A Three-dimensional Finite-element Analysis of von Mises Stress and Strain Distribution Generated by Nickel–Titanium Rotary Files in Primary Root Dentin

Aim and background:The aim of the present study was to evaluate and compare the mechanical behavior of two commercially available nickel-titanium (NiTi) pediatric rotary file systems with different cross-sectional geometries and tapers using three-dimensional (3D) finite element analysis (FEA).Methodology: Two pediatric NiTi rotary file systems, varying in cross-sectional design and taper, were selected for this study.Detailed 3D models of both systems were generated using advanced computer-aided design (CAD) software.These models were then subjected to finite element simulations replicating clinical conditions to evaluate mechanical parameters.The primary variables assessed included von Mises stress distribution, maximum displacement, and strain patterns when subjected to simulated intracanal forces during root canal instrumentation. Results:The FEA demonstrated significant differences in the mechanical behavior of the two file systems.The file with a triangular cross-sectional design and greater taper exhibited higher stress concentrations, particularly in the apical third, increasing susceptibility to deformation or fracture.On the other hand, the file with an S-shaped cross-section and reduced taper showed a more uniform stress distribution pattern, lower maximum displacement, and reduced strain, indicating superior mechanical performance under simulated clinical loads. Conclusion:The design characteristics of pediatric NiTi rotary files, including cross-sectional geometry and taper, play a crucial role in determining their mechanical behavior.Files with favorable cross-sectional designs and lower taper demonstrate better stress distribution and deformation resistance, thereby enhancing their clinical safety and efficiency.Clinical significance: Understanding the design variables on the mechanical performance of pediatric NiTi rotary files influences optimal instrument selection, promoting more efficient endodontic treatment in primary teeth.