Page 204 - My FlipBook

102 PATHOLOGY OF THE HAKD TISSUES OF THE TEETH.
noticed, but in many of my recent grindings with the machine,
in which the final thinning down of the specimen is done, with
all such frail parts held together in hard balsam or shellac, it
has become too prominent to be overlooked. Indeed, in the
grinding by the machine, the preparation is more delicately
done than heretofore and much carious tissue is saved in form
that formerly was lost. This is giving a closer insight into the
actual conditions existing in the beginnings of caries of enamel.
The roughening of the surface of the decayed area is evidently
a factor in the holding of food and the establishment of a pocket
between the teeth. This is aided later by the falling out of the
enamel rods and the more general roughening of the surface on
that account.
Those conditions, which cause the food to lodge, become
a cause of the wide secondary extension of the carious area
toward the gingival line, which creates a very ugly clinical con-
dition, and one that is too often overlooked at a time when it
might be easily remedied. During the preparation of the cavity,
such an extension of decay as is shown in Figures 121, 122, will
show a white line of more or less thickness on the cavo-surface
angle of the gingival wall, while the remainder of the enamel
wall will be hard and firm. This is further illustrated in Figure
123, another photomicrograph from the same specimen as that
in Figure 122, but made with less amplification in order that
more of the relation of the carious areas to the tooth and its pulp
chamber may be shown on the ordinary book page. In this case,
if the occlusal portion of this proximal decay had extended into
the dentin and the cavity had been discovered by the breaking
away of the enamel at a time when the secondary extension of
decay gingivally, as shown, was at its present stage, which often
occurs, it would have been easy to overlook this extension and
prepare the cavity with its gingival wall cut at the line d, instead
of cutting the cavity to the line c. Such an error as cutting the
gingival wall at d would inevitably have resulted in disaster
within a short time. In practice, the only way in which to make
a filling that will not soon be undermined at the gingival wall is
to -continue the extension until all appearance of this secondary
caries of the enamel has been removed. The perfect enamel will
then show the usual solid vitreous appearance at the cavo-surface
angle of the gingival wall. Then the contact point must be so
formed and the filling so finished as to later on prevent the
leakage of food into the interproximal space. Afterward, the
regrowth of the interproximal gum tissue should be encouraged