Comparison of the cleaning efficacy of passive sonic activation and passive ultrasonic activation after hand instrumentation in molar root canals

The purpose of this study was to compare the cleaning-efficacy of passive u ltrasonic activation with that of passive sonic activation after hand instr umentation. Sixty curved molar canals were hand-instrumented to size 35 and divided into three groups. Group 1 received no further treatment. Group re ceived 3 min of passive sonic activation,Group 3 received 3 min of passive ultrasonic activation. The roots were split and photomicrographs (x20) were made of the apical 6 mm of canal. transparent grid was placed over project ed images, and the total number of squares covering the apical 6 mm of cana l space and the number: of squares containing debris were counted,:a debris score was calculated for each specimen by dividing the number of squares w ith debris by the total number of squares. The mean debris scores were 31.6 % for hand instrumentation only, 15.1% for the sonic group, and 16.7% for t he ultrasonic group, The debris scores for the sonic and ultrasonic activat ion groups were significantly lower than that for the hand instrumentation only group (p < 0.01); however, there was no significant difference between the sonic and ultrasonic activation groups. Passive sonics after hand inst rumentation produces a cleaner canal than hand instrumentation alone and is comparable with that of passive ultrasonics.