Is continuous soft chelation protocol more efficacious than conventional irrigation protocol in removing the smear layer? – A systematic review

Introduction: The purpose of this systematic review is to compare the effectiveness of continuous soft chelation and conventional irrigation in removing the smear layer during endodontic treatment. Methods: Two reviewers independently carried out an extensive literature search. Following Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines; PubMed/ MEDLINE, Google Scholar, and Cochrane were searched from 2000 to 2024. In vitro studies comparing continuous and conventional chelation in smear layer removal were included. Nine studies met the criteria. Results: Out of 7097 articles, nine were included. Continuous chelation showed better smear layer removal in four studies, while one study favored conventional irrigation. Four studies reported similar outcomes. Etidronic acid, a soft chelating agent, was commonly used, either alone or in combination with sodium hypochlorite (NaOCl). Variations existed in protocols and outcomes. There was low-certainty evidence that continuous soft chelation protocol is better in removing the smear layer than conventional irrigation protocol. This suggests that combining a weak chelator with NaOCl solution may produce a single irrigation solution mixture that has the ability to dissolve soft tissue, has antibacterial properties, and has the ability to chelate. Conclusion: Hence, continuous chelation shows promise as an alternative to conventional irrigation in smear layer removal, but more research is needed to validate findings and address methodological heterogeneity.