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ATKOPHY OF THE TEETH. 9

ently, of the central and lateral incisors above and below, and
the four first molars. In the case here illustrated the whole of the
incisal edge of each of the incisors above and below is dwarfed
and shortened. This dwarfed portion ends abruptly toward the
gingival. This is common in these cases. In many there is more
or less rounding down of the well-formed part of the crown to
the deformed part, but often it is so abrupt as to form a square
shoulder along which there is apt to be a series of sharp, deep
pits. In the case from which Figure 2 is taken there are no pits
whatever, and the deformity consists purely in the dwarfing of
the incisal edges. But the entire occlusal surfaces of the molars
were in very bad condition because of dwarfing that presented
many abrupt fissures in which decay began almost inunediately
after they had come through the gums. In such cases as this the
appearance of the incisor teeth may be much improved by grind-
ing away the dwarfed portion and shortening the cuspids a little
to correspond with them. The teeth may appear a little short,
but that is sometimes much less noticeable than the blemish.
In other cases, occurring in the same locality and affecting
the same teeth, there may be but little dwarfing of the incisal
edges of the incisors. The effect may be but a slight groove that
may be smooth or more or less pitted, or in cases of a still milder
type the distinct groove may be lacking and a row of fine pits in
the enamel will be the only deformity. Generally, the effect is
more marked in the occlusal surfaces of the first molars than in
the incisors.
In the case illustrated in Figure 3 the injury has occurred
later, when the child was between three and four years old. The
incisal portion of the incisors had been formed, and, therefore,
there is no dwarfing of this portion of these teeth. But there is
a very marked groove encircling the crowns of the incisors and
cuspids, marked with pits, with smoothly rounded bottoms. Both
the groove and the pits in the groove are abrupt toward the gingi-
val and thin away toward the incisal. This is a constant charac-
teristic of these deformities, which will be readily understood
by a study of the histological sections and the calcification lines
of Ritzeus. The circular form of this deformity, as it passes
from tooth to tooth across the front of the mouth, is well marked
in Figure 3 ; indeed, it presents rather more of the circular form
than usual, indicating especially that the cuspids were a little
later than usual in their calcification, and for that reason the
mark is nearer the incisal edge in proportion to the position on
the incisors than it would otherwise have been.