The Effect of Apical Patency on Postoperative Pain Following Root Canal Treatment

The goal of this randomized controlled clinical trial was to evaluate whether implementing apical patency affects the intensity of postoperative pain after single-visit root canal treatment in asymptomatic, vital, single-rooted teeth. The main question it aims to answer is: Does maintaining apical patency by gently extending a #10 K-file 1 mm beyond the working length during canal shaping influence postoperative pain compared with instrumentation confined within the working length? In the patency group, the working length was determined with an electronic apex locator and radiograph, and then apical patency was maintained by passively extending a #10 K-file 1 mm beyond the working length at each instrument change to prevent apical blockage, remove debris, and facilitate irrigant delivery to the apical terminus. In the non-patency group, the working length was likewise established with an electronic apex locator and radiograph, but all subsequent instrumentation was confined within the working length and no file was advanced beyond the apical foramen. In both groups, all other clinical procedures-including anesthesia, rubber dam isolation, access cavity preparation, rotary canal shaping with the One Curve NiTi system, standardized irrigation with 2.5% NaOCl and 17% EDTA, obturation with gutta-percha and epoxy resin-based sealer, and definitive composite restoration-were performed in a single visit using the same protocol. Postoperative pain was recorded on a Numerical Rating Scale (NRS) at 0-6, 6-12, 12-24, 24-36, and 36-48 hours, and analgesic intake within 48 hours was documented.