Page 79 - My FlipBook

CUTTING INSTRUMENTS. 29

ments be selected at random without reference to an even range
of formula gradation. If an instrument of the size of blade
12-5 is wanted, that size will be needed as often in the angle
12 centigrades as in the angle 6 centigrades and is required
to make an evenly balanced set in practical work at the chair.
This is true of any one of the ranges of sizes. When a size of
blade is discarded, the whole range of that size should be dis-
carded. The same should be done with angles. But as a matter
of fact, it is found that less than three angles will not do in any
one range of sizes. When a haphazard selection is made, it
soon becomes unsatisfactory in practice. The formulas come to
apply to the particular instrument only instead of the instru-
ments of its class and its benefits in teaching the possibilities
of the adaptation of instrument forms to practical operations,
as well as the reading of instrument points to facilitate this,
are lost. The important benefit, other than in teaching, which is
greater than all else, is that the student learns to read his instru-
ment points and to know them individually. At the same time,
he learns the use of the individual ranges of sizes and the ranges
of angles of blades of instruments and makes correct selections
without confusion. All of this contributes to accuracy and speed
in operating.
It will be noticed that the side instruments are made up of
uneven forms. The object of introducing this class is to furnish
a place in the mind of the operator, as well as in his operating
case, for such odd forms as he may need, or such forms as do
not fall easily into the general ranges of formula designation.
This prevents the confusion that would occur both in the mind
and in the operating case by mixing these with other instru-
ments that are graded in the definite ranges of forms, sizes and
angles. This is in harmony with all methodical arrangement
of scientific thought and classification and should be carefully
observed. Possibly every man will have a few things of per-
sonal preference which he should drop into this class of side
instruments. Any considerable multiplication of such things
will, however, result in confusion and waste of time.

Instrument Construction.
Dentists should be familiar with the principal points in the
construction of instrument forms that render them adapted to
the particular uses designed. The reduction in the sizes of
instrument points used by dentists that has steadily been going
on for the last hundred years is quite as remarkable as the dif-