Page 342 - My FlipBook

340 PLASTIC FILLING MATERIALS.
a mass of powder, in great a})j)areut excess of that required, is heaped
at a distance from it, taken from the bottle by the scoop (Fig. 317). A
portion of the powder is drawn into the fluid by means of a stout spatula
(Fig. 318), and stirred with a rotary movement until a thin paste is
made ; another portion of powder is then added and is slowly and thor-
oughly incorporated ; more powder is added until the mass is as thick as
putty and difficult to smear with the heavy spatida; the mass is scraped
together, taken from the spatula, and rolled between the forefinger and
thumb, which have been well scrubbed. The mass is now kneaded,
then rolled into an oblong pellet.
If for an occlusal cavity a piece about one-fourth the size of the cavity
is set in the deepest portion and tapped into perfect apposition with the
cavity walls by means of a burnisher. Other pellets are added, and the
process is repeated until the cavity is exactly full, the burnisher form-
ing the surface of the filling and outlining clearly every margin of the
cavity. The filling should remain under rubber dam for at least fifteen
minutes—longer when possible. A coating of ethereal varnish, a solu-
tion of gutta-percha in chloroform, or melted paraffin as suggested by
Dr. Bonwill, is applied to the surface and the grinding of the filling
deferred for a day or two. Should the cavity be upon an approximal
side of a tooth, a matrix is to be employed ; the most satisfactory and
quickly adapted instrument for this purpose is one of the composition
silver strips used for carrying polishing powders (Fig. 319). A strip

Fig. 310.

I'olisliing strip,

as wide as the length of the tooth is to have one end rolled upon itself
until it forms a cylinder more than one-sixteenth of an inch thick (Fig.
320, A). The strip is passed into the next interdental space and drawn
Fig. 320.

through until the cylinder [A] rests firmly upon the teeth; the free end
is now passed through the space into which the cavity opens ; where it