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30 MACROSCOPIC ANATOMY OF THE HUMAN TEETH.

side only so far as tlie lateral protuberances. They are not strongly
marked as u rule. The fossie on eaeh side of the vertieal median ridge,
between it and the marginal ridges, may be quite deep but are usually
shallow and ill defined.
The mesial face in outline is not unlike the central incisor, l)ut its
contour is very different, for it is more or less rounded in all direc-
tions, and the lateral eminence in the lesser third makes this part espe-
cially full (i). From this point the surface is depressed roundly to the
enamel line at the neck, where a depression of greater or less depth is
found. It is somewhat flattened at the cervix. The point of contact
is at the eminence, which touches the lateral incisor.
The dldal face is of similar form to the mesial, except that it is more
full and the eminence more pronounced, which gives the increased width
of the crown on that side. The surface descends rapidly tow^ard the neck
and is rounded labio-lingually. The point of contact with the first l^i-
cuspid is on the lateral protuberance.
The morsal edge presents a prominent cusp which is almost central
to the long axis of the tooth. The side facets slope away, but still retain
The distal side of the edge is longer than the
their cutting edge (6).
mesial, by reason of the increased size of the distal protuberant angle.
The sharp point is soon worn off to a rounded cusp, and, as wear
increases with age, it may be reduced to a straight surface between the
mesial and distal protuberances (g).
The neck is a flattened oval on section, or the lateral direction of the
labial portion may be greater than that of the lingual (h). The enamel
line preserves the same curves as on the incisors, /. e. rounding upward
on the labial and lingual surfaces and dipping downward on the mesial
and distal. The enamel terminates gradually with but a slight ridge,
unless it should be on the lingual side. A depression occurs on both
mesial and distal sides above the curve, which may lead up as a groove
on the root.
The root is longer than that of any other tooth, and it is at least
one-third larger than that of the central incisor. It is of a rounded
trihedral form, or irregularly conical. It is usually straight, and tapers
to a slender point, which may be curved or very crooked. In well-
arranged dentures, where it has erupted naturally, it is usually straight.
The pw/p canal is large and open, of the same form as the tooth, and
easilv entered. It is regularly formed except in those cases Avhere the
root is curved, and even in these it can be filled if not too crooked, as
it is so open and accessible.
11. The Lower Canine.—This is similar to the upper in form and
outline, except that it is somewhat smaller, more slender, and more
rounded in form (Fig. 16, a). It differs also in being more compressed