Efficacy of activation systems in removing calcium hydroxide from 3D printed internal resorption cavities: a new study design

This study aimed to evaluate the efficacy of different irrigation activation systems in removing calcium hydroxide from simulated internal resorption cavities using standardized Three-Dimensional (3D) printed root canal models and objective volumetric analysis. A maxillary central incisor was scanned via micro-computed tomography and reconstructed to create standardized 3D-printed teeth with simulated internal resorption cavities. Sixty-four samples were divided into four groups (<i>n</i> = 16) according to the irrigation method: Conventional Needle Irrigation (CNI), Irrigation Ultrasonic Agitation (IUA), EndoActivator (EA), and XP-endo Finisher (XPF). Following calcium hydroxide placement and incubation, different irrigation protocols were applied. Residual calcium hydroxide volume was assessed using CBCT imaging and segmented with 3D Slicer software. Statistical analysis was performed with one-way ANOVA and Dunnett's T3 post-hoc test (α = 0.05). XPF removed significantly more calcium hydroxide than CNI and EA (<i>p</i> < 0.05). No statistically significant difference was found between XPF and IUA. None of the tested activation systems, except for one specimen in the IUA group, completely removed the calcium hydroxide from simulated internal resorption cavities. XPF removed significantly more calcium hydroxide than CNI and EA, while XPF and IUA exhibited similar performance.