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G. V. Black classified the instruments according to the order, suborder, class, and subclass names. The order names denote the function of the instrument. Suborder names define the position or manner of use of the instrument. Class names describe the working point of the instrument. Subclass names indicate the angle of the shank. Black also evolved the formula by which instruments could be duplicated anywhere. For example, the number of a gingival margin trimmer is given as 15-95-8-12R. The first two digits of the formula designate the width of the blade in tenths of a millimeters, the third and fourth its length also in millimeters, and the fifth represents the angle which the blade forms with the axis of the handle expressed in hundredths of a circle. With the instruments in which the cutting is at an angle to the length of the blade, the last two digits represents the angle made by the edge with the axis of the hand, expressed in centigrades. The handle letter signified that the instrument is one of a pair (R or L) in order to work properly, and more efficiently.

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