Chinese NiTi wire--a new orthodontic alloy.

Chinese NiTi wire was studied by means of a bending test to determine wire stiffness, springback, and maximum bending moments. Chinese NiTi wire has an unusual deactivation curve (unlike steel and nitinol wires) in which relatively constant forces are produced over a long range of action. The characteristic flexural stiffness of NiTi wire is determined by the amount of activation. At large activations NiTi wires has a stiffness of only 7% that of a comparable stainless steel wire, and at small activations 28% of steel wire. For the same activation at large deflections, the forces produced are 36% that of a comparable nitinol wire. Chinese NiTi wire demonstrates phenomenal springback. It can be deflected 1.6 times as far as nitinol wire or 4.4 times as far as stainless steel wire without appreciable permanent deformation. NiTi wire is highly useful in clinical situations that require a low-stiffness wire with an extremely large springback.