Comparison of cavity preparation quality using an electric motor handpiece and an air turbine dental handpiece

BACKGROUND: The high-speed high-torque (electric motor) handpiece is becoming more popular in dental offices and laboratories in the United States. It is reported to cut more precisely and to assist in the creation of finer margins that enhance cavity preparations. The authors conducted an in vitro study to compare the quality of cavity preparations fabricated with a high-speed high-torque (electric motor) handpiece and a high-speed low-torque (air turbine) handpiece. METHODS: Eighty-six dental students each cut two Class I preparations, one with an air turbine handpiece and the other with an electric motor high-speed handpiece. The authors asked the students to cut each preparation accurately to a circular outline and to establish a flat pulpal floor with 1.5 millimeters' depth, 90-degree exit angles, parallel vertical walls and sharp internal line angles, as well as to refine the preparation to achieve flat, smooth walls with a well-defined cavosurface margin. A single faculty member scored the preparations for criteria and refinement using a nine-point scale (range, 1-9). The authors analyzed the data statistically using paired t tests. RESULTS: In preparation criteria, the electric motor high-speed handpiece had a higher average grade than did the air turbine handpiece (5.07 and 4.90, respectively). For refinement, the average grade for the air turbine high-speed handpiece was greater than that for the electric motor high-speed handpiece (5.72 and 5.52, respectively). The differences were not statistically significant. CLINICAL IMPLICATIONS: The electric motor high-speed handpiece performed as well as, but not better than, the air turbine handpiece in the fabrication of high-quality cavity preparations.