(3) Removal of decay. The next major step that the dental office will perform
is the removal of the bulk of decay. Here he will be taking out the carious dentin and
other debris in the cavity itself. The dental officer might choose to use burs in this step of
the procedure. Rather than using burs, the dental officer might use hand instruments,
excavators being the instruments used to accomplish this procedure. The dental officer
can choose from several pairs of excavators. He might choose the large pair of Black's
excavators number 63 and number 64 or the smaller pair of Black's number 65 and
number 66. These are paired instruments, the face of which has parallel sides and a
concave surface. The other excavators that might be used are the smaller pair of Darby-
Perry number 5 and number 6 or the larger pair number 21 and number 22. The face of
the Darby-Perry excavator is shaped much like a rounded spoon. The shape of the
working end of all these excavators makes them ideal for scooping out decayed dentin
(4) Finishing. In the next step, the dental officer will finish the cavity
preparation by cleaving unsupported enamel walls and, where needed, establish bevels
on the proximal surface at the cervical seat(s) of the prepared cavity. The dental officer
might employ hand instruments. He could use the large pair of mono-beveled hatchets
number 51 and number 52, or the small pair number 53 and number 54. These are
called "mono-beveled" because there is only a single bevel on the blade of the
instrument. They are also paired instruments (if the dental officer used one, he will
probably use the other). The other hatchet that might be used is the bi-beveled hatchet
number 17. Looking at the cutting edge, you will notice that it is sharpened on both sides,
thus creating a bevel (angle) on both sides of the blade. The dental officer might also
choose to use any of the chisels available to him. The bin-angled chisels have a sharp
bend in the shank and the blade itself is wider than the shank. Bin-angled chisels are
number 81 and number 83, either one of which may be placed out in the setup. The
straight chisels that might be used are numbers 84, 85, and 86. Chisel number 84 is the
largest and number 86 the smallest of the set. Only one of these is required for the setup.
Some chisels are put out as a pair. These are the Wedelstaedt numbers 41 and 42.
They have a graceful curve in the shank down to the cutting edge rather than a distinct
bend or angle, as did another set of chisels we have already discussed. The cutting edge
is on opposite sides of the blade, indicative of numbers 41 and 42.
(5) Trimming. Sometimes when finishing the cavity preparation, the dental
officer will find it necessary to bevel the enamel at the cervical seat. Gingival margin
trimmers are used to accomplish this. These instruments are also used in pairs. There
are a pair of mesial gingival margin trimmers and a pair of distal gingival margin trimmers.
They are so designated because they can be used on only one of the two proximal
surfaces. The mesial gingival margin trimmers have the sharp point of the cutting edge
on the convex side of the blade. The distal gingival margin trimmers have the cutting
edge on the concave side of the blade. Both the mesial and distal trimmers are made in
large and small sizes.