Effect of different root canal disinfection procedures on postoperative pain: a randomized clinical trial

This study aimed to compare the effects of different root canal disinfection procedures on postoperative pain. Eighty patients with asymptomatic single-rooted and single-canal mandibular premolar teeth diagnosed with pulp necrosis were included in the study. The patients were randomly divided into four groups, and each group received a different final irrigation and disinfection method: conventional needle irrigation (CNI), sonic irrigation (SI), passive ultrasonic irrigation (PUI), and disinfection with KTP laser. In all cases, canal preparation was performed using the One Curve rotary file system. A standardized irrigation protocol with 2.5% sodium hypochlorite (NaOCl), 17% EDTA, and distilled water was applied for each irrigation group. In the KTP laser group, laser application was performed in the root canal after irrigation. The canals were filled with gutta-percha and AH Plus sealer using the single-cone technique, and the restorations of the teeth were completed in the same session. Postoperative pain was evaluated by the patients using a Visual Analog Scale (VAS) at 6, 24, 48, and 72 h, and on the 7th day. The normality of the data was assessed using the Kolmogorov–Smirnov and Shapiro–Wilk tests. Since the VAS scores were not normally distributed, non-parametric tests were used for statistical analysis, including the Kruskal–Wallis, Mann–Whitney U, Friedman, Wilcoxon signed-rank, and Chi-square tests, with Bonferroni correction applied where appropriate. The significance level was set at p < 0.05. There was no statistically significant difference in postoperative pain levels among the groups ( p > 0.05). The highest pain scores were observed at the 6th hour in all groups. Age and gender had no significant effect on postoperative pain. In subgroup analyses according to the presence of periapical lesions, significantly lower pain levels were reported at the 6th hour in the CNI group, at the 48th hour in the SI group, and at the 48th hour in the overall analysis of all patients. Although the study had certain limitations, it was concluded that the different disinfection protocols applied did not result in a significant difference in postoperative pain. This study was retrospectively registered at ClinicalTrials.gov on January 13, 2026 (Identifier NCT07355816).