Page 129 - My FlipBook

FILLING TEETH 113

it on the cohesive principle. The sponge or crystal
gold, known as Solila gold, coheres fairly readily
with tin. Leslie's crystalline gold also coheres
with tin, but this gold seems to have dropped out
of the market. Dr. Shumway produces cohesion
between gold-foil and tin by means of a hot
plugger.
A mere filament of tin added to non-cohesive
gold was used by the late Dr. Lord. This does not
interfere with the colour of the gold filling, it
renders the manipulation easier, and in time the
filling becomes considerably harder. Not more
than a strip one-sixteenth of an inch wide should
be folded up with a whole sheet of No. 4 foil, or
else the surface of the filling will show black
patches. It is wonderful how a very small quantity
of tin seems to work through and into the whole
filling. The strip of tin may be placed on the edge
of the sheet of gold, and the gold then folded over
the tin in such a manner that the tin is in the
centre of the folds. If the folding is loosely done,
the gold may be finally twisted into a rope, from
which pellets can be cut.
Amalgam.—An amalgam for filling teeth is pro-
duced by mixing one or more metals with mer-
cury. The only single metals that have been
used for this purpose are silver, copper, and