108 EARLY DESTRUCTION OF THE TEETH. 



already formed, as some have supposed, but to 

 deposit new bone upon the inner walls of the tooth, 

 in order that the fabric may be strengthened and 

 supported, and compensation made for the waste 

 occasioned by abrasion from without, during the 

 process of mastication. But other bones are not 

 formed in this manner : they are highly organized ; 

 from circumference to centre they abound with 

 vessels conveying nutriment to all parts alike ; and 

 from small soft bones they increase in size and den- 

 sity, until the middle period of life, when they reach 

 maturity. And not only is their mode of forma- 

 tion altogether different from that of the teeth, but 

 their constitution is of a more delicate nature, and 

 requires a covering — a periosteum and other invest- 

 ments — to protect them from the influence of 

 foreign bodies. 



We now come to the enamel of the tooth ; and 

 in giving a short description of the mode of its 

 formation, we shall be enabled to trace the origin 

 of the pits and fissures so frequently seen upon 

 the surfaces of the molar teeth, and which are the 

 principal predisposing cause of their destruction. 



The enamel is more speedily formed than the 

 bone. It is completed before the tooth appears 

 above the gums ; and the membrane that secreted 

 this substance, having fulfilled its office, is removed. 

 There cannot, therefore, be two opinions regarding 

 the inorganic nature of the enamel, for it is certain 



