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METHODS OF FILLING TEETH.
96
must have bitten something on that before it was thoroughly hardened, ' '
but that is no satisfaction either to patient or dentist. The work
remains to be done over, and discussion does not mend matters, es-
as the same risk must be taken
pecially again.
to fracture, in an is due to several
This tendency amalgam filling,
Of course, if the occlusion be the
things. sharp, explanation given
by the dentist may be true ; mastication may have dislodged a portion
of the mass. But where such an accident is possible, the dentist must
note the fact and guard against it in advance. The filling must leave
him so that it will not be disturbed by the of the
shaped closing jaws,
even so much as by the production of a slight scratch. Moreover,
this immunity must be determined, not alone by the perpendicular
action of the jaw, but by the lateral as well. The patient must be
asked to gently move the jaw from side to side, as he would do in eating.
This brings the cusps of the opposing tooth, or teeth, into all the differ-
ent relations which they are to bear; and if the filling is unmarred by
this, the single warning to chew upon the opposite side during the suc-
ceeding day, if obeyed, will bring the filling back in good condition.
But it is often by a cause other than mastication that the filling is
broken. We take the utmost care to keep a gold filling free from
moisture, yet some men do not hesitate to insert amalgam with the
and flooded with This so-called
cavity surrounding parts saliva.
submarine work not only should not be practiced, but a clinician
showing it before assembled students, or practitioners, should be
roundly condemned. In contour work with amalgam it is of the
utmost importance that the perfect crystallization of the mass should
not be interfered with by moisture. The filling should be kept dry
throughout the whole operation, if possible. Where the cavity extends
far beneath the gum-margin, the tooth may be filled in two operations,
though at the same sitting. Using the napkin as a dam, amalgam
must be packed until it extends beyond the margin, sufficiently far so
that the rubber-dam may be placed. Then the cavity, and the amal-
gam already in place, may be dried and the filling continued. Thus
it is shown that because a cavity cannot be kept dry with rubber-
dam from the outset, that is no reason why the filling should be
allowed to become inundated several times, through a vain effort to
control moisture with a napkin.
The next important point is to avoid fracturing the mass during the
This involves the of force, and
operation. simply proper application
the of the material. for use in a
proper consistency Amalgam, large
contour, must be prepared slightly more plastic than for ordinary work.
It is to be packed with balls of bibulous paper, with a wiping motion,
thus the material the as as this action
forcing against cavity-walls, long
can be carried out. By this course the excess of mercury is forced out,