THE TEETH 37 



perfectly sound, the diseased condition being confined to the 

 alveolus. 



The fistula should be then injected with antiseptics, and in all 



cases it is advisable to extract the tooth. 



Dental Caries 



This is the name given to the necrotic process which leads to the 

 destruction of the teeth. The dentine and cement are the parts 

 which are the most quickly destroyed, the enamel remaining compara- 

 tively intact. The disease is not by any means common in the horse, 

 and some observers even go so far as to state that it does not occur at all 

 in this animal. Such, however, is not the case. The disease is very 

 commonly met with in dogs. According to Kitt, " the caries, as 

 observed in the teeth of animals, is of the dry and chronic kind." 



With regard to the exact seat and origin of the disease, there is 

 considerable difference of opinion. Some observers maintain that it 

 commences in the dentine, whilst others are equally definite in their 

 assertions that the cement substance is the part of the tooth which 

 forms the starting-point of the disease. But this is not a matter 

 which greatly concerns us here, since it will suffice for our purposes 

 to know that whether the disease actually commences in the dentine 

 or the cement, both become quickly affected, and the subsequent 

 progress of the disease is gradual. 



Caries of the tables of the molars is very rare. The part which 

 is most commonly affected is the interdental surface. It is supposed 

 that as the teeth are thrust out from the alveoli, the interdental spaces 

 gradually increase in size. The gums shrink slightly, and particles of 

 food material make their way into the spaces between the teeth, where 

 they become permanently fixed. 



The decay of the teeth is generally attributed to the decomposition 

 of this food material, which has thus become insinuated between 

 them. Caries of the interdental surface extends very slowly, so that 



