Page 62 - My FlipBook

46 THE TREATMENT OF TEETH

Some recent experiments conducted by the pro-
fessor of chemistry who made these tests have
oonvinced him that the usually adopted method
is inaccurate as far as testing the density of gold
fillings is concerned. Four fillings that had been
saved when the rest of the original experimental
plugs were consigned to the scrap gold box and
melted up, were then re-tested by a more accurate
method (for description of which see Appendix)
with the following results —The mallet filling made
:
with strips of No. 16 foil, which originally came
out 18*9, now comes out 18-66; the hand-pressure
filling made with unannealed cylinders, originally
17*6, is now 17*54; a crystal gold filling made
with a mallet is reduced from 18"5 to 17*55 ; and
-a hand - pressure filling made Avith unannealed
crystal gold, that was originally determined as 18-4,
is now 17'13. This does not necessarily prove that
very dense fillings cannot be made Avith crystal
gold. It points, however, to the advisability of
determining as far as possible the size of the pieces
of crystal gold that should be used if density of the
tilling is desired. These re-tests were received after
the pages dealing with crystal gold were in the
press, and they certainly emphasise the remarks
made as to the necessity for the most thorough
and careful manipulation of crystal gold. These