Cutting ability of an ultrasonic retrograde cavity preparation instrument.

The aim of this study was to investigate the cutting ability of a working ultrasonic instrument designed for surgical endodontic use (Neosonic, Amadent Corp, Cherry Hill, NJ, USA). Three designs of tip, designated CT 1 to CT 3 were calibrated by measuring their displacement amplitudes in air using light microscopy over a range of power settings. Extracted teeth were sectioned longitudinally and polished to produce a smooth dentine surface onto which the tips were applied for 1 minute over the above range of power settings at a load of approximately 20 g. The depth of cut in the dentine surface was measured using a two dimensional surface profilometry technique. Results showed that a raising of the power setting produced an increase in displacement amplitude and cutting ability for all tip designs. This increase was linear, with minimal cutting occurring at lower power settings. In conclusion the ultrasonic tips could be successfully used to remove dentine, and medium to high power settings optimised their efficiency.