Postoperative pain and 12-month periapical healing after Er: YAG laser–activated versus ultrasonic irrigation: a randomized controlled trial

Abstract Background This randomized controlled clinical trial evaluated contemporary irrigation activation strategies by integrating patient-reported postoperative pain with 12-month radiographic healing outcomes. Er: YAG laser–activated irrigation using photon-induced photoacoustic streaming (PIPS) or shock wave–enhanced emission photoacoustic streaming (SWEEPS) was compared with passive ultrasonic irrigation (PUI) in teeth with apical periodontitis. Methods Ninety teeth were stratified by lesion size and randomly allocated to PUI, PIPS, or SWEEPS ( n = 30 per group). Seventy-two teeth (24 per group) completed the 12-month follow-up and were included in the radiographic outcome analysis. Postoperative pain was assessed using a visual analogue scale for 7 days. Clinical and radiographic outcomes were evaluated at 12 months using the Periapical Index. Multivariable logistic regression was used to identify predictors of complete healing. Results Postoperative pain peaked at 6 h and decreased over time in all groups. At 24 h, pain scores were significantly lower in the PIPS and SWEEPS groups than in the PUI group ( P < 0.05). At 48 h, pain scores remained significantly lower in the SWEEPS group than in the PUI group ( P < 0.05), with no significant differences at other time points. No participant reported moderate or severe postoperative pain. At 12 months, complete healing rates were 58.3% for PUI, 70.8% for PIPS, and 79.2% for SWEEPS, with no statistically significant differences among groups ( P = 0.288). Smaller lesion size independently predicted complete healing (OR = 5.12; 95% CI, 1.52–17.20; P = 0.008). Compared with PUI, SWEEPS showed higher estimated odds of complete healing (OR = 4.03; 95% CI, 0.99–16.48), although the confidence interval included the null value. Conclusions All irrigation activation protocols achieved favorable clinical outcomes, with no statistically significant differences in radiographic healing at 12 months. Estimates of treatment effects on complete healing were imprecise because of the limited sample size and require confirmation in adequately powered randomized clinical trials. Laser-activated irrigation was associated with lower postoperative pain at selected early time points, particularly within the first 24 h. Trial registration The trial was registered in the Chinese Clinical Trial Registry before patient recruitment (registration date: November 28, 2021; ChiCTR2100053722).