CHAPTER III. 



RETROGRESSION OF THE TEMPORARY TEETH. 



The temporary teeth attain their greatest capacity and 

 length at the time of eruption, after which event they at once 

 begin to retrogress under the influences of pressure ab- 

 sorption at the root and of wear from mastication at the 

 ta1)le extremity, until only a shell remains to be expelled 

 into the mouth. The first event of this character (shed- 

 ding) occurs to the first and second molars at two and a 

 half years, and the last to the corner incisors at four and a 

 half years, after which time the denture is entirely free 

 from temporary teeth. The order of shedding of the tem- 

 porary teeth in solipeds is as follows: 



(i) Two and a half years, the first and second molars 

 and the central incisors. 



(2) Three to three and a half years, the third molars and 

 the lateral incisors. 



(3) Four and a half years, the corner incisors. 



This order may be made to apply to all ruminants and 

 solipeds. In the carnivora the destruction of the temporary 

 denture is remarkably rapid, as at the age of seven months 

 no temporary teeth remain. 



RETROGRESSION OF THE PERMANENT TEETH. 



The retrogression of the permanent teeth is the most im- 

 portant feature of dentistry of animals. It includes the wear 

 and eventual destruction of the teeth. The teeth of solipeds 

 and ruminants attain their maximum length and volume 

 the second year after eruption. During the first year they 



