Page 304 - My FlipBook

302 THE OPERATION OF FILLING CAVITIES.

mav be drilk'd into it, wliich will innkc :iii additional hold for the
irold which is to he added. Defects which arise from subsequent caries
arc perhaps nioi-c frc<|ucnt in apjiroxinial surfaces at or near the cervical
margin. These borders are vulnerable |)oints for the recurrence of
caries, and iniperlcct adaj)tation is not inlre(|uently the determining
cause of the beginning of such decay.
To effect a successful repair in such localities amj)le space should be
obtained, especially so if the repair is to be made with gold.
If the decay has not extended beneath the filling, and sufficient
.space has been obtained, there is no greater difficulty in making a suc-
cessful repair than in filling a simple cavity similarly located. If the
o[)erator is skilled in the use of non-cohesive gold, he will do well to
prepare his foil in the form of narrow tape, and work it into the cavity
fold after fold, allowing the loops to extend somewhat above the walls
of the cavity. When the cavity has been completely filled the protru-
ding folds may be well condensed and the filling finished in the usual
wav ; or the repair may be made with cohesive gold, the first piece
having been made fast in a groove or retaining pit.
Such repairs are often required in the bicuspids and molars, and
large fillings otherwise good are saved by a successful repair at the
cervix. The plastics are sometimes indicated in this class of cases,
provided they be not so near the anterior part of the mouth as to be
ruisightly. Gutta-percha often serves a good purpose here, but in some
mouths undergoes decomi)Osition and is less reliable than gold. The
oxyphosphates are contraindicated because of their liability to wash
away after a few months. Amalgams are more frequently used, and
nearly always serve well when thus employed ; but unfortunately the
contact with gold insures discoloration, and an unsightly filling is the
result. Whenever gold and amalgam are brought in contact in the
same tooth, if the surface of each is exposed to the fluids of the mouth,
the amalgam is almost sure to turn quite black. The discoloration of
the surface of the alloy does not lessen its value as a preserver of the
tooth, but its unsightliness is often too great to be tolerated ; nevertheless,
utility enters so largely into the equation that the operator feels justified
in using the alloy, because with it he feels sure of making a better repair.
After the alloy has hardened it should be nicely dressed down and all
overlapping of the material at the gum margin removed, when it should
be smoothed and polished wnth the same care that other fillings receive.
Fracture of one or more of the cavity walls is a common accident,
and one which may be repaired if the filling has been securely anchored
in portions of the tooth not involved in the fracture. Such accidents
sometimes befall bicuspids and molars, especially the bicuspids, where
fillings have been inserted in each approximal surface, the two meeting