166 ANIMAL DENTISTRY. 



sulphate solution and renfewal 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 reaccumulation 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 healing and closure of the cavity. 

 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 insulting agent is the remedy. 



