Page 15 - My FlipBook

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NOMENCLATURE. 11

A lingual wall,
A buccal wall,
A gingival wall,
An occlusal wall,
And —
An axial wall.
But as mesial and distal cavities are usually prepared they
become mesio-occlusal (or disto-occlusal) cavities (complex
cavities), the occlusal wall is missing and a step is cut in the
occlusal surface.
Rule : When one of the surrounding walls of a cav-
ity is missing by reason of extension of decay, or by
extension by cutting in the preparation for filling, so as to
involve another surface, a complex cavity is formed and
the remaining walls extend to the new surface involved.
Therefore, when a mesial or a distal cavity in a bicuspid or
molar has involved the occlusal surface, the buccal and the lin-
gual walls will terminate at the occlusal enamel margin. The
axial wall will also extend to the occlusal enamel margin if no
step has been formed, and the occlusal wall will be missing.
When a step has been formed its walls will be named as in a
simple occlusal cavity, except that that wall toward the cavity
from which the step is formed will be missing.
cavities in the
Therefore, mesio-occlusal (or disto-occlusal J
bicuspids and molars have in the proximate portion (mesial or
distal)
A gingival wall,
A buccal wall,
A lingual wall.
—
And
An axial wall.
In the step portion —
A mesial Tor distal) wall,
A buccal wall,
A lingual wall.
And —
A pulpal wall.
Notice here that in mesial cavities the mesial wall of the step
portion will be missing, and in distal cavities the distal wall of
the' step portion will be missing.