Force deflection comparison of various heat-activated superelastic nickel-titanium archwires: An in-vitro study

Abstract

Objectives: To evaluate the load - deflections, compare superelasticity ratios and evaluate mechanical hysteresis for 5 commercial types of heat-activated superelastic orthodontic arch wires in a customized design of 3-point bend test maintained at a temperature of 37°C. Materials and Methods: The 3-point bending test was executed and provided values for the modulus of elasticity in bending, flexural stress, flexural strain and the flexural stress-strain response of the material. Results: Austenitic nickel-titanium (A-NiTi) exhibited constant forces but over a lesser range of deflection whereas heat-activated, superelastic nickel-titanium (NiTi) wires exhibited lower forces over a larger range of deflection. Conclusions: Heat-activated NiTi wires exhibited lower forces over a larger range of deflection, with the exception of one brand. In addition, they exhibit better superelastic ratios and a higher mechanical hysteresis than A-NiTi. A-NiTi exhibited constant forces but over a lesser range of deflection.