Different activation systems efficacy in calcium hydroxide removal from root canal: XP-endo finisher and M3 max versus conventional and ultrasonic irrigation

Aim: This in vitro study was designed to compare the efficacy of four endodontic irrigation techniques – M3 Max, XP-endo Finisher (XPF), passive ultrasonic irrigation (PUI), and conventional needle irrigation (CNI) – in the removal of calcium hydroxide [Ca(OH) 2 ] from a standardized groove model simulating apical irregularities. Methods: Forty-eight single-rooted human mandibular premolars were sectioned longitudinally. A standardized groove (3 mm × 0.2 mm × 0.5 mm) was created in the apical third (2 mm from the apex) of one half of each specimen and filled with Ca(OH) 2 paste. Specimens were then randomly allocated to four experimental groups ( n = 12) based on the irrigation protocol: CNI, PUI, XPF, or M3 Max. Following treatment, removal efficacy was evaluated qualitatively using a microscopic scoring system (40 magnification) and quantitatively through digital image analysis with AutoCAD software. Results: Quantitative analysis revealed that the CNI group exhibited significantly more residual Ca(OH) 2 (median: 63.7%) than all three activated irrigation groups ( P < 0.05). Conversely, no statistically significant differences in performance were observed among the PUI (median: 19.8%), XPF (median: 5.8%), and M3 Max (median: 5.2%) groups ( P > 0.05). Conclusion: All irrigation activation techniques demonstrated superior performance to conventional irrigation for Ca(OH) 2 removal. The M3 Max and XPF files yielded the highest cleaning efficacy. This study provides the first evidence of the M3 Max file’s effectiveness for this application, positioning it as a viable and highly efficient tool for inclusion in modern endodontic irrigation protocols.