Page 29 - My FlipBook

NOMENCLATURE. O

surface cavities. Lingual cavities in the gingival half of the
molars are also smooth-surface cavities.
Pit and fissure cavities occur in surfaces of the teeth that
are habitually clean, except as the imperfections of the enamel
— pits and fissures — afford places for the lodgment and fer-
mentation of debris, which causes the beginning of decay.
Therefore, in their preparation for filling, they require no exten-
sion for prevention of recurrence of decay, further than a suf-
ficient opening of the cavity to completely uncover the carious
area and to find margins sufficiently level and smooth, i. e., free
from grooves, to allow of a good finish of the margins of the
filling to be made.
Smooth-surface cavities occur in positions in which the
surface of the enamel is habitually unclean, and usually begin
in the central portion of the imelean area. The injury to the
enamel surface tends to spread superficially from the central
area of first beginning toward the margins of the unclean area.
Therefore, such cavities require such extension in their prep-
aration for filling as will include the habitually unclean area
within their outline in order to prevent the recurrence of caries.

Classification of Cavities into Artificial Groups.

In a classification of cavities, it is the intention to group
together in classes cavities of decay that require a similar line
of treatment, in order that these may be more closely associated.
Class 1. Cavities beginning in structural defects in the
teeth; pits and fissures. These are located in the occlusal sur-
faces of the bicuspids and molars, in the occlusal two-thirds of
the buccal surfaces of the molars, in the lingual surfaces of the
upper incisors, and occasionally in the lingual surfaces of the
upper molars.
Class 2. Cavities in the proximal surfaces of the bicuspids
and molars.
Class 3. Cavities in the proximal surfaces of the incisors
and cuspids which do not involve the removal and restoration
of the incisal angle.
Class 4. Cavities in the proximal surfaces of the incisors
which do require the removal and restoration of the incisal
angle.
—
Class 5. Cavities in the gingival third — not pit cavities
of the labial, buccal or lingual surfaces of the teeth.
Classes 2, 3, 4 aud 5 are all smooth-surface cavities. They