Page 217 - My FlipBook

POLISHING FILLINGS 1 85

Technical Exercises

Fill several of the prepared cavities on the technic form, or

in the extracted teeth, with cohesive foil.
Advantages of Non-Cohesive Gold.
1. Insolubility.
2. Adaptability to cavity walls.

3. Ease and rapidity of introduction.
4. Capability of polish.
Disadvantages.
1. Color.
2. Non-weldability and consequent lack of crushing re-
sistance, with the result that it is not indicated on surfaces

exposed to mastication and cannot be contoured.
3. High conductivity.
For the method of preparation and working of non-cohe-
sive gold, the reader is referred to the description of tin (see
page 169), these two materials being worked after the same

method.

METHOD OF POLISHING FILLINGS

I. Fillings in Pit and Fissure and Gingival Third Cavities.
— (a) Remove the excess with Black's or Pichler's trimming
knives, ''fiexo" or Black's files, carborundum stones. Gem

points or sand and emery disks, depending on the size, loca-
tion and shape of the filling. The general direction of the
cutting should be toward the margins. Do not use rough
stones as the outline of the cavo-surface angle is approached,
for fear of damaging the margins; changing to knives, fine
files, Gem stones or disks for this purpose. Trim or grind the

filling down until the original shape of the tooth is restored,
the operation on occlusal surfaces frequently requiring the
application of much esthetic taste as well as mechanical skill