Page 288 - My FlipBook

286 THE OPERATION OF FILLING CAVITIES.

lion-cohesive foil, or a small mat of the same material, may be inserted
into the cavity first, and the fillint;' com|)letecl with cohesive gold as in
other cavities surrounded by strong; walls.
Class F.—As caries rarely attacks the ineisal edge of the anterior
teef/i the operation of filliiij^: with gold is usually confined to artificially
made cavities, with the view of arresting waste of tooth substance
caused by attrition, or where for any reason it is deemed best to " open
the bite." Great strain is often brought to bear upon fillings in this
position, and too great care cannot be exercised in the shaping of the
cavity and the subsequent packing of the gold.
Cohesive gold is best suited to cavities of this description, and each
piece should be freshly annealed, that there may be no doubt about the
perfect union of each piece. It is well to start the first
piece in a small retaining or starting pit and then fill all
of the undercut before attempting to build the gold above
the walls. As fillings in this ])osition are subjected to
great wear, the greatest hardness of surface attainable
Kdge restora- for, otherwise there will be battering
gj^Qi^jij ]jq soup-lit
tion.
. . .
of the edges and possibly flaking of the gold. Platinous
gold is well adapted for this kind of fillings. Narrow strips of No. 20
or No. 30, well annealed and condensed with mallet force, will answer
a better purpose than lighter foil (Fig. 243).

II. Simple Approximal Cavities.
Incisors and Canines.
Class G.—In selecting the kind of gold and the form in which it
should be prepared for fillings upon the approximal surfaces of the
incisors and canines, the operator must consider the size of the cavity
to be filled and the retaining hold which he is able to secure without
sacrificing too much of the tooth structure.
If the cavity be a small one, situated midway between the labial and
palatal walls, and the surrounding borders be strong, a rapid and easy
way of filling such cavities is to prepare the non-cohesive foil in the
form of narrow tape. A leaf of foil cut into four pieces and folded
with a spatula upon a napkin to the width of one-sixteenth of an inch,
and then cut into lengths of three-quarters or one inch, is a good way
of preparing it.
An excavator of an angle of forty-five degrees, with the extreme
point broken off, makes a very good instrument for packing such
fillings. Space should previously be obtained, either by the sIom' pro-
cess of wedging with rubber or linen tape or by means of the Perry
separator.