Page 54 - My FlipBook

of the surface. After the matrix lias been constructed, two holes ex-
tending parallel and in a rootward direction, should be drilled with a
round bur, No. i8 gauge. Platinum pins. No. 19 gauge, should be in-
serted in these holes with a matrix in position, and porcelain mixed to a
thick consistency should be packed around the heads of the pins and

Fic. 49. Fig. 50.
fused to a high biscuit. The matrix should be again adjusted and re-
burnished.
Figs. 48, 49 and 50 show a form of cavity preparation where a step is
cut on the lingual surface. The lingual margins should extend at least
two millimeters farther gingivally than the labial and should be cut about
one-half the thickness of the incisal end, provided the pulp will permit.
Pins mav be used with this method of cavity preparation to give addi-
tional retentive resistance.

Zhi Crcatmcnt of Ccetb JIffccted by IHalformaticn and Erosion.
In many cases of malformations, the teeth are usually marked by
pits and grooves ; they present an atrophied condition, and their inci-
sal halves are partially denuded of enamel. If more than the incisal
one-half is involved, the malformation can be corrected best by con-

50