OF THE TEETH. 471 



CHAPTER II. 



OF THE TEETH. 



THE Teeth (Denies) are by far the hardest portions of the 

 human fabric ; and though they bear in their composition and 

 appearance a strong analogy with bone, yet they diner from it 

 in their more limited duration, their mode of development, 

 their partial nudity, their nutrition, and in the manner by which 

 they are united to the body. 



The greater part of the length of each tooth is implanted 

 into the alveolar process of the jaw, and the part so fixed is 

 technically called the root; immediately beyond this a small 

 portion of the tooth is embraced by the gum; this is the neck; 

 and the free, or projecting 'part of the tooth covered with a 

 shining porcelain like layer called the enamel, is its body. 



SECTION I. 



The whole number of teeth in the adult is thirty-two, sixteen 

 in each jaw, and, when healthy, they are all fixed with so much 

 firmness by the gomphosis articulation, that the very slight de- 

 gree of motion, which, by force, they may be caused to exe- 

 cute, is scarcely perceptible. The differences existing in their 

 shape, have caused anatomists to classify them accordingly; 

 on each side of the middle line of each jaw there are two Inci- 

 sors, one Cuspated, two Bicuspated, and three Molar teeth. 

 There are also some peculiarities, as they belong to the upper 

 or to the lower jaw; but they correspond exactly with their 

 fellows on the opposite side of the same jaw. 



The Incisors (Denies Incisivi) are next to the middle line, 

 and are named from their being brought to a straight cutting 

 edge, like a chisel, by being bevelled from behind. They are 

 somewhat convex on their anterior faces, but behind they are 



