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CHAPTER XL

MANAGEMENT OF PIT AND FISSURE CAVITIES. (CLASS
ONE CONCLUDED.)

Large Cavities in Central Fossa of Molars.
Description. Such cavities are usually the result of knowing
neglect on the part of the patient. HoAvever, in cases where the
enamel is strong and of a good resistant quality, or the teeth are
so occluded as to have received little stress, the patient may be in
ignorance of the great havoc which has been done, due to the
major portion of the enamel remaining intact. There may exist in
such cases only the slightest aperture through a defective fissure
or fault in the enamel.
Outline Form. This division of Class One should be opened with
a straight or bin-angle chisel of rather large size to prevent easy
passage to the sensitive pulpal wall. A chisel of from two to
three millimeters in width is advised. The securing of adequate
finger rest on adjacent tissues is important. The chisel should be
applied so as to throw the chips into the cavity, and the malle't
substituted for heavy hand pressure. It is best to begin on mar-
gins most mesial and nearest the operator's eyes, as this increases
the range of vision to the deeper portions of the cavity at an
early stage in the procedure. This chipping away of the enamel
should be continued until enamel supported by sound dentine is
reached and until the margins have been carried to desired regions
as set forth in general in the chapter on outline form.
When Pulp Exposure is Feared. In this case the sixth step in
cavity preparation will come in third and we have for considera-
tion the removal of remaining decay.
Up to this point only the most superficial examination of the in-
ternal surfaces has been made.
Placing- the Rubber Dam at this point is expedient as dryness is
imperative. The decay is now removed Avith large spoon excava-
tors, whose blades are at least two millimeters Avide. These spoons
which should be keen of edge are carefully Avorked under the edges
of the masses of softened dentine and by a prying, SAveeping move-
ment this lifted en masse from the Avails. The blade of the ex-
cavator should be prevented from scraping, or sliding over the re-
gions of suspected exposure.
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