Vibrations of high-speed dental handpieces measured using laser vibrometry

Objective: To measure in vitro vibration displacement amplitudes of high-speed dental handpieces under unloaded and loaded conditions using a non-contact Scanning Laser Vibrometer (SLV). Methods: Five turbines (two KaVo, three W&H) and two speed-increasing handpieces (one KaVo and one W&H) were investigated using a Polytec SLV (PSV-300). Handpieces were operated under various conditions which included equipping with no rotary cutting instrument (RCI), with a diamond RCI, or with a tungsten carbide bur. Repeated measurements were taken from six selected points on the handpiece. Further tests were performed to study the influence of increasing loads (50 to 200 g) whilst cutting into extracted human teeth. Results were investigated using analysis of variance (ANOVA) at a significance level of p = 0.05, and post hoc tests. Results: Maximum handpiece vibrations were less than 4 μm. Significant differences were found between some handpiece models when unloaded. Increasing the load from 100 to 150 g corresponded with an increase in vibration amplitudes. Interactions between RCI type and handpiece model significantly affected vibrations. Conclusions: Variations in displacement amplitudes were observed under different conditions. It was difficult to determine consistent patterns of vibration. Further research is needed in this area.