition: — A total necrosis of one or more molars of herbivorous animals, of inflammatory origin, due to a pri- mary or secondary infective inllammation of the pulp.
Etiology: — The entrance of food into an imperfectly
152
ANIMAL DENTISTRY.
153
closed infunclibiilum is the cause of more than 95 per cent of the decayed molars of the horse. The crusta petrosa, which should hermetically seal the infundibula, is found wanting and thus leaves an entrance channel for infectious matter. The pulp is therefore the first structure to be involved in the inflammatory process, from which source it traverses through the apical foramena to the blood vessels, alveolar periosteum and bone. In rare cases the infectious matter is admitted directly to the alveolar periosteum through imper- fect gums, the space between the teeth, or through the ex- posure of the periosteum while shedding the temporary predecessor. Cystic tumors located directly upon the root,
Fig. 107. Table View of Tootli Sliown in Figure 106. I, 2. Openings of the infundibula, througb which food enters the tooth.
atheromatous degeneration of the radicals of the superior dental artery, and external violence are the determining causes in a few instances. In these latter circumstances the pulp is the last structure to be involved in the inflammatory process. Systemic disturbances, especially a "ricket dia- thesis" induced by organic diseases or poor quality or insuf- ficient forage during the period of growth, are predisposing influences.
Pathological Anatomy: — Pulpitis, either primary or sec- ondary, is the basis from which to study the decayed molar of the horse. The disease process begins with pulpitis and ends finally in self-extraction of the tooth. Between these
:54
ANIMAL DENTISTRY
Fig. io8. Necrosis of an Inferior Molar in the Early Stage, with Perforation from
Table to Root.
ANIMAL DENTISTRY
155
two events the following chain of abnormalities occur: (i) extension of the inflammation to the blood vessel, nerves and periosteum; (2) abscess formation at the root pointing- through the peridental plate into the sinuses or surface of the skull; (3) destruction of the blood supply of the tooth; (4) death, desiccation and splitting of the tooth; (5) im- paction and decomposition of food in the cavity between the split section ; (6) osteitis and necrosis of the alveolar border from pressure of the split sections; (7) self-extrac- tion. The duration of the process is from three to fifteen years. The above chain of conditions is, of course, not followed to the letter in every instance. For example, an
Fig. 109.
intense periostitis may rapidly loosen a tooth from its cavity and, by admitting infectious matter around it, pro- duce extensive osteitis of the jaw. In the young animals the great length of the tooth, and in the inferior denture, gravity, prevents the self-rejection of the tooth from its cavity, and as a result the loose, dead tooth perpetuates and augments the inflammation and tumefaction of the sur- rounding bones. This condition is seen principally in the inferior molars when the primary lesion has been alveolar periostitis. Primary pulpitis caused by the open infundi-
156
ANIMAL DENTISTRY.
Fig. no. A Superior Molar in the Early Stage of Decay.
A. The table.
I, 2. Openings into tlic tooth admitting food.
B, C. The same tooth split longitudinally to reveal its internal condi-
tion.
ANIMAL DENTISTRY. 157
bulum in the inferior arcades frequently points to the surface of the jaw and constitutes the well known dental fistula of the inferior maxilla. (See Fig. io8.)
The incisor and canine teeth are not susceptible to the condition.
Diagnosis: — The molar tooth of the horse reaches the advanced stage of decay unobserved in most instances, as the incipient stages progress without clinical signs or apparent discomfort to the animal. The fetid breath, fistula or tumefaction of jaws or mouth usually create the first sus- picion of decayed teeth. In the absence of these outward signs they are only encountered accidentally in palpations of the mouth during dental operations. The earliest diag- nosis of a decayed molar is made when the infective inflam- mation extends rapidly into the respiratory mucous mem- brane, before any gross changes occur in the tooth. In these cases the unilateral fetid nasal discharge leads to an examination for abnormal (open) infundibula in one of the superior molars. Anorexia, rejection of partially masti-. cated food, dislike for cold water or turning the head to one side while masticating, are occasional signs of decay in the incipient stage, but the diagnosis must be confirmed by better evidence.
The relative decay of the teeth of horses will assist ma- terially in locating the offending member. The fourth su- perior molar, owing to its position in the center of the arcade and its unstable neighbors during the second year of colt- hood, is the most common seat of the disease. Out of a total of two hundred decayed teeth observed, one hundred and nineteen were fourth superior molars. The fifth superior, the third superior and fourth inferior were next in order, while the remainder were divided quite evenly among the first superiors, the sixth superior and the remaining inferior molars. The second superior was not found decayed until
158
ANIMAL DENTISTRY.
the two hundred and thirty-second case was investigated, showing that this tooth is not frequently decayed.
Treatment: — (i) Removal of the tooth; and, (2), re- moval of the opposing crown. Removal is the palpable duty in dealing with the decayed tooth of the horse, but in the
Fig. Ill
Advanced Stage of Necrosis in a Superior Molar.
A. The tooth.
B. The table.
I, I. The opening through which the tooth became infected.
uncomplicated case removal is warranted only when it can be accomplished in a simple manner (forcep extraction). When a decayed molar produces no apparent inconvenience and is too short to grasp firmly with the forceps, removal of
ANIMAL DENTISTRY. 159
the opposing crown is ample remedy pending the develop- ment of serious complications. A decayed molar, although a foreign (dead) body, may become encysted in a protecting wall and cause no further trouble. The operation of remov- ing a tooth crown is accomplished with a claw cutter. (Fig. lOO.) The removal of teeth is accomplished by either of the following methods :
(i) By extraction wnth forceps.
(2) By repulsion with punch and mallet.
(3) By removal of the external alveolar plate.
(4) By splitting with chisel and mallet.
(i) EXTRACTION WITH FORCEPS.
Equipment: — Open molar extractor, closed molar ex- tractor, separating forceps, hardwood fulcra of assorted sizes, and if operation is performed in the recumbent posi- tion, a mouth speculum.
Indications: — Forcep extraction should be adopted as the universal method to remove molars having crowns long enough to grasp fijrmly. Even though trephining may be necessary to reach the existing secondary condition, forcep extraction should, if possible, precede the trephining.
Restraint: — Choice between the standing and recumbent positions must be decided by the probable complacency of the patient and the skill of the operator. For the standing position the horse is backed into a single stall and confined to the pillars with the dental halter. The head must be brought downward within easy reach. If the operation is resisted by forcible movements of the jaw a mouth speculum may be applied. The mouth speculum should, however, be avoided if possible, as it will interfere with the free use of the instruments. For the recumbent position the patient is placed in a dorso-lateral attitude with the mouth speculum adiusted and the head inclining upward. Anaesthesia is not
160 ANIMAL DENTISTRY
advisable, owing- to the greater danger of l)lood flowing into the trachea.
Modus operandi : — The first recjiiircmcnt is to loosen the tooth. It is safe to assert that the tooth that cannot be loosened cannot be lifted from its cavity without fracture, or injury to the teeth upon which the fulcrum is placed. The loosening process is accomplished by wedging the molar separator into the inderdentia, first on one side, then on the other until it can be easily closed in the spaces. Tor- sion is then applied with the extracting forceps until the tooth is felt to be well loosened. Undue haste or the ap- plication of great force must be avoided and care must be taken to prevent fracture in a sudden movement of the head. The extractor is now adjusted firmly to the crown and the fulcrum block placed as near its head as possible. Gradual, firm outward traction will readily bring the tooth from its implantation. When the tooth is divided into two or more fragile segments the manipulation must be carefully exe- cuted to prevent fracture.
Accidents: — The extraction of molars is not entirely without danger. The possible misfortunes are: (i) Frac- ture of the tooth which will necessitate removal by some more complicated method: (2) wounding the palatine artery with the jaW' of the forceps; (3) excessive hemorrhage from the dental artery.
1. Fracture of the decayed tooth that is uncomplicated with secondary disorders may l)e treated by the simple re- moval of the opposing crown. Tf there are catarrlial or fis- tulous complications repulsion will be necessary.
2. Palatine hemorrhage is serious and unless arrested will endanger life. The accident occurs as a result of the horse chewing forcibly upon the end of the internal jaw of the forcep while being adjusted to the superior tooth. As soon as the accident occurs the operation must cease and
ANIMAL DENTISTRY. 161
the mouth must be packed full of cotton, waste, oakum or any other packing material that can be promptly furnished. When there is delay in procuring a suitable packing the finger must be kept over the wound to temporarily arrest the flow of blood. After the mouth is packed full the jaws are closed tightly by encircling them with a dozen wraps of cord and the patient is backed into a stall and kept on the pillar reins for five to six hours, when the packing may be safely removed.
3. Hemorrhage from the dental artery may occasionally be very profuse, but it is never serious. It is arrested by packing the cavity with wadding of cotton or oakum.
^tL
I
Fig. 113. Decayed Tooth Due to Primary Alveolar Periostitis (Ostertag).
After-care: — The tooth cavity must be wadded with fresh packing every day for a week, at which time a careful examination of the cavity must be made to remove sequestra or fractured segments of bones, which may delay prompt healing of the wound. In two years the opposing tooth will have elongated into the vacant space and will require trim- ming to the level of its arcade.
(2) REPULSION OF TEETH WITH PUNCH AND MALLET.
Equipment — Three-quarter-inch circular trephine, one inch circular trephine, bone chisel, punch, iron mallet, scal- pel, artery forcep, dissection forceps, mouth speculum, cu- rette, razor, antiseptics and packing materials.
162
ANIMAL DENTISTRY.
Indications: — Trephining tlie skull to repulse teeth is in- dicated when the tooth crown is too short to grasp with the forcep, and when there is a complication of fistula or catarrh of the sinuses. In secondary catarrh of the sinuses wnth more or less accumulation of purulent matter, trephining is
Fig. 114. Mallet.
an essential adjunct to tooth extraction, even though the extraction is accomplished with tlie forceps. Trephining is perfonr.ed to evacuate the accumulated secretion and to admit the free irrigation of the catarrhal mucous mend)rane,
Fig. 114a.
Straight Punch.
as well as for the purpose of admitting the punch to repulse the tooth.
The following are the molars that are removed by repul- sion: Fourth and fifth superior, sixth superior of old horses,
6HAHP S SMITH, CHICAGO.
Fi(-,. 114i!. Curved Punches.
first, second, third and fourth inferior and the fifth and sixth inferior wdien accompanied with considerable tumefaction of the jaw.
Restraint:- — The recumbent position, lateral posture, af-
ANIMAL DENTISTRY. 163
fected side uppermost, with a mouth speculum securely ad- justed, is the proper attitude for the repulsion of teeth. The standing posture is never satisfactory. The operating table is par excellence the best method, as the head can be more firmly secured than with the casting harness. General anaesthesia is sometimes harmful, as in the unconscious state blood readily finds its way into the lungs.
Location of the openings: — ^The opening in the skull must be situated so that the punch can be placed on a
Fig. 115.
Cut Representing the 8 Teetli Whicli Can Tc Repulsed and the Location of
the Opening for Each.
straight line with the long axis of the tooth. (See Fig 116.) The transverse range will vary slightly with the age of the horse. In the young horse well toward the median line of the head and in the old one nearer the maxillary spine. The lon- gitudinal range will vary according to the tooth to be re- pulsed, the fourth, fifth or sixth. The exact seat is deter- mined after the animal is secured and otherwise prepared for the operation. The hand is placed into the mouth and a
164 ANIMAL DENTISTRY.
iingci" pressed against the cheek opposite the decayed tooth, and from the bulge thus made in the cheek externally a measurement is made upward to a point indicated by the animal's age. In the young horse a slight variation must be made for the backward direction of the fifth molar. The sixth molar in young animals is reflected backward beneath the eye and cannot be satisfactorily repulsed.
For the inferior molars the openings are made at the very border of the jaw in every case except for the fifth and sixth, in which instance it is made upon the most prominent part of the tumefaction caused by the diseased process. For the third, fourth and fifth inferior molars, due allowance must be made for the marked backward direction of their fangs. (See Fig. 115.)
The openings must be made with due deference for the following important structures : (i) Steno's duct.
(2) Lachrymal canal.
(3) Glossofacial artery and vein.
.(4) Superior dental canal and contents.
(5) Inferior dental canal and contents.
(6) Superior maxillary division of the trifacial nerve
near its exit from the skull. In the repulsion of the superior teeth complicated with catarrh a single additional opening is made to drain the fron- tal sinus and to give free access to the maxillary sinus, as well as to drain the frontal sinus into the nasal fossa. This opening is located in an oblique direction downward and in- ward four centimeters from the nasal canthus. (See Fig.
151)
Opening the Skull: — This step of the operation requires the consecutive dissection of (i) the skin, (2) the subcutane- ous areolar tissue and muscles, (3) the periosteum, (4) the bone, and (5) the mucous membrane.
ANIMAL DENTISTRY.
165
Repulsion of the Tooth: — The right hand is placed in the mouth with a finger pressing firmly against the tooth while the left hand directs the punch. The assistant is then di- rected to strike firmly with the mallet until the impression of the blow is felt by the finger against the tooth, and then forcibly until it is driven from its cavity. Failure to trans- mit an impression into the mouth is an indication that the punch is not advantageously located.
Fig. 1 1 6.
Cut Representing the Proper and the Improper Methods of Placing the
Punch to a Tooth to Be Repulsed.
A. Proper method ; punch on a straight line with tooth.
B. Improper method.
Aftercare: — As soon as the tooth is removed the patient is made to resume the standing position. The frontal sinus, maxillary sinus and nasal fossa are then freely opened into each other by breaking down the fragile septa separating them. The cavities are then emptied, irrigated, and wadded with antiseptic cotton. Daily irrigation with 3 per cent zinc
166 ANIMAL DENTISTRY.
sulphate solution and renewal of the wadding for two weeks or until the discharge ceases, is the necessary after-care.
Sequelae:— (i) Alveolo-nasal fistula, (2) persistence of the catarrh and reaccuniulation of pus in the sinuses, (3) per- sistence of the opening (chronic nasal fistula), (4) sep- ticaemia, (5) deglutition pneumonia.
1. Alveolo-nasal fistula, allowing the free passage of food from the mouth to the nasal cavities or sinuses is a common result of repulsion of teeth of the upper jaw in aged horses or from allowing food to pack tightly into the tooth cavity before it has had an opportunity to close. They also occur spontaneously in decay of the first molar or from extrac- tion with the forceps. In the old horse they are prevented by the application of a gutta percha plug between the crowns of the teeth bounding the vacant cavity and in the young horse by preventing the packing of food into the cavity. A tight wadding placed between the crowns after repulsion will not interfere with the healino' and closure of the cavitv. The treatment of the chronic dento-nasal fistula consists of removing the impacted food from the nasal cavity or sinus by trephining and the application of a permanent plug of gutta percha into the channel. To prevent further packing against the plug the opposing- crown is removed. For fistula of the first molar the surgeon may choose between this method and the obliteration of the channel by removing the external alveolar plate and the opposing crown.
2. Persistence of the catarrh will demand a second opera- ation and more precise after-care. This sequel is the result of failure to properly drain the sinuses into the nasal cavity, or careless and dilatory irrigation.
3. Dental fistula or chronic sinuses of the lower jaw, have their origin in bone necrosis, failure to remove the entire tooth or the proper tooth. Reopening of the wound and removal of the insultinc: agent is the remcdv.
ANIMAL DENTISTRY.
167
4. Septicaemia is the result of improper method of op- erating, the use of septic irrigation fluids, or neglect to irri- gate properly.
5. Deglutition pneumonia results from the flow of blood, antiseptic fluid or pus into the lower air passages during the operation. It is caused either from anaesthesia or the use
Fig. 117.
JNIolar Denture of a Young Horse, in Which Extraction is Difficult, Owing to the Deep Implantation.
of the Speculum, which prevents deglutition of fluids which fall into the pharynx.
(3) REMOVAL OF THE EXTERNAL ALVEOLAR PLATE.
(Williams' Operation) . Equipment: — Bone chisel, narrow-blade saw, scalpel, dissecting forceps, artery forceps, mouth speculum, anti- septics, and mouth gag.
168
ANIMAL DENTISTRY
Fig. ii8.
Molar Dc"li;re rf Mature Aliddle Acred Horse.
Fk;. 1 19. Molar Denture of an .\s:e(l Horse, in Wliich Fxtraction is Easy, Owing
to llie Sliallow Implantation.
ANIMAL DENTISTRY.
169
Restraint: — Lateral recumbent position, under chloro- form anaesthesia or local cocainization, preferably the former.
Indications: — This operation should be adopted univer- sally for the removal of the first, second and third superior molars. Applied to the fourth or fifth superior molars a de- formity of the face results from the removal of the extremity of the maxillary spine, and besides it has no advantages
Fig. 120. Chisel.
Fig. 121. Saw.
