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350 THE TECHNICAL, PBOCEDURES IN FILLING TEETH.

the whole is to be returned to the furnace and baked, and in this
bake a full fuse to a glaze of the surface should be obtained,
taking great care not to heat too much, for this is likely to burn
out the color and the translucence, leaving the inlay an opaque
gray unsuited to the ease. Facility in baking can be acquired
only by careful practice. The eye and the fingers must be
trained to the work by doing it, as in any other technical process
that requires especial skill.
Furnaces for inlay work. There are a number of different
forms of furnaces on the market for inlay work. Generally a
small furnace made especially for this work, or at least one made
for very small pieces, should be used. It may be electric or
some one of the devices for the use of gasoline or gas. The elec-
tric oven is the best, the neatest and most compact. With it
there is no perceptible heat, noise or dirt, and it may be used
beside the chair. But it requires the electric connections and
rheostat for the control of the heat. A considerable variety
of forms of these are also on the market. Any arrangement
by which sufficient heat can be produced with reasonable regu-
larity of control will do. It may be done over the flame of a
good Bunsen gas burner or in the flame of a gasoline blast by
having a small muffle of platinum to protect the procelain from
the direct blast.
SETTING THE INLAY.
When the inlay has been completed, the platinum matrix
is stripped off. Generally this may be pulled away with the
pliers. Occasionally, however, this gives trouble. If the last
traces of it can not be removed by picking it away, it may readily
be removed by i^lacing it in aqua regia and heating a little.
The inlay should now be placed in the cavity and closely
examined to see that the fit, color and all are satisfactory. The
method of handling the inlay deserves some attention. It may
be taken up in a pair of light tweezers and placed in the cavity,
or it may be stuck to the end of some instrument with a little
sticky wax. Whatever the arrangement, the handling should
be done very lightly and accurately, for there is considerable
danger of chipping either the sharp margins of the inlay or the
equally sharp margins of the cavity. Both are veiy hard and
also very brittle. The inlay is to be secured in the cavity by
cementing with oxyphosphate cement.
In selecting the cement for this juirpose, the following points
should be observed: The cement should bo as iTupenetrable to