Page 202 - My FlipBook

1 86 THE TREATMENT OF TEETH

Wolfenden cuts a good groove all around near the
margin— but at a sufficiently safe distance—and
then cuts a number of grooves running from the
original groove round the bottom of the inlay and
up to the original or main groove again. These
grooves are made in opposite directions, so that the
inlay (with the exception of a slight space near the
margin) is covered with a number of criss-cross cuts
or grooves. It may be mentioned that the smallest
size of diamond discs is the most convenient, and
that they should be kept well wet during use. As
soon as a disc ceases to cut easily and rapidly it
should be discarded, or sent to be recharged with
diamond dust.
When the cavity is shallow, and there is, conse-
quently, difficulty in grooving the sides of the inlay,
some operators cut two grooves into the floor or
bottom of the inlay as far apart as practicable, and
then grind out the porcelain between these grooves.
The angles formed by removing the porcelain
between the grooves are then deepened and later-
ally extended into undercuts, so that a space with
dovetail ends is produced.
Mr. Charles Rippon has devised a very ingenious
and original method of retainage, which consists in
embedding a small mass of silex in the inlay in
such a manner that its subsequent removal pro-