Fig. I2IA. Mouth Gag. The Most Appropriate Specuhim for Williams' Operation.
over repulsion for these teeth. It may also be applied to removal of the first, second and third inferior molars, but in these it has no special advantages over repulsion. For the first three superior molars, especially the third and second, the operation is almost indispensable, and it out-classes re- pulsion because the almost perpendicular wall of the skull at this point prevents the placing of the punch on a straight line with the tooth, and finally, in repulsing the third tooth the opening, if properly placed, necessitates division of the
170 ANIMAL DENTISTRY.
superior maxillary branch of the fifth cranial nerve near its exit ivoni the infraorhital foramen.
ist step. — Clip, shave and disinfect a liberal space at seat of operation.
2nd step. — ]\Iake a longitudinal (parallel to long axis of skull) incision two inches long- through the skin and muscles directly over the root of the affected tooth.
3rd step. — Separate the soft tissues from the bone from the incision to the gingival margin in the mouth.
4th step. — Saw through the skull along the interdentium on each side of the tooth ; then chisel the bone fiap loose superiorly.
5th step. — Pry the released plate of bone loose with the chisel, and remove with the forceps.
6th step. — Release and elevate the tooth by prying with chisel and mallet.
7th step. — Close incision with sutures and arrest hem- orrhage by packing from wnthin the mouth.
8th step. — Remove crown of opposing molar to prevent packing of food into the cavity.
After-care. — Remove the packing in twenty-four hours. Irrigate daily with mild antiseptic solution, and keep in- cision well protected with clay paste.
(4) REMOVAL OF TEETH BY SPLITTING WITH CHISEL.
This operation is indicated for the removal of the first superior or first inferior molars when the crowns cannot be held in the forceps. It is performed in the recumbent posi- tion with the aid of a mouth speculum. Recently an inven- tor has placed upon the market a tooth chisel shaped like a horseshoe, that can be used to chisel any molar tooth. Such an instrument is of service in splitting and removing badly diseased fangs when major methods are unwarranted, and to serve as a wedge to dislodge the remaining fangs of
Animal dentistry.
171
teeth accidentally fractured in attempts to extract them with the forceps.
EXTRACTION OF THE INCISORS.
Owing to the deep implantation and curvature of the fang, the incisors cannot be readily extracted by any ordi- nary method, except in extreme old age, when the fang has become shortened. During youth and middle age their ex-
FlG. 122.
Cut Showing the Great Length ancl Curvature of the Incisors, that Prevents
Forcep Extraction.
traction can only be accomplished by removal of the anterior alveolar plate and then prying the tooth out with a chisel or elevator. The subject is placed in the recumbent position and the mouth tied shut with several wraps of sash cord around the muzzle. With knife and forceps the mucous membrane and gums are removed over the fang, the peri- osteum is scraped off with a curette and the bone removed
172
ANIMAL DENTISTRY.
with a chisel. When the fang is exposed throughout its entire length the chisel is driven under the tooth and it is pried out.
The incisors of the solipeds and ruminants are seldom decayed to the point requiring extraction. Longitudinal fractures from falls or IjIows may loosen a part of an incisor and provoke decay of the remaining portion, and occasion- ally a persistent temporary with a long fang may demand attention to improve the appearance of the mouth, but aside from these instances extraction is seldom required. The temporary incisors are frequently extracted to give the horse the appearance of being one year older, or when the shed- ding is delayed beyond the usual period.
EXTRACTION OF THE CANINES OF HORSES.
The deep, curved alveolar cavity of the horse's canines, like the incisors, prevents forcep-extraction, in the young animal. They are removed only in the recumbent posture, by the removal of the external alveolar plate and prying with the chisel as in the case of the incisor.
The canines are seldom decayed except from pulpitis and periostitis following injuries to the tooth or jaw.
CARIES.
Synonyms: — Caries dentium, decayed teeth, ulceration of teeth. (It must not be confounded wMth alveolar perios- titis of herbivora).
Definition: — Caries signifies rotteness. As a diseased process it might be appropriately defined as a biochemic de- composition of the dentinal substance originating at one or more points of a tooth. It might also be defined as a pro- gressive disintegration of a tooth's substance, penetrating from the surface toward the center.
Etiology: — The exciting cause of caries is erosion or frac-
ANIMAL DENTISTRY. I73
ture of the enamel covering, through which channel acids and micro-organisms gain access to the sensitive parts of the tooth. The acids dissolve the calcium salts as the micro- organisms decompose the organic material, producing con- jointly a gradual gnawing away of the substance. The progress of disintegration is frequently arrested by the for- mation of a protecting wall around the cavity not unlike the pyogenic wall of an abscess of the soft tissues. This process is due to the calcification of the intra-tubular substance of the dentine. In other events it progresses until the entire tooth has become destroyed.
The acids responsible for the dissolution of the cal- careous matter of the tooth reach the teeth by being in- gested as such, or by the transformation of food products into acid substances. The micro-organisms are the putrefac- tive parasites which normally inhabit the mouth and which only become pathogenic at the proper opportunity. Efforts to isolate a specific organism have thus far failed.
The predisposing causes are numerous. Impairment of the general health during the period of dental evolution, rickets, pregnancy, irregularities of the arcades, meat diet and uncleanliness of the mouth are the chief conditions re- sponsible for the disease.
Susceptible animals. In man caries is the most common of all pathological conditions. Few mature human beings escape its ravages upon the teeth. It is essentially a disease of mature life, although when the predisposing causes are legion even the temporary teeth may be attacked to a re- markable extent. In the domestic animals it is observed occasionally in the old dog, hog and cat. Solipeds and ruminants are comparatively free from caries. In these ani- mals decay of the teeth takes the form of an inflammatory disintegration. (Necrosis, see page 152). In rare cases the dissolution of the herbivorous tooth may undergo a disin-
174
ANIMAL DENTISTRY.
tegrating process which neither resembles caries (the non- inflammatory condition) nor necrosis (the inflammatory condition), and as a result leaves the impression that caries is existent in the herbivorous animals. Caries, the disease of human teeth having its uniform cause, course and termi- nation, is not seen in the herbivora, and the short lives of the other domestic animals places the disease among the rare disorders in veterinary practice.
Treatment: — The carious tooth of dogs, cats and pigs is treated by prompt extraction. Leveling, burnishing and stopping the carious cavity, which constitutes the universal treatment of the disease in the human tooth is an attainment not expected of a veterinarian at the present time, and the
Fig. I22.\. White's Dog Speculum.
rarity of the indications will doul)tless always prevent its introduction into the veterinarv college curriculum.
EXTRACTION OF THE TEETH OF DOGS.
When the teeth of carnivora are loosened from disease their extraction is easily accomplished with the forceps, but when the implantation is not disturbed they can seldom be extracted without fracture. The canines, especially, are firmly imbedded into a curved cavity and will defeat any ordinary method of removal.
The extraction of the teeth of dogs is best accomplished by first disturbing the implantation with a cutting bone for- ceps along each side of the fang before applying the ex- tracting forceps. The molars, canines and incisors may be
ANIMAL DENTISTRY. I75
treated in the same manner. A handy method of securing a dog for tooth extraction is to tie a piece of tape around each jaw behind the canine teeth, then an assistant stands astride of the dog, pinches the head taut between his knees and holds the mouth open with the tape as the operator appHes the instruments. This method is even preferable to the operating table, which places the mouth in an awkward position for extraction.
ABNORMAL ERUPTIONS OF THE TEETH.
Shedding of the incisor teeth depends upon "growth pres- sure" from the permanent successors. If the forming tooth
Fig. I22B. Baker's Dog Speculum.
does not adjust itself directly upon the apex of the temporary fang the latter may remain wedged between two contiguous teeth through life. If this same condition exists in all the incisors the result is a complete double set of incisors.
When such abnormalities are observed early enough the temporary teeth should be extracted. In later years they are best left undisturbed.
The canine teeth frequently remain covered with the gums for several years after their usual period of eruption, and thus cause a more or less painful irritation to the mouth. The condition is observed most frequently in the six and seven-year-old driving horse by the resistance such animals
176
ANIMAL DENTIS'I'RV.
offer to the adjustment of the l)ridle or by shaking the head while driving. The condition is met by lancing the gums, which is best done with the curved scissors.
The molar teeth having temporary prcclecessors, the first, second and third, for obscn-re reasons occasionally cease to grow sufficiently to force out the temporary ones, and as the latter are not sufficiently stable to perform the function of mastication, the whole, area becomes infected and the result is a large tumefaction of the jaw. When the tem- porary teeth arc extracted the dead undeveloped permanent
Fig. 123. A Persisting Temporary Tooth Due to Faulty Eruption of Its Permanent
Successor.
ones are found lying loosely beneath them. This condition is found chiefly on the lower jaw. The condition will always respond promptly to the removal of both the temporary and permanent teeth involved in the process. One, two or all three teeth may be affected.
On the superior jaw osteoma of the maxilla over the third, second or first molars is often produced 1)y backward pressure of the permanent teeth when their dow^nward growth is blocked by a wedged temporary tooth.
These conditions occur in young horses from two to five years old and are often mistaken for decayed teeth or tumors
ANIMAL DENTISTRY. ]77
of more serious import. They may be unilateral or bilateral. If the temporary tooth is already shed the condition must be treated on the expectant plan. Blisters and time will remove the condition in from two months to one year. They seldom persist longer. Removal of the greater portion of the tumor by trephining it from apex to base with a large trephine will hurry the recovery, but there is some danger of producing a chronic fistula that is difficult to heal.
DENTAL CYSTS.
Dental cysts is the name we apply to cystic growths oc- curring along the course of the artery supplying the tooth. They vary in size from small sacs the size of a marble to growths that entirely fill the sinuses and even cause bulging of the facial bones. They are probably the result of athero- matous degeneration in the wall of the nutrient artery of the molar tooth. They frequently become infected and cause alveolar-periostitis, chronic nasal catarrh, or both. Regard- less of size, they completely destroy the nutrition of the tooth by obliterating the nutrient vessel, and after they ex- pel their contents the dead tooth, entirely stripped of its peridental covering, is left projecting into the sinus. During the early stages of the resulting catarrh a diagnosis of the real condition, before operation, is impossible. A tooth so aiTected will finally become loosened and thereby for the first time reveal the true cause of the catarrh. In rare in- stances the projecting root becomes encysted in a new mass of fibrous tissue and remains intact through life. The dental cyst explains the nature of the cause of some of these ob- scure cases of chronic nasal catarrh which are described as primary. When recognized these cysts are treated by re- pulsion of the afTected tooth, which is located by palpation or inspection after the skull has been trephined. The disease
178
ANIMAL DENTISTRY.
is confined to the fourth, fifth and sixth superior molars, and it originates in the young- animal.
ODONTOMATA.
Synonym: — Tooth tumors.
Definition: — A dentinal growth of non-infiammatory origin, occurring on the fangs of the teeth.
Etiology: — The cause of these growths is obscure. The\^
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Fig. 124. Fig. 125.
A Large Odontoma of the 6th Su- Odontomata of the 3rd and 4th Su- perior Molar. perior Molars.
are probably the result of some perversion of their foetal evolution.
Symptoms: — The odontoma may exist unobserved until attempt is made to extract the tooth to which it is attached. The tooth will be easily loosened, but in spite of all efforts it cannot be lifted from its cavity. There is usually a slight tumefaction of the skull over its fang. In the superior ar- cades and on the posterior teeth of the inferior arcades they
ANIMAL DE/NTISTRY.
179
are occasionally determined by monstrosity of the crown. The crown will be found expanded in all directions, often extending well toward the median line of the palate. They may weigh upward to five or six pounds.
Treatment: — The odontoma causing no inconvenience is left undisturbed. When ablation becomes necessary through decay of the tooth or infection of the surrounding perios-
FiG. 126.
An Odontoma of the 2nd Inferior Molar Weighing 5 Pounds. The White
Portion Is the Table Surface of the Original Tooth.
teum, they are removed by first trephining and chiseling the skull over the most prominent part of the tumor, and then dividing it into sections until repulsion is possible.
BRACHYGNATHISM.
Synonyms — Parrot mouth. Receding jaw. Receding chin.
180
ANIiMAL DENTISTRY
Definition — A congenital deformity in which the supe- rior incisors overlap the inferior.
Etiology — A congenital deformity of obscure cause. The deformity consists of a deficiency in the proper length of the inferior maxillary, or an abnormal elongation of the pre- maxilla.
Symptoms — Overlapping of the inferior incisor by the superior ones with more or less elongation of the first supe- rior and sixth inferior molars. The condition becomes more
Fig. 127. A Typical Ca?e of Bracln-gnathism.
and more aggravated with age. As the molars wear away the inferior incisors reach the palate behind the superior in- cisors. Nature, however, seems to meet the condition by hardening of the palate and rounding the premaxilla so as to accommodate the gradual transgression of the inferior in- cisors. There will be difficulty in the prehension of attached food, and the animal will be difficult to keep in good condi- tion.
Treatment — Parrot mouth is a defect for which horses
ANIMAL DENTISTRY
181
must be condemned in an inspection for soundness. The inferior incisors must be shortened by filing from time to time, and the elongated molars must be trimmed to the level of the other teeth. Shortening the superior incisor is useless and inadvisable. Filing or cutting a considerable portion of either the inferior or superior incisors is harmful, as these teeth, having never been subjected to the influence of wear,
Fig. 128. A Typical Case of Prognathism.
are sensitive to the very tables, and will bleed if much of the crown is removed.
PROGNATHISM.
Synonyms — Undershot. Prominent jaw. Prominent chin.
Definition — A congenital deformity in which the inferior incisors overlap the superior. The deformity consists of a
1S:>
ANIMAL DKXTISTRY
deficiency in the proper leni^tli of the jiremaxilla or an elon- gation of the inferior niaxilhi.
Symptoms — Prognathism exists most frcMfiiently in dogs in which animals it is characteristic of certain breeds. It is, however, occasionally encountered in the horse, the molars sharine the abnormality.
Fig. 129. A Typical Case of Parvignatliisni (Ostertag). A, B. The beveled molars. C. 1st inferior molar absent.
Treatment — Tn the dog, none. In the horse the superior incisor crowns are shortened from time to time by filing and the molars are kept level.
PARVIGNATHISM.
Synonyms — Scissor mouth. Ijevcling of the molars. Definition — A congenital deformity consisting of a de- ficiency in tlie proper width of the lower jaw, or more prop-
ANIMAL DENTISTRY.
183
Fig. 130. Parvignathism, with Beveling of the Buccal Surface of the Inferior Molars
//
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Fig. 131.
Samples of Beveled Molars Removed.
Ig^ ANIMAL DENTISTRY.
erly speaking, a deficiency in the proper distance between the inferior arcades, causing a bevehng of the molars.
Symptoms — The l)eveHng is usually confined to but one side. The molars of one superior arcade become beveled from without inward entirely obstructing the lateral motion toward the affected side. The condition is frequently com- plicated with decay of one or more molars, and mastication is almost impossible in the advanced stage. Parvignathism is one of the most serious irregularities of the horse's mouth.
Treatment — With the large lever cutter (Fig. 92), the beveled crowns of the entire superior and inferior arcades must be trimmed almost to the level of the gums, beginning with the first tnolars, and the decayed teeth, if any, must be removed. This treatment, while placing one-half of all the molars entirely "out of commission," w^ill be met by prompt relief to the patient.
PROJECTIONS ON THE FIRST SUPERIOR AND SIXTH INFERIOR MOLARS.
Definition — A universal irregularity existing in the molar arcades of all mature horses, consisting of sharpened points of enamel at the anterior end of the superior arcades and the posterior end of the inferior arcades.
Etiology — The aggravated forms due to such gross de- formities as brachygnathism or congenital or acquired de- ficiency in the proper length of one or both arcades are not included in this category. The large elongations occurring at the extremities in either of the molar arcades are usually due to a deficiency in the length of the opposing arcade, but in this minor irregularity the lengths of the arcades are equal. These points are caused by the position of the muscles of mastication. The fixed attachments of all the muscles of mastication except the masseter and external
ANIMAL DENTISTRY. 185
pterygoid are located posteriorly, and therefore lift the jaw slightly backward at each contraction. The absence of any muscle with an anterior fixed attachment to antagonize this backward traction is the cause of these universal irregulari- ties. The masseter's influence in that connection is insuf- ficient.
Treatment — In driving horses the anterior ones wound the mucosa and require filing.'
PROJECTIONS ON THE SUPERIOR CORNERS.
(See Fig. 72.)
At about the age of seven years there appears on the superior corner incisor a sharp enamel point which in most instances will disappear during the three ensuing years. This irregularity is due to a congenital deficiency in the di- mension of the inferior corners. They disappear under the influence cited in the preceding paragraph, i. e., the back- ward traction by the muscles of mastication.
ACQUIRED ELONGATION OF THE MOLARS.
Definition — Projections of the molars into vacant cavi- ties on the opposing arcades.
Etiology — The common cause of elongation of this vari- ety is the loss of a molar by extraction. They occur also from the decayed molar that offers no adequate wearing surface for its opponent. Occasionally in old age the molars become excavated from a defect in texture.
Symptoms — Defective mastication, rejection of food, ac- cumulation of food beneath the buccinator and tumefaction of the jaw are the signs usually directing the attention to such teeth. Palpation and inspection will reveal a large tuberous projection involving one or two teeth in one ar- cade, and a vacant tooth cavity or a decayed tooth, in the
186
ANIMAL DENTISTRY.
opposing one. In the aggravated forms there will also be a considerable excavation of the jaw in the vacant cavity. Owing to the frequency of decay in the fourth superior molar the condition appears chiefly in the region of the fourth in- ferior molar.
