Analysis of orthodontic wire springback to simplify wire bending

ABSTRACT Purpose: This study aims to analyse the springback behaviour of commercial orthodontic wires. Materials and methods: The relationship between the predetermined bending angle (x) and the obtained bent angle (y) of commercial stainless steel (SS) and cobalt-chromium alloy (Co-Cr) orthodontic round wires was analysed. The springback value was calculated from the difference between the two angles (x – y). Results: The springback value became larger when (1) the SS wire was used instead of Co-Cr wire, (2) the wire diameter was small, and (3) the curvature radius was large. The relationship can be adequately represented by a linear function in the form of y = ax + b (R 2 > 0.98). Conclusion: By calculating the inverse of the function, i.e. x = (y – b)/a, the necessary bending angle (x) for the desired bent angle (y) can be calculated in advance, thereby obtaining the desired angle in a single bending action. Analysis of the springback property of the orthodontic wire and utilization of the linear function between x and y for a particular shape and composition of wire can help improve accuracy in wire bending.