5"36' OHAPTER 71. 



Size of Molars. 



Plate 46, fi<^. 2, delineates the third molar taken from upper jaw of a 

 seven-year-old horse. Drawn exactly the natural size, it shows at a 

 glance the difficulty presented to the removal of a mature molar, sur- 

 rounded as it is by thin plates of easily frangible bone which compose 

 its socket. 



With age the fang becomes considerably shoi'tened, and extraction an 

 easier matter. So with temporary or deciduous teeth, which are easily 

 removed as Nature absorbs their fangs before the growth of the per- 

 manent teeth. 



Irregularities in Growth. 



These are many and various, from the Parrot Mouth, in which the 

 upper incisors overlap like the beak of the parrot ; or the contrary, 

 where the lower jaw projects, and the horse is said to be underhung. 

 Or in other cases from excessive development of one molar from disease 

 of its opposing tooth. Plate 4G, fig. 1, A. 



Not unfrequently one or more temporary teeth become permanent and 

 overcrowd the jaw. 



An interesting case occurred in my own experience with a four-year- 

 old, which failed to develop the lower tusks, and extreme poverty of 

 condition resulted till nearly five and a half years old, when one tusk 

 appeared veiy close to the centre of the jaw, and with it a rapid im- 

 provement in condition, which he has since maintained; but there is no 

 sign of the missing tusk. 



From irregularities of wear, probably produced by disease of one or 

 other of the teeth, the end molars, both in front and rear, are peculiarly 

 apt to overlap their opposing teeth. Fig. 1, B. Extra molars sometimes 

 appear, and do but little harm if opposed by corresponding teeth in the 

 other jaw. 



Premature removal of the milk teeth with the intention of hurrying 

 on the growth of the permanent teeth, sometimes results in non-appear- 

 ance of the latter. Thus perhaps there may be four incisors only in the 

 lower jaw, while there are six in the upper jaw. 



The treatment of these irregularities is the work of a man intimately 

 acquainted with the anatomy of the head. Surgical relief is alone of 

 any use. 



Projecting molars sometimes occur from want of uniformity in width 

 or length of jaw, and in other cases from disease in crown of opposing 

 tooth, which ceases to present the customary attrition from wear. Where 

 far advanced, the hypertrophied tooth may attain such a size as to pai'- 

 tially lock the jaw when mastication is attempted. See Fig. 1, A. 



Or the projection arising from first-named cause takes place either at 

 first or last grinder as sho^^^l at b. 



Surgical aid in skilled hands is the only remedy. 



