1-3.
PARTS OF DENTAL HAND INSTRUMENTS
There are four parts of a hand instrument (figure 1-1). The longest part is the
handle where the dental officer holds the instrument when using it. The shank joins the
handle and a blade or nib. A cutting instrument has a blade and a cutting edge, whereas
a non-cutting instrument has a nib and a face or point. There are identifying numbers on
the handles of each instrument. These numbers must be used when the instruments are
requisitioned from the supply section.
Figure 1-1. Parts of a hand instrument.
1-4.
BLACK'S CLASSIFICATION OF INSTRUMENTS
Dr. G. V. Black classified instruments according to ORDER names, SUBORDER
names, CLASS names, and SUBCLASS names. Order names denote the purpose for
which the instrument is to be used, such as mallet or clamps. Suborder names define the
manner or position of use of the instrument, such as hand mallet or molar clamps. Class
names describe the working point of the instrument, such as spoon excavator or inverted
cone bur. Subclass names indicate the angle of the shank, such as bin-angle. Dr. Black
also evolved the instrument formula by which instruments could be readily duplicated
anywhere. For example, the number of a gingival margin trimmer is given as 15-95-8-
12R. The first two digits (15) of the formula designate the width of the blade in tenths of a
millimeter, the third and fourth digits (95) its length in millimeters, and the fifth digit (8)
represents the angle which the blade forms with axis of the handle expressed in
hundredths of a circle (100 gradations or centigrades). With the instruments in which the
cutting edge is at an angle to the length of the blade, the sixth and seventh digits
represent the angle made by the edge with the axis of the hand, expressed in
centigrades. The handle letter (R or L) signifies that the instrument is one of a pair made
in "rights" and "lefts" in order to work more efficiently.
MD0503
1-4