Effect of Bracket Width on Bending Deformation of NiTi Arch Wire: A Finite Element Study

Abstract

The force transferred from the NiTi arch wire to the tooth during orthodontic treatment is strongly dependent on the geometry of the wire and brackets used by the orthodontist. This study investigated the effect of orthodontic bracket geometry on the bending behaviour of superelastic NiTi arch wire. A three-dimensional finite element models of wire bending in three-brackets configuration was developed by employing superelastic user material subroutine and contact interaction. The finite element model was used to anticipate the bending forces and stresses of NiTi wires as they were engaged in various slot width dental brackets. Four different bracket widths were considered, ranging from 1.5 mm to 4.5 mm. Throughout the bending course, the superelastic NiTi wire bent in the 4.5 mm width bracket continuously demonstrated the highest bending force in comparison to the other bracket widths. As the bracket width was raised from 1.5 mm to 4.5 mm, the wire unloading force measured at 2.5 mm deflection increased gradually from 0.40 N to 1.7 N. The bending stress of the wire deformed in the 1.5 mm width bracket was 543 MPa, band it increased to 1051 MPa when the 4.5 mm width bracket was used. The proportion of complete martensite structure at the wire curvature gradually increased as the width of the bracket slot was increased.