302 



THE TEETH. 



J 



tissue of the gums, which closely surrounds the neck of the tooth. 

 The fangs of all the teeth taper from the cervix to the point, and this 



Fig. 201. Fig. 201. — Vertical Section 



OF Premolar op Cat. 15 

 DIAMETERS (Waldeyer). 



c, is placed in the pulp- 

 cavity, opposite the cervix or 

 neck of the tooth : the part 

 above is the crown, that below 

 is the root (fang). 1, enamel 

 "with radial and concentric 

 markings ; 2, dentine with 

 tubules and incremental lines ; 

 3, cement or crusta jjetrosa, 

 ■with bone corpuscles ; 4, 

 dental periosteum ; 5, bone 

 of lower jaw. 



form, together with the 

 accurate adjustment to 

 the alveolus, has the 

 effect of distributing the 

 pressure during use over 

 the whole socket, and of 

 preventing it from un- 

 duly bearing on the 

 point of the fang, 

 through which the blood- 

 Tessels and nerves enter. 

 The thirty-two perma- 

 nent teeth consist of four 

 incisors, two canines, 

 four bicuspids, and six 

 molars in each jaw. The 

 twenty temporary teeth 

 are four incisors, two 

 canines, and four molars 

 above and below. There 

 are no bicuspids among 

 the temporary teetli, the 

 eight deciduous molars 

 preceding eight bicuspids 

 of the permanent set. The relative position and arrangement of the 

 different kinds of teeth in the jaws maybe expressed by the following 

 formula, which also exhibits the relation between the two sets in these 

 respects : — 



Temporaiy teeth . . . •: 



Permanent teetli . 



( Upper 

 ( Lower 

 (Upp 

 ( Lower 



MO. CA. IN'. CA. MO. 



2 14 ] 2 



= 10 

 - =20 



MO. BI. CA. 



ler 3 2 1 



4 1 2 =10 



IX. CA. 151. JIO. 



4 1 2 3 ==16 

 =32 



1 



3=10 



The Peumanext Teeth.— Tlie incisors (fig. 202), eight in number, 

 ave the four front teeth in each jaw, and are so named from being 



