Page 311 - My FlipBook

CONSTRUCTION AND PLACING OF PORCELAIN INLAY 307
surface of the tooth. The matrix is then shaped over this impres-
sion with the fingers, using the soft part of the ball of the thumb
as a counter die.
The most prominent parts of the impression will represent the
deepest portion of the cavity and will assist in causing the matrix
to reach this without tearing which is accomplished by using the
impression to crowd the matrix to position. The impression
should be removed leaving the matrix, which has been by this
means partially swaged, in the cavity.
The Removal of the Impression Without Carrying Away the
Matrix is accomplished by bending the portions of matrix exposed
above the cavo-surface angle away from the impression. The
matrix should not be burnished down onto the external surface of
the tooth until the other portion has been made to thoroughly con-
form to the cavity walls.
When the impression has been removed the matrix should be
thoroughly burnished to all cavity walls beginning at the seat of
the cavity first. This burnishing is done with suitable smooth-
faced instruments, keeping moistened chamois skin discs between
the instrument and the matrix.
The cavity should now be packed with daynp cotton halls crowd-
ing the matrix ahead of them to every part of the cavity. While
this cotton is in position, the matrix should receive thorough burn-
ishing at the cavity margins and finally be turned out on to the ex-
ternal surface of the tooth a distance of one-fourth of a millimeter
to one full millimeter in all locations except one, which may be
two or three millimeters.
This one place will facilitate handling during the process of fill-
ing in the porcelain. The cotton may now be removed and gum
camphor or gold inlay casting wax croAvded into the cavity over
the matrix, filling the cavity nearly full with one piece of material
packed to place with a flat-faced amalgam burnisher as large as
the cavity will admit.
Removal of Matrix. The matrix is then removed from the cav-
ity by sticking the tine of an explorer into the body of the cam-
plior or wax near its central portion. The matrix and wax or
camphor still on the tine of the explorer should be immersed in
alcohol if camphor has been used or chloroform if wax has been
used, which will immediately loosen the tine and dissolve the ma-
terial from the matrix, after which the matrix should be picked up