Page 169 - My FlipBook

FILLING TEETH 153

desired height, and allow it to completely set before
inserting the gold. Starting pits and grooves can
then be cut in the amalgam, or a little non-cohesive
gold worked in, and the filling then completed with
cohesive gold. This also admits of the amalgam
being so cut away that nothing but gold shows, and
this is not so easy to exactly calculate when the
filling is made at one sitting. The hard amalgam
enables the gold to be more rapidly and freely
manipulated, and does away with the delicate—not
to say " finicky " — packing that is resorted to, to
prevent the gold coming away from the partially
set amalgam. As soon as gold is placed on freshly
packed amalgam it absorbs the mercury, and this
produces an extremely dry but unset and conse-
quently friable amalgam. This necessitates the
greatest care being taken in order to prevent the
lifting or breaking away from the amalgam base
of the first few layers of gold under the pressure
used in packing.
When the gold has absorbed all the mercury it
can take up, it will show its true colour, but it
will then be difficult to make the next layer stick.
Then again, an examination of these fillings a day
or two after insertion will sometimes reveal a trench-
like, shallow depression at the line of junction of
the gold and amalgam, no matter how carefully