Treatment — Trimming to the level of the arcade with the lever cutter in young animals and extraction in the aged patient. In horses more than fifteen years old the implan- tation is so unstable that the cutting process may loosen the tooth.
Fig. 132. Typical Case of Elongation of the 4th Inferior Molar (Ostertag).
OPERATION OF CUTTING ELONGATIONS.
Restraint — Standing position with the dental halter and without the use of the speculum. The speculum will pre- vent placing the cutter evenly over the crown of the tooth.
Equipment — Dental halter, open molar cutter, floats and file.
Modus Operandi — For the left side guide the head of the cutter to the tooth with the left hand, as the other hand supports them by the handles. Place the left handle
ANIMAL DENTISTRY.
187
of the cutter against the chest and open it with the right hand, then adjust the jaws over the base of the elongation. Retract the left hand and cut off the tooth with both hands. In the superior arcades the great volume of the elongation may necessitate the application of considerable force. Care
Fig. 132a. (Also Fig. 92.) The Open Molar Lever Cutter.
must be taken in aged horses, and in the case of the molars at the extremities of the arcades, that the tooth is not loos- ened by a sudden movement of the patient's head. After cutting the elongation the arcade is leveled with the floats
Fig. 132b. (Also Fig. 98a.) Handles for Figs. 92, 92a, 94, 94a, 95, 97 and 98.
and file. Small pointed projections on the inferior arcades may be cut with the closed molar trimmers when they are too narrow for the large opening of the lever cutter.
ENAMEL POINTS.
Synonyms — Sharp teeth. Lateral enamel projections. Enamel points of herbivora.
Definition — Sharp points of enamel at the table extrem-
188 ANIMAL DENTISTRY.
ity of the lonp^itiulinal ridges of the molars, occurring rilong the buccal border of the superior arcades and the lingual border of the inferior.
Etiology — Enamel points are not pathological. They are a normal part of the dental mechanism, serving the pur- pose of a rake to maintain fibrous forage between the teeth. Being normal structures their causes are strictly of an in- tended, predisposing character, namely:
(i) The relative narrowness of the inferior molars.
(2) The relative narrowness of the lower jaw.
(3) The ginglymoid character of the temporo-maxil-
lary articulation, limiting the lateral motion of the jaw.
(4) The longitudinal ridges, the enamel of which ren-
ders possible the formation of points.
(5) The herbivorous characteristic of which three
substances of unequal densities are in wear.
(6) The normal wear of the teeth.
Symptoms — Under strictly natural conditions they are not harmful, but from the artificial influences to which the horse is subjected they frequently wound the buccal sur- faces. The widely accepted impression that they limit mas- tication by obstructing the free lateral swing of the jaw is not founded upon facts. Their sole harmful effect is the wound- ing of the mucous membrane. The wounds are usually lo- cated on the cheek opposite the first and second, and fifth superior molars. The former are caused by the friction of the bit and bridle and the latter by the forcible movements of the masseter muscle. The lesions vary from slight ero- sions of the mucous membrane to large ulcer-like patches one inch in diameter. Other parts of the cheek and the tongue are seldom wounded. They attain the greatest size between the ages of 5 and 8 years.
Wounds of the cheeks which are being perpetually ag-
1
ANIMAL DENTISTRY. 189
gravated by enamel points limit mastication and favor gas- tric indigestion. In drivers, runners and saddle horses they are the greatest sources of annoyance. The expert reinsman will promptly recognize their presence by the horse's be- havior in harness. Lugging, side-reining, ptyalism, tender- ness about the seat of bit, manifestations of pain from the bridle are symptoms of these lesions.
Treatment — The treatment consists of filing with the floats and file. Trimming with the closed molar trimmers (Fig. 91) preceding the filing cannot be defended by any logical argument. If this instrument could be accurately adjusted to the very tips of the points, as they are intended, they would materially lessen the labor of the operation, but as only the very skillful operator can properly accomplish this feat, the use of the trimmers should be dispensed with in the interest of judicious and scientific dentistry. A few carefully directed strokes of the fioat equipped with the rasp blade will rapidly blunt the sharp projections to the desired point. Rounding the borders of the molars is harmful. The aim in dressing the teeth of a horse should be to simply blunt the enamel points along the course of the arcades and to "round up" the first superior and first inferior molars as smooth as an ivory ball. The wounds from the bridle are thus prevented and there will be no interference with mas- tication from the too liberal use of instruments along the whole arcade. The closed incisor trimmers are indispensable to trim the projection at the extremities of the arcades, and on the first inferior molar the angular trimmer may be used. (Fig. 98.)
OPERATION OF TRIMMING AND FLOATING THE MOLARS.
Equipment — Straight float, angular float, closed molar trimmers, twelve-inch file, a pail of water, and the dental halter.
190 ANIMAL DENTISTRY.
Restraint — The horse is secured in the stan(iin_£^ position, backed into a single stall and fastened to the pillar with the dental halter. The halter ropes are fastened to the pillars low enough to hold the head at the proper height. When the construction of the pillars prevents tying the ropes low enough, an additional rope is fastened from the halter at the lower extremity of the iron band and passed between the forelegs around the withers, and back again between the legs to the halter, for the purpose of preventing the head from being held too high. This method is also serviceable in securing horses in a loose box or paddock where stalls are wanting. (See Fig. 105.)
The mouth speculum must be dispensed with, as it posi- tively interferes wnth the free use of the instruments and provokes resistance, which is otherwise avoided. The twitch also is contra-indicated, even on the vicious animal.
The aim in securing the horse, as in performing the oper- ation, is to avoid the use of any force that will be resented.
Examination of the Mouth — First, the incisors are in- spected to determine the age and the presence of any harm- ful disorders or irregularities. Then the palmar surface of the thumbs is passed along the interdental space of the lower jaw to locate possible bit lesions, and without withdrawing them they are turned upward against the interdental space of the upper jaw to palpate for wolf teeth. Third, the mo- ^ lars are palpated by passing the hand backwards between the tongue and molar arcades. (See diagnosis.)
Modus Operandi — The canines may first be blunted with the twelve-inch file, to prevent wounding the hands, but the blunting process must be limited to the very tips of the crowns, owing to the fact that a short blunt canine gives the appearance of age, and thus leaves an opportunity for just criticism.
The second step of the operation consists of trimming the
ANIMAL DENTISTRY.
191
ends of the arcades, with the closed molar trimmers, but only when the projections are long enough to warrant their use. The first superior molar and the sixth inferior alone require this treatment, in the normal mouth.
The remainder of the operation — the floating and filing — is performed as follows: . •
1st. Float the posterior two-thirds of the right superior arcade, with the straight float, the anterior one-third with the angular float, and then blunt the anterior end of the first molar with the twelve-inch file.
2nd. Observe the same routine on the left superior ar- cade.
Fig. 89.
Fig. 89a. Straight and Angular Floats, with Lines showing the Proper Angle of
Each.
3rd. Float the entire left inferior arcade with the straight float, and bevel smoothly the anterior end of the first molar with the twelve-inch file.
4th. Observe the same routine on the right inferior ar- cade.
5th. Extract wolf teeth, if any exist, and complete the operation by blunting any sharp projection, on the superior molar, that may exist behind them, and which could not have been reached prior to their extraction.
It will be observed that in the above routine the arcades beginning with the right superior, are dressed consecutively. The work on each one is completed before passing to the next, until all four have been perfectly attended to. The
192
ANIMAL DENTIS'I'RY.
only ol)jcction to this order of manipulations is the loss of time consumed in changing instruments. When speed is a consideration, all the work required of each instrument is completed before the instrument is laid aside, as follows:
1st. Float the posterior two-thirds of the superior ar- cades, and all of both inferior arcades, with the straight float.
2nd. Float the anterior one-third of the superior ar- cades, with the angular float.
3rd. Blunt and bevel the ends of the arcades with the twelve-inch file.
Whatever is adopted, it will be found advantageous to
Fig. 90.
form the hal)it of following the routine in either plan, in order to avoid omissions and unnecessary examinations of the mouth to determine the amount of filing that has been done. It is an error to use the floats promiscuously and to repeatedly palpate to note the results. Such methods pro- voke resistance, which is avoided in more systematic work.
METHOD OF USING THE FLOATS AND FILES IN THE FORE- GOING OPERATION.
It is undeniable that one operator can float the teeth of horses, and in fact, use any of the dental instruments without provoking the least resistance, while another will have more or less troulile with every animal approached. So marked is the difference in this connection that bystand-
ANIMAL DENTISTRY. I93
ers frequently gain the impression that some operators exert a mysterious influence over their patients. The secret Hes solely in avoiding the use of force. A horse will resent forcible opening of the jaw, forcible insertion of the hand backwards into the molar region, forcible restraint, and injury to the soft structures inflicted by improperly directed instruments. In avoiding these manipulations the secret is found. Forcible opening of the mouth is unnecessary in
Fic. 133. Position of Hands to Float the Right Superior Molar Arcade.
using the float. As only the edges of the arcades are floated the instrument may be passed unobstructed to their very end without opening the mouth more than half an inch. In the lower arcades the hand must be passed into the inter- dental space to guide the shaft of the float, and, as a result, the mouth is opened slightly more than in floating the superior ones, but to prevent resentment, the hand in the interdental space must not be used to force the mouth open when the animal attempts to close upon it. Its pres-
194
AXl.MAL DI-'-XTISTRY.
ence there is simply to i^uidc tlic tUjat and not to open the mouth. Injury to the hand is prevented Ijy keeping it where it cannot be squeezed when the mouth is closed. Resistance is usually provoked in this manner by forcibly attempting to prevent closure of the moutli in fear of being bitten. The operator must learn to place the hand only where it cannot be bitten or squeezed, and the horse must be permitted to use its jaw ad libitum. The dental operation must not be a
Fig. 134. Position of Hands to Float the Left Superior Molar Arcade.
fight for superiority in strength between the dentist's hand and the patient's jaw. The following position of the hands to guide the instruments will serve the purpose.
For the right superior arcade place the tips of the fingers of the left hand palm upwards, into the interdental space, just in front of the commissure, or, in other words, in front of the first superior molar. Work the float with the right hand and guide its shaft with the palmar surface of the fingers of the left. In this position the finger tips are not
ANIMAL DENTISTRY.
195
passed beyond the outer border of the jaw (upper branch of the premaxilla) but are fortified gently upon it. The float head is kept flat against the outer edge of the arcade and not upon the table surface. (See Fig. 133.)
For the left superior arcade pass the left hand, palm up- ward, through the interdental space, from right to left, until the tips of the fingers protrude slightly from the left commis- sure, and let the thumb rest easily on the palate in the re-
FiG. 135- Position of the Hands to Float the Left Inferior Molar Arcade.
gion of the first superior molar. Work the float with the right hand and guide the shaft with the palmar surface of the fingers of the left. (See Fig. 134.)
For the left inferior arcade pass the left hand, palm down- ward, through the interdental space, from right to left, under the tongue, and when the left border of the tongue is reached with the finger tips, direct the hand upward between the tongue and left arcades (the dorsal surface to the tongue and palmar surface to the arcades), and let the thumb pro-
196
AMMAL l)i;\'riS'l'RV
trmlc thr()Ui;li the left commissure. In this position the anterior end of the arcade h'es between the tluimh and first finger, and the wrist is kept Hat on the interdental space of tlie lower jaw, to keep the tons^ue from slipping beneath it. The float is worked with the riglit hand, and the shaft is guided by the palmar surface of the base of the thumb. The fioat head is kept flat against the internal border of the arcade, and not (^n tlie tables. (See Fig. 135.)
Fig. 136. Position of tlie Hands to Float tlic Riglil Inferior Molar Arcade.
For the right inferior arcade i)lace the right hand in the same relative i)osition as the left was placed for the oppo- site inferior arcade, and work the float with the left hand. Although the left hand is the awdcward one, it is advisable to train it to accomplish this feat, as it is the only position that will give universal satisfaction. Another method con- sists of placing the left hand upright into the interdental space and guiding the shaft between the second and third, or third and fourth lingers. Still another method consists
ANIMAL DENTISTRY.
197
of passing the left hand into the interdental space, through the right commissure, grasping the free end of the tongue firmly with the fingers and then passing it gently out of the opposite commissure. In this position the float is worked with the right hand, and the shaft is guided by the wrist, which is slightly arched upward into the roof of the mouth. The right inferior arcade is more dif^cult to float than the others and as a result is usually found neglected posteriorly. (See Fig. 136.)
Fig. 137. Position of the Hands and File to Blunt the Right First Superior Molar.
To blunt the right first superior molar place the left hand into the right cominissure between the cheek and the molar arcades, then pass the twelve-inch file (in the right hand) through the interdental space from the opposite commissure to its finger tips. Work the file with the right hand and guide it around the end and side of the arcade with the finger tips of the left. Change positions to round the arcade an- teriorly and internally as follows : Place the left hand to- ward the nasal roof and the thumb into the commissure to
198
ANIMAL DENTISTRY
retract and elevate it. then work the file with the right hand. (See Figs. 141-137.)
To blunt the left first superior molar place the right hand in the left commissure, between the cheek and teeth, then pass the twelve-inch file through the interdental space from the opposite side to the finger tips of the right hand. Work the file with the left hand and guide it with the linger tii)s of the right. Change the position to bhmt the anterior end of
Fig. 138. Second Position of tlie Hands and File to Rlunt the Left l-'irst Superior
Molar.
the tooth, as follows: Place the palm of the left hand over the nose and with the thumb retract and elevate the com- missure of the mouth, then work the file with the right hand as in filing the opposite side. (See Fig. 138.)
. To bevel the right first inferior molar place the palm of the left hand on the inferior border of the lower jaw, and re- tract and depress the commissure with the thumb, then work the file with the right hand. (Fig. 139.) Change the position
ANIMAL DENTISTRY.
199
as follows : Pass the file through the interdental space from left to right, and hold it upon the tooth with the thumb of the left hand, then work the file by short movements of both hands.
To bevel the left first inferior molar open the mouth gently by grasping the tongue and turning it perpendicularly in the interdental space ; then work the file over the molar with the right hand. The beveling process may be pre-
FiG. 139. First Position of the Hands and ImIc to Revel and Blunt the Right First
Inferior INIolar.
ceded, to advantage, by first trimming the anterior angle of the crowns with the angular cutter. (See Fig. 140 )
The above is simply "a" method by which the sharp points on the molars may be blunted with but little labor, and without provoking resentment from the horse. Other meth- ods may serve the same purpose, providing they can be carried out without the use of force.
Occasionally a horse that has been roughly handled or
200
ANIMAL DENTISTRY.
one that has never l)econK' accustomed to l)eing handled about the head, will resent the attempt to open the mouth when first approached. Such animals can never be conquered by force or rough treatment, sufficiently to enable the operator to properly carry out the procedure, but by the use of kindness and gentle manijmlations to first gain the patient's confidence, few dental operations need be abandoned on account of resentment. It will be found that
Fig. 140. Position of the ITaiifl and I''ile to Revel and RInnt the Left First Inferior
Molar.
the most resistance is offered by such horses while the float is being adjusted to the teeth or while the hand is being- placed in position to receive the float, and that the resistance immediately ceases as soon as the filing begins. The re- markable fact that a horse will stand "at attention" while the rasping proceeds suggests itself as a method of taking advantage of a resisting horse. Instead of first placing- the hand into the interdental space, the float may first be
ANIMAL DENTISTRY.
201
promptly passed into the mouth, and as the horse becomes attracted by the unusual sound and sensation produced by the filing no further resistance may be offered and the hand may then be placed unresented into the interdental space to guide the float.
Enamel points will recur in about three months, but not to a sufficient degree to produce injuiy until the twelfth to the eighteenth month after the operation. At the age of five
Fin. 141.
Position of the Hands and File to Complete the Rlnnting Process on the
Superior Molars, Externally.
to eight years their recurrence is more rapid than in aged animals.
Modifications — \\'hen one of the arcades contains a de- cayed or elongated molar the normal arcades are floated and filed before any attention is given to the abnormal one. The painful part of the operation is performed last to avoid the resistance that might be provoked thereby, and when a tooth is extracted, to avoid working in a bloody mouth.
202 ANIMAL DENTISTRY.
In very vicious animals the recumljcnt position may be neces- sary to properly trim tlic molar teeth, hut such animals are rarely encountered. In our experience with upwards of fifty thousand horses only two such cases have been met — one was a trotting bred stallion and the other a hackney gelding. Both of these animals would resent any attempt to place a float into the mouth l:)y striking viciously with tlie fore feet. In such cases the veterinarian is warranted in resorting to an appropriate means of restraint, in the recumbent position.
FLOATING THE TEETH OF THE OX.
The ox carries the head low, has an imyielding tongue and a strong jaw^ and is so unaccustomed to being handled about the mouth that it makes a rather unwelcome subject for dental operations. These obstacles are met by securing the head and neck to the post of the stall, in an upward inclination, and by keeping the mouth open with a strong speculum consisting of an ol)long loop of iron placed within the interdental s])acc. The ordinary horse speculum is too frail to withstand the forcible jaw of an ox.
