Comparative evaluation of four endodontic rotary systems for removal of gutta-percha and sealer in root canal retreatment: In vitro study

Background: Nonsurgical endodontic retreatment is done mainly to eliminate the persistent infection of the root canal system. Enterococcus faecalis has been identified predominantly from the failed root canals. Retreatment requires the complete removal of the root canal filling material. Objectives: The objectives of the study were to compare and evaluate the removal of gutta-percha (GP) and sealer among four different endodontic rotary systems used in retreatment cases. Materials and Methods: Eighty freshly extracted human single-rooted teeth with a single straight patent canal which was verified radiographically were used for the study. A modified step-back flare technique of biomechanical preparation was used for canal preparation by the sequential use of K-files up to size 30 at working length, then step backed by reducing 1 mm in increments to a file size 55. The obturation was done by lateral condensation method. A heated instrument was used to shear off the GP at the entrance of the canal. Teeth were sectioned at cervical level to remove crown portion, and the root portion was obtained. The roots were randomly divided into four groups for canal preparation, namely, I, II, III, and IV consisting of twenty teeth each. Group I: ProTaper Universal Retreatment System (TM). Group II: ProTaper Universal Rotary System (TM) (PTUS). GROUP III: Mtwo Retreatment System (TM). Group IV: Mtwo Rotary System (TM). Results: Statistical analysis was done using ANOVA and Tukey's Post hoc test. P <= 0.05 was used to determine significance. All instruments left filling material inside the root canal, in decreasing manner mention below. Group I < Group III < Group II < Group IV. Conclusions: Apical third area of the root canal system plays a vital role in successful outcome of the root canal treatment. In this study, all the re-treatments shown to have some amount of filling material remaining in the apical third area.