Use of higher concentration of NaOCl during endodontic treatment can increase postoperative pain significantly, reveals a study published in The Journal of the American Dental Association.

This study aimed to evaluate whether using 8.25% sodium hypochlorite (NaOCl), compared with using 2.5% NaOCl, leads to higher postoperative pain after endodontic treatment. A total of 154 patients were randomly assigned into 2 groups: 8.25% and 2.5% NaOCl. A single-visit endodontic treatment was performed using a standard protocol, varying only the NaOCl concentration. Postoperative pain was assessed using the numeric rating scale multiple times over 30 days. Overall pain scores over time were explored via multilevel mixed-effects negative binomial regression. The need for pain medication was recorded and compared between groups via the Mann-Whitney U test. Results: Using 8.25% NaOCl increased postoperative pain scores over time by 3.48 times compared with using 2.5% NaOCl (incident rate ratio [IRR], 3.48; 95% CI, 1.57 to 7.67).

Furthermore, the 8.25% NaOCl group exhibited higher pain incidence than the 2.5% NaOCl group during the 12-hour through 3-day period, with scores at these times ranging from 2.21 (IRR, 2.21; 95% CI, 1.35 to 3.62) through 10.74 (IRR, 10.74; 95% CI, 3.74 to 30.87) higher. No difference was detected in the number of analgesic capsules administered between groups. The use of 8.25% NaOCl resulted in higher postoperative pain than the use of 2.5% NaOCl, with pain scores increasing by 3.48 times when this solution was used. Furthermore, the 8.25% NaOCl group exhibited higher pain incidence than the 2.5% NaOCl group during the 12-hour through 3-day period. The use of 8.25% NaOCl during endodontic treatment can increase postoperative pain significantly.
Reference:
Vitali FC, Santos PS, Garcia LDFR, Teixeira CDS. Postoperative pain after endodontic treatment using 8.25% vs 2.5% sodium hypochlorite in necrotic mandibular molars with apical periodontitis: A randomized double-blind clinical trial. J Am Dent Assoc. 2024 May 30:S0002-8177(24)00242-3. doi: 10.1016/j.adaj.2024.04.011. Epub ahead of print. PMID: 38819357.