The superior arcades are floated with the hand in the same position as in the horse, but in the inferior ones it is kept in the interdental space and not between the tongue and teeth. The float is directed from within outward to follow the direction of the arcades.
Enamel points are less harmful in the ox owing to the toughness of the buccal mucosa, yet buccal wounds from sharp teeth are not uncommon in animals past the age of three years.
WOLF TEETH.
Synonyms — Remnant teeth. Supernumerary teeth. Sup- plementary teeth. I'^ye teeth.
Definition — The wolf teeth may be defined as retrogres- sive teeth representing the premolars of the prehistoric
ANIMAL DENTISTRY
203
horse. They are not the result of accidental dental develop- ment but a constant normal part of the equine denture un- dergoing degeneration under the influence of selection, as the "wisdom teeth" of man are disappearing under the in- lluence of civilization. The use of the bit through innumer- abe generations appears to have rid the interdental space of the premolars.
Wolf teeth are constant in foetal life in both the inferior and superior dentures, and many of them never develop to the point of eruption, but instead degenerate, and become incorporated with the maxilla. Those which finally erupt vary from small homogeneous masses of soft dentine to well
Fig. 142. Wolf-Teeth.
developed teeth possessing all the distinguishing character- istics of the herbivorous molar.
Symptoms — Wolf teeth are harmless with the exception of their possible interference with the overcheck bit or com- plicated coach-horse rigging, such as bridoons. They have no effect upon the eyes, and are diagnosed solely by palpa- tion. Their position is the interdental space of the upper jaw, more or less closely related to the first molar. In some instances they are located on the inner aspect of the molar and occasionally on the lower jaw.
Treatment — The wolf tooth should be extracted, as it serves no useful purpose and may at some time interfere
204 ANIMAL DKN'IMS'l'RV.
with the bitting ri^g^ing of a driving horse. In the treat- ment of eye affection their extraction is particularly advis- able, owing to the popular prejudice against them.
They are difficult to extract without fracture because their location j^rexents direct outward traction and l)ecausc of the impossibility of perfectly immobilizing the head and especially the lower jaw. Their removal is accomplished by first disturbing their implantation with the wolf tooth sep- arator (Fig. 93) prior to the application of outward traction with the forceps, or with the separator alone.
Fig. 143. Supcrmimcrary Incisors of a 6- Year-Old Gelding.
SUPERNUMERARY TEETH.
Definition — Teeth existing in excess of the normal num- ber in any of the arcades, are designated as supernumerary. 'Jliey must be differentiated from wolf teeth, which are nor- mal structure and from persisting temporary teeth, due to displacement of the permanent tooth germ.
Etiology — The supernumerary teeth result from the pro- jection of more than one stalk from the common enamel germ. This occurrence is frequent if not universal, but un- der normal development, all the stalks degenerate as a chief one predominates. Whenever two or more keep pace witli one another until tooth development is well advanced, the
ANIMAL DENTISTRY.
205
result is the formation and growth of more than one tooth at a given point. Some such teeth may never erupt, but remain imbedded in the jaw along the arcade.
An additional seventh molar frequently occurs behind the sixth in either arcade. This incident is the result of the
Fig. 144. Supernumerary Incisors of a 9-Year-Old Horse.
backward extension of the common enamel germ from pre- cocity of the sixth molar.
Symptoms — The abnormality is observed chiefly in the incisor arcades which may contain an entire double row of teeth. In most instances one or two additional incisors are
Fig. 145. Supernumerary Molars.
observed projecting in an irregular fashion to the table level of the arcade. The lateral incisors are most frequently the seat of the abnormality.
In the molar arcades they may remain hidden through
206 ANIMAL DKX'nSTF-iV.
life, or remain un()l)scr\c(l until their existence is revealed in the treatment of diseased conditions — extracting, trephin- ing, etc.
Treatment — As long as the supernumerary tooth pro- duces no apparent harm no treatment is advisable. In the incisor arcades their extraction gives even a worse appear- ance to the arcade than if they had been left undisturbed. When encountered within the sinuses in the course of den- tal operations they are removed or left undisturbed, ac- cording to whether they are involved in the morbid process.
ELONGATIONS OF THE INCISORS.
As decay or loss of incisor teeth is a rare condition ac- quired elongations of the incisors by growth into vacant cavities are also rare. The gradual lengthening of the whole superior incisive arcade as an animal becomes older is a natural condition resulting from a gradual receding of the alveolar border, and the constant increase in the inclination.
The common impression, especially among laymen, that the elongation of the incisors prevents contact of the molar denture is erroneous. The only detriment is the evidence they furnish of the real age of the animal, on which account alone their shortening is advisable. Shortening the superior incisors of the old horse is always harmful in proportion to the amount removed. Prehension of attached food is im- paired.
SHORTENING THE INCISOR TEETH.
The incisor teeth of the horse are reduced in length for the purpose of disguising the evidence they furnish as to the age of the subject. The popular impression that they prevent contact of the molars is as positively ridiculous is it is physically impossible. The incisors can only wear as fast as the molars will permit them, and vice versa. In rare instances the veterinarian is re(|uired to reduce their length,
ANIMAL DENTISTRY.
207
to hide the crowns beneath the hps, when the latter no longer cover them completely, in which case only the operation is excusable.
The operation is performed only upon the superior ar- cade, as the inferior one is seldom inspected for its senile changes.
Modus Operandi — First, cut ofY the internal table angle of each corner tooth and file them to the length decided upon, and then use the length as a guide for reducing the remain- der of the arcade. Second, file a deep groove, through the enamel across the laterals and centrals connecting the new table level of the corners. Third, cut off the laterals with
Fig. 14S.\. Fig. 145b.
Lip Retractor and Mouth Gag, useful in shortening incisor teeth.
the nippers and file them to the level of the corners. Fourth, cut off the centrals and file them to the level of the laterals. Fifth, bevel the tables backwards by patient filing. Sixth, remove the crusta petrosa and tartar and polish with emery paper.
In cutting the incisors great care is necessary to prevent chipping of the enamel, which accident will leave an un- sightly defect in the arcade. The accident is prevented by cutting the transverse groove completely through the enamel and by not grasping too much substance with the nippers. It is preferable to cut an incisor tooth by small sections, rather than by grasping the entire crown.
208 ANIMAL DKNTISTRV.
EROSION OF THE ENAMEL.
Definition — A disease of the anterior face of the superior incisor teeth, cliaracterized l)y a i^ra(hial n])\var(l denudinu,- of the external enamel covering.
Etiology — The cause depends solely upon a faulty con- struction of the teeth, both anatomically and morphologi- cally. The disease occurs in animals having an observable softness of all the teeth. The dentine is devoid of its char- acteristic hardness and the crusta petrosa is deficient in qual- ity as well as quantity. Defective cementing of the enamel to a soft underlying dentine favors the gradual breaking and wearing away of the former. Iron feed boxes, cribbing and the habit of gnawing hard objects hurry the denuding process, but are never solely responsible.
Treatment — Polishing with emery paper to give a better appearance is the only possible help.
TARTAR.
Definition — An accumulation of calcareous matter along the gingival margin of the teeth.
Etiology — Tartar simulates calculi in other parts of the body. It is the result of the chemical action of saliva and mucus on the calcium sa'ts of the food. It is composed of
Phosphates 80.
Mucus 1 1.5
Ptyaline i.
Animal matter 7.5
Symptoms — Tartar occurs as a yellow incrustation along the gums. In animals it is found mostly on the canines and incisors; on the canines it frequently accumulates in large quantities and gives the crown the appearance of a mon- strosity (odontoma). It is difTerentiated from the latter by being readily removed, and from the normal crusta petrosa
ANIMAL DENTISTRY. 209
by its lighter color and by not adhering firmiy to the crown. Treatment — Tartar is removed with a curette or file. It produces slight irritation of the gums.
FRACTURE OF THE TEETH.
Fracture of the teeth occurs to the incisors from falling or stumbling on hard pavements, blows or kicks from other animals. The molars seldom sustain such injuries. Frac- ture of incisors is usually complicated with considerable con- tusion and laceration of the lip. The fractured loose sections must be removed and the lip treated according to the char- acter of the injury.
SPLITTING OF THE MOLARS.
Synonym — Fissuring of the molars.
Definition — A condition peculiar to the molars of her- bivorous animals consisting of a division of a decayed molar into two or three plate-like segments.
Etiology — Splitting of the teeth is an incident of the ad- vanced stage of decay. It is not a separate entity nor an accident. Pulpitis, alveolar periostitis and the subsequent necrosis following these inflammatory conditions, deprive the tooth of its nutrition and moisture, and the resulting desiccation, predisposed by the "layer arrangement" of the tooth, favors splitting and fissuring as a termination of the disease process. In the long process of decay which the molar teeth undergo, splitting is the incident preceding the final ejection of the tooth from its cavity — self-extraction.
Fissuring limited to the buccal or lingual surface of the crown in the absence of any gross lesion is also of common occurrence to the back molars of both arcades. This condi- tion is evidently due to an inadequate union between the external enamel and dentine of the crown, and greatlv re-
210 AXl.MAL DHNTIS'IRV.
scniblcs the abnormality of the incisors known as "erosion" or "ilenuchni^." It is a harmless condition in itself, Ijut should be regarded as evidence of a poor quality of teeth.
Pathological Anatomy — The incfdent occurs most fre- fjuently to the superior molars, Init is seen also in the in- ferior ones. The splitting may be limited to the crown or may extend through the entire length of the tooth. In the greatest number of cases it terminates just l)eyon(l the al- veolar margin on the lingual side of the tooth, dividing it into two very unequal segments, one of which comprises the principal part of the tooth, and the other a thin shell consist- ing of the crusta petrosa and external enamel.
In other instances the tooth is broken into three seg- ments— two lateral shells and a central large one, which in- cludes the fang and roots.
In rare cases a superior molar is divided into two equal portions by splitting from table to root between the two layers of the internal enamel.
The condition is complicated with considerable osteitis and necrosis from lateral pressure against the alveolar mar- gin, and from the decomposition of impacted food. In the old case the opposing tooth will be found elongated and the tongue and cheek may be severely wounded from friction of the protruding segments.
Treatment — Removal of the tooth and leveling of the opposing arcade. (See extraction.)
FOREIGN BODIES IN THE MOUTH.
Foreign bodies become lodged in the mouth of all the do- mestic animals. In the horse and ox pieces of corncob and sticks of wood become wedged between the superior arcades, and pins, tacks and splinters lodge between the teeth: In the dog, cat and i)ig, pieces of bones are frequently found.
ANIMAL DENTISTRY. gll
In one case a tack was found firmly lodged in the infiindibii- lum of the lateral superior incisor.
Diagnosis — Attention is attracted to disturbed mastica- tion, rejection of partially masticated food, disinclination to eat, ptyalism and later to the fetor caused by pressure necro- sis, and the decomposition of food.
Treatment — Removal of the object followed by irriga- tions of the mouth with solution of borax, alum or boric acid.
FRACTURE OF THE INFERIOR MAXILLA.
Varieties :
(i) Simple fracture of the neck of one ramus.
(2) Simple fracture of the neck of l)Oth rami.
(3) Simple fracture of one ramus along the molar
arcade.
(4) Fracture of the angle without dental complica-
tions.
(5) Comminuted fracture along the molar arcade.
(6) Fracture near the articulation.
Etiology — Kicks from horses sustained as the victim is walking through the stable aisle is the most common cause of fractures of the inferior maxilla. Collisions with vehicles and cars and other forms of violence seldom fracture this bone. Solutions in the continuity of the ramus from bit gnathitis is an occasional cause (see page 214). And finally too forcible blows on a misdirected punch while repulsing teeth occasionally fractures the jaw. In the dog and cat the bite sustained during a fight is the chief cause of this injury.
Symptoms — The diagnosis of fractured inferior maxilla is by no means a simple matter under all circumstances. The subject is usually presented several days after the accident, at which time the tumefaction will require differentiation from other diseased condition characterized by enlargement of
212 ANIMAL DENTISTRY.
the inferior maxilla. In the recent case tlie diai^nosis is equally difficult owing to the ]ial)i]ity of the fracture remain- ing a suhperiosteal one until displacement occurs from move- ments of the jaw, some days later, at which time the condi- tion continues to be masked by swelling.
Deformity at the angle, crepitation or movement of the fractured ends felt within the mouth as the jaw is moved with the other hand, and the loosening of one or more mo- lars, wiU confirm a diagnosis, but in the al)sence of these plain pathognomonic symptoms the nature of the injury may remain masked tmtil an abscess forms and points to the
Fir;. 146. A Well Healed Comminuted Fracture of the Inferior Maxilla, with Dental
Complications.
surface and thereby admits direct palpation of the bone Fracture of the neck of one or both rami is easily recog- nized by palpation.
In addition to the above phenomena there is always a serious disturbance to mastication. There will be little in- clination to eat during the first days, but finally, from sheer starvation, food will be ingested unmasticated, in which condition it will be found in the feces. The subject will lose flesh rapidly, become emaciated, suffer from colics and probably die.
Treatment — The principal treatment consists of feeding crushed f(KKl and licjuid food, in order to prevent unnetessary
ANIMAL DENTISTRY. 213
use of the jaw. Appliances to immobolize the fracture are never satisfactorily retained, and prove of little service. When abscesses form their contents are evacuated and the wound searched for comminuted segments. The loose teeth must be extracted.
In fracture of both rami near the incisor teeth, in small animals amputation can be successfully performed.
Prognosis — In young animals even the severe commi- nuted fractures may reunite by an extensive deposit of new bone, and the patient make a rather tardy recovery with con- siderable permanent tumefaction of the jaw. In old animals the bad fracture is always fatal. Fractures of one ramus near the neck is not serious and will reunite with but little deformity and only slight interference with the general health. Fractures without dental complication are less seri- ous than those involving the molar teeth.
FRACTURES OF THE PREMAXILLA AND SU- PERIOR MAXILLA.
Although the premaxilla is an exposed bone, its fracture is remarkably rare. The superior branch is occasionally fractured from a kick, and the body from a fall upon the incisor teeth. The superior maxillary is frequently frac- tured conjointly with the other facial bones as a result of kicks or other of the usual forms of violence. Owing to the fixed articulations of these bones fractures recover promptly and without much deformity. Crushing of the maxillary spine leaves a somewhat unsightly blemish, but otherwise these lesions are not serious.
DISLOCATION OF THE TEMPORO-MAXILLARY ARTICULATION.
Etiology — This dislocation is possible only in the car- nivora. In the herbivora the arrangement of the condyle and
214 ANIMAL DENTISTRY.
coronoid process prevents luxation. In the dog it occurs while masticating bones, or in yawning.
Pathological Anatomy — The dislocation is a forward one in all instances and like all luxations is accompanied with considerable injury to the binding and secretory ligaments. It is usually bilateral, but may be unilateral.
Symptoms — Inability to close the mouth is the pathogno- monic symptom. The jaw will be locked open and cannot be closed 1)y force. In the unilateral luxation the jaw is open but is turned to one side.
Treatment — A piece of hard wood two feet long and about one-half inch thick, wide enough to rest along both mferior arcades, is firmly fastened to the lower jaw (within the mouth) l^y wrapping with strong cord. The stick thus adjusted is then used as a lever to depress the jaw pos- teriorly. When sufficient pressure is brought to bear the condyle snaps into its cavity.
BIT GNATHITIS.
Synonyms — Bit contusions. Fractured jaw. Bit sores.
Definition — A traumatic inflammation of the interdental space of the low^er jaw^ produced by bruising with the bit.
Etiology — Bit gnathitis is caused by the use of harsh bits, especially curb bits. The straight or snaffle bit will occasion- ally produce the trouble in horses inclined to "pull" heavily upon reins in the hands of a powerful reinsman. Habitual "pullers" are the susceptible subjects, when attempts are made to control them by the use of harsh riggings. The condition is seen most frequently in the coach horse, saddle horse, hunter and polo ponies, and in the light harness horse that is difficult to control.
Pathological Anatomy — The lesion consists of an intense local stomatitis, periostitis and osteitis occurring simultane- ously. The indammatory action may be confined to a small
ANIMAL DENTISTRY. 215
circumscribed area at the very edge of the jaw, or extend across the entire ramus to the inferior border. Tbe process subsides by the separation of the bone from the soft sur- rounding structures, and by the exfoliation of a sequestrum the size of which will vary with the extent and severity of the pre-existing inflammation. Complete division of the ramus may result in the extremely aggravated forms.
Symptoms — Tenderness manifested in adjusting the bit, ptyalism, side reining and disinclination to "take" the bit are prominent symptoms. Palpation and inspection of the inter- dental space will reveal a wound in the mucous membrane. The abrasion is usually large enough to expose the edge of the jaw, which is easily felt with the finger. In other cases the mucous membrane may remain intact with the exception of a small almost imperceptible opening which, if enlarged with a bistoury, will reveal the bare jaw beneath. In the early stage, before the abscess points, there may be con- siderable swelling externally across the ramus, giving tlie appearance of an external trauma. In the advanced state of the process, the bare bone is found to be loose and easily removed. With this event the process terminates and the wound heals rapidly, but leaves a tenderness of the "seat of the bit" for several months.
