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162 OPERATIVE DENTISTRY

The Use of the Matrix either upon the posterior or anterior teeth
should be the same as that for the introduction of the amalgam
filling. With Class Three fillings, one end of the matrix is left
loose until the cavity has been filled more than full with the ma-
terial. The loose end is then brought over the tooth and tapped on
the outside of the surface as it is being tightened upon the filling.
This jarring process of bringing the matrix to position results in a
homogeneous mass beneath the matrix. Immediately after pad-
dling the filling and the detection of the glossy surface, the filling is
to be entirely coated with cocoa butter to exclude the air during
the process of setting.
Finishing' the Filling. After the filling has been allowed to stand
undisturbed for three or four minutes (no longer), there should be
applied a very thin-edged knife or chisel and by a scraping motion

Fig. 103.—A homemade mallet and point used by the author in paddling and jarring
silicate to position in the cavity. The mallet should be of light weight and have a soft sur-
face. The plugger point here shown is made of platinized gold. Tandilum would be better
for this provided it had a handle attached which was of very light material. It is quite neces-
sary in this process that both hammer and plugger point are of the least possible weight.
parallel with the cavity outline the excess is cut away to within
one-tenth of a millimeter of the cavo-surface angle, at the same
time reducing the general contour to that desired, keeping the
filling submerged in the cocoa butter. When the filling has been
in position five or six minutes, very fine strips or disks coated Avith
cocoa butter may be used to produce the desired gloss. The author
prefers to leave the filling with file and knife finish and has aban-
doned the use of strips and discs as injurious. This completed
filling should be scrubbed with cotton balls in order to remove all
of the cocoa butter possible and the finished filling painted with a
copal-ether varnish. No varnish of which alcohol is a part should
be used. Evaporate to dryness with air, remove the rubber dam
and test for occlusion and articulation, provided the filling in-