Page 107 - My FlipBook

METHODS OF PRODUCING CONTOUR FILLINGS.
93
To take up these two points separately for a moment : Let us
suppose
with
an ordinary cavity surrounding walls ; it is half filled ; the oper-
ator places a pellet, and mallets it less thoroughly than he has done its
predecessors. He adds another, and continues the malleting. Of
course the force of the blows will further condense the under
pellet.
Even if it be not completely condensed, the fact that the shape of the
remainder of the cavity is retentive without regard to that part already
filled, makes it a matter of no moment whether that one pellet is, or is
not, thoroughly packed. With a contour filling it would be a most
hazardous oversight to leave even a single pellet of gold insufficiently
condensed. That point would be a weak spot. However solid the
rest of the filling may be made, the time may come when, under
strong pressure in mastication, a fracture of the filling will occur
where that was If foil is
just pellet placed. heavy being used, the
rule is even more imperative. Every layer must be thoroughly con-
densed before the next is added, for the reason that, with this kind
of more than any other, an is. less to be
gold underlying layer likely
condensed where another is superimposed before the malleting is com-
For a similar reason, no matter how much need there
pleted. may
be to hurry, the dentist should never pick up two or three pieces of
foil at one time and to condense them in that form
heavy attempt ;
the ends, being irregularly arranged, will fold one over the other in
such shapes as to offer the greatest possible resistance to the mallet,
the result being improper condensation.
With the other point, relative to cohesion, the necessities for extreme
caution, extending to every pellet, become evident along the same
lines of argument. It is as bad for a filling to fracture because one
layer did not cohere, as because there was a flaw from lack of solidity.
As before, non-cohesion, or slight cohesion, may be overlooked in the
body of a cavity having surrounding walls, because what is placed
above it will still be retained by the upper part of the cavity. It is
If one
otherwise with the contour filling. only layer, especially if it
be of heavy foil, fails to cohere, all that which follows is but added
to, and is not a part of, the filling. A fracture may be expected at
any time.
or of
It therefore follows that the size of the pellets, strips heavy
foil, should not be increased near the end of the filling in order to
hurry the work. Larger pellets or pieces will render solidity and
cohesion both less liable. Above all things, large or. even moderate-
sized are to be avoided, though more permissible with
foot-pluggers
the Bonwill mechanical or the electric mallet than where a hand-mallet
or hand- pressure is relied upon. I wish to condemn the foot-plugger
for this class of work, yet must speak with caution. Many men of skill
than where
use the foot-plugger with success, and with more rapidity