THE FRAMEWORK OF THE BODY 



53 



sometimes not erupted until late in life, if at all. Since these groups of 

 teeth are common to the mammals in general and vary in number, kind, 

 and use from one animal to another, it is customary to express the dental 

 armature of a given kind of mammal by means of a shorthand formula 



enamel 



crown 



pulp ca 



dentine 



cementum 



connective 



blood 



erve 



Fig. 3.14. Longitudinal section through an incisor tooth. 



that shows the number of upper and lower teeth on one side of the jaw. 

 The dental formula of man and of all his nearest allies is 



2 1 2 3 

 I 2' C I' P 2' M 3 = 16 



The structure of a typical tooth is shown in Fig. 3.14. The outer layer 

 of enamel that covers the surface of the exposed parts of the tooth is the 

 hardest tissue in the human body. 



