Evaluation of plastic deformation resistance of nickeltitanium round wires

Vol. 15 – Number 59 – 2022 NA VISÃO D’ELAS Page 102-109 Evaluation of plastic deformation resistance of nickeltitanium round wires Leniana Santos Neves1 Pedro Damas Resende2 Esdras de Campos França3 Rodrigo Hermont Cançado4 Leandro de Arruda Santos5 Fernanda Silva Viana6 Abstract Nickel-titanium (NiTi) alloys have high elasticity without suffering permanent plastic deformations, widely indicated in the early stages of orthodontic treatment. This study aims to evaluate the heat-activated NiTi orthodontic wires’ resistance to plastic deformation. The wire from 6 commercial brands (GAC®, Morelli®, American Orthodontics®, Infinity®, and 3M®) was evaluated first from prototype models, simulating the relationship between plastic deformation and deflection by the inter bracket distance at four levels of force at 37° C for 30 days. A second experiment was carried out by analyzing standardized photographs with diagrams observing the before and after deformation was applied to the wire at different temperatures. The first test showed that all tested trademarks returned to their original shape after deflecting for 30 days. The second experiment showed that GAC® and American Orthodontics® wires did not present statistically significant differences comparing the wire measurements before deformed deformation and after heating (heated wire). On the other hand, 3M®, Orthometric® and Infinity®, Morelli wires showed significant differences between new and deformed wires and between twisted and heated wires; however, there were no significant differences between new and heated wires. It was concluded that no wire, at any magnitude of applied deflection, suffered plastic (permanent) deformation. Thus, all wires of the commercial brands tested were considered satisfactory for the clinical practice of Orthodontics in terms of resistance to plastic deformation. Descriptors: Orthodontic wires, orthodontic appliances, tooth movement techniques. 1 Professor, Department of Restorative Dentistry – Discipline of Orthodontics – UFMG, Master and Doctor in Orthodontics – FOB-USP. 2 Master in Metallurgical Engineering – UFMG. 3 Specialist in Orthodontics – UFMG, Substitute Professor, Department of Restorative Dentistry – Discipline of Orthodontics – UFMG, Master and Doctor in Dentistry – UFMG. 4 Professor, Department of Restorative Dentistry – Discipline of Orthodontics – UFMG, Master and Doctor in Orthodontics – FOB-USP. 5 Professor at the Department of Metallurgical Engineering, Faculty of Engineering – UFMG, Master in Materials Engineering – UFSC, Doctor in Metallurgical Engineering – UFMG. 6 Specialist in Orthodontics – UFMG. DOI: 10.24077/2022;1559-0261209