Assessment of Pain Intensity after Instrumentation by MPRo and Hyflex Rotary Files in Molars with Irreversible Pulpitis: A Randomized Single-Blind Clinical Trial

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Aim: To assess the intensity of postoperative pain after endodontic treatment using full-sequence rotary Ni–Ti system either MPro or Hyflex in mandibular molars with irreversible pulpitis. Materials and Methods: This was a randomized, prospective, single-blind clinical trial. Fifty patients were randomly assigned into two equal groups according to rotary system used: Hyflex CM or MPro (n = 25). Both groups were mechanically prepared. Patients were asked to assess their postoperative pain using the numerical rating scale (NRS) at 3, 6, 24, 48, and 72 h after instrumentation. Data were presented as mean, standard deviation, median, and interquartile range values to be statistically analyzed with R statistical analysis software using Friedman’s test followed by Nemenyi post hoc test at different time intervals within each rotary system. Mann–Whitney U test was conducted to compare NRS values between both rotary systems. Results: The intensity of pain postoperatively was low significantly in Hyflex group in all observation periods. MPro group showed a decreasing mean from 3h to 72h time intervals. 3h recorded the highest mean (3.72±1.88). Statistically, there was a significant difference between all intervals except after 48 and 72h. Hyflex group showed the same. 3h recorded the highest mean (1.72 ± 1.34). Statistically, there was a significant difference between 3 h and the rest time intervals, but no significant difference was found between the 6, 24, 48, and 72 h. For both groups, there was no significant association between gender and pain and there was no significant correlation between age and pain Conclusion: Both Hyflex and Mpro systems resulted in postoperative pain with a different degree but Hyflex system represented lower postoperative pain intensity when used for mechanical instrumentation of mandibular molars with irreversible pulpitis.

Keywords: Clinical Trial, Hyflex Files, Irreversible Pulpitis, MPro Files, Pain Assessment