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PROXIMAL CAVITIES IN INCISORS AND CUSPIDS 77
gingival Mall meet the axial at a definite angle, but should in no Avay
be a ditch or groove.
The Gingivo-Labial and Gingivo-Ling-ual Line Angles should be
cut away from their point angles out to and end at the dento-enamel
junction. As the general form of the cavity is that of a triangle
these angles Avill always be acute.
Gingival Wall. The gingival wall should be flat in every direc-
tion.
Axial Wall. The axial wall should be left as decay has left it in
the central portion and all additional cutting should tend to make it
take on the form, in miniature, of the surface of the tooth in which
the decay has originated. A disregard of this rule will endanger
the pulp, Avhereas if the axial wall is left as convex as possible the
pulp has all possible protection.
Labial and Lingual Walls. These walls should be, as far as pos-
sible, of the same thickness for their entire length, which ^Vill re-
sult in their inner surfaces being of the same contour as the ex-
ternal surface of the tooth.
Convenience Form. Two convenience points are advisable in this
class of cavities, cut in each of the gingivo-axio-labial and the gin-
givo-axio-lingual angles. The filling should be begun in the latter
angle.
Removal of Remaining Decay. At this point inspect the dento-
enamel junction for softened dentine. Also the entire axial wall
should be scraped with large spoons for the removal of the last of
the softened dentine, the cavity disinfected, dried, phenolized and
again dried. Pulp protector should be applied Avhen indicated.
Finish of Enamel Walls. The enamel Avails should be planed to
full cleavage, with suitable instruments of chisel edges, not forget-
ting the incisal and gingival inclination of the rods of these loca-
tions. Bevel the cavo-surface angle, give the cavity its toilet and
immediately place the filling.
In Non-Vital Cases. When the axial wall has been lost by reason
of pulp removal the entire pulp chamber should be filled with ce-
ment of a very light yellow color or even a white cement may be
used. In extremely frail teeth this may be only partially filled and
the remaining portion used for retention.