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CHAPTER XII.
MANAGEMENT OF PROXIMAL CAVITIES IN BICUSPIDS AND
MOLARS. (CLASS TWO.)

Location. Class Two cavities are those which originate on the
proximal surfaces of molars and bicuspids at a point slightly gin-
gival from the point of contact.
Predisposing Cause. The predisposing cause is the fact of the
presence of the adjoining tooth Avhich establishes and maintains
the sheltered position for the accumulation of substances Avhich un-
dergo fermentative decomposition.
Early Detection of These Cavities is Essential. It is of the ut-
most importance that Class Two cavities be discovered early. More
pulps are lost to the teeth from the neglect of these cavities than
from an.y other cause. Their early detection is by no means an
easy matter to the inexperienced operator, as often their presence
IS shown only by a change in the color of the overlying enamel.
There are yet other cases where the teeth must be separated for
an examination of the suspected surfaces.
It requires education in the use of the explorer to detect the dif-
ference in the ''feel" of the explorer tine in the proximal space
and the entry of the point into a cavity of slight depth. When!
the decay has extended along the dento-enamel junction the case
becomes much easier and should never escape the detection of the
operator.
Small Proximal Cavities (Class Two).
Description. By examination there is found to be established
an area of decay upon the enamel surface between contact point
and the free margin of the gum, or one or both teeth which go
to form the space in question. The dentine may or may not be
involved. The marginal ridge is yet intact and firm. The enamel
shows no signs of injury in either the buccal or lingual embrasures.
(Molar, Fig. 3.)
Gaining Access. Opening the cavity is often the most difficult
step in the procedure.
There are three plans of procedure open to the operator.
The First Method. The one most common and often the best
is to place the angle of a sharp, straight chisel, say one milli-
meter in width, on the proximal slope of the marginal ridge and
tap it lightly with a mallet ; turn the other angle so that the chisel
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