Characterization of closed nickel-titanium orthodontic coil springs

Abstract

Nickel-Titanium orthodontic coil springs are used to move teeth with low forces and slow deactivation. The present paper provides data on transfomation temperatures and on load-deflection rate at buccal temperature of closed Nickel-Titanium coil springs available on the market from ORMCO® and GAC®. All the springs exhibited superelasticity but their properties were not stable in the range of buccal temperatures and varied not only from one manufacturer to the other but they also varied from one batch to the other of each supplier. The need for more stability is stressed.