Teeth. 



334, Incisor, Bicuspid and Molar Teeth, in section. 



That part of the teeth, Denies, which projects above the gums, 

 is called body or crown, Corona; the part fixed in an alveolus of the 

 upper or lower jaw, the root, Radix; between the crown and the root 

 is the constricted portion, the neck, Collum, covered by the gums. Cor- 

 responding to the crown and neck of the tooth, a hollow cavity, Cavum 

 dentis, is found in its interior; this is continuous with a canal, Canalis 

 radicis, which opens by a minute orifice at the extremity of the root. 

 The cavity is occupied by a soft, highly vascular and sensitive substance, 

 the dental pulp, Pulpa dentis. 



The tooth is composed of three substances: 



a) The enamel, Substantia adamantma s. vitrea, encrusts and pro- 

 tects the crown ; it is thickest on the grinding surface of the crown, 

 and becoming gradually thinner, ends at the neck; it consists of hard 

 and dense hexagonal fibres, which pursue a more or less wavy course. 



b) The ivory or dentine, Ebur s. Substantia propria, forms the 

 body of the tooth ; it consists of a structureless mass, which has numerous, 

 very fine tubes, opening at their inner ends into the pulp cavity, and 

 pursuing a wavy and undulating course towards the periphery. 



c) The cement, Crusta ostoides radicis, covers the external surface 

 of the root, and has the structure of bone. 



Heitzmann, Atlas. II. 2 



