Page 172 - My FlipBook

156 THE TREATMENT OF TEETH

come in contact with the tinfoil wrapping of butter-
scotch. The writer has himself more than once
experienced it when eating a piece of Roquefort
cheese, the tinfoil of which had not been com-
pletely removed. There is no fear of electric shocks
happening as the result of placing gold and amal-
gam in absolute contact either as fillings or compound
gold and amalgam crowns.
Amalgam and White Cement.—It is often advan-
tageous to line a cavity with cement, and then fill
with amalgam. Pellets of a tough slow-setting
cement may be placed against the walls, pressed
to place, and the surplus removed ; this forms a
complete lining before the amalgam is inserted. The
more usual practice is to place a thin mix of
cement in the cavity, spread it against the walls,
and at once insert the amalgam ; using the latter as
a buffer to properly form the lining, and press out
the surplus cement. To do this is not quite so
easy as it seems—the cement must be mixed just
right. If too thin it will probably be all but com-
pletely pressed out, while, if it is too thick, it will
be very difficult to press enough out of the cavity
to produce clean, strong amalgam edges. It may
easily happen that at one or more points the cement
forms too thick a layer, and the amalgam is merely
wrapped over what is practically a cement margin.