Load Deflection Characteristics of Orthodontic Gummetal® Wires in Comparison with Nickel-Titanium Wires: An In Vitro Study

The aim of this study was to investigate the load deflection characteristics of Gummetal (R) wires in comparison to nickel-titanium (NiTi) wires. Four different NiTi wires and one Gummetal (R) archwire were analyzed in two dimensions (0.014 '' (0.36 mm) and 0.016 '' x 0.022 '' (0.41 mm x 0.56 mm)) and in two different orientations (edgewise and ribbonwise) using three-point bending tests at T = 37 degrees C. Force-displacement curves were recorded and analyzed. The Gummetal (R) 0.014 '' wires exhibited higher forces compared to the NiTi wires at 2.0 mm deflection. At 1.0 mm deflection, the opposite pattern was observed. For the 0.016 '' x 0.022 '' Gummetal (R) wires, the forces were within the force interval of the NiTi wires at 2.0 mm deflection. At a deflection of 1.0 mm, no residual force was measurable for the Gummetal (R) wires. All the NiTi wires investigated showed hysteresis and a superelastic plateau. However, the Gummetal (R) did not form a plateau, but hysteresis was present. An easier plastic deformability compared to the NiTi wires was observed for all the tested geometries.