title: Cytotoxic effects of polycarbonate-based orthodontic brackets by activation of mitochondrial apoptotic mechanisms.
abstract: OBJECTIVE
  The aim of the study was to evaluate the biological effects of water eluents from polycarbonate based esthetic orthodontic brackets.
  
  
  METHODS
  The composite polycarbonate brackets tested were Silkon Plus (SL, fiber-glass-reinforced), Elan ME (EL, ceramic particle-reinforced) and Elegance (EG, fiber-glass-reinforced). An unfilled polyoxymethylene bracket (Brilliant, BR) was used as control. The brackets' composition was analyzed by ATR-FTIR spectrometry. The cytotoxicity and estrogenicity of the eluents obtained after 3 months storage of the brackets in water (37 °C) were investigated in murine fibroblasts (NIH 3T3), breast (MCF-7) and cervical cancer (CCl-2/Hela) cell lines.
  
  
  RESULTS
  SL and EG were based on aromatic-polycarbonate matrix, whereas EL consisted of an aromatic polycarbonate-polyethylene terepthalate copolymer. A significant induction of cell death and a concurrent decrease in cell proliferation was noted in the EG eluent-treated cells. Moreover, EG eluent significantly reduced the levels of the estrogen signaling associated gene pS2, specifically in MCF7 cells, suggesting that cell death induced by this material is associated with downregulation of estrogen signaling pathways. Even though oxidative stress mechanisms were equally activated by all eluents, the EG eluents induced expression of apoptosis inducing factor (AIF) and reduced Bcl-xL protein levels.
  
  
  CONCLUSIONS
  Some polycarbonate-based composite brackets when exposed to water release substances than activate mitochondrial apoptosis.
authors.affiliation: Department of Orthodontics and Dentofacial Orthopedics, Faculty of Medicine, University of Bern, Switzerland.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kloukos
authors.forename: Era
authors.initials: E
authors.lastname: Taoufik
authors.forename: Theodore
authors.initials: T
authors.lastname: Eliades
authors.forename: Christos
authors.initials: C
authors.lastname: Katsaros
authors.forename: George
authors.initials: G
authors.lastname: Eliades
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D051033:Apoptosis Inducing Factor / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D004967:Estrogens / Q000032:analysis*; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008928:Mitochondria / Q000187:drug effects* / Q000378:metabolism; D041681:NIH 3T3 Cells; D016910:Orthodontic Brackets / Q000009:adverse effects*; D011076:Polycarboxylate Cement / Q000633:toxicity*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D051033:Apoptosis Inducing Factor; D004967:Estrogens; D011076:Polycarboxylate Cement; C005506:polycarbonate