Treatment — Bit gnathitis must be treated on the ex- pectant plan until the exfoliating process is complete, that is until the sequestrum is well loosened. To prevent the bur- rowing of pus downward, as well as to hurry the exfoliation, the edge of the jaw may be exposed by a free longitudinal incision. The incision is then kept free from food by daily irrigations until the sequestrum is sufiiciently loosened to be easily lifted with a small lever or curette. Undue haste in the removal of the sequestrum is harmful by retarding the final closure of the wound. About five days after removal of the sequestrum the bottom of the wound is curetted to
216
AMMAL DENTISTRY.
remove small roughened projections that might delay the cicatrization.
During the inflammatory period and until the sequestrum is removed the bit must not be used, unless, when the w^ound is small, it can be adjusted at a safe distance above.
OSTEOMATA OF THE SUPERIOR MAXILLA.
Definition — A non-inllammatory tumefaction on the su- perior maxillary of young horses, due to obstructed down- ward growth of the permanent molars.
Etiology — This abnormality occurs chiefly over the fang of the third superior molar, the last of the permanent molars, having temporary predecessors to erupt. At the period of its eruption, three years old, it frequently finds its down- ward course blocked in a wedge-shaped space, between the second and fourth molars, which occupy fixed positions in the jaws. The growth of the tooth in its blocked position produces pressure against the skull and a tumor results.
Pathological Anatomy — Osteoma of the maxilla is a non- inflammatory growth due to a proliferation of bone cells somewhat loosely arranged. Their macroscopic appearance is that of dense cancellated tissue, unlike the osteophyte of inflammatory origin. They are difTused over the anterior end of the superior maxilla and are occasionally bilateral.
Differential Diagnosis — They are differentiated from osteo-porosis by the absence of any general symptoms, the absence of any abnormality in the lower jaw and by their anterior location, and from growth of traumatic origin by the absence of heat, pain or swelling of the soft tissues; fron: odontomata by the age of the patient.
Symptoms and Treatment — (See abnormal eruptions,
page 1/5).
CARCINOMATA OF THE PALATE.
The palate of the horse, opposite the fourth, flftli and sixth molars, is frequently the seat of carcinomatous growths.
ANIMAL DENTISTRY.
217
They begin by the appearance of one or more malignant look- ing foci, and gradually invade more and more widely into the surrounding tissues. They usually perforate the bony palate and establish a free communication between the mouth and nasal cavities. In the old cases that are allowed to survive, the process may extend backward to the ethmoid and sphenoid bones and from the point of origin through the fauces into the pharynx. They become complicated with an offensive catarrh of the nasal mucosa and with more or less
Fig. 147. The Effect of a Carcinoma Beginning at the Palate of a Young Horse.
disturbance to the eye. One case coming to our notice ex- cavated a large opening externally through the malar and lachrymal bones and totally destroyed the globe of the eye and its appendages. The condition is of course incurable and is met by recommending the killing of the patient. (Fig
I47-)
SARCOMATA OF THE MOUTH.
Sarcomatous growths in the palate of the horse are of frequent occurrence. They begin in the periosteum of the
218
ANIMAL I )ENTISTRY.
palate, usually in the religion of the fifth molar, and traverse upward hetween the teeth and alonsj;- the alveolar border. They are first ol)served by the appearance of a (hfifused swell- ing of the palate extending along the molars and transversely across the raphe. They extend upward into the alveolar cavities around two, three, or even four molars, into the sinuses, and even produce bulging of the facial bones. The molars loosen and fall out or are easily extracted with the fingers, and their removal is always followed by severe hemorrhage. After the teeth are removed the cavities rapidly fill with sarcomatous tissue, which will bleed profusely when disturbed by mastication. The course of the process is slow in the early stages but very rapid after the teeth have be-
Fic. 148. A Sarcoma of the Jaw Involving the Entire Molar Arcade.
come seriously involved. They occur as clinical conditions
in horses past the age of ten years, but probably escape
notice during the early period of growth. They belong in the
category of incurable diseases. The disease must not be
designated "osteo-sarcoma," a condition we have never had
the opportunity of seeing in the domestic animals, although
its existence is not doubted. (See Fig. 148.)
ACTINOMYCOSIS.
Synonym — Lumpy jaw.
Definition — Actinomycosis is a chronic infectious disease due to the actinomyces, characterized by the formation of a neoplasm at the seat of infection.
Susceptible Animals — Ox, sheep, swine, horse and man. The disease is not entirely foreign to any of the domestic
ANIMAL DENTISTRY.
219
or wild herbivora and omnivora, and it has been produced experimentally in rodentia and carnivora.
Etiology — The cause of lumpy jaw is the growth of the actinomyces in an infected tissue. The organism is a saprophyte of forage, through which medium it gains entrance into the body by inhalation into the air passages and by ingestion into the digestive tract. Eruption of teeth, dental irregularities and wounds produced by fibrous forage produce favorable channels of entrance, hence the frequency of the disease about the mouth and pharynx. The organism is, however, capable of producing its pathogenicity in the
Fig. 148A. Lumpy Jaw in the Ox.
nasal cavities, lungs, stomach and liver where wounds are not etiological factors.
Affected Organs — Mouth, lips, nostrils, tongue, jaws, salivary glands, Schneiderian membrane, velum, pharynx, rumen, omasum, liver, lungs, and mammae.
Diagnosis — The early signs of actinomycosis located in visible parts of the body, consist of the formation of one or more wart-like nodes which may, when first noticed, be only the size of a pea. These nodes contain a calcareous or case- ous center. In the tongue the condition usually remains unnoticed until the organ has become indurated (wooden tongue). In the jaw the disease is first manifested by the
220
ANIMAL DENTISTRY.
appearance of a more or less diffused tumefaction of the in- ferior maxilla (lumpy jaw) or l)y rounded exostoses. As the soft structures become involved more and more by spread- ing of the diseased process, the head may assume an un- sightly appearance from the enormity of the swelling. The condition is further complicated by dental disorders — loosen-
Fig. 148B. Actinomycostic Superior Maxillary in the Ox.
ing of the teeth. In the pharynx the disease is manifested by tumefaction of the parotid region and by dysphagia and dyspnoea. Actinomycosis of the lungs and other internal structures is diagnosed only at the autopsy. Symptoms of organic disorder may lead a diagnostician to suspect the ex-
Fig. 148c.
Actinomycostic Inferior Maxillary in the Ox.
istence of the disease in districts where actinomycosis is prevalent, but a positive diagnosis of it in the internal struc- tures is not possible in the living animal.
Treatment — In the operable actinomycotic tumor abla- tion is the most effectual line of treatment. To further
ANIMAL DENTISTRY.
221
\'
\
*g^B>^t^,j^
Fig. 149. Dental Teratoma and Concha! Fistula. (Williams),
1. Mouth of the conchal fistula.
2. Bottom of the fistulous tract.
3. Guhernaculum dentis.
4. 9. Bony plates from the temporal hone.
5. The tooth.
6. External auditory meatus.
7. Wall of the fistulous tract.
8. Petrous temporal bone.
10. Zygoma.
11. Temporo-maxillary articulation.
222 ANIMAL DENTISTRY.
assure destruction of the organism the surgical wound may be treated with powdered copper sulphate at intervals of four to five days during the healing process. The inoperable tumor on the surface of the body is injected with a solution containing some form of iodine. Lugol's solution, potas- sium iodide, 2 per cent, or tincture of iodine, may be used for this purpose. Internally potassium iodide will prove bene- ficial. The loose teeth must be extracted and the caustic treatment applied to the entire diseased area when possible.
DENTAL TERATOMATA.
Synonyms — Dentigerous cysts, dental cysts, mastoid fistulac.
Definition — An abnormality of early embryonic origin in ^vhich one or two teeth develop on the temporal bones near the base of the ear. It is a common abnormality of solipeds but occurs occasionally in other mammals.
'Etiology — The cause of dental teratomata is found in an aberration of the embryonic evolution of the teeth, guttural pouch and external car, the mechanism of which is so compli- cated as to be susceptible to variations. The condition is closely allied to conchal fistula, with which it is frecjuentlv associated.
Symptoms — Dental teratomata of the mastoid region exist from the time of birth, although they may escape detec- tion until maturity, lliey appear at the surface in the form of a fistulous opening below the base of the ear or along- the margin of the conchal cartilage, discharging a limited cjuan- tity of a viscid mucoid secretion. The channel is lined with a well organized epithelial membrane continuous with the skin at the orifice. They are susceptible to pathological con- ditions which may for the first time direct attention to their presence. When they become infected the resulting osteitis.
ANIMAL DENTISTRY.
223
periostitis and dentitis augment the discharge, and change its character into a fetid, purulent secretion, and the region becomes painful to the touch.
When opened by incision the cyst is found to contain a tooth or two, which vary from the size of a hazel nut to that of a full sized molar. The smaller ones are quite round,
Fig. 150.
Two Teeth Removed from the Squamous Temporal Bone of a Clydesdale
Mare.
while the larger ones assume the typical tooth dimensions.
Treatment — The patient is placed in the lateral recum- bent position, preferably under the influences of an anaesthe- tic, A liberal incision is made over the tumefaction so as to expose the hard object within. This will always be found to be a tooth. When a part projects it can be extracted with
224 ANIMAL DENTISTRY.
an ordinary \\ olf tootli foccps, but frcc|uently the surround- ing's will require chiseling- to first loosen it from its cavity. When removed the cavity must be searched for a possible second tooth, and if the canal is long-, as in the case of conchal fistula, the entire lining must be resected to prevent a per- petual discharge.
DENTAL FISTULAE.
Definition — A fistulous tract related to the teeth, ex- tending from within the mouth to the outer surface of the jaw.
Etiology — Dental fistulae result from the outward point- ing of an abcess accompanying a decayed molar. The en- trance channel may be the infundibula or alveolar perios- teum. In the upper jaw they are occasionally caused by defective gums admitting food along- the external surface of the second or third molar, in the grooves between the prominent longitudinal ridges which exist on these teeth, and in the lower jaw they may in rare instances result from external violence. And again, sequestra of bones allowed to remain between the alveolar plates after the repulsion of teeth may produce a chronic fistulous opening.
Pathological Anatomy — In addition to the lesions ac- companying a decayed molar (see page 152) the dental fis- tula is nothing more than a tract through the bone from the apex of the tooth to the surface of the jaw.
Symptoms — They are seen most frequently on the lower jaw opposite the apex of the second, third, fourth, fifth and sixth molars. In the upper jaw the second and third molars are the teeth usually responsible for the condition. They appear as small openings, always near the border of the jaw, which discharg-e a limited amount of pus. In the old case the skin is drawn inward by the process of cicatrization. The jaw around the ofi^cnding molar is thickened to a perceptible
ANIMAL DENTISTRY.
225
extent. The diagnosis is confirmed by an examination of the dental arcade. When the tract is direct a small probe may be passed from the external opening to the mouth, but ordin-
FlG. I50A.
Inferior Molar Responsible for a Fistula of the Jaw in a 7- Year-Old Horse.
arily it pursues a tortuous course through the bone and comes to the surface at a point more or less remote from the affected tooth.
Treatment— The treatment of the dental fistula should
226 ANIMAL DliXTlSTRV.
first be limited to the extraction of the offenchng niokir with the forceps. If after four weeks the tract still exists the skull plate around the openins:^ is trephined and the tract well curetted alonq- its course into the alveolar cavity.
TRAUMATIC STOMATITIS.
Definition — Stomatitis signifies inflammation of the mucous membrane of the mouth.
Etiology — Primary, traumatic stomatitis is a common disease of all the domestic animals. It is seen in the most aggravated forms from the accidental ingestion of irri- tants and from the administration of irritating medicines. Among the other causes are dental irregularities, severe bits, traction on the tongue and the prehension of sharp objects. But in these instances the inflammation is of a circumscribed rather than a diffused character.
The mucosa of herbivora is well protected against wounding by masticating coarse food. Beards of cereals will, however, occasionally penetrate through it around the an- terior portion of the mouth and produce an alarming stomatitis simultaneously in a number of animals before the cause is discovered.
Pathological Anatomy — A simple inflammatory process promptly terminating in resolution. Purulent, catarrhal or necrotic inflammations of the mouth are rare. The severity and extent depend, therefore, upon the trauma.
Symptoms — Ptyalism, champing the jaws, disturbed pre- hension and mastication and a disinclination to eat are the principal symptoms. The mucous membrane is sensitive to the touch and the patient will resent examinations. On inspection there will be redness and in the severe case desquamation of the superior surface of the tongue.
Treatment — Stomatitis is not a serious disease. Removal of the cause, the administration of soft diet, and demulcent
ANIMAL DENTISTRY. 227
or mild, astringent solutions, is the only necessary treat- ment. A useful mouth wash for the treatment of either cir- cumscribed or diffused stomatitis is:
R.
Alum
Sodii boras aa 30
Spirits gaulthcria 10
Aqua q.s. ad 480
M et sig.
Inject free'y into the mouth three to four times daily.
STOMATITIS, INFECTIOUS.
Synonyms — Contagious pustular stomatitis; aphthous stomatitis; contagious aphtha.
Definition — An infectious inflammatory condition of the buccal mucosa characterized by the formation of a multi- plicity of pustules.
Etiology — Infectious stomatitis evidently owes its ex- istence to a specific virus, the identity of which is unknown.
Symptoms — Contagious aphtha usually occurs simultane- ously in a number of horses belonging to the same stable. Outbreaks often occur at race tracks, fairs or sale stables in which few of the exposed animals escape. The virus is evidently carried into the mouth through the medium of watering places, pails, cleaning utensils, bridles, etc. The first clinical symptom observed is ptyalism and slight anor- exia, which is followed by the rapid development of many small pimples which point and leave an ulcer. In some cases the skin around the commissures of the mouth becomes in- fected and leaves behind a depigmentated spot at the seat of each ulcer.
Treatment — Infectious stomatitis runs a favorable course
ANIMAL DHXTISTRY
it
- E
m
ANIMAL DENTISTRY. 229
in every case and it requires but little treatment. Preventive measures are the most important and these consist of isola- tion of the affected animals and the disinfection of the infected stalls, implements, feed boxes, etc.
(For a more complete description see works on General Medicine.)
ULCERATIVE GINGIVITIS OF DOGS.
Definition — Ulcerative gingivitis is a disease of young carnivorous animals beginning as an inflammation of the gums. It however spreads rapidly to the surrounding mucosa, alveolar periosteum and jaw.
Etiology — The cause of the disease is undoubtedly the propagation of microbes which habitually inhabit the mouth of meat eating animals, and which become pathogenic under the influence of a lowered vitality of the animal. Attempts to isolate a specific microbe have thus far failed.
Symptoms — Foetid breath occurring simultaneously with red or bluish red gums are the first distinguishing symptoms. The teeth are found to be coated with an excess of tartar around the gingival margin, and in the more ad- vanced stage they are loosened and easily extracted. The gums, cheeks and tongue may become the seat of numerous ulcers as the disease progresses, but often this feature is wanting. The process usually terminates favorably or fatally in from one to two weeks, according to its severity and the vitality of the patient, or it may become chronic and last as long as four to five weeks.
Treatment — The first treatment should consist of ex- tracting the loose teeth and removing, with the curette, all of the tartar from the stable ones. The mouth is then washed freely with mild antiseptics, boric acid and borax water being the most appropriate ones for the purpose. A 50 per cent solution of tincture of iodine painted carefully
230 ANLMAL DENTISTRY.
over the .e:ums, ulcers and vacant tooth cavities after the saliva has been wiped away will frcf|nently arrest the pro- cess, and would undoubtedly prove a specific if its toxicity did not prevent its repetition.
RETENTION CYSTS.
Besides the large cyst that occurs in the fraenum of the tongue (ranula), the mucous membrane of the mouth of horses is occasionally the seat of mucoid cysts varying from the size of a millet seed to that of a pea. The common location is around the commissures, either superiorly or inferiorly. Anatomically they consist of a dilated mucous follicle resulting from an obstructed outlet. They are per- fectly benign and yield to evacuation of the contents by incision.
TUMORS OF THE MUCOUS MEMBRANE OF THE
MOUTH.
The following is an enumeration of the various tumors affecting the mucous membrane of the mouth : (i) Actinomycosis, see page 218.
(2) Sarcoma, see page 218.
(3) Carcinoma, see page 217.
(4) Ranula, see page 250.
(5) Retention cysts, sec page 230.
LAMPAS.
Definition — Tumefaction of the hard palate just behind the superior incisor arcade.
Etiology — Lampas is a physiological condition occurring from dental nutrition during the growth of the teeth. It occurs at a time wdien the crowns of the teeth are still too short to overlap the first bars of the palate. In old horses
ANIMAL DENTISTRY. 231
the palate may project beyond the level of the arcade from wear of the incisors, when the latter are soft in texture.
