Mechanical Performance of Nickel-titanium Archwires

The purpose of the present work is to compare the mechanical properties of commercially available NiTi orthodontic archwires lots. Superelastic (SE) and heat-activated (HA) NiTi archwires from two lots of six manufacturers (3M, GAC, Tp, Orthosource, Orthometric and Morelli) were partitioned into eleven groups (n=132) and tested under three-point bending tests. The difference between the highest (151.35 gf, Tp) and lowest (98.43 gf, 3M) unloading stresses among SE groups was 53.77% (p<.05), while the difference between Tp and Orthosource HA group was 168.20% (p<.05). Between same manufacturer lots, Tp SE showed the highest average unloading stress difference (50.7%) while GAC SE disclosed the lowest difference (0.25%) at p<.05. HA wires showed better mechanical properties than SE wires, however there was no evidences of shape memory effect. Matches were seen between SE and HA from different and same manufacturers (p>.05), whereupon there are equivalences in wires commercial offered at different costs.

Keywords:
nickel-titanium alloy; superelasticity; shape memory; mechanical properties; biomaterials