Effect of Low-level Laser Therapy on Postoperative Pain after Root Canal Retreatment: A Preliminary Placebo-controlled, Triple-blind, Randomized Clinical Trial

Abstract Introduction Low-level laser therapy (LLLT) is a practical, nonpharmacologic technique for reducing pain. This study evaluated the effect of LLLT on postoperative pain after root canal retreatment (RCR). Methods This study enrolled patients ( N  = 36) who required root canal retreatment (RCR) on mandibular molar teeth, presented with periapical lesions with periapical index scores of 2 or 3, and had a pain visual analog scale (VAS)  n  = 18) and (2) patients scheduled for RCR followed by a mock LLLT (placebo) ( n  = 18). Postoperative pain was assessed using the VAS. Data were collected and statistically analyzed with the chi-square test, the independent sample t test, and the Mann-Whitney U test ( P  = .05). Results On the first 4 days, postoperative pain significantly reduced in the LLLT group compared with the placebo group ( P P  > .05). The number of patients who needed analgesics was lower in the LLLT group than in the placebo group ( P Conclusions LLLT may reduce postoperative pain after RCR of mandibular molars.