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30 PATHOLOGY OF THE HARD TISSUES OF THE TEETH.

be delayed as long as possible. The roots of these teeth are just
as good for the purpose of artificial crowns as the roots of fully
developed teeth; in fact, all of that portion of the tooth root-wise
of the atrophied part is normally developed as a rule. In all
of this work there is an opportunity for the exercise of great
skill and taste in bringing about excellent esthetic effects.
Pits in the Enamel.
Pits in the enamel are a common accompaniment of atrophy
of the teeth, but not in any way a necessary part of it, as is
shown by the many cases of even the severer injuries in which
they are absent. Indeed, in reckoning up the cases coming under
my notice, enamel pits seem not to have been present in more
than one-fourth of them. Further, these enamel pits occur in
teeth that are otherwise normal. It is not very rare to find a
single pit in the enamel of some one tooth of an otherwise per-
fect set of teeth. In exposing such pits by cutting sections, the
same histological characters are found as shown by the pits
accompanying atrophy. They mark an imperfection, or partial
failure, in the development of the enamel rods, confined to a
small area, usually round, and evidently are most apt to occur
in cases where there has been some marked difficulty in enamel
development, resulting in atrophy. Hence, they are a frequent
accompaniment of atrophy. Not infrequently, the rows of pits
in the enamel are the only signs of injury to the teeth as a result
of an illness. In this case the rows of pits form zones on the
parts of the teeth contemporaneous in development, as one of
the expressions of atrophy. When they occur in the absence of
atrophy, they may occur in any part of the enamel, showing no
especial preference as to teeth or locality on any tooth.
The pit marks the failure of development of the enamel rods
at a point, leaving a hole of more or less depth. This is generally
filled, or party filled, with an amorphous material, dark in color,
varying from a yellowish hue to a deep black. I have never yet
made a section of one of these in which the dentin was exposed,
though some are as deep or deeper than the normal thickness of
the enamel. In all of these cases of very deep pits there is a
depression in the dento-enamel junction, as shown in Figure 34,
and a lining of enamel, in which the enamel rods are arranged
in a segment of a whorl, all pointing to the center like the spokes
of a wheel, in the bottom of the i)it. When the enamel rods
forming these whorls have grown about a certain length, growth
ceases, and an opening is left, and this may extend as an o])en