title: Effect of fluoride on nickel-titanium and stainless steel orthodontic archwires: an in-vitro study.
abstract: OBJECTIVE
  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 commercially available NiTi archwires exposed to 0.05 wt% and 0.2 wt% fluoride mouthwashes.
  
  
  METHODS
  Three different types of NiTi archwires, 0.016″ in diameter, 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 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.
  
  
  CONCLUSIONS
  The NiTi wires experienced deterioration of their corrosion properties under the effect of fluoride but not as much as the stainless steel archwires.
authors.affiliation: Department of Orthodontics, School of Dentistry Mashad University of Medical Sciences, Mashhad, Iran.
authors.forename: Farzin
authors.initials: F
authors.lastname: Heravi
authors.affiliation: Department of Materials and Metallurgical Engineering, Ferdowsy University, Mashhad, Iran.
authors.forename: Mohamad Hadi
authors.initials: MH
authors.lastname: Moayed
authors.affiliation: Department of Orthodontics, Academic Center of Education, Culture and Research (ACECR), Mashhad, Iran.
authors.forename: Nima
authors.initials: N
authors.lastname: Mokhber
keywords: Corrosion; Fluoride; Nickel-titanium alloy; Scanning electron microscopy