DISEASES OP BONES 187 



Wliat do you understand hy necrotic caries f 



The separation or expulsion of dead bony fragments of a 

 carious bone. 



What is dental caries ? 



Seen at times in the molar teeth, of the horse, it represents 

 a( progressive destruction of the dentine and cement of such a 

 tooth. 



Saw is dental caries produced ?» 



When the enamel of the tooth is injured, destructive 

 agents (bacteria, decomposing food) enter and exert their per-^ 

 nioious influence upon the dentine and cement substance. 



Is there any difference betiveen dental caries and alveolar 

 periostitis ? 



Decidedly. They are two entirely different pathological 

 processes, as dental caries may eventually lead to alveolar 

 periostitis, but alveolar periostitis can never produce dental 

 I caries, at least in the sense in •which caries is here, according 

 to modern views, employed. Dental caries usually starts at 

 the crown of the tooth, working upward toward the root, 

 while alveolar periostitis begins at the periosteum of the 

 alveolar cavity and root of the tooth. 



I)o all authors accept the above definitions of necrosis and 

 caries ? 



Most modern authors on pathology recognize the above 

 definition as compatible with progressive medicine, while 

 some authors yet understand by necrosis destruction of bone 

 in mass, while by caries is understood by them molecular death. 

 of bone. 



