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CAVITY PREPARATIOX FOR GOLD INLAYS 109
way hinder the removal of the model. Model should make exit
to the incisal with a slight lingual travel.

Fig. 67. Fig. 68.
Pig. 67.—Cavity of Class Four, plan four, for gold inlay. Black wax has been spread on
the labial wall before making the pattern to prevent the gold from touching this wall when
setting the inlay for two reasons. First: It removes liability of fracture of this wall when
setting the inlay. Second: This wax is replaced with cement and the color of the tooth is
preserved. The wire loop secures the alinement of the two posts and facilitates handling the
pattern. When the wire is not entirely buried, platinized gold should be used. When it is
entirely buried tungsten may be used.
Fig. 68.—Class Four, plan four, showing cavity side of pattern with pins.

Fig. 69.—Class Four, i)lan four, inlay in position before removing wire loop. Cavity and
pattern shown in Figs. 67 and 68.
Preparation of Cavities of Class Five.
Of this class the large buccal cavities call for gold inlays, in
which they are the ideal filling, and should largely replace amal-
gam so commonly used.