Note: The hard parts of teeth are principally made up of
dentine, or ivory, and a very hard substance called
enamel. These are variously combined in different
animals. Each tooth consist of three parts, a crown, or
body, projecting above the gum, one or more fangs
imbedded in the jaw, and the neck, or intermediate
part. In some animals one or more of the teeth are
modified into tusks which project from the mouth, as in
both sexes of the elephant and of the walrus, and in
the male narwhal. In adult man there are thirty-two
teeth, composed largely of dentine, but the crowns are
covered with enamel, and the fangs with a layer of bone
called cementum. Of the eight teeth on each half of
each jaw, the two in front are incisors, then come one
canine, cuspid, or dog tooth, two bicuspids, or false
molars, and three molars, or grinding teeth. The milk,
or temporary, teeth are only twenty in number, there
being two incisors, one canine, and two molars on each
half of each jaw. The last molars, or wisdom teeth,
usually appear long after the others, and occasionally
do not appear above the jaw at all.
How sharper than a serpent's tooth it is To have
a thankless child ! --Shak.
These are not dishes for thy dainty tooth. --Dryden.
3. Any projection corresponding to the tooth of an animal, in
shape, position, or office; as, the teeth, or cogs, of a
cogwheel; a tooth, prong, or tine, of a fork; a tooth, or
the teeth, of a rake, a saw, a file, a card.
4.
(a) A projecting member resembling a tenon, but fitting
into a mortise that is only sunk, not pierced through.
(b) One of several steps, or offsets, in a tusk. See
{Tusk}.