Page 314 - My FlipBook

3]0 OPERATIVE DENTISTRY

oughly warm the fire clay entirely tliroiigh, and then the lever re-
turned to the first button to maintain a v.arm oven.
When ready to fuse, the furnace is completely shut off provided
the oven shows any redness. Never put an inlay mix into a hot
oven, as it causes too rapid evaporation of the moisture, producing
checks and an extremely friable porcelain.
When the inlay is in position in the oven the lever is put on the
second or third button and advanced only when the needle of the
milliamperemeter ceases to advance. The heat should be increased
gradually and when it has reached the desired degree immediately
shut off. Each furnace has a way peculiar to itself and each oper-
ator should learn the time for perfect results.
Grinding' to Contour. After the final fusing the inlay should l)e
tried in and ground to contour and articulation on the incisal or
occlusal surface before removing the matrix.
To Remove the Matrix. Drop the inlay and the matrix in alco-
hol or Avater, then remove and peel the matrix from the inlay, draAv-
ing from the margins all around first, then from the body of the
filling. This procedure prevents chipping at the margins.
Etching the Cavity Side of Inlay. When the matrix has been
removed the inlay should be embedded, contour surface down, into
a sheet of pink base plate wax. With a warm spatula it is sealed
entirely around, being sure to cover the edges of the inlay on the
cavity side for a short distance, say one-half millimeter. This
leaves the cavity side exposed, upon which is applied hydrofluoric
acid. This is applied by dipping a stick in the wax bottle in Avhieh
the acid is delivered, and painting the inlay with a small quantity
of the acid. Two minutes will generally be sufficient to thoroughly
etch the surface.
Toilet of Inlay. The inlay should be, flooded Avith Avater, re-
moved from the Avax and placed in boiling Avater for a few minutes
and then given a chloroform bath, and dried Avith Avarm air Avhile
laying on spunk or blotting paper, and should not be again con-
tacted Avith the hands on the caA^ty side.
Toilet of Cavity. The cavity should be rendered dry. All in-
lays, and particularly the large ones, are best set Avith Avhite ce-
ment with the faintest tinge of cream. The attempt to match the
color of tooth substance Avith the cement is an error as the pigment
in the cement increases the shadoAV line Avhich is objectionable.
Use a AA^hite cement mixed to the consistency of greatest adhesive-
ness yet thin enough to floAv from betAveen inlay and cavity Avails