Alignment Efficiency of Superelastic and Heat-Activated Nickel–Titanium Archwires During Initial Orthodontic Alignment: A Randomized Clinical Trial

Abstract

Background: Levelling and alignment constitute the initial and one of the most critical phases of fixed orthodontic
treatment. Nickel–titanium (NiTi) archwires are routinely used during this stage because of their favourable biomechanical
properties; however, the comparative clinical alignment efficiency of superelastic and heat-activated NiTi archwires
remains uncertain.
Aim: To compare the clinical alignment efficiency of superelastic nickel–titanium (SENT) and heat-activated
nickel–titanium (HANT) archwires during the initial alignment phase of fixed orthodontic treatment in patients with mild-
to-moderate anterior crowding.
Methods: In this randomized clinical trial, orthodontic patients aged 11–25 years presenting with 3.0–6.9 mm of anterior
segment crowding and requiring non-extraction fixed appliance therapy were randomly allocated (1:1) to either the HANT
or SENT group. Both groups followed an identical archwire sequence (0.014-inch, 0.016-inch, and 0.018-inch NiTi), with
each archwire maintained for four weeks. Anterior segment crowding was measured at baseline and at 4-week intervals over
a 12-week period. Changes in alignment were analysed using repeated-measures analysis of variance (ANOVA), with
statistical significance set at P < 0.05.
Results: Thirty-eight dental arches were randomized and included in the final analysis (19 arches per group). The mean
participant age was 20.05 ± 5.14 years, and baseline demographic and clinical characteristics were comparable between
groups (P > 0.05). Over the 12-week observation period, the mean reduction in anterior segment crowding was 3.90 mm in
the HANT group and 3.46 mm in the SENT group. The between-group difference was not statistically significant (P =
0.809).
Conclusions: Heat-activated and Superelastic nickel–titanium archwires demonstrated comparable clinical efficiency for
the alignment of mild-to-moderate anterior crowding during the initial phase of fixed orthodontic treatment.