The Novel Assessment to Explore the Cutting Performance of Rotary Instruments Using Dynamic Finite Element Analysis With Failure Mode.

Introduction: The separation of Nickel-Titanium (NiTi) endodontic instruments due to excessive torque adversely affects treatment outcomes. Previous studies have analyzed torque values under static conditions and failed to accurately simulate the dynamic conditions of instruments within root canals. This study aimed to apply a novel finite element analysis (FEA) to assess the real-time dynamic performance of NiTi endodontic instruments during operation in root canals.

Methods: In this study, three-dimensional geometric models of commercial NiTi endodontic instruments (ProTaper Universal) and simulated root canals were developed. In the first part, dynamic analyses of the instruments operating within root canals were simulated using finite element fracture theory and validated through experimental methods. To assess the consistency between the experimental results generated by different instruments (ProTaper Universal SX, S1, S2, and F1) and the FEA results, we utilized Bland-Altman plots for visualization and the Intraclass Correlation Coefficient for comparing continuous data. In the second part, the FEA was employed to establish a safe and efficient sequence for root canal shaping.

Results: The findings indicated a similar trend between the analyzed and experimental groups. The Bland-Altman plot demonstrated a high level of consistency, with Intraclass Correlation Coefficient values ranging from 0.6407 to 0.9351. To evaluate the dynamic performance of commercial endodontic instruments in canals, the instruments experienced excessive torque values and significant loading. Based on torque control, new sequences for safe and effective root canal preparation were proposed.

Conclusion: FEA with failure mode was demonstrated to simulate the real-time dynamic performance of instruments working in the simulated canals. This assessment offers guidance for clinical protocols and the development of innovative instruments with improving safety and efficacy in endodontic treatments through computer-aided techniques.