Prospective comparative study on postoperative pain after single-visit root canal treatment using rotary and reciprocating kinematics.

This prospective clinical study aimed to compare postoperative pain and analgesic intake following single-visit root canal treatment using two rotary file systems with different kinematic motions: reciprocating (T-endo MUST, TeM) and continuous rotary (Scope RS Narrow, SRN). A total of 121 patients with vital mandibular premolars were prospectively allocated using an alternate, non-randomized approach to single-visit root canal treatment performed by the same operator. The primary outcome was postoperative pain intensity, measured using a 100-mm Visual Analog Scale (VAS) on day 3 after treatment. The secondary outcomes included the VAS scores recorded at 1, 5, and 7 days and the analgesic consumption. A responder analysis was conducted, defining responders as patients who achieved ≥ 30% or ≥ 50% reduction in pain or a VAS score < 10. Pain intensity decreased significantly over time in both groups (p < 0.001). The TeM group was associated with higher pain scores on the third postoperative day (8.31; 95% CI: 3.89-12.72) than the SRN group (3.39; 95% CI: 0.34-6.44) (p = 0.019), whereas no significant differences were observed at other time points. Analgesic use was reported by 12.9% of patients in the TeM group and by none in the SRN group (p = 0.004). Responder analysis confirmed that the SRN system resulted in a higher proportion of pain-free patients on day 3 (RR = 0.83; 95% CI: 0.70-0.98; p = 0.027). Both reciprocating and continuous rotary systems showed a gradual reduction in postoperative pain after single-visit endodontic treatment. A modest and short-lived difference was observed on day 3, with slightly higher pain levels in the reciprocating group, suggesting a temporary variation in the early postoperative response rather than a clinically decisive effect of instrument kinematics.