title: Effects of lipopolysaccharides on the corrosion behavior of Ni-Cr and Co-Cr alloys.
abstract: BACKGROUND
  Lipopolysaccharides (LPS) are constituents of gingival crevicular fluid and may affect the base metal alloys used in metal ceramic crowns. The role of LPS in base metal alloys is currently unknown.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the effects of gram-negative bacterial LPS on the electrochemical behavior of Ni-Cr and Co-Cr alloys.
  
  
  METHODS
  Alloy specimens were divided into 4 groups according to Escherichia coli LPS concentration (0, 0.15, 15, and 150 μg/mL) in acidic saliva (pH 5). Open circuit potential (OCP) and potentiodynamic polarization behavior were examined using a computer-controlled potentiostat. Metal ions released from the 2 alloys were measured by immersion in LPS-free solution and 150 μg/mL LPS solution and analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES). Data were evaluated using 1-way ANOVA (α=.05).
  
  
  RESULTS
  Compared with control groups, medium LPS concentration (15 μg/mL) accelerated Ni-Cr alloy corrosion (P<.05), whereas high LPS concentration (150 μg/mL) accelerated Co-Cr alloy corrosion (P<.05), as determined by OCP, corrosion current density, and polarization resistance parameters. After immersion in high LPS concentrations (150 μg/mL), a slight increase in Ni ion release (P >.05) was observed for the Ni-Cr alloy, while a more significant Co ion release (P<.05) was observed for the Co-Cr alloy.
  
  
  CONCLUSIONS
  LPS negatively affected the electrochemical behavior of both the Ni-Cr and Co-Cr alloys.
authors.affiliation: Physician-in-charge, Department of Prosthodontics, School of Stomatology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Research Institute of Stomatology, Shanghai, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Yu
authors.affiliation: Doctoral candidate, Department of Prosthodontics, School of Stomatology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Research Institute of Stomatology, Shanghai, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Qian
authors.affiliation: Associate Professor, Department of Prosthodontics, School of Stomatology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Research Institute of Stomatology, Shanghai, China. Electronic address: wengwm1961@126.com.
authors.forename: Weimin
authors.initials: W
authors.lastname: Weng
authors.affiliation: Physician-in-charge, Department of Prosthodontics, School of Stomatology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai Research Institute of Stomatology, Shanghai, China.
authors.forename: Songmei
authors.initials: S
authors.lastname: Zhang
mesh_terms: D002858:Chromium Alloys / Q000737:chemistry*; D003343:Corrosion; D004926:Escherichia coli; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry*; D008422:Materials Testing; D016876:Metal Ceramic Alloys / Q000737:chemistry*; D009532:Nickel / Q000737:chemistry; D012464:Saliva, Artificial / Q000737:chemistry
chemical_list: D002858:Chromium Alloys; D008070:Lipopolysaccharides; D016876:Metal Ceramic Alloys; D012464:Saliva, Artificial; D009532:Nickel