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.