Simulations On Safe Irrigation Strategies In Apically Open Root Canals

To determine the maximum irrigation velocity for root canal with open apex under a safe apical pressure thresholds and evaluate flow characteristics and irrigation efficacy using computational fluid dynamics (CFD) simulations. A high-fidelity CFD model specifically developed for apical open root canal was performed on a CBCT-derived root canal geometry. Numerical simulations were performed under the constraint of apical pressure≤30 mmHg (intraosseous blood pressure, Charara et al., 2016). Irrigation parameters including maximum allowable velocity, flow field patterns, and wall shear stress (WSS) distributions were analyzed at three needle insertion depths (1, 3, and 5 mm short of Working Length). Under identical apical pressure (30mmHg), significantly different maximum permissible irrigation velocities were obtained: 2.1 m/s (WL-1 mm), 8.5 m/s (WL-3 mm) and 10.1 m/s (WL-5 mm). Current research suggests clinically effective irrigation requires flow velocities exceeding 0.1 m/s or wall shear stress surpassing 100 Pa. By comprehensively evaluating both flow velocity and wall shear stress, our results demonstrate that irrigation effectiveness at 1 mm from the apex was significantly lower than at 3 mm and 5 mm positions, with 3 mm showing intermediate effectiveness and 5 mm exhibiting the greatest irrigation efficacy. The computational methodology developed in this study effectively characterizes flow dynamics in apically open root canals. Optimal positioning of the syringe irrigation needle away from the apical region (WL-5mm) achieves balanced enhancement of irrigation efficiency and periapical tissue safety.