50 



COMPAEATIVE DENTAL ANATOMY 



Fig. 13. — B e a k of 

 Sawfish (Pristis pecti- 

 na'tus) , showing theco- 

 dont ankylosis. 



There are three forms of 

 the tooth which are attached 

 by gompho sis. The brachydont 

 tooth, the hypsodont tooth and 

 the tooth of continuous growth. 



In the brachydont tooth, the 

 length of the root exceeds that 

 of the crown. The crown, very 

 early in the life of the tooth, 

 emerges from the gum. In 

 those teeth we also find that the 

 enamel covers the crown of the 

 tooth and the cementum only 

 extends to the gingival border 

 of the enamel. The teeth of 

 man is an example of this form 

 of attachment. Fig. 14 also 

 shows brachydont teeth. 



The hypsodont is character- 

 ized by the length of the crown 

 being as great or greater than 

 the root. The entire crown 

 does not emerge from the socket 

 and gums as one, but as the 

 crown is worn off the tooth con- 

 tinues to erupt. The tooth is of 

 continuous eruption but not of 

 continuous growth. Figs. 15, 

 65, 70 and 71 are examples of 



