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reflected to the surface with practically no change of color other than
intensifying it. Pure white would be the best opaque cement for setting
all simple approximal and approximo-incisal inlays constructed of a
multi-colored porcelain, because white bodies do not absorb light, but
reflect it. The same rays that are reflected to the cement would then
be reflected to the surface for the reason that white has greater reflec-
tive power than any of the colors. Unfortunately the manufacturers
are unable to produce a pure white cement. We can not, therefore, en-
tirely overcome the change of color caused by the cement's dimly reflect-
ing and partially absorbing the transmitted rays.
In order to obtain the greatest adhesiveness the cement powder and
liquid should be mixed in definite proportions, and they should be
spatulated thoroughly. The consistency of the cement is to be deter-
mined by its adhesiveness, and the operator should familiarize himself
with the proper proportions of cement and liquid to yield the greatest
adhesive quality. A large glass slab and a bone, ivory, glass or agate
spatula should be used for mixing. The powder and liquid should be
placed on the slab, each in a separate position, so that a small portion
of the powder may be easily incorporated with the liquid. Moreover,
small portions of the powder are to be added, and the mass should be
manipulated as each addition is made, until there is the "feel" and ap-
pearance of complete mixture. After sufficient powder has been worked
into the liquid, the mass should be spatulated thoroughly.
A thin film of cement should now be spread over the walls and mar-
gins of the cavity with a small bone spatula or a wooden point. After
this a thin film is to be placed on the etched surface of the inlay, which
should then be forced into position. If the cavity is on the labial or
buccal surface the inlay should be pressed into place with soft wood or
rubber, and then forced into absolute relation by tying a silk ligature
around the tooth, making a surgeon's knot on the inlay. At this point
in the operation care should be taken not to exert sufficient pressure to
fracture the inlay. If the case is for a simple approximal or an ap-
proximo-incisal cavity the inlay should be inserted with pliers or the
fingers, and then forced into place with a strip of thin linen tape. The
force should be exerted in such manner that the inlay will be rocked into
position. After the surplus cement has been expressed the inlay is to be
forced into its place by exerting constant pressure with the tape. If a
hydraulic cement has been used the surplus should be moistened with
water. If a non-hydraulic cement has been used it should be kept dry
for ten or fifteen minutes, after which time remove the surplus and paint
the margins with sandrac varnish.

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