To evaluate the load–deflection characteristics of Damon™ Ultima (0.014 × 0.0275“) wires compared with heat-activated nickel–titanium (HANT, 0.014 × 0.025”) wires across different passive self-ligating brackets (PSLBs).

One hundred eight bracket–wire assemblies were allocated into six groups based on three PSLB systems (Damon™ Ultima, Damon™ Q, Unitek™ Gemini SL) and two wire types. A modified ISO 15841 three-point bending test was performed at 37 ̊C using an Instron machine, with deflections recorded at 0.5 mm steps from 3.0 to 0.5 mm. A supplementary wet-after-thermocycling protocol (5000 cycles; artificial saliva) assessed ecological validity. Statistical analysis (SPSS v23) included t -tests, one-way ANOVA/Kruskal–Wallis tests, and effect-size estimation (Cohen's d , Hedges’ g ) with 95% confidence intervals; multiple comparisons were adjusted using the Holm–Bonferroni method.

Damon™ Ultima wires produced significantly lower deactivation forces than HANT wires across PSLBs at 1.0- and 1.5-mm deflections ( P < 0.001). Activation differences were bracket-dependent, with significant reductions observed mainly in Damon™ Ultima brackets. Wet-after-thermocycling reduced deactivation forces by 23–37% at 1.0–1.5 mm, with large paired effect sizes (Hedges’g ≈–1.5 to–1.9). Force delivery remained light and consistent despite the larger 0.0275″ cross-section.

Within the limits of this bench study, Damon™ Ultima wires exhibited lower unloading forces at clinically relevant deflections across PSLBs, potentially facilitating earlier bracket engagement and rotational efficiency. However, rotational control was not directly measured, and clinical trials are warranted to validate these findings.