114 EARLY DESTRUCTION OF THE TEETH. 



loosen and drop out, but their loss takes place in 

 the absence of decay. 



Again, the attack is always made upon the teeth 

 from without, and never from within. The bone, 

 so long as it is covered with the enamel ; and the 

 fangs, so long as they are protected by the gums 

 and periosteum ; are safe. It is only when these 

 parts are exposed, and present resting-places for 

 the destructive agent, that an attack upon them 

 begins. 



We also observe, that the teeth are liable to 

 decay in pairs ; and this is readily accounted for 

 from the striking resemblance they bear to each 

 other in shape, and in the distribution of their 

 enamel. If a molar tooth shows one or more deep 

 pits upon its surface, its fellow on the other side of 

 the mouth will show a similar formation. 



Again, the teeth are more liable to decay in 

 youth than in the after periods of life. It often 

 becomes necessary to remove one or more of the 

 permanent molar teeth soon after their appear- 

 ance ; and the parent of the child is surprised when 

 told that the faulty tooth belonged to the second 

 set and not to the first. The predisposition of 

 these teeth to early destruction is easily accounted 

 for, when we consider that the enamel is completed 

 before the tooth appears above the gums ; and if 

 the distribution of this substance be irregular, so as 

 to present deep pits and fissures upon the tooth's 

 surface, these parts immediately become resting- 



