Effect of Fluoride on Nickel-Titanium and Stainless Steel Orthodontic Archwires: An In-Vitro Study

Objectives: The commonly used Nickel-Titanium (NiTi) archwires in orthodontic treatment are often exposed to fluoride-containing mouthwashes. The aim of this in-vitro study was to evaluate and compare the corrosion resistance of three com- mercially available NiTi archwires exposed to 0.05 wt% and 0.2 wt% fluoride mouthwashes. Materials and Methods: Three different types of NiTi archwires, 0.016” in di- ameter, from Dentaurum, Global, and GAC, and a stainless steel archwire from Dentaurum were examined to assess their corrosion resistance in Fusayama- Meyer artificial saliva and in two other artificial saliva containing 0.05 wt% and 0.2 wt% sodium fluoride (NaF). After the primary setup of wires, they were tested by potentiodynamic and potentiostatic polarization and corrosion potential/time analyses. Their surfaces were evaluated using a scanning electronic microscope (SEM). Results: The results showed that all the wires were passive in artificial saliva. In Corresponding author: N. Mokhber, Department of Orthodontics, Academic Center of Education, Culture and Re- search (ACECR), Mashhad, Iran nimamokhber@yahoo.com Received: 2 August 2014 Accepted: 12 November 2014 contrast, by adding fluoride ions to the solution, the decrease in the archwires’ corrosion resistance was in direct proportion to the increase in fluoride concentration. Conclusion: The NiTi wires experienced deterioration of their corrosion proper- ties under the effect of fluoride but not as much as the stainless steel archwires.