VETERINARY DENTAL SURGERT. 105 



for the purpose of removing teeth. The exostoses 

 if solid very seldom do any harm until they exert 

 undue pressure upon the teeth or walls of the sinus. 

 I am inclined to believe from the frequent discovery 

 of these exostoses, when trephining, that they are 

 often the true cause of caries of the teeth, or inflam- 

 mation of the dental periosteum. 



CAUSES. 



Exostoses on the walls of the sinus are due to both 

 local and constitutional causes. The local causes are 

 injury to the walls of the sinus by external violence, 

 which either fractures the bones or sets up an inflam- 

 mation of the inner lining of the sinus. Nature in 

 endeavoring to assist the restoration of the parts, 

 causes new bone cells to form, which greatly multi- 

 ply, forming bony tumors of variable sizes, according 

 to the extent of the injury. The constitutional causes 

 would be the same as those which bring about the 

 production of bony tumors in other parts of the bony 

 framework, an ossific diathesis. We sometimes see 

 colts that were born with exostoses upon certain 

 parts of the skeleton. This is especially true of the 

 inferior maxilla. We have seen numerous instances 

 where there was an exostosis on this bone about the 

 region of the anterior and the middle third, varying 

 in size from a bean to an English walnut, and of 

 various shapes; some oblong, others oval, and in 

 some cases very elongated ones have been observed. 



