Page 87 - My FlipBook

DYSTROPHIES OF THE TEETH. 33
had been separated by a -very weak acid, or those taken from
the whitened enamel in backward decays.
This condition of the enamel had not rendered the teeth
more than ordinarily liable to caries, as was shown by the gen-
eral soundness of the teeth.
This condition reminded me strongly of the white spots
so often seen in the enamel of teeth that are in the main per-
fectly formed; and is undoubtedly of the same character, Fig-
ures 36, 37. The only difference seemed to be that the usual
white spots seen are covered with a very perfect glaze, or Nay-
smith's membrane, so that a sharp instrument will glide over
them. This man's teeth had no such glazed surface. A sharp
explorer would catch anywhere with very little pressure. In
fact, it would not glide over the surface at all. The teeth evi-
dently had not a normal Naysmith's membrane. The enamel in
the two cases seemed very similar to cutting instruments.
One other, somewhat similar, case has come under my obser-
vation in which the incisal portion of the incisors and cuspids
and the occlusal portion of the bicuspids and molars were cov-
ered with normal enamel, but a large part of the axial surfaces
were white enamel, much of which lacked the glazed covering,
or Naysmith's membrane. At all points this glazed membrane
was projected to some distance from the normal over the abnor-
mal enamel.
These cases, taken together with the frequent occurrence
of white spots, led me to the supposition that the failure of the
cementing substance between the enamel rods is a special form
of dystrophy or abnormality in formation to which the enamel is
liable. The occurrence of this in isolated spots, which are usually
of an ashy white color, is not very uncommon, but its occurrence
in the whole of the enamel in the teeth of a person is certainly
extremely rare. I have seen this in but the two cases mentioned,
in the one with abnormal form, in the other with normal form.
Nothing seems to be known of the pathology that brings
about this condition.
The study of such cases is of great importance, as it may
lead to further knowledge of the formation of this tissue. Cer-
tainly the facts developed show that either the functioning tissue
or the functioning of the tissue that forms the enamel rods is
so different from that which forms the cementing substance
between the rods that the rods may be formed and the cementing
substance fail. Also, we have seen in the illustrations many
failures of the enamel rods with the space filled in part with
something else apparently without histological form. This some-
thing may be the cementing substance.