Page 134 - My FlipBook

120 METHODS OF FILLING TEETH.
or a molar, sound in other such a as
bicuspid respects, but having cavity
the one in 128 which is nearer to the crown, and the removal of
Fig.
enough tooth-substance to reach the cavity from the crown, as is indi-
cated by the dotted lines, leaves us a tooth with which one could eat for
it were
years without fear of fracture even if left unfilled, imagining
for the sake of argument that caries would not supervene. This being,
as it is, true, it follows that when protected by a perfect gold filling the
tooth will be safe enough. In the last statement I based my argument
upon mechanical laws, for the moment forgetting physiological ones,
yet it is by physiological laws that the theory of not cutting through to
the crown is most easily proven to be fallacious. The whole aim of a
is to restore the of caries and to prevent a recur-
filling depredations
rence. Granting now for a moment that the cavity is better made
without cutting to the crown, which of course is true, yet if it cannot
be made fully accessible by separating, it will be improperly filled, so
that caries, which is not hindered
by mechanics, will be sure to recur,
and destroy that arch which the operator so thoughtfully preserved.
Of course there are men so skillful and so patient that they can make
perfect fillings through the narrowest of spaces. But these men are
rare, and the best set of principles is that which may be employed by
the number.
greatest
Now, that I may not be misapprehended, let me state my position
The borders of a should never be ex-
once more, succinctly. cavity
tended when a dentist can by a fair expenditure of time and skill make
a perfect filling. However, wherever from lack of space, or other
good cause, a perfect filling can be better made by extension of the
borders, it may be done, and such extension may be allowed to en-
croach upon the crown. Indeed, there are cases where there will be
no other adequate method of properly retaining a filling, as has been
shown.
already
Another point is pertinent here. Supposing that such cavities as
shown can be filled with amalgam without extension, would that be
preferable to extending the borders and filling with gold ? I should
decide in favor of the in instance. Gold is always
gold filling every
preferable to amalgam for durability, wherever it can be inserted pro-
what we term a
ducing perfectfilling. Dogmatic, but true.
The retentive shaping of these two cavities differs somewhat. In the
undercutting along
one nearer the crown, very little should be made
the labial border, but a considerable groove may be cut along the
palatal, with a distinct dip toward the gingival corner as indicated by
the dotted line a. In the other, which after extension will be filled
through its labial opening, a moderate groove toward the gum and
one toward the crown will suffice. At the palatal end, here the bot-
tom of the a be made to retain
cavity, depression may deep enough