Page 146 - My FlipBook

METHODS OF FILLING TEETH.
132
Next we come to abrasions. When seen in the earlier stages the
edges of the incisors present, worn off on an oblique plane, the den-
tine being exposed and cupped out so that it appears as a marked
or At first this We
depression concavity. concavity is puzzling.
the fact that the or tooth is the main
appreciate opposite occluding
when
factor in the depredation, yet brought together the offender by
no means fits into the grooved dentine. Some have, from this argu-
ment, claimed that all these concavities in the masticating surfaces of
teeth are results of erosions. This is most probably an error. They
are abrasions, and are accounted for by the fact that the food which
is chewed plays a part in the destruction. As long as the end of the
tooth is protected by enamel, the abrasion goes on horizontally ; the
occluding tooth accurately fits into the abraded surface. No concavity
in the enamel appears. This in itself is siifficient to eliminate the idea
of erosion, for erosions invariably form concavities in the enamel
before the dentine is exposed, whilst after it is exposed there is no
in the dentine than in the enamel, the whole
more marked concavity
a continuous The is true with
presenting single cupping. contrary
abrasion. As soon as the dentine is reached the concavity begins to
and
appear, becoming greater greater as the dentine is wasted away.
The cause is, that the friction from the food caiiscs a more rapid
wearing away of the dentine than of the more resistant enamel.
I have taken this up at some length, because, while I am not deal-
ing in this work with etiology, it becomes essential to be able to decide
between an abraded and an eroded surface, because they require
different modes of treatment. An abrasion may safely be filled with
gold, while to so treat an erosion is often futile.
These in the 'incisive of incisors
FIG. 142 groovings edges
then are abrasions, and should be filled with
gold,
or gold and platinum, as early as possible, when
is demanded. case
filling Fig. 142 shows a typical
in a central incisor. The palatal aspect of the tooth
is shown, because from this view we may best see
the depredation. It is observable that the abrasion
is greater at the distal corner. This is frequently
the case, due probably to the fact that this corner
occludes with two teeth, thus 1 two corners instead
striking against sharp
of one. Or it may be because, as v/e are prone to pass the food into
one side of the mouth or the other, the distal corner will be
given
more work than the mesial.
Here we find a tooth needing filling, but having no cavity. It will
be requisite for the dentist to be able to thoroughly explain the neces-
sities of the case to his patient, and he should also command his full
confidence. The first point to be decided is whether or not the in-