DECAY, EXOSTOSIS, AXD ABSCESS. 137 



Dr. G. A. Mills says that when the tone of a tooth 

 can )3e brought to the point of resistance of the in- 

 flammatory process, dentists will have gone a long 

 way in providing against the effects of caries. The 

 dentine decays faster than the enamel. 



Prof. Owen says a tooth has no inherent power of 

 reparation ; that in growing teeth, with roots not fnilj 

 formed, the cement is so thin that the Purkinjean 

 cells are not. visible. It looks like a fine membrane, 

 and has been described as the periosteum* of the 

 roots. It increases in thickness with the age of tlie 

 tooth, and is the seat and origin of what ai'e called 

 exostoses of the roots. These growths are subject to 

 the formation of abscesses and all morbid actions of 

 true bone. Of a diseased fossil horse's tooth he says : 



" But the cavity had eWdently been the result of 

 some inflammatory and ulcerative process in the origi- 

 nal formative pulp." 



Dr. Boon Hayes says : 



"I think it would not be difficult to prove that 

 caries of the teeth more frequently proceeds from in- 

 flammation beginning in the pulpal cavity than from 

 any other cause." 



Dr. Robley Dunglison says : 



"The most common causes of caries are blows, the 

 action of some virus, and morbid diathesis." 



* Sarpfeon John Hughes says : " The periosteum of the teeth 

 is not supplied with blood in the way the same membrane in 

 other parts of the body usually is. It is sap]:»Iied by means of 

 vessels coming from the pulp of the tooth." If this is true, then 

 it would be easy for ioflammation to be conveyed from one to 

 the other. 



