The biomechanical properties of orthodontic archwires influence the efficacy and biological response of tooth movement. Austenitic (A-NiTi) and Martensitic (M-NiTi) nickel-titanium wires are widely used in clinical practice, yet their mechanical behavior under varying displacements remains quantified. Finite element analysis (FEA) offers a tool to simulate and evaluate such differences under conditions. To compare the force delivery, stress-strain distribution in the periodontal ligament (PDL), and dentoalveolar deformation induced by A-NiTi and M-NiTi archwires using a three-dimensional finite element model. A CBCT-derived model of a mandibular central incisor with its supporting structures was developed using MIMICS and CATIA software. A standard bracket-archwire system was modeled, incorporating 0.016-inch A-NiTi and M-NiTi wires. Displacements ranging from 0.5 mm to 2 mm were simulated in six directions (extrusive, intrusive, inward, outward, rotational, and angular). Forces generated by the wires were computed, and these were applied to the tooth model in ANSYS Workbench 15.0 to analyze stress-strain responses and deformation . A-NiTi wires exhibited higher force output and induced greater PDL stress and tooth deformation across all displacement types. Inward and outward displacements resulted in the highest mechanical responses. M-NiTi wires delivered lighter, more uniform forces, generating stress and strain , particularly favorable in multi-directional or rotational movements. The biomechanical performance of A-NiTi and M-NiTi wires varies significantly with displacement direction and magnitude. A-NiTi wires may be advantageous for rapid alignment, while M-NiTi offers gentler force profiles suited for biologically sensitive cases. Finite element modeling provides critical insights for optimizing wire selection in clinical orthodontics.
