title: Cytotoxicity of esthetic, metallic, and nickel-free orthodontic brackets: cellular behavior and viability.
abstract: BACKGROUND
  In this study, we evaluated the cellular viability of various esthetic, metallic, and nickel-free orthodontic brackets.
  
  
  METHODS
  The sample was divided into 11 groups (n = 8): cellular control, negative control, positive control, metallic, polycarbonate, 2 types of monocrystalline ceramic, 3 types of nickel free, and polycrystalline ceramic brackets. Cell culture (NIH/3T3-mice fibroblasts) was added to the plates of 96 wells containing the specimens and incubated in 5% carbon dioxide at 37°C for 24 hours. Cytotoxicity was analyzed qualitatively and quantitatively. Cell growth was analyzed with an inverted light microscope, photomicrographs were obtained, and the results were recorded as response rates based on modifications of the parameters of Stanford according to the size of diffusion halo of toxic substances. Cell viability was analyzed (MTT assay); a microplate reader recorded the cell viability through the mitochondrial activity in a length of 570 nm. The values were statistically analyzed.
  
  
  RESULTS
  All tested brackets had higher cytotoxicity values than did the negative control (P <0.05), with the exception Rematitan and Equilibrium (both, Dentaurum, Ispringen, Germany) (P >0.05), suggesting low toxicity effects. The values showed that only polycarbonate brackets were similar (P >0.05) to the positive control, suggesting high toxicity.
  
  
  CONCLUSIONS
  The brackets demonstrated different ranges of cytotoxicity; nickel-free brackets had better biocompatibility than the others. On the other hand, polycarbonate brackets were made of a highly cytotoxic material for the cells analyzed.
authors: Department of Dental Materials, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre, Brazil. retamosolb@gmail.com
authors: Luciana Borges
authors: LB
authors: Retamoso
authors: Tatiana Blaya
authors: TB
authors: Luz
authors: Daniel Rodrigo
authors: DR
authors: Marinowic
authors: Denise Cantarelli
authors: DC
authors: Machado
authors: Luciane Macedo
authors: LM
authors: De Menezes
authors: Maria Perpétua Mota
authors: MP
authors: Freitas
authors: Hugo Mitsuo Silva
authors: HM
authors: Oshima
mesh_terms: D000535:Aluminum / Q000633:toxicity; D000818:Animals; D001559:Benzhydryl Compounds; D001672:Biocompatible Materials / Q000633:toxicity; D002245:Carbon Dioxide / Q000008:administration & dosage; D018929:Cell Culture Techniques; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002516:Ceramics / Q000633:toxicity; D002858:Chromium Alloys / Q000737:chemistry; D004396:Coloring Agents; D003722:Dental Alloys / Q000633:toxicity*; D003764:Dental Materials / Q000633:toxicity*; D004955:Esthetics, Dental; D005347:Fibroblasts / Q000187:drug effects; D051379:Mice; D041681:NIH 3T3 Cells; D009532:Nickel / Q000633:toxicity; D016910:Orthodontic Brackets; D010636:Phenols / Q000633:toxicity; D011076:Polycarboxylate Cement / Q000633:toxicity; D013696:Temperature; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D014025:Titanium / Q000633:toxicity; D000098826:Bisphenol A Compounds
chemical_list: D000535:Aluminum; D001559:Benzhydryl Compounds; D001672:Biocompatible Materials; D002245:Carbon Dioxide; D002858:Chromium Alloys; D004396:Coloring Agents; D003722:Dental Alloys; D003764:Dental Materials; D009532:Nickel; D010636:Phenols; D011076:Polycarboxylate Cement; D013778:Tetrazolium Salts; D013844:Thiazoles; D014025:Titanium; C005506:polycarbonate; C022616:thiazolyl blue; C006780:bisphenol A; D000098826:Bisphenol A Compounds