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CAVITY PREPARATION FOR GOLD INLAYS 101
the gold inlay than the cohesive gold filling, for we do not have the
assistance of the elasticity of the dentine in retention made pos-
sible by the use of the Avedging pi-inciple in the manipulation of
cohesive gold.

Preparation of Cavities of Class One.
Of the cavities of this class calling for gold inlays only the large
occlusal surface cavities in molars are of importance. Small pit
and fissure cavities are more quickly and easily filled by other
methods.
Outline Form. In large occlusal cavities the outline should be

A B
Fi^. 56.—Cavities of Class One for gold inlays. Cavity side of inlays shown.

SO carried as to avoid eminences at the crest of marginal ridge.
AVhen this is reached on the buccal or lingual the outline should
include the marginal ridge and at least one millimeter of the axial
wall be involved. All deep grooves should be included. The
curves should be as generous as possible.
Resistance Form. The same rules apply as to other fillings.
When much of the supporting dentine has been removed through
decay or cavity preparation from either the buccal or lingual walls,
that portion within the cavity should l)e covered with a thin layer
of black wax, which prevents the wax pattern from coming in eon-