330 PHYSIOLOGY. 



by unequal expansion and contraction, as is readily ascer- 

 tained by the assistance of the microscope. Teeth thus 

 injured, almost always decay in consequence of the exposure 

 of the bony substance of the tooth to the action of corro- 

 sive fluids.) 



16. (There are three prevalent general causes of the de- 

 struction of human teeth, besides occasional accident : viz. 

 accumulation of tartar, ulceration of the fangs, and dental 

 gangrene/ Ulcers of the fangs extend to the alveoli or 

 sockets, which are also destroyed, together with the invest- 

 ing gum. The well informed dentist can best prescribe and 

 apply the proper remedies for all these forms of dental dis- 

 ease. 





