Thermo-Mechanical Characterization of Innovative Side-Rounded Superelastic CuNiTi Orthodontic Wires

This study evaluates the thermal and mechanical behavior of innovative copper–nickel–titanium (CuNiTi) rectangular orthodontic wires featuring rounded edges across two different sizes for clinical applications. Differential scanning calorimetry (DSC) was performed from −20 °C to +80 °C to determine phase transformation temperatures according to ASTM F2004. Three-point bending tests were conducted in accordance with ISO 15841 to evaluate unloading forces (at 3, 2, 1, and 0.5 mm deflections) and permanent residual deflection at 23 °C (room temperature) and 37 °C (oral environment). DSC analysis revealed a single-stage phase transformation within the range 10 °C to 27 °C, indicating near-superelastic behavior at room temperature. Mechanical testing demonstrated reproducible force-deflection profiles and low permanent deformation. At body temperature (37 °C), unloading forces in the 2.0–0.5 mm activation range averaged between 1.9 N and 3.2 N depending on wire cross-section. In conclusion, the evaluated CuNiTi wires provide consistent force delivery during unloading at physiological temperature, offering suitable mechanical properties for orthodontic alignment applications.