Effect of working length determination on postoperative pain using Electronic Apex Locator versus Radiographic method: a systematic review of randomized control trials.

Abstract

When it comes to root canal therapy, the right working length (WL) must be established in order to minimize material extrusion and the resulting post- procedure pain. Although electronic apex locators (EALs) are a radiation-free, time-saving substitute for conventional or digital radiography techniques, but their impact on postoperative pain has been controversial. This systematic review was registered in PROSPERO (CRD420251247626) and adhered to PRISMA 2020 guidelines. Randomized controlled trials (RCTs) comparing EAL versus radiographic WL determination, with postoperative pain as an outcome, were searched in PubMed, Cochrane CENTRAL, and ScienceDirect from January 2000 to November 17, 2025. Only peer-reviewed RCTs involving permanent teeth were considered. Bias risk was evaluated using Cochrane RoB 2.0. Four RCTs (total n = 414 patients) met the inclusion criteria. Four RCTs (2014-2024) showed no statistically significant difference in postoperative pain incidence, intensity (measured by VAS or 4-point verbal rating scale), analgesic consumption, or time to pain resolution between EAL and radiographic groups at any time point (4 h to 7 days). Pain levels were generally low to moderate and resolved within 72 h in both groups. One three-arm trial demonstrated significantly lower early pain (6-48 h) with a simultaneous/hybrid EAL plus radiographic technique compared with either method alone. No flare-ups or serious adverse events were reported. Based on limited evidence from four RCTs with methodological concerns (including risks in randomization, blinding, and subjective pain assessment) and very low certainty, electronic apex locators and radiographic methods may yield similar postoperative pain outcomes in single-visit root canal treatment of vital teeth. A combined method of both techniques showed preliminary indications of early pain alleviation in one small trial on symptomatic conditions, but this requires confirmation. EALs may represent a radiation free alternative or supplement to radiography that does not appear to increase pain, though the evidence is insufficient to draw firm conclusions.