Postoperative Pain Following Single-Visit Nonsurgical Retreatment Using Minimally Invasive Rotary vs. Reciprocating Nickel-Titanium File Systems: A Two-Arm Parallel Randomized Clinical Trial.

Objective: This study aimed to compare postoperative pain following the single-visit retreatment procedures of asymptomatic and symptomatic teeth using two different nickel-titanium file systems. Materials and Methods: Eighty patients were divided into symptomatic and asymptomatic groups, each further subdivided based on the use of rotary or reciprocating files. Retreatment involved removal of filling material with one flare and MicroMega REMOVER files, followed by shaping with one curve mini (rotary) or One RECI (reciprocating) files. Postoperative pain was recorded using a visual analogue scale (VAS) at 24 h, 48 h, 72 h, 7 days, and 14 days. Data were analyzed using Shapiro-Wilk, Mann-Whitney U, Kruskal-Wallis, Dunn-Bonferroni, and Pearson chi-square tests (p < 0.05). Results: No significant differences in postoperative pain were found among the four groups. Pain levels were not associated with sex, age, or tooth position. Analgesic use significantly decreased over time in all groups except the asymptomatic rotary group. Patients requiring analgesics reported higher pain scores within the first 48 h (p < 0.05). Conclusions: Postoperative pain was low and comparable across all groups. File kinematics (rotary vs. reciprocating) did not influence pain outcomes. Single-visit retreatment is a viable alternative to multivisit procedures for both symptomatic and asymptomatic cases. Clinical Relevance: This study supports the clinical feasibility of single-visit root canal retreatment, potentially improving patient comfort and reducing chair time. Trial Registration: ClinicalTrials.gov identifier: NCT06357481.