THE TEETH 



1121 



edge slopes to the lateral angle. The medial limb of the cutting edge is usually 

 somewhat shorter than the lateral, rendering the crown asymmetrical. The 

 labial surface is convex, the lingual somewhat concave. The root is single, long, 

 flattened from side to side and grooved on the sides as in the incisors. The canine 

 root is usually slightly curved lateralward. The bony alveolar protuberances 

 [juga alveolaria] are more prominent than those of any other teeth. 



The upper canine slants forward and overlaps the lower, as in the incisors. The upper 

 canine also presents a well-marked cingulum, and usually a distinct lingual cusp (fig. 871) 

 below which a slight median ridge extends along the hngual surface. On the lower canine, 

 these structures are poorlj^ marked or absent. The lower canine is somewhat smaller than the 

 upper, and its root is occasionally bifid. 



The premolars.— (Figs. 868, 869, 870, 876, 877.) The premolars [dentes 

 premolares] are so named on account of their position in front of the molars. The 



Fig. 876.- 



-DissECTioN Showing the Roots of the Teeth. 

 (From Toldt's Atlas. 



Teeth in Occlusion. X 1 



Buccal surface 

 Wisdom tooth 



Canine 

 tooth 



Molar teeth 



Premolar teeth 



Mental foramen 



crown presents on the masticating surface two prominent cusps, on account of 

 which the premolars are often called 'bicuspids.' The buccal and lingual sur- 

 faces are convex especially from side to side, so that the crown is somewhat 

 cylindrical in form, with flattened, quadrilateral anterior and posterior contact 

 surfaces. The root is (usually) single and more or less flattened antero-posteriorly, 

 and usually somewhat curved backward. 



The upper premolars are distinguished from the lower by a greater antero-posterior flatten- 

 ing of the crown and by a deep groove separating the cusps (excepting at their anterior and 

 posterior margins) on the masticating surface. In the first upper premolar the lingual cusp 

 and surface are decidedly smaller than the buccal; and the root is frequently bifid or double 

 (occasionally even triple). In the second upper premolar the lingual cusp and surface are as 

 large as the buccal; and the root, though deeply grooved, is rarely bifid. 



In the lower premolars, the crowns are more cylindrical in form, and the cusps are united 

 by a median ridge so that the masticating surface presents two small pits. The roots are more 

 rounded and tapering, and rarely grooved. In the first lower premolar (like the corresponding 

 upper) the hngual cusp and surface are much smaller than the buccal, the hngual cusp some- 

 times being rudimentary; while in the second they are more nearly equal. The second lower 

 premolar is often slightly larger than the first, while in the upper premolars the converse is true. 

 It should be noted, however, that the premolars are quite variable in all respects, and it is 

 therefore often difficult to identify the individual isolated teeth. 



The molars.— (Figs. 868, 869, 870, 872, 875, 876.) The molars [dentes mol- 

 ares] or 'grinders' are characterized by their large size, and by the presence of 



71 



