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 



