Displacement amplitude of ultrasonic scaler inserts

Objectives: Scanning laser vibrometry is a noninvasive method of measuring the velocity, displacement amplitude and oscillation frequency of vibrating objects. The purpose of this study was to assess, using a scanning laser vibrometer (SLV), the performance of different designs of commercially available ultrasonic scaler generators by measuring the oscillatory characteristics of various scaler tips. Methods: Four ultrasonic generators were tested (Cavitron SPS and Cavitron Select (Dentsply, York, PA, USA) and Piezon Master 400 and Mini Piezon (Electro-Medical Systems, Switzerland)) with various designs of scaler tip. The tips were positioned with their anterior surface perpendicular to the direction of the laser. A graduated scale, placed over the manufacturer's power dial, enabled incremental power setting selection. For each power setting, the laser beam from the SLV was scanned over the surface of the oscillating tip. Results: The ranges of longitudinal displacement amplitudes (in micrometres) were as follows: Mini Piezon (P-tip): 12.90+/-1.44 to 44.03+/-7.80; Piezon Master 400 (P-tip): 16.02+/-2.66 to 35.85+/-5.29; Cavitron SPS (TFI-10 tip): 7.81+/-0.51 to 29.70+/-1.12; Cavitron Select (TFI-10 tip): 13.13+/-1.44 to 33.77+/-4.27; Cavitron SPS (TFI-3 tip): 5.50+/-0.46 to 31.35+/-3.62. Conclusions: This study shows that there are differences between commercially available generators and that tip movement varies between tips of the same style as well as between the generator and tip design. Users of ultrasonic scalers should be made aware of this inherent variability that may influence clinical procedures.