Mechanical Properties of Copper-Nickel-Titanium Archwires

MECHANICAL PROPERTIES OF COPPER-NICKEL-TITANIUM ORTHODONTIC WIRES Margaret Rosen, D.M.D. Marquette University, 2016 Introduction: The initial phase of orthodontic therapy relies on flexible wires, usually composed of a nickel-titanium alloy, to apply a substantially constant load during tooth movement. Copper has been added to nickel-titanium archwires, resulting in an alloy with potential clinical advantages such as a lower stress hysteresis. Many orthodontic companies claim that their copper-nickel-titanium manufacturing process allows for the production of more consistent transition temperatures in the wires, allowing the orthodontist to customize treatment to various patients based on the force level needed. There are currently many manufacturers of these wires, creating a wide range of coppernickel-titanium archwires from which orthodontists may choose. The goal of this research study was to test various manufacturers’ copper-nickel-titanium archwires to see if their mechanical properties are comparable to each other. Materials and Methods: Six different companies’ copper-nickel-titanium archwires wires were tested: Ormco, American Orthodontics, Dentsply GAC, Ortho Organizers, Rocky Mountain Orthodontics, and Ortho Technology. Within each of the 6 brands, 0.018” round and 0.016” x 0.022” rectangular wires at both 27 ̊C and 35 ̊C transition temperatures were identified. Three-point bending test was utilized to determine the activation and deactivation forces present within segments of the various wires. Forces for the deflection were recorded directly onto the computer software program. Data were compared using one-way analysis of variance at a 0.05 significance level with a Tukey's HSD test post hoc analysis, when required. Results: Statistically significant differences were observed in force levels between brands for all round and rectangular wire/temperature combinations. Overall, within both 27 ̊C and 35 ̊C and both round and rectangular wires, Ormco tended to behave the most uniquely when compared to all of the other brands. Conclusions: Wires of the same materials, dimensions, and transition temperature but from different manufacturers do not always have the same mechanical properties. Improvements should be made in the standardization of the manufacturing process of copper-nickel-titanium archwires in order to provide orthodontists with CuNiTi archwires that have consistent mechanical properties.