title: Cytotoxicity of orthodontic wire corroded in fluoride solution in vitro.
abstract: OBJECTIVE
  To investigate the toxicity of fluoride corrosion extracts of stainless steel (SS) and nickel-titanium (NiTi) wires on a human osteosarcoma cell line (U2OS).
  
  
  METHODS
  The SS and NiTi wires were corroded by an electrochemical method with the application of three kinds of electrolytes: 0.2% pH 3.5 acidulated phosphate fluoride (NaF) in artificial saliva, and pH 4 and pH 6.75 artificial saliva solutions. The extracts were analyzed for nickel, chromium, and titanium ions by the atomic absorption method. The extracts were diluted with medium to different concentrations (1, 0.1, and 0.01 microL/mL). The cell survival rate was determined by the ability of test cells to cleave the tetrazolium salt to form a formazan dye.
  
  
  RESULTS
  The results were compared using one-way analysis of variance. Differences between the treatment means were analyzed using a Student-Newman-Keuls (SNK) test and were considered significant at P < .05. The release of ionic nickel was different in different extract groups (P < .05). The SS and NiTi wires in the 0.2% pH 3.5 NaF artificial saliva group caused a dose-dependent decrease in the survival rate (P < .05). Survival rates of cells in the groups exposed to extracts of SS and NiTi wires in pH 4 and pH 6.75 artificial saliva solutions showed no statistical differences (P >.05).
  
  
  CONCLUSIONS
  Orthodontic wires in acidulated fluoride saliva solution can cause U2OS cell toxicity.
authors.affiliation: Institute of Medicine, Institute of Oral Material Science, Chung Shan Medical University, Taiwan.
authors.forename: Chia-Tze
authors.initials: CT
authors.lastname: Kao
authors.forename: Shinn-Jyh
authors.initials: SJ
authors.lastname: Ding
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.forename: Ming Yung
authors.initials: MY
authors.lastname: Chou
authors.forename: Tsui-Hsien
authors.initials: TH
authors.lastname: Huang
mesh_terms: D002327:Cariostatic Agents / Q000009:adverse effects*; D045744:Cell Line, Tumor / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003343:Corrosion; D003603:Cytotoxins / Q000009:adverse effects*; D005459:Fluorides / Q000009:adverse effects*; D006801:Humans; D009532:Nickel / Q000009:adverse effects; D009969:Orthodontic Wires / Q000009:adverse effects*; D012516:Osteosarcoma; D012464:Saliva, Artificial / Q000009:adverse effects; D013193:Stainless Steel / Q000009:adverse effects; D014025:Titanium / Q000009:adverse effects
chemical_list: D002327:Cariostatic Agents; D003603:Cytotoxins; D012464:Saliva, Artificial; C040654:titanium nickelide; D013193:Stainless Steel; D009532:Nickel; D014025:Titanium; D005459:Fluorides