Optimization of Side-vented Root Canal Irrigation Needle Design: Aperture Bevel Angle and Configuration Analysis using CFD and Multicriteria Decision Analysis with In Vitro Validation and C-shaped Canal Simulation.

Introduction: This study aimed to enhance the efficacy and safety of root canal irrigation in #25/.06 canals by optimizing side-vented needle designs, focusing on bevel angle adjustments and sealing configurations.

Methods: Computational fluid dynamics simulations were performed on modified 30G side-vented needles with varying bevel angles and configurations (solid vs hollow). Metrics analyzed included irrigant exchange distance, apical pressure, wall shear stress and velocity distribution. Statistical regression analysis and the entropy-weighted TOPSIS method were applied to find the optimized needle designs. The optimized needle and the standard needle were placed in a C-shaped canal model for computational fluid dynamic simulations. Modified side-vented root canal irrigation needles were also evaluated in vitro for performance.

Results: Solid-bevel needles outperformed hollow-bevel designs, achieving up to a 35% increase in irrigant exchange distance compared to standard needles. Medium bevel angles in solid-bevel needles provided an optimal balance between efficient irrigant exchange and reduced apical pressure. Enlarging the canal dimensions further improved irrigation performance.

Conclusions: Optimized solid-bevel needle designs significantly enhance irrigant distribution within root canals, with medium bevel angles demonstrating superior performance. Design modifications, such as enclosing the bevel surface below the aperture, present a promising avenue for improving irrigation efficiency.