Investigations into the use of an ultrasonic chisel to cut bone. Part 1: forces applied by clinicians

Objectives: To measure in vitro the direction and force of applied loads ap plied by clinicians when using both a conventional slow surgical handpiece (CH) and an ultrasonic chisel (USC) for cutting bone. Study design: Five clinicians were asked to cut bovine bone using either an USC or a CH. The bone was placed on a force measurement system that could measure both longitudinal and downward loads. The rate of cut was calculate d over a fixed time-period and the depth of cut measured using a penetratom eter. Results: The magnitude of the longitudinal forces generated varied between 1.48 and 3.22 N (USC) and 0.04 and 4.56 N (CH). The CH had a pulling force directed towards the operator. Both instruments produced a similar range of downward forces although there was intra- and inter-operator variability. The rate of cut varied in a similar manner, however, the CH produced a sign ificantly greater depth of cut (p < 0.05). Conclusions: The force measurement system demonstrated differences in the w ay clinicians used the USC and CH instruments to cut bone. Of the two cutti ng methods investigated, the rotary bur is more efficient than the ultrason ic chisel. An ultrasonic chisel does cut bone in a different manner from a conventional bur and clinicians may require training before using it clinic ally. (C) 1999 Elsevier Science Ltd. All rights reserved.