Page 121 - My FlipBook

APPROXIMAL CA 1'ITIES IN IXCISORS.
107
border would show defects, and it is because gold must be builded
over this palatal border that more space must be obtained than is fur-
nished by the loss of tooth-substance. To arrange such a cavity so
as to retain a filling is readily accomplished, except where the pulp
is nearly approached, a condition which renders more difficult the
preparation of any form of cavity. Deep extensions are to be made
at a and <, the labio-gingival and the palato-gingival angles of the
These, where is should be to hold
cavity. it possible, deep enough
the of themselves. A slight groove should extend
rilling along the
palatal portion c, but care should be observed at this point. It should
be neither too deep nor too near the pulp, nor too near the edge of the
cavity. Its object is not so much to add to the retentive strength of
the cavity as to facilitate the packing of the gold, when the points at
a and b having been filled and connected, we come to extend the gold
along this portion. If there be a slight groove we avoid tipping. At
d, which is toward the incisive edge, we avoid anything in the nature
of an undercut, but it is wise to produce a we: marked concavity which
1 -
will serve as a counterpoise to the upper retainers. Along the labial
border e there should be no grooving, or undercutting of any kind.
Such a procedure only undermines the enamel, producing a weak
edge with probable fracture during the operation, or at least the pro-
duction of a crack which will later bring the tooth back to us with an
imperfection at this point. No strength whatever is gained for the
so that but mischief can accrue.
filling, nothing
To fill this cavity with gold, the first pellet is to be placed in the
palato-gingival extension b, which should be so formed that it will hold
it without tipping. I anneal this pellet and mallet it to place. It should
be large enough to be readily wedged to place. The succeeding pellets
should be small enough to reach their predecessors without compres-
sion, and each should be malleted thoroughly. The correct shaping
of a retaining point is rendered futile unless the filling be solidly packed
into it. Otherwise, though it may retain what is in it, it will fail to
retain the bulk of the to which it should lend From
filling strength.
the palato-gingival extension proceed toward the labio-gingival pit a,
and when both are thoroughly and solidly filled, proceed to cover the
palatal groove c and the cavity-edge at this point. Here it will be
wise to use hand-pressure for a brief period. With this milder force
pack the gold along the groove and over the edge until a thin layer
reaches the incisive concavity at d, when the mallet may be resumed.
In this way we avoid fracturing the palatal edge by saving it from direct
contact with the mallet-stroke. From this point on, the only care
needed is to constantly bear in mind the rule, to fill the part farthest
from us first, being sure that it is made full enough. Otherwise we
find the filling pitted when we come to polish it.