200 



A MANUAL OF DENTAL ANATOMY. 



period than is natural, they sometimes become elevated to 

 the general level of the permanent teeth (which is consider- 

 ably higher than that of the temporary teeth), so that they 

 take their share of work in mastication. When this is the 

 case the alveoli are developed round them, and co/ne to 

 occupy with the tooth a higher level than before. 



FIG. 86 (). 





j* 



Enough has perhaps been said to illustrate the entire 

 dependence of the alveoli upon the teeth, a relation of which 

 dentists every day avail themselves in the treatment of 

 i regulation cases : it remains to say a few words as to the 

 ^forces which do determine the position of the teeth. 



Inasmuch as when a tooth leaves its bony crypt, the 

 bone does not at first closely embrace it, but its socket is 



(!) From a child aged fourteen. The specimen well exemplifies the fact 

 that the height of the alveolar edge corresponds exactly to the position of 

 the neck of each tooth, on which it is wholly dependent. A temporary 

 tooth (the first right lower temporary molar) has been elevated, so that it 

 has attained to the level of the surrounding permanent teeth, and the edge 

 of the socket follows the level of the neck of the tooth. 



