THE TEETH 



419 



THE DECIDUOUS TEETH. 



1 '- 



Formula : di -, do -> dm - 



o _L -j 



The upper deciduous incisors (Fig. 339) are almost exactly like the 

 permanent teeth ; they are smaller, and the crowns of the inner and 

 middle appear to be more pointed, owing to the elongated middle cusp. 



The upper deciduous canines (Figs. 340, 341) are much more 

 slender than the permanent. The crowns are more strongly curved ; 

 the posterior borders are so deeply emarginate that the cingulum pre- 

 sents a decided heel. On the anterior border near the base, in very 

 young teeth, is a sharp angle, below which the border is sharp and 

 straight, to cut against the posterior outer border of the lower canine. 



FIG. 340. 



Incisors. 



FIG. 339. 



Canine. 



First Molar. 



Second Molar. 



Third Molar. JE 



ANTERIOR DECIDUOUS TEETH. 



RIGHT UPPER DECIDUOUS 

 TEETH. INFERIOR ASPECT. 



The first upper deciduous molar (Figs. 340, 341) is a very small 

 tubercle, resembling the permanent tooth. 



The second upper deciduous molar (Figs. 340, 341) is a sectorial 

 tooth. It differs from the permanent sectorial in general by its smaller 

 size and the acuteness of its cusps. The internal cusp and fang are 

 not at the anterior end, but at the middle of the tooth ; the cusp 

 projects but little beyond the gum. The central cusp is very acute ; 

 in front of the anterior cusp, which is inclined inward, is a distinct 



