title: Corrosion resistance of different nickel-titanium archwires in acidic fluoride-containing artificial saliva.
abstract: OBJECTIVE
  To test the hypothesis that different nickel-titanium (NiTi) archwires may have dissimilar corrosion resistance in a fluoride-containing oral environment.
  
  
  METHODS
  Linear polarization test, a fast electrochemical technique, was used to evaluate the corrosion resistance, in terms of polarization resistance (R(p)), of four different commercial NiTi archwires in artificial saliva (pH 6.5) with various NaF concentrations (0%, 0.01%, 0.1%, 0.25%, and 0.5%). Two-way analysis of variance was used to analyze R(p) with the factors of archwire manufacturer and NaF concentration. Surface characterizations of archwires were analyzed using scanning electron microscopy, atomic force microscopy, and x-ray photoelectron spectroscopy.
  
  
  RESULTS
  Both archwire manufacturer and NaF concentration had a significant influence on R(p) of NiTi archwires. Different surface topography was present on the test NiTi archwires that contained the similar surface chemical structure (TiO(2) and trace NiO). The surface topography did not correspond to the difference in corrosion resistance of the NiTi archwires. Increasing the NaF concentration in artificial saliva resulted in a decrease in R(p), or corrosion resistance, of all test NiTi archwires. The NiTi archwires severely corroded and showed similar corrosion resistance in 0.5% NaF-containing environment.
  
  
  CONCLUSIONS
  Different NiTi archwires had dissimilar corrosion resistance in acidic fluoride-containing artificial saliva, which did not correspond to the variation in the surface topography of the archwires. The presence of fluoride in artificial saliva was detrimental to the corrosion resistance of the test NiTi archwires, especially at a 0.5% NaF concentration.
authors.affiliation: Institute of Medicine, Chung Shan Medical University, Department of Dentistry, Chung Shan Medical University Hospital, Taichung, Taiwan.
authors.forename: Tzu-Hsin
authors.initials: TH
authors.lastname: Lee
authors.forename: Ta-Ko
authors.initials: TK
authors.lastname: Huang
authors.forename: Shu-Yuan
authors.initials: SY
authors.lastname: Lin
authors.forename: Li-Kai
authors.initials: LK
authors.lastname: Chen
authors.forename: Ming-Yung
authors.initials: MY
authors.lastname: Chou
authors.forename: Her-Hsiung
authors.initials: HH
authors.lastname: Huang
mesh_terms: D002327:Cariostatic Agents / Q000737:chemistry*; D003343:Corrosion; D003722:Dental Alloys / Q000737:chemistry*; D005459:Fluorides / Q000737:chemistry*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D009532:Nickel / Q000737:chemistry*; D009969:Orthodontic Wires; D056951:Photoelectron Spectroscopy; D011048:Polarography; D012464:Saliva, Artificial / Q000737:chemistry*; D012969:Sodium Fluoride / Q000737:chemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D002327:Cariostatic Agents; D003722:Dental Alloys; D012464:Saliva, Artificial; C040654:titanium nickelide; C009495:titanium dioxide; D009532:Nickel; D012969:Sodium Fluoride; C028007:nickel monoxide; D014025:Titanium; D005459:Fluorides