The influence of high amplitude cyclic straining on the behaviour of superelastic NiTi

The influence of high amplitude cyclic straining on the behaviour of a superelastic NiTi wire and of NiTi endodontic instruments was assessed. Cyclic bending tests to 1/2 and 3/4 of the wires fatigue life, for tensile strain amplitudes of 2.0, 3.0 e 4.5%, were performed. The NiTi endodontic instruments were tested in fatigue to 1/2 and 3/4 of their fatigue life, at maximum strain amplitudes between 3.3 and 5.0%. The wires transformation temperatures, determined by DSC, increased for higher strains. The values of torque to failure of the NiTi instruments, measured in torsion tests, were also influenced by cyclic straining.