Nitinol corrosion under force stresses in simulated physiological fluid with and without fluorides

Abstract

Introduction: nickel-titanium (nitinol) wires may potentially corrode oral environments causing biocompatibility problems. The purpose of this study was to compare the behavior of corrosion of nitinol wires in artificial saliva with different levels of pH, fluoride concentration, and tension degrees. Methods: an experimental study applying four electrochemical techniques: corrosion potential, linear polarization resistance, Tafel curves, and electrochemical impedance spectroscopy. Samples were cemented on teeth simulating different crowding degrees (56 gf and 224 gf) at various levels of fluoride concentration (0% and 0.5%) and pH (4 and 7). Results: the corrosion strength values for a sample submerged at pH 4, 0% NaF during 5 hours is lower for a force of 224 gf than for 56 gf. When the electrolyte is added a concentration of 0.5% sodium fluoride, it increases polarization resistance for a force of 224 gf. Conclusions: this study confirmed the existence of oxides on the nickel-titanium surface, especially on the arch exposed for 14 days to pH 4 and 0.5% NaF.

Keywords

• nickel-titanium alloy
• fluorides
• corrosion
• electrochemical techniques
• aleación níquel-titanio
• fluoruros
• corrosión
• técnicas electroquímicas