Alignment Efficiency of Nickel-Free Niobium–Titanium–Tantalum–Zirconium Compared to Nickel–Titanium Orthodontic Archwires during Initial Treatment Phase: A Randomized Controlled Trial

Abstract Objective  This randomized controlled trial investigated the efficiency of nickel–titanium (NiTi) and nickel-free archwires during the initial leveling and alignment stage. Materials and Methods  A total of 30 patients (mean age, 17.81 ± 1.96 years) were randomly grouped to receive either single-strand or niobium–titanium–tantalum–zirconium (nickel-free Gummetal), or multistrand NiTi archwires. All the patients had moderate anterior crowding and were treated via a nonextraction approach. Three-dimensional digital models were taken at baseline (T0) and 4-week intervals for three months (T1, T2, and T3). The amount and percentage variations in Little's Irregularity Index (LII) scores during the 3-month observation period were used to estimate alignment efficiency and rate. Statistical Analysis  The Analysis of variance (ANOVA) and Kruskall–Wallis tests were used to test the differences between the three archwire groups. The difference between variables within each group at different measurement intervals was assessed using paired t -test. Results  The LII scores were reduced in all the three archwire groups; however, there were insignificant differences in the scores between the tested archwire groups ( p  < 0.05). For the single-strand NiTi group, the LII scores reduced by 2.15 mm (28.38%) after 4 weeks (T1) by 3.79 mm (47.93%) after 8 weeks (T2), and by 5.61 mm (73.98%) after 12 weeks (T3). The LII scores decreased by 1.90 mm (26.93%) after 4 weeks, 3.59 mm (50.84%) after 8 weeks, and 5.28 mm (74.85%) after 12 weeks with Gummetal archwire. Similar to the other groups, the LII scores for multistrand archwire reduced by 1.82 (27.83%), 3.34 (51.07%), and 4.54 mm (69.38%) at T1, T2, and T3, respectively. There was nonsignificant differences in the alignment rates (mm) and percentage (%) of changes among the groups at all measurement intervals ( p  > 0.05). Conclusion  All three tested archwires were equally effective for correcting moderate mandibular anterior crowding. Furthermore, all three archwires produced a comparable rate of alignment after 12 weeks of initiating orthodontic therapy.