Page 747 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

722 CHAPTER 4

VetBooks.ir 4.1 103 102 101 201 202 203

111 110 109 108 107 106 105 104 204205 206 207 208 209 210 211
Buccal

Palatal
lingual

Buccal
411 410 409 408 407 406 405 404 304 305 306 307 308 309 310 311

403 402 401 301 302 303

Fig. 4.1 Diagram showing Triadan dental nomenclature for Equidae.

wear, the occlusal surfaces of opposing incisors meet Premolars
closely to enable close cropping of grass. Inspection The first premolars (‘wolf teeth’) are often rudimen-
of the occlusal surfaces reveals a conical indenta- tary with a short reserve crown and lie variably from
tion in the enamel and cementum, which when worn the middle of the interdental space to a position in
appears as a ring of enamel or infundibulum (termed close apposition just rostral to the second premo-
historically as the dental cup), the appearance of lar. They are present in most horses and historically
which varies with the age of the horse. Progressive have been removed empirically, although there is lit-
attrition reveals the brown-stained secondary den- tle clinical evidence to indicate this to be necessary.
tine, laid down by odontoblasts in the pulp cavity The remaining premolars and the three molars,
labial to the infundibulum, which is termed the termed ‘cheek teeth’, differ between the mandibular
‘ dental star’. and maxillary arcades.
The marginal enamel on the palatal and lingual
Canine teeth aspects of the maxillary cheek teeth contains undu-
The canine teeth are present in male, and occa- lations forming sharp lateral cusps on the buccal
sionally female, horses and erupt in the interdental aspect and wear results in occlusal transverse ridges
space midway between the corner incisor and the giving the surface a serrated appearance. Although
first premolar. The lower canine is more rostral. covered with peripheral enamel at eruption, occlu-
The canine teeth are brachydont and sustain no sal attrition exposes occlusal dentine within a few
attrition of the occlusal surfaces, and their role weeks of wear. In the middle of the occlusal surface
is in defence rather than mastication. As a result, lie two crescent-shaped enamel infundibula that are
the surface retains its peripheral enamel coating lined with infundibular cement making them vari-
and only peripheral cementum is worn away. The able in appearance. Ongoing attrition reveals five
reserve crown is sickle shaped and extends caudally dark areas of secondary dentine each of which over-
towards the apex. lies a pulp horn lined with odontoblasts. These cells