Efficiency of using microscope with ultrasonics in nonsurgical endodontic retreatment

The aim of the study was to study the effectiveness of using clinical microscope and ultrasonics with rotary Universal Protaper files in removing gutta-percha and sealer from root canals. Twenty single straight-rooted, extracted human mandibular premolars were prepared, filled with gutta-percha and sealer (Zinc oxide with eugenol). Specimens were then divided into two groups. Root filling material was removed using rotary Universal Protaper system with eucalyptol in group 1 (n=10);Rotary Universal Protaper system with eucalyptol followed by using microscope with ultrasonic tip were applied in the group 2 (n=10).After retreatment, the efficacy of each technique was examined at 8× magnification of a stereomicroscope then the images were analyzed using AutoCAD 2010 according to Hulsmann and Stotz scale. Data were statistically analyzed using Mann–Whitney U-test. There was a significant difference when using clinical microscope and ultrasonics (p<0.01), when considering the root canal in its entirety. When the root canal was divided to three thirds, there was a significant difference between groups 1 and 2 in the middle and the apical thirds (p<0.01). However, there was no statistically significant difference between the two groups in the cervical third.The use of the dental operating microscope and ultrasonic tips to remove the filling material from root canal walls rendered better results even though remnants of filling material were observed on the canal walls in all the examined teeth in both groups.