title: Characterization and cytotoxicity of ions released from stainless steel and nickel-titanium orthodontic alloys.
abstract: The purpose of this study was to qualitatively and quantitatively characterize the substances released from orthodontic brackets and nickel-titanium wires and to comparatively assess the cytotoxicity of the ions released from these orthodontic alloys. Two full sets of stainless steel brackets of 20 brackets each (weight 2.1 g) and 2 groups of 0.018 x 0.025 Ni-Ti archwires of 10 wires each (weight 2.0 g) were immersed in 0.9% saline solution for a month. The immersion media were analyzed with inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and the ionic content was statistically analyzed with 1-way analysis of variance (ANOVA). Human periodontal ligament fibroblasts and gingival fibroblasts were exposed to various concentrations of the 2 immersion media; nickel chloride was used as a positive control for comparison purposes. The cytotoxic or cytostatic activity of the media was investigated with the MTT and the DNA synthesis assays. The results of the cytotoxicity assay were analyzed with 2-way ANOVA and the Tukey test with solution and concentration variants as discriminating variables (alpha=0.05). The results indicated no ionic release for the nickel-titanium alloy aging solution, whereas measurable nickel and traces of chromium were found in the stainless steel bracket-aging medium. Concentrations of the nickel chloride solution greater then 2 mM were found to reduce by more than 50% the viability and DNA synthesis of fibroblasts; however, neither orthodontic materials-derived media had any effect on the survival and DNA synthesis of either cells.
authors.affiliation: Biomaterials Laboratory, School of Dentistry, University of Athens, Greece. teliades@ath.forthnet.gr
authors.forename: Theodore
authors.initials: T
authors.lastname: Eliades
authors.forename: Harris
authors.initials: H
authors.lastname: Pratsinis
authors.forename: Dimitris
authors.initials: D
authors.lastname: Kletsas
authors.forename: George
authors.initials: G
authors.lastname: Eliades
authors.forename: Margarita
authors.initials: M
authors.lastname: Makou
mesh_terms: D000328:Adult; D005347:Fibroblasts / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D007477:Ions / Q000633:toxicity; D008422:Materials Testing; D008875:Middle Aged; D009532:Nickel / Q000633:toxicity*; D016910:Orthodontic Brackets / Q000009:adverse effects*; D009969:Orthodontic Wires / Q000009:adverse effects*; D010513:Periodontal Ligament / Q000166:cytology; D013193:Stainless Steel / Q000633:toxicity*; D014025:Titanium / Q000633:toxicity*; D018675:Toxicity Tests
chemical_list: D007477:Ions; C040654:titanium nickelide; D013193:Stainless Steel; C022838:nickel chloride; D009532:Nickel; D014025:Titanium