[Clinical evaluation of the ultrasonic root canal instrumentation].

Five hundred and fifty-nine teeth from 432 patient' were divided randomly into the ultrasonic or the hand root canal instrumentation group. The results are shown as follows: Less instrumentation time was needed significantly in the ultrasonic group (anterior tooth: 2.37 +/- 1.37 minutes, posterior tooth: 5.33 +/- 2.83 minutes) than in the hand group (anterior tooth: 3.15 +/- 2.43 minutes, posterior tooth: 8.42 +/- 4.64 minutes); The rate of instrument fracture in the ultrasonic group (5.28%) was significantly lower than in the hand group (10.97%); No significant difference both in the rate of postoperative pain within 1 week after root canal instrumentation and the 1 year treatment effective rate were found between two groups.