Scanning electron microscopic evaluation of root-end preparations

The use of an ultrasonic apical preparation technique has been advocated recently. Root-end preparations in 30 extracted single-canaled human teeth were evaluated, comparing those prepared with ultrasonic instrumentation alone, or in combination with rotary bur preparation, to those prepared with rotary instrumentation alone. Specimens were evaluated for the presence of debris, smear layer, and the smoothness and uniformity of the preparations. The apical preparations were completed according to the varying techniques, examined, and photographed under scanning electron microscopy. Those cavities prepared with the ultrasonic, either alone or in combination with rotary instrumentation, showed the presence of significantly less smear layer compared with those made by burs alone. Cavities prepared with ultrasonic instrumentation in combination with rotary instrumentation contained significantly less debris than those prepared with rotary instrumentation alone. There were no significant differences between the techniques in the smoothness or uniformity of the preparations.