[Studies on the performance of the dental air turbine handpieces. (Part 4) Analysis of the rotational performance of air turbine handpieces (N = N0 - CvFv gamma (author's transl)].

By the introduction of the diamond instruments and carbide burs measurably improved the quality and ease of cavity preparation, the several kinds of the air turbine handpieces, that is, standard type, torque type and miniature type air handpieces have been recently developed. In this paper, the performance tests of these air turbine handpieces have been carried out, and obtained the relations are indicated speeds and the vertical and horizontal loads or torque using the test bur. These relations are indicated by the logarithmic expressions, N = N0 - CvFv gamma, where N is the rotational speed of the air turbine handpieces during rotation, N0 is the free rotational speed of the air turbine handpieces, Fv is the vertical loads on the tests burs and Cv and gamma is the experimental constants. And then, the maximum performed work or the air turbine handpieces is presented by the expression as follows. W max = pimicrod/60(1/Cv)1/ gamma gamma (N0/gamma + 1)(1 + gamma)/gamma And we proposed the formula to be calculated for the performance ability of the air turbine handpieces.