Effect of different chelating agents and irrigation activation techniques on apical irrigant extrusion in simulated immature permanent tooth models: an in vitro study

This in vitro study evaluated the effects of chelating agents and irrigation activation techniques on apical irrigant extrusion in simulated immature permanent teeth with open apices. A total of 72 single-rooted human teeth with standardized open apices were randomly assigned to eight groups ( n = 9) based on the chelating agent used—17% ethylenediaminetetraacetic acid (EDTA) or 9% etidronic acid (HEDP)—and the irrigation technique applied: conventional needle irrigation (CNI) using a 30-gauge side-vented needle, passive ultrasonic irrigation (PUI), photon-induced photoacoustic streaming (PIPS), or shock wave-enhanced emission photoacoustic streaming (SWEEPS). The Myers and Montgomery model was used to quantify apical extrusion. Kruskal–Wallis and Mann–Whitney U test were used for statistical analyses. All experimental groups exhibited apical irrigant extrusion to varying degrees. In the EDTA subgroups, activation techniques (PUI, PIPS, and SWEEPS) resulted in significantly higher extrusion levels compared to EDTA-CNI. HEDP groups demonstrated significantly lower extrusion overall, and no statistically significant differences were observed among the different activation methods. Comparisons between corresponding EDTA and HEDP groups revealed that HEDP consistently produced less extrusion than EDTA when paired with the same activation technique. These findings indicate that both the choice of chelating agent and the method of irrigation activation significantly influence apical extrusion in immature permanent teeth. Within the limitations of this in vitro study, HEDP demonstrated lower apical irrigant extrusion than EDTA, while irrigation activation techniques generally increased extrusion compared with CNI.