title: Electrochemical impedance spectroscopy study of Ti-6Al-4V alloy in artificial saliva with fluoride and/or bovine albumin.
abstract: OBJECTIVE
  To investigate the electrochemical mechanism of Ti-6Al-4V alloy in acidic artificial saliva with NaF and/or bovine albumin (BA).
  
  
  METHODS
  The electrochemical behavior of Ti-6Al-4V alloy was investigated using electrochemical impedance spectroscopy (EIS) measurements at the open circuit potentials. The electrolytes used included artificial saliva with 0-0.5% NaF, with 0.1% NaF+0.01-0.5% BA, and with 0.01-0.5% BA at pH 5 and 37 degrees C. One-way ANOVA was used to analyze the influence of NaF and BA concentration on the polarization resistance (Rp) obtained from the EIS data. Surface chemical analyses were performed with X-ray photoelectron spectroscopy.
  
  
  RESULTS
  The impedance was mainly characterized by the resistance and capacitance of a protective TiO2-based passive film on Ti-6Al-4V alloy when NaF concentration was low (< or = 0.01%). When NaF concentration was higher than 0.1%, the impedance was characterized by two capacitive and one inductive effects, which were related to the metal's charge transfer reaction and the decayed TiO2-based oxide film (capacitive effects), and the relaxation of the adsorbed Ti-F complex compound (inductive effect). The addition of 0.01-0.5% BA in 0.1% NaF-containing artificial saliva significantly increased the impedance of Ti-6Al-4V alloy compared to that without BA addition (p < 0.001). The presence of BA in fluoride-free artificial saliva had no influence on the electrochemical impedance of Ti-6Al-4V alloy (p > 0.05).
  
  
  CONCLUSIONS
  The EIS measurement technique is suitable for the study of the electrochemical behavior of dental alloy. The electrochemical mechanism of Ti-6Al-4V alloy in artificial saliva is related to the fluoride and bovine albumin concentration.
authors.affiliation: Institute of Oral Materials Science, Chung Shan Medical University, Taichung 402, Taiwan.
authors.forename: Her-Hsiung
authors.initials: HH
authors.lastname: Huang
authors.forename: Tzu-Hsin
authors.initials: TH
authors.lastname: Lee
mesh_terms: D000418:Albumins / Q000737:chemistry*; D000497:Alloys; D000818:Animals; D002327:Cariostatic Agents / Q000737:chemistry*; D002417:Cattle; D003722:Dental Alloys / Q000737:chemistry*; D004553:Electric Conductivity; D017097:Electric Impedance; D004563:Electrochemistry; D006801:Humans; D008422:Materials Testing; D012464:Saliva, Artificial / Q000737:chemistry*; D012969:Sodium Fluoride / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013057:Spectrum Analysis; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D000418:Albumins; D000497:Alloys; D002327:Cariostatic Agents; D003722:Dental Alloys; D012464:Saliva, Artificial; C031462:titanium alloy (TiAl6V4); C009495:titanium dioxide; D012969:Sodium Fluoride; D014025:Titanium