title: Activity of amine oxide against biofilms of Streptococcus mutans: a potential biocide for oral care formulations.
abstract: OBJECTIVE
  To assess the potential bactericidal activity of amine oxide (C10-C16-alkyldimethyl N-oxides) against Streptococcus mutans grown as planktonic suspension and as biofilm on hydroxyapatite discs, and its ability to control acidification of the media.
  
  
  METHODS
  Amine oxide bacteriostasis was investigated using the Bioscreen C Microbiological Growth Analyser, while a standard suspension test was used to determine its bactericidal efficacy. In addition, the lethal activity of amine oxide was studied against sedimentation biofilms of S. mutans on hydroxyapatite (HA) discs and resuspended biofilms. Several parameters were considered such as the surfactant concentration, pH, the starting inoculum and the maturity of the biofilm.
  
  
  RESULTS
  Amine oxide was bacteriostatic against planktonic S. mutans at a low concentration (0.006% v/v) and highly bactericidal against S. mutans in suspension or in a mature biofilm on hydroxyapatite, although the concentration required to achieve the latter effect was four times higher. The activity of amine oxide against biofilms depended upon its concentration and the age of the biofilm. In addition, amine oxide pre-treatment of the HA discs did not affect the growth of the biofilm. Finally, amine oxide did not prevent the acidification of the medium, although lower pHs had a potentiating effect on amine oxide activity.
  
  
  CONCLUSIONS
  Amine oxide showed high potential for controlling early biofilms caused by periodontal bacteria. Further investigations should be carried out, particularly on the potential toxicity of amine oxide and its efficacy in complex formulations for oral care products.
authors.affiliation: School of Pharmacy and Biomolecular Sciences, Brighton University, Brighton BN2 4GJ, UK.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Fraud
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Maillard
authors.forename: Michael A
authors.initials: MA
authors.lastname: Kaminski
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Hanlon
mesh_terms: D000473:Alkanes / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D009910:Oral Hygiene; D010087:Oxides / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects* / Q000254:growth & development* / Q000502:physiology
chemical_list: D000473:Alkanes; D000900:Anti-Bacterial Agents; D010087:Oxides