Hydraulic Turbine Contra-Angle Handpiece

Abstract

A high rotary speed enhances the effi­ ciency of instruments used for cutting teeth in operative procedures. The small diameters of the dental cutting tools make it necessary to turn the instru­ ments at high rates of speed in order to obtain effective linear speeds for the re­ moval of enamel. For example, a /s inch (22.2 mm.) disk rotating at 1,000 rpm has the same linear or surface speed as a 5/32 inch (3.9 mm.) disk dental tool rotating at 5,600 rpm. Some dentists have been reluctant to use high speeds in many operations in the mouth because of the hazard to the patient. This danger is due chiefly to the high inertia of the revolv­ ing instrument. This report describes a contra-angle dental handpiece containing a small tur­ bine which is propelled by a high speed stream of fluid in a closed system. This handpiece was developed at the National Bureau of Standards in cooperation with the American Dental Association. Because of certain characteristics inherent in hy­ draulic systems, many o f the objections to the use of high rotary speeds in cavity preparation can be eliminated with the use of this new instrument.