Symptoms — Tumefaction and redness of the first bars of the palate. Sensitiveness is not a characteristic feature. The bars project to the level or below the tables of the incisors.
Treatment — The popular impression that lampas is inimical to the welfare of an animal necessitates the appli- cation of efforts to diminish the size of the tumefaction. This is done by scarification and actual cautery. The latter is the effectual method. The thermo-cautery is par excel- lence the neatest micthod of satisfying the popular prejudice against them. Confine the horse with the dental halter and twitch, and elevate the head. Pass a round stick through the interdental space and hold it, together with the tongue, in the left hand. Hold the mouth open by downward pres- sure upon the stick and tongue and keep the upper lip elevated with the twitch, and then with the right hand caut- erize the first two or three bars until they shrink below the table level.
SECONDARY CHRONIC NASAL CATARRH.
Synonyms — Chronic nasal catarrh. Unilateral chronic rhinitis. Nasal gleet. Ozena. Purulent accumulations in the facial sinuses.
Etiology — Primary chronic nasal catarrh is a rare disease in the herbivorous animals. The chronic nasal catarrh of the horse and ox has its origin in the surrounding structures and hence can only be described as a secondary condition. The primary lesion can usually be found in the superior dental arcades. Decayed teeth, usually the fourth superior molar, are responsible for 95 per cent of the cases. Alveolo- nasal fistula, fractures, foreign bodies, parasites, glanders, tumors and chronic bronchitis constitute the primary lesions of the other five per cent.
232 ANIMAL DEXTISTRY
Pathological Anatomy — The features of a typical case are: Purulent or muco-purulent catarrh of the affected side, accumulation of the secretions in the recesses of the sinuses, over-filling of the sinuses and bulging of the bones, pressure necrosis of the turbinated bones and the septa of the sinuses, outward discharge of the secretion, alveolar periostitis and necrosis of a molar.
Diagnosis — The pathognomonic symptom is the chronic, fetid, unilateral discharge from the nostril occurring simul- taneously with a dental disorder on the affected side. The decayed tooth in the early stage of decay may be dif^cult to locate, but owing to the frequency of this cause a special examination of the superior dental arcade must be made before the other causes are given any consideration. Nega- tive results from the pa'pation or inspection of the teeth with or without a mouth speculum is not sufficient reason to exclude the decayed tooth as a cause. The patient must be placed in a recumbent position, a mouth speculum ad- justed, and by the aid of good light each tooth, beginning with the fourth, must be carefully examined with a sharp steel pick. Diseased teeth which would otherwise have escaped notice are in this manner found to have one or both infundibula admitting food into the pulp cavity. AVhen the teeth have been excluded by this circumspect investigation the attention may be directed to the other possible causes, but in no case of chronic catarrh must the examination of the teeth be omitted. Even in the bilateral catarrhs the lesion may be found on one side of the head and in many instances decayed teeth co-exist on both sides of the head.
Differential Diagnosis — Nasal gleet is differentiated from glanders by the mallein test; from guttural pouch catarrh by the profuse discharge during mastication in the latter disease ; from bronchitis by the absence of cough and con- stitutional disturbance, and by the frothy bubbles usually
ANIMAL DENTISTRY.
233
contained in secretion coming- from the lower air passages. Treatment — The treatment includes: (i) Removal of the primary lesion; (2) evacuation of the accumulated secre- tions from the sinuses, and, (3) irrigation of the diseased mucous membrane. Internal medication is of little value in terminating nasal catarrh. Local applications in the form of douches are equally useless.
Fig. 151. Correct Locations of Openings to Perfectlj' Drain the Sinuses of a Horse's Head. The upper opening drains the frontal sinus outward, and hy per- forating its floor in the turbinated bone, it also drains the sinus into the nasal cavity. The dotted line on the lower opening shows the direction to elongate the orifice when a tooth is to be repulsed.
OPERATION OF TREPHINING THE SKULL FOR NASAL
CATARRH.
Equipment — Two scalpels, three-fourths inch circular tre- phine, one inch circular trephine, dissecting forceps, chisel, artery forcep, needles and thread (punches and mallet if teeth are to be repulsed), razor, wadding of cotton or oakum and antiseptics.
234
ANIMAL DENTISTRY.
Restraint — Horses may be trephined in the stanchnj^ po- sition witli the dental halter and twitch. When teeth are to be repulsed or when any chiseling- of the bone is necessary the recumbent position is essential.
U
Fi:;. i5i.\. Plain Circular Trephine.
ist Step — Clip, shave and disinfect the space intervening between the maxillary spine and longitudinal suture of the nasal bones.
2nd Step — First open the maxillary sinus about one inch
l''i(,. 1511;.
Assorted Trephines and Tooth Drills, with Brace.
from its external border and one inch from the anterior ex- tremity. l)Ut vary in the antro-posterior direction according to tooth to be repulsed.
3rd Step — Make a T-shaped incision through the skin with the base of the T pointing to the median line of the head.
ANIMAL DENTISTRY
235
4th Step — Dissect the muscle and connective tissue from the bone and arrest the hemorrhage.
5th Step — Cut a circular ring in the periosteum slightly larger than the diameter of the trephine to prevent tearing it beyond the area of the circle.
6th Step — Remove the skull plate with the three-fourths inch trephine.
7th Step — If a tooth is to be repulsed, enlarge the open-
FiG. 152. Surgical Areas of the Sinuses.
A, A. Maxillary sinuses.
B, B. Frontal sinuses.
ing toward the median line of the head with chisel and mallet, so that the punch can be placed on a straight line with the tooth.
8th Step — (See repulsion of teeth, page 161).
9th Step — Open the skull with the one-inch trephine, at a point 4 to 5 centimeters obliquely downward and inward from the nasal canthus . (See Fig. 151.)
loth Step — Break down the thin, bony septa with the
236 AXI.MAI. I)K\TIS'rR^'.
Ihigcrs so as to freely drain the frontal sinus into the maxil- lary sinus and nasal cavity.
nth Step — Empty and irrigate the sinuses in the stand- ing position and wad the openings with oakum or cotton.
1 2th Step — Suture the transverse incision of the T-shaped wound, leaving the longitudinal one for wadding and drain- age.
After-care — Irrigate with 3 per cent zinc sulphate solu- tion daily. Prevent food from entering the cavity by wad- ding the tooth cavity.
Note — The two openings above referred to are the only ones necessary to drain the sinuses of the horse's head. Openings higher up along the frontal sinus serve no useful purpose. The important feature of the operation is to drain the sinuses into the nasal cavity by breaking down the bony septa. Unless there is free flow from the upper opening to the nostrils the trephining operation for nasal catarrh is a useless procedure.
CHRONIC PERFORATION OF THE SKULL.
Definition — Under this head we include the openings of the skull covering the facial sinuses or nasal cavities, that persist after the regenerative process has ceased.
Etiology — The chronic or peristent perforations of the skull of horses follow large surgical openings necessary to remove nasal tumors, severe contusions of the skin compli- cated with comminuted fractures of the skull plate, attended with sloughing of the injured area, and circular trephine openings followed by necrosis of the surrounding bone. The sequel is most liable to occur in old horses from the dimin- ished nutrition of the bone tissue and periosteum. It is seldom seen in young animals, except in accidental perfora- tion of large dimensions, accompanied with loss of a large area of common integument. Surgical perforations, al-
ANIMAL DENTISTRY.
237
though quite large, will always heal eventually in the young horse but may threaten to become permanent in horses past the age of eighteen years. The most aggravated forms occur from comminuted fractures.
Fjg. 153. Prof. Edw. Merillat's Cperation for Closing Chronic Skull Pcrforatio:-:^.
A. 3rd step of operation.
I, J. "Melon slice" resection of the skin. See description.
B. 4th step of operation. See description.
C. 6th step of operation. See description.
Treatment — Large perforations accompanied with loss of considerable skin may be incurable, but when the orifice
?38 ANIMAL 1)KXTISTR\.
IS of nomin.'il dimensions its closure is effected by the fol- lowing operative intervention :
ist Step — Secure the subject in the lateral recumbent position without anaesthesia.
2nd Step — Shave the hair from the surgical area and dis- infect with mercuric chloride solution 1-500.
3rd Step — (hig. 153A.) Make a "melon-slice" resection of the skin, extending above and below the orifice, so as to include the orifice within its widest portion.
4th Step — (Fig. 153B.) Make a longitudinal incision (Fig. 153B. 3. 3.) through the skin on each side of and about one inch from the orifice, extending the entire length of the re- sected skin.
5th Step — Loosen from the bone all of the skin between the longitudinal incisions.
6th Step — (Fig. 153C. 5.) Suture the "melon-slice" wound with interrupted stitches, bringing the raw edges into 'perfect apposition.
7th Step — Protect the whole area with a clay dressing.
After-care — Alaintain perfect protection during eight days and then remove the sutures. Apply astringent lotions to the gaping longitudinal wounds (Fig. 153C. 4. 4.) which will heal by granulations.
APPLICATION OF GUTTA PERCHA PLUGS.
An artificial filling for the vacant alveolar cavity subse- quent to the extraction of r.iolars is indicated when the cavity refuses to close and thereby admits food into the nasal cavities or sinuses, in chronic dento-nasal fistula and in wadding a recently made tooth cavity that cannot receive daily attention.
The filling suitable for this purpose is a gutta percha mixture known to the human dentist as "temporary stop-
ANIMAL DENTISTRY 239
ping." It is hard at the temperature of the body but readily becomes pliable with heat.
Modus Operandi — Soften a liberal amount of the filling in hot water and roll it into an egg-shaped mass, larger than the cavity to be filled ; then, with the aid of a speculum to open the mouth, force the mass into the cavity to mold it to the proper shape and dimensions. Then remove it and trim of¥ the superfluous portion, re-heat and re-adjust to the cavity, leaving its exposed end beneath the table level of the arcade.
The gutta percha plugs should reach beyond the alveolar margin, but not to the bottom of the alveolar cavity, and to prevent disturbance from mastication the opposing crown should be removed with the claw-cutter. (Fig. loo.)
When applied as temporary filling it should be removed after five or six days to clean the cavity of accumulated secretions, and then be readjusted for one week more, at which time a tooth cavity is usually safely filled.
CRIBBING AND WIND-SUCKING.
Definition — Cribbing and wind-sucking are identical, the latter being an aggravated form of the former. Cribbing may be defined as a pertinacious habit of the horse, charac- terized by attempts to ingest air, while wind-sucking may be defined as the same habit in which the attempt is successful.
Etiology — The actual cause of cribbing is yet to be satis- factorily demonstrated. Idleness and the empty manger are circumstances generally accepted as favoring the acquire- ment of the habit. Nervousness, gastric indigestion and ob- scure neuroses, are also mentioned among the possible etio- logical factors. These assertions are based only upon specu- lation, and are doubted most by those who have had the widest range of observation. It may, however, be safely
240
ANIMAL DENTISTRY
Stated that llic habil is one of domestication, a stable habit or pastime having- its origin in some unknown cause.
Symptoms — Grasping an object with the teeth, contrac- ting the inferior cervical muscles, and uttering- the character- istic grunt consecutively, is the clinical picture of tlie typical cribber. Some subjects follow this phenomena by the de- glutition of a considerable quantity of air at each attempt, until marked tympany of the abdomen becomes apparent. Others again succeed in the deglutition without grasping an object with the teeth.
Fu;. 1 53 A. The Mouth of a Young Cribber.
Treatment — The application of a wide leather strap tightly around the throat will prevent the ingestion of air and diminish in number the attempts at cribbing. If the strap is equii)ped with tacks that will prick the throat when the attempt is made the cril)l)ing will cease while the strap is in place. A second method consists of removing from the stall all ol)jects that can be grasped with the teeth.
The surgical intervention once recommended, consisting of a myotomy of the sterno-maxillary muscle in the upper third of the cer\-ical region, has become obsolete through the revelation of its uselessness as a permanent remedy.
ANIMAL DENTISTRY. 241
The pertinacity of the cribbing habit was demonstrated
by Mr. A , of Des Plaines, 111., in the case of a large
Shetland pony that acquired the habit at the age of three years. This pony was confined in a polished hardwood cage w^ith the walls inclined at an angle of forty-five degrees from above downwards and outwards, for three years, during which time special care was taken to prevent any contact with objects that could be touched with the teeth. At the end of three years it was experimentally placed into a stall with a manger. In less than ten seconds the cribbing begun and continued until returned to the hardwood cage.
HABITUAL PTYALISM.
Synonym — Slobbering.
Definition — A habit of carriage horses characterized by an excessive flow of saliva from the mouth while driving.
Etiology — Habitual ptyalism of carriage horses is caused by the abnormal curbing of the neck in horses inclined to "pull" heavily upon the reins. The position of the head as- sumed under such circumstances prevents the free degluti- tion of the saliva secreted, which in the "pulling horse" is alwa3^s excessive. Besides, the mind of the "pulling" car- riage horse is so occupied wMth the bit that no deglutition is attempted.
Ptyalism is also caused by sensitiveness of the mouth, wounds, bit gnathitis, and other forms of stomatitis, but these causes "constitute an entirely different entity than that referred to in this paragraph.
Symptoms — An excessive flow of saliva while driving in the absence of any lesion of the mouth determines a case of habitual ptyalism. The secretion is churned into a stringy froth, and is blown by the wind over the harness, horse, car- riage and even the coachman. There is also a tendency to- wards "champing" the bit when the reins are relaxed.
242 ANIMAL DENTISTRY.
Treatment — In the treatment of ptyalism of carriage horses, the first requisite is to remove all dental irregulari- ties that would tend to provoke a flow of saliva by irritating the buccal surface. The front molars must especially be well rounded. Wounds of the interdental space must be healed and wolf teeth extracted. The attention must then be directed to the bitting. The bridoon is removed and the head is checked with an overdraw passing beneath the chin. The reins are placed in the "cheek" or "half-cheek" loop of the curb bit : or, if the horse cannot be managed thus, a rubber cover is placed over the l)it and the rein attached to the middle or lower bar. The bridle is fitted neatly so as
Fin, 154. The Best Rit for a Side Pulling Light Harness Horse.
to bring the bit to a comfortable position near the inferior molars. "Dropping the bit" a habit of coachmen to gain advantage of a "pulling" horse must be avoided. And finally, by patient "schooling," the horse must be taught to drive with a "light line."
SIDE REINING.
Definition — A habit of driving horses consisting of con- stant inclination to carry the head to one side of the median line of the body.
Etiology — The habit of side reining is due to an ingenious attempt to take advantage of the reinsman by placing the
ANIMAL DENTISTRY.
243
head in a more advantageous position for leverage. Such animals often have serious lesions of the jaws, but these are effects rather than causes of the habit. The habit is often acquired by driving an ambitious, prompt horse with a "loafer."
The horse that drives on but one line without pulling heavily and shifts gradually to one side of the street belongs to an entirelv different class. In this incident the cause is
Fk;. 155-
Fic. 156.
The suitable bit to equip witli the
flexible rubber hose. See
description below.
Fig. 157.
Tongue Lolling Bits.
A. Port bit.
B. Spoon bit.
C. Combined snaffie and overcheck bit.
always due to some defect in the locomotory apparatus. Spavin or other slight painful condition of the hind extremity is the usual cause of this defect.
Treatment — The side reining horse must first be treated for defects of the teeth and lesions of the interdental space.
244 ANIMAL I)l-:N"riS'lRV.
The first molars must be well rounded to prevent buccal wounds. The bit is then kept on a straig-ht line with the jaws by means of washers fastened inside the rings. A com- fortable check is used, and the horse is driven only with one well mated in promptness.
HABITUAL PROTRUSION OF THE TONGUE.
Synonym — Tongue lolling.
Definition — The habit of extending the end of the tongue from the commissure of the mouth while driving:.
Etiology — The habit may be first acquired in an attempt to protect an al^-asion of the mouth from further injury, but its continuation is due to the relief to the respirations. When the tongue is dropped from the fauces the lumen of the pharynx is increased and the respirations are facilitated suf- ficiently to induce a continuation of the habit. Paralysis of the tongue, in which retraction is impossible, is entirely another condition, occurring as a result of progressive bul- bar paralysis — a fatal disease.
Treatment — Dental irregularities must be corrected and the head while driving must be elevated with the overdraw check to bring the air passages toward a straight line. The mouth may be closed with a nose band attached to the bridle. Attaching the check bit to the main bit by means of a flexible rubber hose, will frequently prevent the habit.
When these measures fail, amputation of the tongue is the only recourse.
OPERATION OF AMPUTATION OF THE TONGUE.
Restraint — Lateral recumbent position under chloroform anaesthesia.
ist Step — i\Lake a circular incision, convexity forward, from the center of one border to the center of the opposite, so as to make one-half of a dove-tail flap.
ANIMAL DENTISTRY. 245
2nd Step — Turn the tongue upward to expose the lower surface, and by a similar incision complete the inferior half of the dove-tail.
3rd Step — Close the wound with interrupted sutures.
After Care — Feed on soft diet and remove sutures in eight days. Amputation of the tongue produces a temporary in- convenience in the prehension of liquids but is otherwise a harmless operation. The above method leaves a flat ex- tremity similar to that of a normal tongue.
