THE TEETH. 



199 



sufficiently masticated, the tongue pushes it back into the 

 pharynx to be swallowed. 



The Teeth. The teacher can easily get a lot of teeth 

 from almost any dentist for the asking. These should be 

 cleaned before using them in the class. Use pearline or any 

 washing-soda. If there be enough time, let each pupil make 



Longitudinal Section 



- Enamel 



Pulp Cavity 



Dentine 



Cement 



Side View 



Face View 



Crown 



- Neck 



Root 



: Hole for Blood Tubes and Nerves 



Fig. 56. Parts of a Tooth. (Incisor.) 



a drawing of one of each of the four kinds of teeth ; and it 

 would be well to draw both a front (outer surface) and a side 

 view (surface adjacent to another tooth), of each of the four 

 kinds. 



The study of a single tooth. 



1. External features of a tooth. 



Examine one of the front teeth. It has the following parts 



1. The Crown, the part that is above the gum. 



2. The Root, the part that was buried beneath the gum. 



3. The Neck, a more or less constricted part, dividing 

 the crown from the root ; it is normally at about the surface 

 of the gum. 



4. A Hole at the tip of the root. 



