Objectives: To measure in vitro vibration displacement amplitudes of high-speed dental handpieces using a Scanning Laser Vibrometer (SLV), whilst cutting extracted teeth under various loads.
Methods: Extracted molar teeth were mounted on a laboratory pan-balance so that the tooth crown contacted the cutting instrument at a known load. A Polytec SLV (PSV-300) measured vibrations at the head and angle whilst handpieces were clamped in a fixed position. Repeated measurements were taken using a new diamond rotary cutting instrument (Ash HiDi 541) both unloaded and with increasing loads of 0.5 to 2.0 N. Drive air pressures fell within ranges recommended by the manufacturers. Handpieces were operated at maximum speeds with a coolant water spray. Results were investigated using analysis of variance (ANOVA).
Results: Vibration displacement amplitudes of handpieces were not significantly greater under loading compared to the unloaded situation (p > 0.05); increases in loading did not correspond with increases in displacement of the handpiece. Vibration activity at the head was greater than at the angle of the handpiece.
Conclusion: Contrary to expectations, increasing the loading of rotary cutting instruments did not result in increased vibration displacement amplitudes. However the data was consistent with our earlier work in that greater activity was found at the head, and the levels of vibration remained low (< 5 µm).
This work is supported by an EPSRC project grant (EP/D500834/1).