EXOSTOS1S, INFLAMMATION, BLOWS, VIRUS. 137 



drop of stagnant water. Dr. Miller says : " The 

 fungi have not the power either to penetrate or to 

 decalcify sound dentine." (See pages 299, 300-3.) 



In order to facilitate the study of and cast further 

 light on the subject, I have brought into juxtaposi- 

 tion as it were a summary of the views of a few able 

 men as to the causes of caries, which, better still, 

 is followed by the reports of well-known surgeons, 

 who give the results of their experiences in detail. 



Prof. Owen says a tooth has no inherent power of 

 reparation ; that in growing teeth with roots not 

 fully formed, the cement is so thin that the Purkin- 

 jean cells are not visible. It looks like a fine mem- 

 brane, and has been described as the periosteum* of 

 the roots. It increases in thickness with age, and is 

 the seat and origin of what are 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 Prof. Owen says : 

 " But the cavity had evidently been the result of 

 some inflammatory and ulcerative process in the 

 original formative pulp." 



Dr. Boon Hayes says : "I think it would not be 

 difficult to prove that caries of the teeth more fre- 

 quently proceeds from inflammation beginning in 

 the pulpal cavity than from any other cause." (A 

 great mistake. This cause is a very rare one.) 



Dr. Robley Dunglison says : " The most common 

 causes of caries are blows, the action of some virus, 

 and morbid diathesis." 



* Surgeon 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 supplied by means of vessels 

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

 be easy for inflammation to be conveyed from one to the other. 