BIT-LUGGING.
Definition — A fault or habit of coach, light-harness and saddle horses, consisting of a constant or periodical tendency to pull heavily upon the bit.
Etiology — Dental irregularities, while never the primary cause of the habit, irritate the seat of the bit and render its cure impossible, by aggravating the animal's temper.
The whip, reinsman or equestrian recognizes three dis- tinct classes of bit-luggers. The first is the young horse that lugs from failure to understand the nature of the complicated bitting riggings applied for the first time; the second class comprises the mature horse that has developed the habit from improper training; and the third class is the lugger by nature that will "pull to the end of the road" in spite of the punishment inflicted by severe bits.
Complications — Bit gnathitis from severe pressure and lacerations of the buccal surface opposite the first and second superior molars from friction of the cheek against the sharp enamel points are certain to result in the lugging horse, and in turn these injuries, which are frequently of no small pro- portions, are prone to augment a bad disposition.
Treatment — The treatment of bit-lugging belongs more to the domain of that part of horse training known as "bit- ting" or "mouthing" a horse than that of dentistry. The
246
ANIMAL DENTISTRY.
latter is, liowcvcr, an essential feature of the cure. The proficient teacher of tlie horse of (luality will always demand that the anterior extremities of the molar arcades be rid of all projections that may irritate the buccal surfaces, as a prerequisite to the development of the tactile sense of the seat of the bit. The dental operation for this purpose con- sists of trimming- and filing the anterior molars smooth and round with the angular cutter and file. The horse must, in addition, be n^adc to become gradually accustomed to the
Fig. 158. Fig. 159.
I5it.s for Confirmed Luggers.
A. J. I. C. Iiit.
B. California cnrl), and port.
complicated riggings. In the coach and saddle horse the dumb-jockey is indispensalde, to develop the sensibility of the mouth. It should be equipped with a soft bit one to one and a half inches in diameter to develop the tactile sense over as large an area as possible, and the elastic reins should be made tighter from day to day as the horse becomes more and more accustomed to its mechanism. Among the best coachmen it is the custom to e(|uip the dumb-jockey with a
ANIMAL DENTISTRY. 247
straight and snaffle bit on alternate days. The Hght harness horse is trained to the bit by jogging in the breaking cart with the simplest possible riggings and all forcible restraint is avoided, the aim being to drive the youngster vi^ith a ''light hand" and teach it to respond to the slightest touch instead of pulling heavily upon the bit.
The habitual confirmed lugger that has formed the habit from the faulty first lessons may be improved by handling in the same manner, and in addition careful attention must be given to the w^ounds of the mouth, by attending to the teeth and application of bits that will control the horse and at the same time inflict no further injury. If the jaw is sore, for example, the covered port bit may be serviceable by protecting the wounded part and transferring the punish- ment to the palate, while if the palate is sore the straight curb may be applied, and the lines attached to the lower bar, the ol)ject point being to prevent the unnecessary aggrava- tion of the horse's disposition. In the light harness horse habitual lugging may be palliated considerably by proper over-checking. The higher the horse is checked the easier it will be to control. The chin-overdraw is probably the best rigging for this purpose, owing to the fact that the mouth is kept closed, and that there is no over-check bit to irritate the interdental space. In this connection it must, however, be understood that what will answer for one horse will prove useless for another, and vice versa.
The confirmed lugger of the third class is incurable ex- cept by giving plenty of hard work to lower its spirit, which in many cases may impair the animal's health before the habit is abandoned. In such animals more than the others the anterior molars must be free from points to mutilate the soft structures. Beveling the first inferior molars from the gingival margin backward over the crown to the posterior border of the table has often been practiced for the purpose
248 ANIMAL DENTISTRY.
of preventing the bit from lodging against the teeth, or to prevent grasping the bit between them, but this operation is never eiifectual in palliating the lugging habit. In the young horse it is harmful in that the sensitive dentinal substance is thus exposed to the surface. Extraction of the first in- ferior molar is likewise ineffectual.
The veterinarian's full duty ends when all sharp points are removed from the molars, and when appropriate bits have been recommended.
FACIAL PARALYSIS.
Synonyms— Bell's paralysis. Paralysis of the lips. Par- alysis of the seventh cranial nerve.
Definition — A partial or complete unilateral motor par- alysis of the muscles controlled by the seventh cranial nerve.
Etiology — Facial paralysis is caused by injuries to the mastoid region where the seventh nerve leaves the cranial cavity. The contusion is sustained by hanging in the halter in the recumbent position, striking the head to the floor during surgical restraint or in the struggles of painful dis- eases, or from blows.
Symptoms — The upper lip is drawn to the opposite side, the corner of the lower lip is dropped so as to show its mucous membrane, the nostril draws inward during inspira- tion and in the severe case food will accumulate in the check from paralysis of the buccinator. When the paralysis is par- tial these symptoms are less pronounced. Bilateral facial paralysis occurs occasionally when both sides of the head are contused simultaneously from the above causes. In such cases the symptoms presented are total inability to move either lip, difficulty to retain food between the teeth and audible inspirations from vapidity of the nostrils.
Differential Diagnosis — Facial paralysis of this variety is recognized from that of central origin by the sensibility of
ANIMAL DENTISTRY.
249
the paralyzed region determined by pricking- the parts with a pin.
Treatment — Removal of the cause, liniments, blister and massage along the course of the seventh nerve will hasten the recovery. The return of motion to the parts usually occurs in from six weeks to three months. If the injury was severe enough to destroy the continuity of the axis cylinders of the nerve the paralysis may continue through life.
Fig. i6o. Facial Paralvsis, Right Side.
LACERATIONS OF THE LIPS.
Injuries to the lips are of considerable import in the horse, owing to their prehensile and tactile functions, and because of the unsightliness of a permanent division of their con- tinuity.
Etiology — Contact with sharp objects. Falls on hard pavement. Dog bites.
Treatment — The labial wound, which includes division of the border of the lip, requires scrupulous attention in order to prevent a permanent defect. Perfect disinfection
250 ANIMAL DENTISTRY.
l)y prolonged irrimalioti with weak antiseptic solution is the
Hrst necessary stej). 'I'hc wound is fn-sl brought together
with mattress or button suture to immobili/cc the edges, and
then closed neatly with interrupted stitches. A thick coat •
ing of collodion will still further hold the parts in apposition
and serve as a protection against injur\- and infection. The
patient iiuist be fed only upon gruel, and tied on the pillar
rein for at least six days.
RANULA.
Definition — A cystic tumor, belonging to the class of re- tention cysts, located under the free extremity of the tongue.
Susceptible Animals — Dog, cat, ox and man. Rare in the horse.
Etiology — Ranula is generally supposed to be caused by obstruction of one of the ducts of the sublingual salivary gland.
Diagnosis — Disturbed prehension and mastication ; pal- pation and inspection.
Treatment — Ranula is an obstinate disease and will yield to no treatment except total resection of the entire cyst wall. Evacuation of the contents and injections of irritants, iodine, ammonia, silver nitrate, etc., is never a lasting success.
ACTINOMYCOSIS OF THE TONGUE.
(See i)ages 218-19.)
FOREIGN BODIES IN THE TONGUE.
Pins, needles, tacks, spicula of wood, bones or iron fre- quently become lodged deeply into the substance of the tongue near its base. The condition is manifested by dis- turbed mastication, ptyalism, rejection of partially masti- cated food and disinclination to eat freely. The penetration is usually well under the base of the tongue at a location that defies detection Ijy an ordinary palpation or inspection
ANIMAL DENTISTRY. • 251
of the mouth. With the aid of a mouth specukmi palpation of the base of the tongue will reveal a hard, painful area in the center of which the penetrating body will be found pro- truding. The treatment consists of removal of the foreign body and free incision across the infected area, followed by mild astringent irrigations, alum, borax, sodium chloride, or
boric acid solutions.
FROST BITES.
Frozen tongues are common in horses having the habit of protruding the tongue while driving (tongue lolling), and not infrequently the injury thus sustained will cause necrosis of the entire free extremity. Radical treatment must be de- ferred until the extent of the frozen area becomes apparent by the appearance of a well defined line of demarcation. Amputation will hasten recovery.
LACERATIONS OF THE CHEEKS.
Lacerations of the cheek that mutilate or divide the buccinator muscle transversely may prove a permanent detri- ment to animals by destroying its necessary elasticity and contractility. Constant packing of food in the cheek or re- striction to the movements of the jaw (cicatricial trismus) are frequent results. It is therefore evident that these wounds should receive intelligent and circumspect attention. Careful disinfection, ingenious closure and drainage, and immobilization of the parts should not be omitted in the treatment.
TUMORS OF THE LIPS AND CHEEKS.
Carcinomata, sarcomata, actinomycosis, warts and re- tention cysts are the classes of tumors usually found on these organs. The growths should be promptly removed when first observed to prevent their diffusion over too great ^n area. Pedunculated warts are removed by surgical abla-
252 ANIMAL DENTISTRY.
tion or lij^ation and tlic diffused ones by the use of caustics. Copper sulphate and arsenic are specific ag^ainst warts. Quit- man recommends the external and internal use of Fowler's solution as a spccil'ic remedy at^'ainsl warts coverinj^ a larc^e surface. Retention cysts usually yield to simple evacuation of their contents hy a free incision. Widely spread carcino- mata and sarcomata arc incurable.
LACERATION OF THE TONGUE.
Etiology — Traction on the tone^ue in examining the mouth or administration of medicines is the common cause of laceration of the fraenum. The body of the organ sustains injury from the tie chain, iron work of the stall or by being bitten by animals in tlie neighboring stall. Sudden fright while sleeping with the tongue between the incisor teeth is the probable cause of the mysterious lacerations of the tongues of horses.
Symptoms — Ptyalism, disinclination to eat and drink, champing of the jaws, rejection of food and in the later stages of severe lacerations, fetor, are the chief symptoms.
Treatment — Reposition and retention of the lacerations with sutures and amputation. (Operation of amputation see page 244.)
Prognosis — The tongue is well nourished and will heal well when sutured if the blood supply is not too greatly dis- turbed. In the horse amputation of the free extremity causes only tem])OTary inconvenience in the prehension of liquids. In the ox, dog and cat loss of the free extremity is a per- manent impediment in the prehension of food.
INFLAMMATION OF THE TONGUE.
Synonym — Glossitis.
Etiology — Ingestion of irritants, administration of irri- tating medicaments, bit bruises, wounds from dental irregu-
ANIMAL DENTISTRY. 253
larities, pin punctures, etc. Specific inflammations of the tongue are seen in actinomycosis and infectious stomatitis.
Symptoms — Same as lacerations of the tongue.
Treatment — Removal of the cause; soft food; mild as- tringent irrigations; alum, borax, boric acid.
Prognosis — Seldom serious. Necrosis of the extremity may require amputation.
ABERRATIONS OF THE FUNCTION OF MASTICA- TION.
The common aberrations of mastication in animals are quidding, ejecting, bolting, and wadding of food.
QUIDDING.
Definition — Quidding refers to that aberration in which the food is rolled and shifted about in the mouth and then finally ejected into the manger.
Etiology and Symptoms — This abnormality occurs in three distinct forms: (i) From dental irregularities which produce pain when attempt is made to masticate, or from some lesion of the temporo-maxillary articulation. In these cases the food is not comminuted, but is simply rolled about in the mouth and ejected in large masses soaked with saliva. (2) From senile dissolution of the molar arcades. The molars will be found irregular, short in the crowns and fre- quently loosened in their cavities, and the food will be ejected, as in the former cases, because the molars are no longer capable of performing their function. (3) From a neurosis affecting the nerves of deglutition. In this variety of quidders the food is finely comminuted before being ejected into the manger. The condition is seen most fre- quently in horses past the age of fifteen years.
Treatment — The quidding horse must be treated ac- cording to the cause. Sometimes the extraction of a tooth,
254 ANIMAL DHXTISTRY.
the trimming- of an elongation, or the filint^ of enamel points whieh wound the mucous meml)rane, will promptly cure the aberration. In cases of senile orii^in, loose teeth are ex- tracted and the elongations are carefull}' hlunted without further disturhing their implantations. The food should be of a character recjuiring but little mastication. Ground corn, ground oats, cut ha}- and bran, given dr}\ is the most suit- able diet to i)r()long the life of an old animal so afflicted.
In the third fcMMii the aberration may often be overcome by withholding hay from the food allowance. For reasons difficult to explain, hay is the foodstuff usually c|uid(lcd. Corn, oats, barley and bran are seldom ejected in this form. In addition, the molars must be well examined to exclude them as the cause of the disorder.
EJECTING FOOD.
The ejection of food, partially or completely masticated, occurs as a symptom of (|uidding, from causes enumerated above, and from abnormalities of the mouth or teeth that produce pain when mastication is attempted. A split molar tooth that wounds the buccal surface, carcinoma of the pal- ate, sarcoma of the jaw, foreign bodies in the tong-ue or cheek, and a decaying molar, are among the lesions often responsible for this condition.
BOLTING FOOD.
Bolting food refers to the aberration of eating rapidly and without suf^cient comminution. It is more of a habit than a disease, and is often acquired by allowing animals to become too hungry. The nose-bag method of feeding is prolific in the production of the habit, which is still further augmented by dental disorders that induce animals to avoid persistent mastication. The habit causes indigestion and colics, and results in the loss of no small amounts of food, that is found unmasticatcd in the feces. The treatment
ANIMAL DENTISTRY. 255
consists of first attending to the molar teeth, and of feeding in such a manner as to effectually prevent rapid eating. Nose-bag feeding should be discontinued. When horses are fed in harness the grain. should be spread upon the ground over a large surface. In the stable the feed box is taken out and the grain is spread over the entire surface of the hay manger or upon the floor along the front of the stall. Rapid eating under these circumstances is impossible and the habit will soon be abandoned. Specially appointed feed- ing troughs which allow the food to flow slowly outward as it is eaten are commendable.
WADDING OF FOOD IN THE CHEEK.
The accumulation of food between the cheek and molar arcades is a common aberration. It is caused frequently by a serious dental disorder — fissured molar, loss of the outer half of a molar crown, elongation that wounds the cheek, etc. The most obstinate form of this disorder, however, is due to a defect in the buccinator muscle. The defect may be either a partial or complete paralysis, which may be either co-existent with a general facial paralysis (see facial paralysis, page 248) or which may exist as a circumscribed paralysis of the muscle itself. The cause of the paralysis, when circumscribed, is usually a trauma of the buccinator branch of the seventh nerve as it passes superficially over the masseter. A lacerated wound over the masseter, that divides the continuity of the branches of the nerve, is always liable to be followed by this condition.
Impactions of food in the cheek are also caused by wounds of the buccinator muscle which interfere with its normal contractility. A trivial surgical or accidental wound may disturb the function of this highly motile muscle suf- ficiently to interfere with its function throughout the re- mainder of the animal's life. And finally cicatrices of the
256
ANIMAL DENTISTRY.
l)iiccal mucosa which destroy its scnsibihty arc sufficient injury to 1)C followed by this aberration of mastication.
The treatment must vary with the cause. When due to a dental disorder a cure is at hand by correcting the defect. The cicatricial forms are incurable, but can be benefited somewhat by thoroughly beveling the buccal border of the superior molar arcade. The paralytic form is either curable or incurable, according to the severity and duration of the injur}'.
INDEX
A BERRATIOXS of the Function of
-^*- Mastication 25."'.
Abnormal Eruption of the Teeth. . . .17.'!
Accidents 160
Acquired Elongation i,f Molars. ... 18r>
Actinomycosis 218, 251
Age — Determination of 71, 113
Ago — Birth to One Year 74
Age — One to Two and Ouo-IIalf
Years 75
Age — Two and One-half to Five
Y'ears 80
Age — Five to Eight Years S'.i
Age — Nine to Old Age 8!)
Age — Twenty to Twenty-five Yefsrs..li;5
Age— Old Age li::
Age — Routine of Examination to De- termine a Horse's 11.'.
Alveolar Cavity 4S
Alveolar Margin — Kcctding cf 7."!
