STRUCTURE OF TEETH 



101 



Enamel- 

 Dentine 



Periosteum 

 of socket. 



Cemen 

 Bone of ja 



Pulp Cavity 



whereas others have roots which are forked near the 

 tip. Most of the molars have three roots. 



Structure. Each tooth consists of the exposed por- 

 tion, or crown; the narrowed part enclosed by the edges 

 of the gums, called the 

 neck; and the portion 

 imbedded in the bones, 

 the roots. When sawed 

 through lengthwise, a 

 tooth is found to consist 

 of a bony portion and an 

 inner cavity. The crown 

 of the tooth is capped 

 with the hardest substance 

 found in the human body, 

 a white enamel, which is 

 all of the tooth that we 

 ordinarily see. Enamel is 

 made up of the same 

 earthy material as bone 

 but contains none of the 

 animal matter and but a slight amount of water. 



Within the enamel lies a less hard bony material, the 

 ivory or dentine, which forms the bulk of both crown 

 and root. Dentine also contains less animal matter 

 and less water than bone. The dentine of the root is 

 protected by a substance which closely resembles true 

 bone. It is called cement, because it serves to hold 

 the teeth firmly in their sockets by wedging their roots 

 against the bony walls. 



The cavity within the tooth is filled with blood-vessels 

 and nerves, which form the so-called pulp of the tooth 

 and enter it through small holes at the tips of the roots. 

 They supply the dentine with nourishment and keep it 



FIG. 66. Section through jaw bone and 

 tooihofcat. (Waldeyer.) 



