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18 THE TECHNICAL PROCEDURES IN FILLING TEETH. ;

from its connection witli the shaft to where the blade begins.
The blade is the part bearing a cutting edge. It begins at the
angle which terminates the shank — the last one, if there are
two or more — and terminates in a cutting edge.
Pluggers have no cutting edge. The part corresponding
with the blade in excavators terminates in a blunt point called
the nib, or simply the point. The end of this nib is called the
face of the plugger, and is usually finely serrated or roughened
to prevent slipping. The face itself may be flat or rounded.
The form of the face may be round, square, or a parallelogram.

Names of Operating Instruments.
Each of the names applied to instruments has a meaning.
They are descriptive of their uses, as excavator, plugger, sepa-
rator or the manner of use, as hand plugger. They describe
;
the forms of blades of cutting instruments, as hatchet, hoe,
spoon ; or they describe the form of the shank, as contra-angle,
binangle, etc.
Note especially that there are four classes of names. First,
those which denote the purpose, are order names, as plugger,
excavator; second, those which denote position or manner of
use, sub-order names, as hand or mallet plugger, enamel hatchet
third, those which describe the form of point, class names, as
hatchet, spoon; and fourth, those which describe the form of
shank, sub-class names, as binangle, contra-angle, bayonet, etc.
These names are classified as follows
Order names.
Sub-order names,
Class names.
Sub-class names.
Order names denote purpose and answer the question,
"what for I"
Examples : Excavators,
Pluggers,
Separators,
Scalers,
Clamps, etc.
Sub-order names denote the manner or position of use,
and answer the question, "where or how used?" and are usually
a prefix to an order name.
Examples : Hand mallet.
Hand plugger.
Mallet plugger,