Instrumentation

Nomenclature and classification of hand instruments is given by GV Black.

Metals used in the manufacturing of hand instruments are made of two types of steel- carbon steel and stainless steel.

	CARBON STEEL	STAINLESS STEEL
COMPOSITION	Fe-98% C- 1-1.2% Mn-0.2% Si-0.2%	Fe-81% Cr-18% C-0.6-1%
CORROSION RESISTANCE	Very low	High
CUTTING EFFICIENCY	High	Low and becomes dull rapidly
PHYSICAL PROPERTIES	Stiffer, stronger, harder but more brittle	Hardness is less than carbon steel but it is not brittle
EFFICIENCY	Superior at high speeds and wgen cutting enamel	Superior at low speed and when cutting dentin

INSTRUMENT FORMULA:

Blade width in tenths of a millimeter
Angle of the cutting edge with the shaft ( cutting edge angle) when other than at right angles to the the axis of the blade. This is always greater than 50°.
Length of the blade in millimeters
Angle of the blade with the shaft (Blade angle) in centigrades or hundredths of a circle. This is always less than 50°.

Eg: 10-85-8-14 indicates:

10- Blade width in tenths of a millimeter ie, 1mm

85- Cutting edge angle in centigrades or hundredths of a circle

8- Length of blade in millineters

14- Blade angle in centigrades

4 types of grasps used with hand instruments:

Modified pen grasp permits the greatest delicacy of touch

The materials in use for sharpening stones are:

Arkansas stone	For sharpening steel instruments
Silicon carbide	Industrial abrasives are most commonly used for grinding wheels, sand papers and for sharpening stones
Diamond hones	These are small blocks of metal impregnated with diamond particles on the surface. Used for sharpening steel and carbon instruments

Classification of hand instruments:
Speed ranges: