VETERINART DEXTAL SURGERY. 81 



Caries of the third upper molars is frequently 

 the source of excessive pain, and is to be very much 

 dreaded. It is more sensitive when diseased than 

 any other tooth, from the fact that the maxillary 

 branch of the fifth pair of nerves make their exit 

 upon the face through a foramen, which is located 

 directly over the root of this tooth. This fact must 

 not be lost sight of in trephining for its removal; 

 for, should this nerve be injured in any manner 

 during the operation, the animal will suffer greatly 

 and become unmanageable for further operation 

 unless it be cast and secured. 



The fourth, fifth and sixth molar teeth of the 

 upper jaw are situated directly below the large 

 maxillary sinus, from which they are separated by a 

 thin plate of bone. They communicate with the 

 sinus as easily as do .the first and second with the 

 nose ; but lead to far different results. 



When inflammation or caries is sufficient to destroy 

 this thin plate of bone, the pus which is formed 

 passes into the sinus, sometimes particles of food 

 accompanying it. By its presence the mucous mem- 

 brane of the sinus becomes irritated and will either 

 slough or become thickened, developing large eleva- 

 tions of the nature of polypi; or they may form 

 osseous tumors. Both forms by addition attain suffi- 

 cient volume to fill the sinuses and cause a bulging 

 of the facial bones. The pus all this time is very 