Alveolar Periostitis 152
Alveolar Plate — Removal of Exter- nal 107
Alveolo-Dental Periosteum l!l, 2 1
Alveolo-Xasal Fistula 100
Amputation of the Tongue 244
Animal Dentistry — Scope of 15
Anomalies — Artificial 110
Anomalies of the Teeth — Natural
and Artificial 117
Anorexia 157
Aphtha — Contagious 227
Aphthous Stomatitis 227
Apical Foramen 4 7
Application of Gutta I'crcha Plugs. 2:!8
Arcades — Inferior 34, 35
Arcades — Superior 3:5, 35
Artificial and Natural Anomalies of
the Teeth 117
Artificial Anomalies 110
BELI/S Paralysis 245 Beveling of the Molars 182
Beveling of Left First lufrrior
Jlolar 100
Beveling of Right First Inf(M'ior
Molar lO.s
Bishoping 120 to 120
Bites — Frost 251
Bit Contusions 214
Bit Gnathitis 214
Bit Lugging 245
Bit Sores 214
Blood Vessels 19
Blunting of Left First Superior
Molar 108
Blunting of Right First Superior
Molar 107
Bodies in the Mouth — Foreign 210
Bolting Food 254
Brachygnathism 179
r V\NL\ES . .18. 51, .54, 61, 64, 65. 127 ^-^ Canine Teeth of the Horse
27, 28, 30, 175
Carcinomata 251
Carcinomata of the Palate 217
Caries 152, 172
Caries Dentium 172
Catarrh — Ctironic and Primary
Chronic Nasal 231
Catarrh — Persistency of 166
Catarrh — Secondary Chronic Nasal.. 231
Champing 241
Character of the Food 119
Cheeks — Lacerations of the 251
Cheeks — The 130
Cheeks — Tumors of the Lips and... 251
Chin — Prominent 181
Chin — Receding 170
Chronic Nasal Catarrh 231
Chronic Nasal Catarrh Primary and
Secondary 231
Chronic Perforation of the Skull. . . .236
Chronic Rhinitis — T'nilateral 2."{1
Chronic Sinuses of Lower .T;uv 106
Cement 10, 22
Central Incisors
. .40, 51, 52, 54, 56, 00, 63, 64, 65
Common Enamel Germ 47
Complete Denture of a Horse 18
Contagious Aphtha 227
Contagious I'ustular Stomatitis 227
Contusions — Bit 214
Corner Incisors
50, 51, 52, 54, 57. 01. 01. 65
Cribbing 239
Crowns — Polishing the 120
Crowns — Shortening of 120
Crusta Petrosa 10, 22, 23
Cupping the Incisor Teeth 123
Cups of the Infundil3ula 118
Cups — Renewal of the 120
Cuticle of the Enamel 22
Cysts — Dental 177. 222
Cysts — Retention 230. 251
257
258
INDEX.
DECAYEI* Tooth ir.li, 1712 Docayod Tooth — Kractmo of...l(>i»
DeRhitition rneumonia 107
Dental Artery — IIemorrha>;e from
the 101
Dental Cysts 177. 2:22
Dental Diapnosis i:5.'{
Dental Kvohition and Ketrofression
Applied to Determination of Age
— Summary of 74
Dental Follicle 48
Dental Fistula IGG. 224
Dental Halter 148
Dental Instruments — Their Uses . . . . 1 .'?."
Dental Papilla 47
Dental Teratomata 222
Dental Tissues — Arrangement of in
Incisor 24
Dentigerous Cysts 222
Dentinal Substance 47
Dentine 10. 20, 2."i
Dentitis l.-)2
Denuding 210
Destruction of Temporary Tooth liy
the Permanent 60
Determination of Age 74
Determination of Age — Routine of
Examination to 113
Diagnosis — Dental l.".."'.
Digastricus Muscle — The 131
Diseases and Irregularities of Teeth. 1.52 Dislocation of the Tomporo-^Iaxillary
Articulation 213
Divisions of a Tooth 19
Dog— Denture of.... 30. 40. 41. 42. 43
Dog Speculums 174. 17;")
Dog — Temporary Teeth of .")4
Dogs — Ulcerative Gingivitis of 220
EJECTING Food 2.54 Elongation of the Molars — Ac- quired 183
Elongation — Operation of Cutting. .18G
Elongations of the Incisors 200
Embryonic Evolution 44
Enamel 19, 21
Enamel^CnticIe of the 22
Enamel — Erosion of the 208
Enamel Germ — Common 47
Enamel Organ 47
Enamel Points 187
Enamel Points of Ilerbivora 187
Erosion of the Enamel 2(tS, 210
Eruptions of the Teeth 117
Eruptions of the Tooth — Abnormal .. 17.5 Evolution and Retrogression of the
Teeth Tabulated 124. 12.5
Evolution — Embryonic 44
Evolution of Permanent Teeth 5s
Evolution of Temporary Teeth 40
Examination of the Mouth 190
{•Extraction of the Canines of Horses. 172 Extraction of the IncisofS 171
F.xl Taction of the Teeth of Dogs. . . .174
Extraction with Forceps 159
Eye 'I'eetli 202
T^ ACIAL Paralysis 245
■*- Facial Sinuses — Purulent Ac- cumulations in 231
Fang 47
File — Flat and Rasp 137
I'issuring of the Molars 209
Fistula — Alveolo-Xasal 166
Fistula —Dental 100. 224
Fistulae— Mastoid 222
Float- The Angular 1.36
Float— The Straight 130
Floating and Filing 191
Floating and Trimming Molars 189
Floating the Teeth of the Ox 202
I'loats and Files — Methcds of Using
on Molars 192
Floats and Float Blades 135. 130
Follicle— Dental 48
Food-Bolting 2.54
Food — Character of the 119
Food — Ejecting 254
Food— Wadding of in the Cheek.... 225
Foramen — Apical 47
Foreign Bodies in the Month 210
F'oreign Bodies in the Tongue 250
Formulae of Temporary and Per- manent Dentures of .\nimals
00. 67
Fracture of Decayed Tooth 160
Fracture of the Interior Maxilla. . . .211
Fracture of the Teeth' 209
Fractured .Taw 214
Fractures of the Premnxilla and
Superior Maxilla 213
Frost Bites 251
Functions of the Teeth 127
GERM — Common Enamel 47 Gingivae 19
Gingival Cushions 45
Gingivitis of Dogs — Ulcerative 229
(Jleet- Nasal 231
Glossiti-s 252
Gnathitis— Bit 214
Gutta Porcha Plugs — Applications
of 2.38
HABPriTAL Protrusion of the Tongue 244
Habitual Ptyalism 241
Hard Palate— The 130
Hard Tissues 19
llomorrhage from the Dental Artery. 101
Hemorrhage — Palatine 100
Horse — Complete Denture of 18
Horse— Temporary Teeth of 49
INCISOR Nippers 143 Incisor Teeth of the Ox. . .37. 51
INDEX.
259
Incisor Teeth — Sheddinpr of 175
Incisor Teeth — Shortening 123, 206
Incisor Teeth — -Polishing, Cupping
and Staining the 123
Incisors IS, 127
Incisors — Central
49, 51, 54, 56, 60, 03. 64, 63
Incisors — Corner
50, 52, 54, 57, 61. 64, 65
Incisors — Elongation of 206
Incisors — Extraction of 171
Incisors — Inferior 51
.51,
64
Incisors — Intermediate
Incisors — Lateral
50, 51, 54, 56, 60, 64. 65
Incisors — Permanent of Horse. .27, 28 Incisors — Permanent of Ruminants. . 34
Incisors — Temporary of Horse 50
Infectious Stomatitis 227
Inferior Arcades 34, 35
Inferior Incisors 51
Inferior Maxilla — Fracture of the. .211
Inferior Maxillary 129
Inferior Molars 32, 33, 34, 39
Inferior Molar of Ox 38
Inflammation of the Tongue 252
Infundibula— The 118
Infundibula — Cups of the 118
Infundilmlum 19. 21
Inspection of the Mouth 135
Instruments — Dental — Their Uses ..135
Intermediate Incisors 51. 57
Introduction 13
Irregularities and Diseases of Teeth. 152
T AW — Fractured 214
^ Jaw — Prominent 181
Jaw — Receding 179
T ACERATIONS of the Cheeks 251
-'— ' Lacerations of the Lips 249
Lacerations of the Tongue 252
Lampas 230
Lateral Enamel Projections 187
Lateral Incisors
50, 51, 54, 56, 60, 64, 65
Lips and Cheeks — Tumors of the... 251
liips — Lacerations of the 249
Lips — Paralysis of the 245
Lolling — Tongue 244
Lugging — Bit 245
Lumpy Jaw 218
MARGINS of the Teeth 20 Masseter Muscle — The 130
Mastication — Mechanism of 129
Mastoid Fistulae 222
Maxillary — The Inferior 127
Maxillary — The Superior 127
Maxillo-Nasal Notch 130
Mechanism of IMastication 129
Merillat's (Prol. Ed's) Operation for Closing Chronic Skull I'erfora-
tions 237
Micro-Organisms 17;!
Molar Crown Cutter 144
Molar Cutter — Angular 142
Molar Cutter — Or Trimmer — Closed. 1. ".7
Molar Cutter — Open 13,s
Molar Extractor — Closed Ill
Molar Extractor — Open 14 J
Molar Separator 140
Molar — Fourth 54
Molar — Natural Cavities of,...:... 23
Molar Teeth 176
Molars IS, 30, 127
Molars — Acquired Elongation of. ...1S5
Molars — Fissuring of the 209
Molars — Fourth and Fifth.. 62. 04, 65
^lolars — Sixth 63,64, 65
Molars — First, Second and Third
50, 54, 57, 61, 64, 65
Molars — Inferior 32, 33, 34, 39
Molars — Permanent of Ruminants.. 30
Molars — Projections on 184
Molars — Splitting of the 209
Molars — Superior 30, 31, 32
Molars — Trimming and Floating
189, 191, 192
Mouth — Inspection of the 135
Mouth — Palpation of the 133
Mouth — Sarcomata of the 217
Mouth Speculum 144, 145, 146
Muscle — The Digastricus 131
Muscle — The Mas.seter 130
Muscle — The Pterygoid Externus ...131 Muscle — The Pterygoid Internus ...131
Muscle — The Sterno Maxillaris 131
Muscle — The Stylo Maxillaris 131
Muscle — The Temporalis 131
N
ASAL Catarrh — Chronic, Primary Chronic and Secondary Chronic
231
Nasal Gleet 231
Natural and Artificial Anomalies of
the Teeth 117
Neck ■i"
Necrosis of the Teeth of Herbivora
152, 154
Nerve and Blood Supply of Horses'
Teeth 25
Nerves 19
Nippers — Incisor 143
Nomenclature of the Teeth 18
ODONTOMATA 17S Opening the Skull 164
Operation of Cutting Elongations. . .186 Operation of Trimming and Float- ing Molars ISO
Osteo-Dentine 70
Osteoma of the Maxilla 176
Osteomata of Superior Maxilla 210
Ox — Floating Teeth of 202
Ox — Temporary Teeth of 51
260
INDEX.
O7.ona 231
"P AI.ATR- Carcinomala of the... 217
^ I'alalc — Tho Hard i:{(t
I'alatine Ilemorrliairt' 1<'><^
I'alpation of the Mouth i:'.:{
I'apilla — Dental 47
raralysis — Boll's, Facial, of tho Lips,
of the Seventh Cranial Nerve. .248
Parrot Mouth .-. . 170
ParviffnatUism 182
Perforation of the Skull— Chronic. . 230
Pericementitis 152
Peridentitis l.")2
Permanent Incisor Teeth of Horse
27, 28
Permanent Incisors of Uuminants. . . .34 Permanent Molars of Ruminants ... 37 Permanent Teeth — Evolution of ... 58
Permanent Teeth — Number of 05
Permanent Tooth — IJotrogression of. OS
Persistency of Catarrh 100
IMs — Temporary Teeth of 52
Polishing the Crowns 120
Polishing Incisor Teeth 123
Poll Strap 149
Predisposing Causes 173
Preface 0. 10
Prehension 128
Premaxilla — Fractures of the 213
Premaxilla — The 129
Primary Chronic Nasal Catarrh . . . .231
Prognathism 181
Projections on the First Superior
and Sixth Inferior ]MoIars 184
Projections on Superior Corners . . . .185
Prominent Chin 181
Prominent .Taw 181
Protrusion of the Tongue — Habitual. 244 Pterygoid Externus Muscle — The. . . .131 Pterygoid Internus Muscle — The... 131
Ptyalism — Habitual 241
Pulling 241
Pulp 19, 24, 47
Pulpitis 152, 153
Purulent Accumniulatinns in Facial
Sinuses 231
Pustular Stomatitis — Contagious. . . .227
/^UIDDING 253
RANULA 250 Receding Chin 179
Receding .Taw 179
Receding of Alveolar Margin 71
Reining — Side 242
Remnant Teeth 202
Removal of External Alveolar Plato. 107 Removal of Teeth by Si)lilting witli
Chisel .170
Renewal of the Cups 12(»
Repulsion of Teeth with Punch and
Mallet 101
Repulsion of the Tooth 105
Restraint 148
Retention Cysts 23it, 251
Ri'trogression and Evolution of the
Teeth Tabulated 124, 125
Retrogression of the Permanent
Teeth 68
Retrogression of Temporary Teeth . . 68
Rhinitis — TTnilateral Chronic 231
Routine of Examination of Horse's
Mouth to Determine the Age. .113
SARCOMATA 251 Sarcomata of the Mouth 217
Scissor Mouiu 182
Search Light 134
Secondary Chronic Nasal Catarrh. . .231
Septicaemia 167
Seventh Cranial Nerve — Paralysis
of 248
Sharp Teeth 187
Shedding of the Incisor Teeth 175
Sheep — Temporary Teeth of 56
Shortening of the Crowns 120
Shortening of the Incisor Teeth.... 123
Side Reining 242
Sinuses — Chronic of Lower .Taw.... 100 Skull — Chronic Perforation of the.. 2.36
Skull— Opening the 104
Skull— Trephining the 102
Skull — Trephining for Nasal Catarrh2.33
Slobbering 241
Soft Tissues 19
Sores— Bit 214
Splitting of the Molars 209
Staining the Incisor Teeth 123
Sterno Maxillaris Muscle — The ....131
Stomatitis — Aphthous 227
Stomatitis — Contagious Pustular. . . .227
Stomatitis — Infectious 227
Stomatiti-s — Traumatic 226
Structures of the Tooth 19
Stylo Maxillaris— The 131
Summary of Dental Evolution and Retrogression Applied to Deter- mination of Age 74
Superior Maxilla — Fractures of the. 213
Superior Arcades 33, 35
Superior Maxillary 129
Superior Molars 30, 31, 32
Superior .Molar Arcade of Ox 38
Superior Molar Table of Ox 39
Surfaces of the Teeth 19
Supernumerary Tooth 2i)2, 201
Supplementary Teeth 202
Susceptible Animals 173
TABLE of Superior Molar of Ox.. 39 Tabulated Evolution and Re- trogression of Tci'th 124. 125
Tartar 208
Teeth —Abnormal Eruptions of the. .175 Teeth — Anomalies of the Natural and Artificial 117
INDEX.
261
Teeth — Canine of Horse ..27, 28, 175
Teeth — Decayed 152, 172
Teeth — Diseases and Irregularities
of 1.52
Teeth — Eruption of the 117
Teeth — Evolution and Retrogression
Tabulated 124, 125
Teeth — Evolution of the 44
Teeth — Evolution of the Temporary. 49
Teeth — Eye 202
Teeth — Fracture of the 209
Teeth — Function of the 127
Teeth — Incisor of Horse (Per- manent ) 27, 28
Teeth of Ruminants 36, 37, 36, 39
Teeth of the Dog . . .39, 40, 41, 42, 43
Teeth — Margins of the 20
Teeth— Molar 18, 30, 127, 176
Teeth — Nerve and Blood Supply
( Horses' ) 25
Teeth — Nomenclature of the 18
Teeth — Number of Permanent 65
Teeth — Number of Temporary 65
Teeth — Repulsion of 161
Teeth — Retrogression of Permanent
68
Teeth — Retrogression of Temporary. 68
Teeth — Structures of the 19
Teeth — Supernumerary 202, 204
Teeth — Textures of the 118
Teeth — Ulceration of 172
Teeth — Wolf 202
Temporalis Muscle — The 131
Temporary Teeth — Evolution of 49
Temporary Teeth — Number of 65
Temporary Teeth — Retrogression of. 68 Temporo-Maxillary Articulation — Dis- location of 21.!
Teratomata — Dental 222
Texture of the Teeth 118
Tie Ropes 149
Tissue — Interdental Cancellated .... 48
Tissue — Ossifled Connective 48
Tissues — Hard 19
Tissues — Soft 19
Tongue 130
Tongue — Foreign Bodies in 250
Tongue — Habitual Protrusion of the. 247
Tongue — Inflammation of the 252
Tongue — Laceration of 252
Tongue Lolling 244
Tongue — Operation of Amputation of
the , ... .244
Tooth — Divisions oi: a 19
Tooth Chisel — The 144
Tooth — Repulsion of the 165
Tooth— Self Extraction of the 153
Tooth Tumors 176
Traumatic Stomatitis 226
Trephining the Skull 162
Trephining the Skull for Xa.sal
Catarrh 233
Trimming and Floating Molars. ... 189 Tumefaction on Superior Maxillary .216 Tumors of the Lips and Cheeks. .. .251 Tumors of the Mucous Membrane of
the Mouth 230
I TLCER.VTIONS of Teeth 172
^-^ Ulcerative Gingivitis of Dogs.. 220
Undershot 181
Unilateral Chronic Rhinitis 231
WADDING of Food in the Check. 255 Warts 251
Wear from Mastication 10
Williams' Operation 167
Wind Sucking 239
Wolf Teeth 202
Wolf Tooth Forceps 140
Wolf Tooth Separator 140
Wooden Tongue 219
Vv'ebster i-amiiy Library of Veterinary Medicine Cummings School of Veterinary Medicine at Tufts University 200 V\/estboro Road North Grafton, MA 01536
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