title: Metallic ions released from stainless steel, nickel-free, and titanium orthodontic alloys: toxicity and DNA damage.
abstract: BACKGROUND
  The aims of this study were to determine the amounts of metallic ions that stainless steel, nickel-free, and titanium alloys release to a culture medium, and to evaluate the cellular viability and DNA damage of cultivated human fibroblasts with those mediums.
  
  
  METHODS
  The metals were extracted from 10 samples (each consisting of 4 buccal tubes and 20 brackets) of the 3 orthodontic alloys that were submerged for 30 days in minimum essential medium. Next, the determination of metals was performed by using inductively coupled plasma mass spectrometry, cellular viability was assessed by using the tetrazolium reduction assay (MTT assay) (3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide), and DNA damage was determined with the Comet assay. The metals measured in all the samples were Ti(47), Cr(52), Mn(55), Co(59), Ni(60), Mo(92), Fe(56), Cu(63), Zn(66), As(75), Se(78), Cd(111), and Pb(208).
  
  
  RESULTS
  The cellular viability of the cultured fibroblasts incubated for 7 days with minimum essential medium, with the stainless steel alloy submerged, was close to 0%. Moreover, high concentrations of titanium, chromium, manganese, cobalt, nickel, molybdenum, iron, copper, and zinc were detected. The nickel-free alloy released lower amounts of ions to the medium. The greatest damage in the cellular DNA, measured as the olive moment, was also produced by the stainless steel alloy followed by the nickel-free alloy. Conversely, the titanium alloy had an increased cellular viability and did not damage the cellular DNA, as compared with the control values.
  
  
  CONCLUSIONS
  The titanium brackets and tubes are the most biocompatible of the 3 alloys studied.
authors: Docent Unit of Integral Pediatric Dentistry, Faculty of Medicine, Dental Clinic, University of Murcia, Murcia, Spain. ajortiz@um.es
authors: Antonio José
authors: AJ
authors: Ortiz
authors: Esther
authors: E
authors: Fernández
authors: Ascensión
authors: A
authors: Vicente
authors: José L
authors: JL
authors: Calvo
authors: Clara
authors: C
authors: Ortiz
mesh_terms: D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002858:Chromium Alloys / Q000633:toxicity; D020552:Comet Assay; D003470:Culture Media / Q000737:chemistry; D004249:DNA Damage; D003722:Dental Alloys / Q000633:toxicity*; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D007477:Ions / Q000032:analysis; D013058:Mass Spectrometry / Q000379:methods; D008670:Metals / Q000032:analysis*; D016910:Orthodontic Brackets / Q000009:adverse effects*; D013193:Stainless Steel / Q000633:toxicity; D013778:Tetrazolium Salts; D013844:Thiazoles; D014025:Titanium / Q000633:toxicity
chemical_list: D002858:Chromium Alloys; D003470:Culture Media; D003722:Dental Alloys; D007477:Ions; D008670:Metals; D013778:Tetrazolium Salts; D013844:Thiazoles; D013193:Stainless Steel; D014025:Titanium; C022616:thiazolyl blue