In vitro antibacterial and cytotoxicity assessments of an orthodontic bonding agent containing benzalkonium chloride.
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.
Saito
Kayo
K
Department of Orthodontics, Nihon University School of Dentistry, Japan. saito.kayo@nihon-u.ac.jp
Hayakawa
Tohru
T
Kawabata
Rihito
R
Meguro
Daijiro
D
Kasai
Kazutaka
K
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
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