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 "OJ^? 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 of the constant change in their formation and ap- 
pearance they serve as a guide in telling the age of the horse. 
L 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. 
n. — 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, 
m. — 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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