The effect of intraoral aging of the working stainless steel archwire on the rate of premolar extraction space closure: a randomized clinical trial.

Objectives: The aims of this study were to investigate the effect of the working archwire intra-aging on the rate of upper first premolar space closure and to measure frictional resistance during space closure.

Methods: A total of 28 subjects participated in this study. All patients were treated by upper first premolar extraction.