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. Subjects were subdivided into 2 groups: non-replacement side: consisted of the right or left sides of the upper arch where space closure was done using the same 0.019 × 0.025-inch SS; replacement side: comprised the other side of the subjects where the working archwire was replaced with a new one each visit. The working archwire in the upper arch was split into 2 halves (new archwire on one side and old one on the other side); each one-half was connected to the other in the midline by a joining shim. Elastomeric chain was used to close extraction spaces. The amount of space closure (mm) was recorded each visit for 3 months. RESULTS: In the non-replacement side, the rate of upper space closure was 0.80 mm/month coronally and 0.75 mm/month gingivally. In the replacement side, it was 0.69 mm/month coronally and 0.67 mm/month gingivally (p > 0.05). Mean frictional force for the non-replacement side was 3.58 ± 1.20 N, and it was 2.43 ± 1.21 N for the replacement side (p < 0.01). CONCLUSIONS: Intraoral archwire aging has no effect on the rate of upper premolar space closure/month although frictional resistance of the aged archwire was higher than of the new one. Clinical relevance No need to replace 0.019 × 0.025-inch SS every visit during space closure to overcome corrosion and frictional resistance.