Post-instrumentation pain after the use of either Mtwo or the SAF system: a randomized controlled clinical trial.

Aim: This randomized controlled trial compared the incidence of post-instrumentation pain associated with Mtwo rotary NiTi files and the self-adjusting file system following canal shaping and cleaning.
Methodology: Following sample size estimation, a total of 130 patients were randomized into two groups based on selection criteria [group Mtwo and group SAF (self-adjusting file)]. Root canal treatment was carried out in two appointments. The teeth were endodontically treated with the appropriate allotted systems following the similar clinical parameters. Patients were asked to rate the intensity of pre-instrumentation and post-instrumentation pain (at 2, 4, 6, 8, 24, 48 h) using the VAS score. The Kruskal-Wallis test was carried out for the overall comparisons of the two systems. The Friedman test was used to compare between time-points with each system. Subgroup analyses for independent variables (gender, pulp status and diagnosis) used the Mann-Whitney test and Wilcoxon signed ranks test (P < 0.05).
Results: No significant difference was found between the two groups with respect to post-instrumentation pain. Teeth with pulpal necrosis had significant pain at 8 h compared with teeth with vital pulps (P = 0.04). Teeth with vital pulps in the SAF group had significantly less post-instrumentation pain compared with those in the Mtwo group at 6 h (P = 0.042). Patients who had teeth with nonvital pulps in the SAF group experienced more post-instrumentation pain at 8 h (P = 0.017) and 24 h (P = 0.005).
Conclusion: The incidence of post-instrumentation pain at different time intervals in patients undergoing root canal treatment was similar for both the self-adjusting file and Mtwo file systems.
(© 2016 International Endodontic Journal. Published by John Wiley & Sons Ltd.)