The effect of varying the ultrasonic power setting on canal preparation

The purpose of this study was to evaluate the effect of instrumenting root canals using an ultrasonic device (Enac) at different power levels on the prepared canal shape and instrumentation time, and to compare these results with those obtained using a standardized hand instrumentation technique. The mesial canals (120) of 60 human mandibular first and second molars were randomly assigned to one of six groups. In groups A through D, the canals were instrumented using the Enac ultrasonic unit at different power settings (1,2,3, and 5, respectively). Group E was hand instrumented. Group F served as uninstrumented controls. The roots were then sectioned horizontally and the canal shapes examined, as was the mesiodistal canal diameter as it relates to the external root surface. Instrumentation time for each group was recorded. Ultrasonic instrumentation at the different power settings was significantly faster than hand instrumentation (p