Effects of Continuous Chelation with Etidronate on Mechanical Properties of the Root Canal Dentin: A Systematic...

Background: Continuous chelation with etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP) has been proposed as a less aggressive alternative to sequential irrigation with ethylenediaminetetraacetic acid (EDTA) in endodontics. This systematic review and meta-analysis aimed to compare the effects of these two protocols on the mechanical properties and structure of root dentin. Methods: PubMed, Scopus, and Cochrane Central databases were searched up to June 2026 for in vitro studies comparing continuous chelation (NaOCl + HEDP mixture) with sequential irrigation (NaOCl and EDTA) on root dentin of permanent teeth. Studies on coronal dentin and those not using NaOCl + HEDP as a mixture were excluded. Risk of bias was assessed using the QUIN tool. Meta-analyses were performed for fracture resistance using a random-effects model. This review was registered in PROSPERO (CRD420250630663). Results: Twenty studies with a total of 572 specimens were included. Six studies had a low risk of bias and thirteen had a medium risk. The qualitative synthesis showed that HEDP generally resulted in similar or lower levels of erosion, microhardness reduction, demineralization, and collagen degradation compared to EDTA. The meta-analysis revealed no significant difference in fracture resistance (5 studies; SMD = 0.28; 95% CI: -0.37 to 0.92; p = 0.40); however, substantial heterogeneity was observed (I² = 66.7%). Conclusions: The evidence was limited by substantial heterogeneity and mainly medium risk of bias. Within the limitations, in vitro evidence suggests that continuous chelation with HEDP is comparable to EDTA in terms of root dentin mechanical properties and composition, supporting its use as a chelating agent in endodontic practice. This research received no external funding.