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176 FILLING MATERIALS

fibrous and crystalline in nature. These preparations are
not in sheet form, but are supplied in strips, bricks, mats and
similar shapes.
Advantages of Cohesive Gold.

1. Insolubility.
2. Adaptability to cavity walls.
3. Great crushing resistance and edge strength.
4. Freedom from molecular change.
5. Capability of polish.
Disadvantages.

1. Color.
2. High conductivity.
3. Difficulty of manipulation.
It will be seen that cohesive gold more nearly fills the re-
quirements of an ideal filling material than any other sub-

stance yet introduced, its chief disadvantage being its objec-
tionable color. Until something less conspicuous, having the
necessary lasting qualities, is introduced, though, it will
continue to maintain, as it has in the past, its position as
King of filling materials.
Indications for Use.—Gold may be placed in any portion

of the mouth where proper access may be obtained, where its
color is not objectionable, and the strength of cavity walls
permits.
Non-cohesive gold may be used, on account of its rapidity

of manipulation, in simple cavities with four strong walls, lo-
cated on surfaces not subject to wear. It may also be used
in combination with cohesive gold, for beginning fillings on
the gingival wall in proximal cavities, or on the pulpal or
axial wall in others, as a time-saver. It is not indicated on
surfaces subjected to the stress of mastication, or for contour

work. Cohesive gold, though, is now used almost exclusively,
on account of its great crushing resistance, its ability to con-