Impact of Chelators on FAC Following Interaction With NaOCl: A Focused Evidence Synthesis Based on a Systematic Search.

Abstract

This systematic review following PRISMA guidelines evaluated the effects of endodontic chelators on free available chlorine (FAC) in sodium hypochlorite (NaOCl), with emphasis on the influence of concentration, contact time, temperature, and pH. Risk of bias was assessed using the Quality Assessment Tool for In Vitro Studies (QUIN). Twelve in vitro studies met the inclusion criteria, all using iodometric titration to measure FAC. Seven studies had low risk of bias and five had moderate risk. Seventeen chelators were evaluated, with Na₂EDTA, malic acid, citric acid, ATMA, and SmearOFF causing rapid FAC loss (> 70% within 1 min), whereas Na₂EDTA, HEDP-based chelators, and several aminopolycarboxylates showed minimal FAC reduction (0%-25%). FAC degradation was influenced by chelator type, pH reduction, temperature, and exposure time. Chelator interactions can markedly reduce FAC, potentially limiting antimicrobial and tissue-dissolving efficacy. Clinicians should tailor irrigation protocols, considering chelator choice, contact time, and irrigant replenishment to optimise clinical outcomes.