THE TEETH. 



1543 



cases. We shall speak instead of the inner and outer sides of the incisors and 

 canines and of the anterior and posterior sides of the bicuspids and molars. If the 

 position of the tooth in the jaw be remembered, no confusion is possible. 



The Incisors. The crowns are characterized by slightly convex quadrilateral 

 labial surfaces, rather broader than the lingual ones, and ending in straight cutting 

 edges, slightly concave lingual surfaces slanting forward and bevelled at the edge, 

 triangular lateral surfaces, and single roots. The labial and lingual surfaces of the 

 crowns are bounded at the root by curved lines, the convexity being towards the 

 gums. At the sides these borders are continued as straight lines towards the free 



FIG. 1297. 



Partly developed fangs of last molar, 



Crown of last molar. 



Permanent teeth, showing their forms and relations; outer surface of jaws partly removed. Last molars are only 



partially formed. 



edge, and meet at an acute angle. The enamel is continued farther on the lingual 

 surface, especially in the lateral incisors of both jaws. The cutting edge shows three 

 small scallops on its first appearance, but they speedily wear away (Fig. 1298). 



The superior median incisors are much the largest. The labial surface of 

 the crown is nearly square. The inner half of this surface is more strongly convex 

 than the lateral. Traces of three swellings are often found on the labial side of the 

 lower half of the crown extending to the three primitive scallops on the edge. The 

 free edge meets the internal border at nearly a right angle, but the outer angle is 

 rounded. The lingual surface, narrower than the labial, is a little concave. Some- 

 times the edges are raised so as to leave a distinct V-shaped depression, in the 

 middle of which runs a vertical ridge, the cingulum, which ends below in a tiiberde. 



