Alloys corrosion resistance used in fix orthodontic appliances

The advance of science has made possible expressive development in many areas, facilitating in significant way determined procedures, also in orthodontics. Diverse materials when present in a orthodontic device and inserted in buccal medium are exposed to deterioration due to corrosion mechanisms. Objectives: Evaluate the occurrence of corrosion in assemble materials of a orthodontic device. Experimental Method: 0,016 inch orthodontic archwires of stainless steel, cobalt-chromium, titanium-beta (TMA), nickel-titanium (superelastic and thermoactivated) as well as stainless steel (304 and 316L) and pure titanium samples were introduced in solution of artificial saliva at 37oC with and without fluorine. All materials were then evaluated by anodic polarization techniques. Results: Corrosion Potential varied from -477 mV (solution without fluorine) and -558 mV (solution with fluorine) up to +100 mV (solution without fluorine) in the case of pure titanium and +127 mV (solution with fluorine) in the case of the CrNi alloy. Conclusion: All the tested alloys and the pure titanium showed to be resistant to corrosive processes. Also, NiTi alloys (superelastic and thermoactivated), TMA and pure titanium were more corrosion resistant in solutions with and without fluorine.