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NOME\XLATURE. 17

name the point angles in any directions for cavity preparation or
in cavity description.
These Hsts of cavity angles may seem long and tedious, but
it must be remembered that in any directions for the preparation
of cavities, or in cavity descriptions, very few of them need to
be mentioned. However, the student should be able to under-
stand just what is meant when any one of them is mentioned, or
be able to name any of them in any cavity. This he will not do
by memorizing lists that are given, but by so learning the appli-
cation of the rules as to be able to name at once any angle of any
cavity.
Nomenclature of Enamel Margins.
The enamel margin includes the whole outline of the
cavity and is equivalent to the marginal lines of the cavity.
In this sense the enamel margin marks the oudines of the
cavity.
The Cavo-surface angle of a cavity, or of the enamel, is
the angle formed by the juhction of the wall of the cavity with
the surface of the tooth. The cavo-surface angle of a cavity
will ordinarily be of enamel ; under some unusual conditions it
may be of dentin ; or in buccal and labial cavities that extend
beyond the gingival line the cavo-surface angle will be of
cementum. The term cavo-surface angle is used especially
when it is desired to indicate the form to be given this angle in
any particular portion of the enamel margin, or oudine of a
cavity ; as, the buccal cavo-surface angle was beveled.
The dento-enamel junction is the line of junction of the
dentin and enamel as it appears in the walls of cavities.
The enamel wall is that portion of the wall of a cavity
which consists of enamel. It includes the thickness of the
enamel from the dento-enamel junction to the cavo-surface
angle.
The dentin wall is that portion of the wall of a cavity
which consists of dentin.
The Planes of the Teeth and the Inclination of Cavity
Walls.
The teeth have three planes which may frequently be used to
advantage in cavity description, and especially in speaking of
the inclination of cavity walls.
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