Page 274 - My FlipBook

120 THE TECHNICAL PROCEDURES IN FILLING TEETH.

In connection with the presentation of the subject of cavity
preparation, the instruments most frequently used in typical
cases of each class are illustrated, and are presented in tabular
form on the preceding pages. It should be borne in mind that
these lists are only suggestive and many deviations will be neces-
sary to meet conditions in particular cases. Generally, however,
similar instruments of different sizes will be suitable. If one is
ambitious to do the best operating in the least time, he should
learn to systematize the preparation of each cavity so that each
step will be performed in its proper order and the cutting to
be done by each instrument will be completed while that instru-
ment is in the hand. He should learn to decide beforehand just
what part of the preparation of a given cavity will be performed
by each instrument to be used. If one will form the habit of
selecting the instruments to be used in the preparation of each
cavity and placing them on the operating tray in the order that
he expects to use them, it will be of material aid in systematiz-
ing these operations. The illustrations of groups of instruments
presented in connection with the preparation of cavities of each
class, form a good basis for this study. If the operator will
place these instruments on his tray in their proper order for each
cavity to be prepared, he will soon learn what deviations from
the lists are necessary for particular cases.
Class 1. Cavities Beginning in Pits and Fissures.
ILLUSTRATIONS: FIGURES 120-163.
These occur in the occlusal surfaces of the bicuspids and
molars ; in the occlusal half of the buccal surfaces of the molars,
or in the buccal pits ; more rarely in the lingual portion of the
disto-lingual groove of the upper molars; and in the lingual sur-
faces of the upper incisors ; most frequently in the laterals.
The primary physical condition loading to the location of
caries in these positions is a fault, or imperfection in the enamel
— an imperfect closure of the enamel plates — which leaves an
opening of more or less depth in the enamel as a pit or fissure.
It is in these that decay starts. (See Figures of beginning decays
in pits, First Volume, Figures 68, 75, 76, 77, 104, 106.) The sur-
face of the enamel in the immediate neighborhood of these is
fully exposed to the friction of mastication and is kept well
cleaned. For this reason there is no disposition to the spreading
of the carious process ujion the surface of the enamel. There-
fore, these cavities all Ix'long to tlie class wliicii do not require
extension of the cavity outlines for tlie prevention of the recur-