A comparison of the rate of space closure using a nickel-titanium spring and an elastic module: a clinical study.

A study of the efficiency of space closure after premolar extraction was undertaken, comparing a nickel-titanium closed coil spring and an elastic retraction module by using sliding mechanics along an 0.019 x 0.025-inch stainless steel arch wire in 0.022 x 0.028-inch preadjusted stainless steel brackets. The rate of space closure in 17 subjects was analyzed from study models and was found to be significantly greater and more consistent with the nickel-titanium closed coil springs than with the elastic modules, in both arches. There were no clinically observable differences in the tooth positions between the respective techniques.