Page 24 - My FlipBook

4 THE TECHNIC.Uj PROCEDURES IN FILLING TEETH.

In each of these localities decay has peculiarities in its
mode of attack, or there are differences of approach and of
instrumentation in the preparation for filling and in the inser-
tion of fillingg, that render differences in their consideration
necessary.
Cavities are also divided into two groups; pit and iissure
cavities forming one group, and smooth-surface cavities form-
ing a second group. This constitutes a most important divi-
sion of cavities, calling for a radical distinction in consideration
and treatment.
Pit and fissure cavities have their beginning in minute
faults in the enamel of the teeth. Pits are formed where three
or more lobes of the teeth join, because of imperfect closure of
the enamel plates, as upon occlusal surfaces of the bicuspids
and molars and the lingual surfaces of the incisors, or at the
endings of grooves, as upon the buccal surfaces of the molars.
Fissure cavities occur where there is imperfect closure of the
enamel plates along the lines of the grooves. These latter may
occur along the lines of the grooves of any of the teeth, but are
seen mostly in the occlusal surfaces of the bicuspids and molars.
Smooth-surface cavities are those formed by decay begin-
ning in surfaces of the teeth that are without pits, fissures, or
faults of the enamel, i. e., in perfectly smooth surfaces. These
positions are all on the axial surfaces and in such positions that
the surfaces are habitually unclean, either because of the posi-
tion in relation to the motions of food in chewing or the proxi-
mation of the surfaces of other teeth, as uijon the joroximal
surfaces. Decay is the result of fermentation in these positions
with the formation of an acid which dissolves the calcium salts
of the teeth.
Among the groups of cavities, all of the occlusal cavities
in the bicuspids and molars are, in their beginning, pit or fissure
cavities. A part of the buccal cavities in the molars are pit or
fissure cavities occurring in the buccal pits or fissured grooves,
and part are smooth-surface cavities, occurring in the smooth
portion of the enamel of this surface to the gingival of the pit,
or in the gingival third of the buccal surface. All buccal cavities
in the bicuspids are smooth-surface cavities. All labial cavities
in the incisors and cuspids are smooth-surface cavities. All
lingual cavities in the upper incisors are pit or fissure cavities.
A few fissure cavities occur in the occlusal half of the lingual
surfaces of the molars. All })roxiinal, or mesial and distal
cavities, whether in Uic molars, bicuspids or incisors, are smooth-