CHAPTER III 



THE TEETH 



Structure of the Teeth 

 A tooth is made up of two parts, one of which is firmly implanted in 

 the socket or fossa, technically called the alveolus, in the bone which 

 carries the tooth. This part is called the root. The other portion is 

 exposed and its base is surrounded by the gum. The surface of this 

 portion, which is subjected to wear on account of the friction during 

 mastication, is called the table of the crown. The constricted portion 

 of the tooth which separates these two parts is the neck. 



The extremity of the fang shows a small perforation opening into 

 a cavity which extends for some distance up the middle of the tooth. 

 This is the pulp cavity, and into it a small protoplasmic mass extends 

 from which the tooth obtains its nutrient supply. This mass is the 

 dental pulp, and it contains minute blood-vessels and nerves. The table 

 of the crown being the part subjected to wear, undergoes considerable 

 variations in form and appearance. 



Three substances essentially enter in the composition of all teeth, 

 namely, dentine, enamel, and cement. 



The dentine is the yellowish-white, bone-like material which makes 

 up the greater part of the tooth, and surrounds the pulp cavity. Micro- 

 scopically it presents a number of wavy tubules, which radiate outwardly 

 from the cavity. Each tubule is surrounded near the cavity by a 

 delicate layer of hardened material, and into the tubule passes a fine 



