ABSTRACT
@#Introduction: Most patients with malocclusion are given orthodontic leveling therapy with the aim of reducing the vertical discrepancy between teeth. This computational study aims to evaluate the degree of deformation of superelastic NiTi arch wire upon bending at different deflections in a bracket system. Methods: A three-dimensional finite-element model of a wire-bracket system was developed to simulate the bending behavior of superelastic NiTi arch wire in three-brackets configuration. A superelastic subroutine was integrated in the model to anticipate the superelastic behavior of the arch wire. The mid span of the arch wire was loaded to different extent of deflections, ranging from 1.0 to 4.0 mm. The mechanical deformation of the arch wires was accessed from three parameters, in specific the unloading force, the bending stress and the martensite fraction. Results: The superelastic wire deflected at 4.0 mm yielded smaller unloading force than the wire bent at 1.0 mm. The bending stress was highly localized at the wire curvature, with the stress magnitude increased from 465 MPa at 1.0 mm to 951 MPa at 4.0 mm deflection. The martensite volume consistently increased throughout the bending, with a fully transformed martensite was observed as early as 2.0 mm of deflection. The magnitude of bending stress and the volume of fully transformed martensite increased gradually in relation to the wire deflection. Conclusion: The wire-bracket system induced localize wire deformation, hindering complete utilization of superelasticity during orthodontic treatment.