NiTi alloys are usually used in orthodontic application. From knowledge that the addition of third elements may change the mechanical properties of the material, the addition of Cu became an important possibility for this application. The addition of Cu narrow the mechanical hysteresis, improving the super elasticity and the fatigue resistance. These changes are important in order to promote the adequate tooth movement under a lower and constant force. The NiTiCu became a good choice for tooth movement in periodontal patients who needs a lower force on the periodontal structure. The aim of this study was to evaluate the corrosion behavior of NiTi and NiTiCu thermoactive commercial archwires that were employed currently in clinical orthodontics. The archwires were submitted to electrochemical tests, such as electrochemical impedance spectroscopy and anodic polarization. The results showed that the Cu addition has influence on the passive range - AE, but this effect is not relevant in terms of corrosion resistance. The archwires were analyzed by SEM, before and after electrochemical tests and a few manufacture defects were identified. This study suggests that the choice of composition to be employed can be more related to the need for orthodontic treatment and the mechanical properties of the alloy than to corrosion resistance.
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