Efficacy of Different Irrigation Needles and Ultrasonic Activation on Calcium Hydroxide Removal: A Micro-CT Study Using 3D-Printed Endodontic Models

Introduction: The aim of this study was to evaluate the efficacy of different irrigation needles and passive ultrasonic activation in removing Ca(OH)₂ from an endodontic model that duplicated a root canal configuration of a human natural tooth. Methods: An extracted human maxillary premolar was subjected to root canal preparation and scanned with microcomputed tomography. A 3-dimensional reconstruction model of the natural tooth was printed to endodontic models using a polyjet printer. The root canals of the models were filled with Ca(OH)₂ paste and divided into 2 groups based on the irrigation protocol: conventional syringe-needle irrigation (conventional group) and passive ultrasonic irrigation (PUI) group. Each group was subdivided into 3 groups (n = 10) according to the type of needle: half-cut, side-vented, and TruNatomy irrigation needle. Microcomputed tomographyimaging was used to assess the percentage of reduction of Ca(OH)₂. Data were analyzed using two-way analysis of variance test (α =.05). Results: The side-vented and TruNatomy irrigation needles showed significantly higher percentage reductions than the half-cut needle (P <.05) in the conventional irrigation group. The PUI group showed significantly higher percentage reductions of Ca(OH)₂ than the conventional group regardless of the type of needle (P <.05). However, no significant difference was found among the needles in the PUI group. Conclusions: The type of irrigation needle and the use of PUI influenced the removal efficacy of Ca(OH)₂. PUI enhanced the removal of Ca(OH)₂ regardless of the type of irrigation needle.