CHAPTER XV. 

 THE TEETH. 



THE teeth are situated in the upper and lower jaws. 

 They are made of the sane tissue as bone but con- 

 tain "*0J/> per cent, more of earthy salts. This fact 

 accounts for their extreme hardness. Unlike bene 

 they can stand exposure to air and friction without becoming 

 diseased. Teeth are used to masticate or chew the food, and 

 because cf the constant change in their formation and ap- 

 pearance they serve as a guide in telling the age of the horse. 



I. COMPOSITION OF THE TOOTH. 



A tooth is made up of three hard substances, viz: dentine 

 or ivory, enamel and crusta petrosa. 



1. The Dentine or ivory is situated in the upper part 

 around the pulp or nerve cavity. It is of a yellowish color 

 and largely supplied with nerves which pass through it from 

 the pulp cavity. 



2. The Enamel is the hardest substance of the tooth, 

 and covers the outside of all the exposed part. This sub- 

 stance is characterized by its whiteness and, unlike the 

 dentine, contains no blood vessels or nerves. If part of the 

 enamel is broken off it is never replaced, and the tooth 

 below the broken part generally becomes decayed. 



3. The Crusta Petrosa is found in the fang or root and 

 the parts situated below the gum. It is the softest part of 

 the tooth. 



II. — PARTS OF A TOOTH. 



Each tooth is divided into four parts, viz: the body or 

 crown, that part above the gum ; the table, the part that 

 comes into wear on the top ; the neck, the part to which the 

 gums are attached ; and the fangs or roots, the parts situated 

 down in the bone. 



IIL CLASSES OF TEETH, 



There are three kinds of teeth found in the horse, viz: 

 the incisors, the canine, and the molars. 



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