CHANGES IN THE TEETH FEOM AGE. 745 



4. The permanent incisors grow more and more oblique, owing 

 to their shape, and position in the jaws. Consequently, the angle 



Fig. 198. — Longitudinal section from front to rear of a 



permanent central incisor of the lower jaw. 



FA, anterior face. FP, posterior face, C, cement. 



E, enamel. I, ivory or dentine. {From Goubaiix and Barrier.) 



formed by the respective teeth of both jaws, when the mouth is 

 shut, becomes more and more acute with age. Their crowns 



