Page 324 - My FlipBook

322 PLASTIC FILLING MATERIALS.
.Vn exam nation of" an amalgam fillinjji; immediately after com-
Hllint;-. i
pletion will show the marginal portions to contain the softer amalgam,
the harder being in the more central parts.
The too common })raetice of placing in the prepared cavity sufficient
amalgam in one mass to nearly or quite half fill it, is faulty. By no
means can this method secure the accuracy of adaptation of filling
material to cavity walls which is demanded of a correct filling.
At the completion of the packing operation, unless the filling has
been finished by wafering, the surface will be found still soft. It has
been recommended ' that small pieces of annealed No. 1 gold foil be
burnished over the surface of the amalgam, until no more gold can be
amalgamated by this means, when the filling will be found quite hard.
The indefinite cementing amalgam has combined with the gold, for
wdiich mercury has a strong affinity, and formed a distinct amalgam
upon the surface of the filling proper. As amalgams of gold are com-
paratively soft, it is advisal)le to first fill the cavity more than full, apply
the gold foil, then scrape the filling down to the cavity margins. Dr.
Rhein's procedure is to fill the cavity with plastic amalgam and rub on
the pieces of gold until no more gold is amalgamated. This gold amal-
gam is permitted to remain. The surplus of mercury may also be con-
veniently removed by absorbing it from the surface of the filling by
pieces of sponge or crystal mat gold.
An amalgam filling should be hard enough to resist cutting before
the rubber dam is removed.
In those situations where the rubber dam cannot be successfully
employed, it is the accepted practice to prepare the cavity, sterilize it,
when access is difficult sealing a germicide in the cavity for a day; next
adjust a napkin, and having mixed a submarine amalgam (one contain-
ing copper and a high percentage of silver), the cavity is dried as well
as possible ; a piece of the amalgam is then carried to the deepest recess
of the cavity and quickly and forcibly compressed with a mass of
bibulous paper. Another piece of amalgam is added and compressed,
driving the surplus mercury from the amalgam. While the napkin is
in position, a mass of temporary stopping (which see) is softened and
placed in the remainder of the cavity. A knife blade passed over the
edges of the amalgam will remove overhanging portions. At a subse-
quent visit, the rubber dam is adjusted, the temporary stopping is
removed, and the filling completed with amalgam.
If the operator prefer, the rubber dam may be adjusted at once and
the filling completed at one sitting ; the former method is, hoAvever, pre-
ferable, as the cervical portion of the filling may be perfectly finished,
and not be in danger of displacement, while the second section is packed.
1 Ottolengui's Methods of Filling Tenth, " Method of M. L. Rhein."