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COMPOUND CAVITIES. 235
All margins must be smooth and nicely bevelled.
No angles or checked enamel must exist along the borders.
All enamel should be supported by underlying dentin, although
to avoid the exposure of gold the labial plate (whicli is thicker than
the lingual) may sometimes be left thus unsupported for a short distance
along the approximal and ineisal margins.
No deep anchorages will be required. Oidy slight ones are needed
to start the filling at the cervical wall, for the form of the filling, when
completed, will be such as to aiford the greatest possible security.
BICUSPIDS AND MOLARS.
Class P. Jlesio-occlasal cavities in bicuspids and molars represent
a class not only frequently met with and difficult to fill, but one also in
which a large proportion of fillings fail. This is largely due to the
improper shaping of the cavity and the imperfect placing and adaptation
of the fillino-. When these cavities are of moderate size, not extendinsr
as far as the gingival margin on the mesial surfixce and without any
great width in a buccal or lingual direction, the preparation and filling
of them is iK^t attended with any great difficulty ; but where they
extend beneath the gum margin and are much spread out laterally they
present complications that are difficult to overcome.
The cervical margin of such cavities as extend only to or near to
the free margin of the gum has been aptly styled the " vulnerable
point," because when failure occurs in these fillings it usually begins at
this margin. When, however, the cavity wall extends beneath the gum
margin, although the difficulties of operating are increased, recurrence
of decay is seldom met with, because the conditions favorable to decay
are not present there.
In the preparation of these cavities the teeth should have been pre-
viously wedged in order to affi:)rd light and room for excavating, as well
as for the subsequent introduction and finishing of the filling. If the
cavity extend beneath the margin of the gum the hitter should be
pressed away by packing the cavity over-full with gutta-percha for a
day or two previously.
After opening and roughly preparing the cavity the rubber dam
should be adjusted and the cavity thoroughly dried, after which the prep-
aration can be completed more satisfactorily, as the dryness of the tooth
will enable the operator to readily distinguish between sound and un-
sound tissue.
Whether the cavity be of large or moderate size, simple or difficult
in character, the niceties of preparation must receive due consideration.
The cervical portion of the cavity should be dressed until a strong
sound wall is obtained. In it there must be no angles, and bordering
COMPOUND CAVITIES. 235
All margins must be smooth and nicely bevelled.
No angles or checked enamel must exist along the borders.
All enamel should be supported by underlying dentin, although
to avoid the exposure of gold the labial plate (whicli is thicker than
the lingual) may sometimes be left thus unsupported for a short distance
along the approximal and ineisal margins.
No deep anchorages will be required. Oidy slight ones are needed
to start the filling at the cervical wall, for the form of the filling, when
completed, will be such as to aiford the greatest possible security.
BICUSPIDS AND MOLARS.
Class P. Jlesio-occlasal cavities in bicuspids and molars represent
a class not only frequently met with and difficult to fill, but one also in
which a large proportion of fillings fail. This is largely due to the
improper shaping of the cavity and the imperfect placing and adaptation
of the fillino-. When these cavities are of moderate size, not extendinsr
as far as the gingival margin on the mesial surfixce and without any
great width in a buccal or lingual direction, the preparation and filling
of them is iK^t attended with any great difficulty ; but where they
extend beneath the gum margin and are much spread out laterally they
present complications that are difficult to overcome.
The cervical margin of such cavities as extend only to or near to
the free margin of the gum has been aptly styled the " vulnerable
point," because when failure occurs in these fillings it usually begins at
this margin. When, however, the cavity wall extends beneath the gum
margin, although the difficulties of operating are increased, recurrence
of decay is seldom met with, because the conditions favorable to decay
are not present there.
In the preparation of these cavities the teeth should have been pre-
viously wedged in order to affi:)rd light and room for excavating, as well
as for the subsequent introduction and finishing of the filling. If the
cavity extend beneath the margin of the gum the hitter should be
pressed away by packing the cavity over-full with gutta-percha for a
day or two previously.
After opening and roughly preparing the cavity the rubber dam
should be adjusted and the cavity thoroughly dried, after which the prep-
aration can be completed more satisfactorily, as the dryness of the tooth
will enable the operator to readily distinguish between sound and un-
sound tissue.
Whether the cavity be of large or moderate size, simple or difficult
in character, the niceties of preparation must receive due consideration.
The cervical portion of the cavity should be dressed until a strong
sound wall is obtained. In it there must be no angles, and bordering
