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324 PLASTIC FILLING MATERIALS.
evidence of pastiness. To insure the removal of the excess of the sol-
vent, gold foil may be burnished over it as already described until it
requires some eifort to cut the mass with a lancet blade. Amalgam
when set is more difficult to cut and polish than gold ; the greater por-
tion of the carving is therefore done at the same sitting as the filling,
but should never be undertaken while the filling is soft. It should be
in such a condition that it is necessary to carve, not smear, it into shape.
A suitable cutting instrument of the form of Nos. 37 to 40 of Flagg's
set (see Fig. 286) is passed first across the cervical border of the filling,
removing any excess due to imperfect contact of the matrix witli the
cervical margin of the cavity ; next the lateral borders are carved, and
then the masticating surface. The body of the filling is left full, so that
after two days, when the filling receives its final dressing and polishing
with cuttlefish disks, strips, pumice, etc., the filling will be reduced to
correct contour. A polished amalgam filling w^ill retain an untarnished
surface when an unpolished one will discolor very objectionably.
Many of the cases in which it was at one time the usual prac-
tice to fill or restore almost entire tooth crowns with amalgam,
Fig. 293. are trimmed down, shaped, and artificial
crowns applied. One class of cases is fre-
quently seen in which the indication is for
an enormous amalgam filling rather than an
artificial crown ; this is, the loss of the dis-
tal half of the crown of a molar. As a
rule the teeth are pulpless, or it is necessary
^ Restoration of lower molar with to devitalize the pulp. The ai)])earance of
„
,
.,,,
r
,.
,
i
i
i
amalgam. the crown after the removal of carious den-
tin and cutting away frail enamel walls is seen in Fig. 293.
A Herbst matrix is fitted, closely embracing all the margins of the
cavity. The rubber dam is adjusted. It is of course understood that
the root canals have been properly sterilized and filled. The posterior
canal is drilled out fi)r about \ in. and screw-tapped. A thin solution
of zinc phosphate is mixed and the tip of a screw to fit the tapped
root has its point dipped into the cement, and then quickly screwed
into place. The amalgam is packed in larger masses than usual, using
bibulous paper to compress it about the screw and into such scant
undercuts as may be secured in the anterior portion of the tooth. The
filling is completed with amalgam wafers.
Such a filling should be well set before the rubber dam is removed.
The upper surface is carved into cusps and sulci to occlude properly
with the antagonizing teeth. The matrix should remain for twenty-
four hours, when it may be split and removed. If the matrix has been
exactly adjusted there should be no trimming of the margins required,
324 PLASTIC FILLING MATERIALS.
evidence of pastiness. To insure the removal of the excess of the sol-
vent, gold foil may be burnished over it as already described until it
requires some eifort to cut the mass with a lancet blade. Amalgam
when set is more difficult to cut and polish than gold ; the greater por-
tion of the carving is therefore done at the same sitting as the filling,
but should never be undertaken while the filling is soft. It should be
in such a condition that it is necessary to carve, not smear, it into shape.
A suitable cutting instrument of the form of Nos. 37 to 40 of Flagg's
set (see Fig. 286) is passed first across the cervical border of the filling,
removing any excess due to imperfect contact of the matrix witli the
cervical margin of the cavity ; next the lateral borders are carved, and
then the masticating surface. The body of the filling is left full, so that
after two days, when the filling receives its final dressing and polishing
with cuttlefish disks, strips, pumice, etc., the filling will be reduced to
correct contour. A polished amalgam filling w^ill retain an untarnished
surface when an unpolished one will discolor very objectionably.
Many of the cases in which it was at one time the usual prac-
tice to fill or restore almost entire tooth crowns with amalgam,
Fig. 293. are trimmed down, shaped, and artificial
crowns applied. One class of cases is fre-
quently seen in which the indication is for
an enormous amalgam filling rather than an
artificial crown ; this is, the loss of the dis-
tal half of the crown of a molar. As a
rule the teeth are pulpless, or it is necessary
^ Restoration of lower molar with to devitalize the pulp. The ai)])earance of
„
,
.,,,
r
,.
,
i
i
i
amalgam. the crown after the removal of carious den-
tin and cutting away frail enamel walls is seen in Fig. 293.
A Herbst matrix is fitted, closely embracing all the margins of the
cavity. The rubber dam is adjusted. It is of course understood that
the root canals have been properly sterilized and filled. The posterior
canal is drilled out fi)r about \ in. and screw-tapped. A thin solution
of zinc phosphate is mixed and the tip of a screw to fit the tapped
root has its point dipped into the cement, and then quickly screwed
into place. The amalgam is packed in larger masses than usual, using
bibulous paper to compress it about the screw and into such scant
undercuts as may be secured in the anterior portion of the tooth. The
filling is completed with amalgam wafers.
Such a filling should be well set before the rubber dam is removed.
The upper surface is carved into cusps and sulci to occlude properly
with the antagonizing teeth. The matrix should remain for twenty-
four hours, when it may be split and removed. If the matrix has been
exactly adjusted there should be no trimming of the margins required,
