Deformation of nickel-titanium closed coil springs: an in vitro study.

Objective: The aim of this paper was to determine the amount of deformation in four commercial brands of nickel-titanium closed springs.

Methods: A total of 130 springs were divided into 13 subgroups, according to their features and manufacturers (Morelli, Orthometric, Ormco and GAC) and activated from 100% to 1000% of the effective length of the nickel-titanium portion present at the spring, at 37 °C. Deactivation data were plotted and deformation was found graphically.

Force system evaluation of symmetrical beta-titanium T-loop springs preactivated by curvature and concentrated bends.

Introduction: The objective of this research was to compare the effect of preactivation on the force system of beta-titanium T-loop springs (TLSs).

Methods: Twenty TLSs with dimensions of 6 × 10 mm, of 0.017 × 0.