Page 65 - My FlipBook

CUTTING INSTRUMENTS. 27

one of these infinite number of forms might be designated accu-
rately by class names and formulas, but why? Can there be any
possible advantage gained in general operative procedures?
When it is understood that a certain number of definite angles
serve our purpose, why not make up the set of instruments of
these alone?
The instruments illustrated in Figures 19, 20, 21, are avail-
able for use in schools or in practice. They are divided into
Ordinaries (48), consisting of an equal number of hatchets and
hoes formed on definite ranges of formulas; Specials (38)
formed on separate ranges of formulas from the Ordinaries,
consisting of enamel hatchets — beveled rights and lefts, spoons,
— double plane rights and lefts, or lateral cutting instruments,
gingival margin trimmers for the especial purpose indicated
by the name, straight and binangle chisels ; side instruments (8),
consisting of a few instruments of radically different forms
from the others named ; and a set of 8 long blades.
Notice that each of these are designated by special class
names in addition to the formula names. These are so few
and simple as to be easily remembered. And yet the number
(102) is much greater than any dentist should have in his case
for daily use; or better stated, he would not use so large a
number of forms if he had them. However, if any one wants
some special instrument among his side instruments, a class
designed for odd forms, he can order what he may want by
the formula plan and get just what his formula calls for. An
instance illustrating this occurred some time ago. A dentist
ordered an instrimient made, giving the formula "Hatchet
20-2-25." This form was so unusual that the manufacturer
thought there must have been some error in writing the formula.
He therefore made a careful drawing of the instrument and
returned it with the question. The answer was, "Correct, send
it on." The object of such a large number of gradations of form,
size, angles, etc., is to give range of choice under the formula
plan of forming definite sets of instruments to suit the varying
notions of men, for practitioners and for schools. In forming
instrument sets from the Ordinaries, strike out from this list
all of a certain range of formulas, retaining all of other certain
ranges of formulas, of both hatchets and hoes. As these forms
have a similar range of use, their numbers and sizes should be
equal.
A LONG SET may be made by taking the sizes 12-5, 8-3 and
6-2, in each of the four angles, cutting this general list in half.