Page 235 - My FlipBook
P. 235
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COMPOUND CAVITIES. 233
Where simple cavities upon the approximal surface are large they
may extend so near to the occlusal surface as to weaken it. When this
is the case the enamel wall should be cut away and the cavity converted
into a compound one of the approximo-occlusal type.
III. Compound Cavities.
INCISORS AND CANINES.
Classes / and /. Mesio-lahial and disto-Iabial cavities occur from
the near approach or union of simple cavities upon their
respective surfaces. Cavities of considerable length up-
on the approximal and labial surfaces are very apt to
join one another by extension of caries. When they
do not join they are usually separated by a narrow terri-
tory of more or less impaired tooth tissue, and in such Mesio-iabiai cav-
cases must be united to obtain a satisfactory result. Each
cavity should be as nearly prepared as possible separately, after which
the intervening tissue should be cut away and the lines of the channel
connecting the two be made as strong and smooth as possible. This
channel will usually be of less width than either of the cavities, but not
more difficult to fill on this account. Fig. 190 shows a front view of
such a compound cavity.
Whether the cavity be a mesio-labial or a disto-labial one will not
materially affect the manner or difficulty of operating.
Classes K and L.— Jlesio-Iingual and disto-Iingual cavities are
formed in the same manner as those of classes / and J except that in
these cases the lingual surface is involved instead of the labial. ^ .^i
Extensive caries in the region of the basilar pit or of the
fissures connected with it often approaches so nearly to an
approximal cavity in the same tooth as to demand the union
of the two (see Fig. 191). The method of preparing and
uniting the two is substantially the same as that followed in
classes / and J, just described.
A mesio-lingual cavity is perhaps more easily prepared and filled
than a mesio-labial one, for in its preparation the free cutting away
of the intervening wall is permissible, which affords increased room for
operating.
Fortunately, a lingual cavity rarely extends so far as to connect with
both a mesial and a distal cavity. When it does, the joining of the
three cavities very seriously weakens the crown at the point where the
greatest strain occurs.
Classes J/ and X.—These classes include cavities upon either the
mesial or distal surfaces connecting with a cavity upon the incisal edge.
COMPOUND CAVITIES. 233
Where simple cavities upon the approximal surface are large they
may extend so near to the occlusal surface as to weaken it. When this
is the case the enamel wall should be cut away and the cavity converted
into a compound one of the approximo-occlusal type.
III. Compound Cavities.
INCISORS AND CANINES.
Classes / and /. Mesio-lahial and disto-Iabial cavities occur from
the near approach or union of simple cavities upon their
respective surfaces. Cavities of considerable length up-
on the approximal and labial surfaces are very apt to
join one another by extension of caries. When they
do not join they are usually separated by a narrow terri-
tory of more or less impaired tooth tissue, and in such Mesio-iabiai cav-
cases must be united to obtain a satisfactory result. Each
cavity should be as nearly prepared as possible separately, after which
the intervening tissue should be cut away and the lines of the channel
connecting the two be made as strong and smooth as possible. This
channel will usually be of less width than either of the cavities, but not
more difficult to fill on this account. Fig. 190 shows a front view of
such a compound cavity.
Whether the cavity be a mesio-labial or a disto-labial one will not
materially affect the manner or difficulty of operating.
Classes K and L.— Jlesio-Iingual and disto-Iingual cavities are
formed in the same manner as those of classes / and J except that in
these cases the lingual surface is involved instead of the labial. ^ .^i
Extensive caries in the region of the basilar pit or of the
fissures connected with it often approaches so nearly to an
approximal cavity in the same tooth as to demand the union
of the two (see Fig. 191). The method of preparing and
uniting the two is substantially the same as that followed in
classes / and J, just described.
A mesio-lingual cavity is perhaps more easily prepared and filled
than a mesio-labial one, for in its preparation the free cutting away
of the intervening wall is permissible, which affords increased room for
operating.
Fortunately, a lingual cavity rarely extends so far as to connect with
both a mesial and a distal cavity. When it does, the joining of the
three cavities very seriously weakens the crown at the point where the
greatest strain occurs.
Classes J/ and X.—These classes include cavities upon either the
mesial or distal surfaces connecting with a cavity upon the incisal edge.
