The Effectiveness of Conventional and Advanced Aligning Archwires: The Insights of Two Randomized Clinical Trials

This study aimed to compare the clinical effectiveness of four aligning archwires: Superelastic Nickel-Titanium (Superelastic-NiTi), SmartArch, Copper-Nickel-Titanium (Cu-NiTi), and Speed Tubular coaxial-Nickel-Titanium (Tubular coaxial-NiTi), regarding the alignment efficiency, associated perception of pain, and possibility of inducing root resorption.This study includes two randomized clinical trials run in parallel. Patients with 5 to 9 mm of mandibular anterior teeth crowding according to Little's irregularity index (LII) who needed fixed orthodontic appliances without extraction were randomly assigned to four groups of aligning archwires (each trial with two groups): 0.014-inch, 0.018-inch Superelastic-NiTi; 0.016-inch SmartArch; 0.014-inch, 0.018-inch Cu-NiTi; and 0.016-inch, 0.018-inch Tubular coaxial-NiTi. LII was measured pretreatment and every 4 weeks for the next 16 weeks. Pain perception was assessed using a visual analogue scale in the first 7 days after the placement of each archwire. Periapical radiographs for mandibular central incisors were taken pretreatment and after 16 weeks to assess root resorption. The alignment efficiency was tested using a repeated measures analysis of variance test with mixed factorial design (between and within-subject effect), while pain perception and root resorption were tested using the Kruskal-Wallis test and Wilcoxon signed-rank test.A total of 73 patients were recruited from different centers. The analysis included 64 patients who completed the trials. Neither clinical nor statistical significance was found between the groups regarding the alignment. Similarly, there was no significant difference between the four groups regarding pain perception and root resorption. However, root resorption was slightly more in the Superelastic-NiTi group than in the other groups.The short time that root resorption was reported.The four types of archwires performed comparably regarding the alignment efficiency, associated perception of pain, and the possibility of inducing root resorption.The trials included in this study were registered with ClinicalTrials.gov on May 26, 2022 (Registration number: NCT05391542) and August 18, 2022 (Registration number: NCT05510206).