title: In vitro antibacterial and cytotoxicity assessments of an orthodontic bonding agent containing benzalkonium chloride.
abstract: OBJECTIVE
  To assess the antibacterial activity and cytotoxicity of an orthodontic bonding material containing an antibacterial agent.
  
  
  METHODS
  Superbond C&B (4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane [4-META/MMA-TBB]) resin was mixed with benzalkonium chloride (BAC) to obtain final BAC concentrations of 0.25%, 0.75%, 1.25%, 1.75%, 2.5%, and 5.0% (wt/ wt). Antibacterial activity against Streptococcus mutans and Streptococcus sobrinus was evaluated by soaking the BAC-resin in distilled water at 37 degrees C for periods of 30, 90, and 180 days. Antibacterial activity of the BAC-resin was measured by the disk diffusion method, and the inhibition zone around each sample was measured and recorded. For evaluation of cytotoxicity, BAC-resin samples were put into cell culture inserts placed above human gingival cells and were incubated at 37 degrees C for 1, 3, and 6 days. Cytotoxicity was assessed with a tetrazolium bromide reduction assay.
  
  
  RESULTS
  The antibacterial activity of BAC-incorporated resin samples decreased significantly after immersion in water for 180 days, regardless of BAC concentration. The antibacterial activity of nonimmersed resin containing 0.25% or 1.75% BAC was comparable with that of 5.0% BAC-resin immersed for 180 days. In cytotoxicity tests, most cells died when exposed to resins containing 1.75%, 2.5%, and 5% BAC. No difference was observed between resins containing 0.25% and 0.75% BAC at 1, 3, and 6 days of culture.
  
  
  CONCLUSIONS
  The addition of BAC to 4-META/MMA-TBB resin confers an antibacterial effect even after immersion in water, and 4-META/MMA-TBB resin containing 0.25% to 0.75% BAC has no significant cytotoxic effect.
authors.affiliation: Department of Orthodontics, Nihon University School of Dentistry, Japan. saito.kayo@nihon-u.ac.jp
authors.forename: Kayo
authors.initials: K
authors.lastname: Saito
authors.forename: Tohru
authors.initials: T
authors.lastname: Hayakawa
authors.forename: Rihito
authors.initials: R
authors.lastname: Kawabata
authors.forename: Daijiro
authors.initials: D
authors.lastname: Meguro
authors.forename: Kazutaka
authors.initials: K
authors.lastname: Kasai
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001548:Benzalkonium Compounds / Q000494:pharmacology*; D001896:Boron Compounds / Q000494:pharmacology; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D004396:Coloring Agents; D003603:Cytotoxins / Q000494:pharmacology*; D001840:Dental Bonding; D005347:Fibroblasts / Q000187:drug effects; D005881:Gingiva / Q000166:cytology / Q000187:drug effects; D006801:Humans; D008422:Materials Testing; D008689:Methacrylates / Q000494:pharmacology; D008768:Methylmethacrylates / Q000494:pharmacology; D016910:Orthodontic Brackets; D019279:Resin Cements / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects; D016986:Streptococcus sobrinus / Q000187:drug effects; D013696:Temperature; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D001548:Benzalkonium Compounds; D001896:Boron Compounds; D004396:Coloring Agents; D003603:Cytotoxins; D008689:Methacrylates; D008768:Methylmethacrylates; D019279:Resin Cements; D013778:Tetrazolium Salts; D013844:Thiazoles; D014867:Water; C049495:Super-bond; C022616:thiazolyl blue