title: Eradication of Enterococcus faecalis biofilms by cetrimide and chlorhexidine.
abstract: BACKGROUND
  Enterococcus faecalis is the most commonly isolated bacteria from root canals of teeth with persistent periapical periodontitis. Its ability to grow as a biofilm impedes the elimination of E. faecalis by using irrigating solutions. The purpose of this study was to assess the efficacy of cetrimide and chlorhexidine (CHX), alone and in association, in combined and alternating form, in eradicating biofilms of E. faecalis.
  
  
  METHODS
  Biofilms grown in the MBEC-high-throughput device for 24 hours were exposed to irrigating solutions for 30 seconds and 1 and 2 minutes. Eradication was defined as 100% kill of biofilm bacteria. The Student t test was used to compare the efficacy of the associations of the 2 irrigants.
  
  
  RESULTS
  Cetrimide eradicated E. faecalis biofilms at concentrations of 0.5%, 0.0312%, and 0.0078% at 30 seconds and 1 and 2 minutes of contact time, respectively. CHX did not eradicate the biofilms at any of the concentrations (4% initial concentration) or times assayed. The association of 0.1% and 0.05% cetrimide with any concentration of CHX, whether in combined or alternating application, effectively eradicated E. faecalis biofilms at all the contact times tested. Eradication was also achieved with 0.02% and 0.01% cetrimide at 2 minutes. Statistical analysis revealed significantly better results with alternating rather than combined use of cetrimide and CHX (P < .05).
  
  
  CONCLUSIONS
  The associated use of cetrimide and CHX provided better results than their applications as single agents against E. faecalis biofilms, and the alternating application was significantly more effective than the combined mode of application.
authors.affiliation: Department of Microbiology, School of Dentistry, University of Granada, Granada, Spain. mtarias@correo.ugr.es
authors.forename: María Teresa
authors.initials: MT
authors.lastname: Arias-Moliz
authors.forename: Carmen María
authors.initials: CM
authors.lastname: Ferrer-Luque
authors.forename: María Paloma
authors.initials: MP
authors.lastname: González-Rodríguez
authors.forename: Mariano José
authors.initials: MJ
authors.lastname: Valderrama
authors.forename: Pilar
authors.initials: P
authors.lastname: Baca
mesh_terms: D000891:Anti-Infective Agents, Local / Q000008:administration & dosage / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D002710:Chlorhexidine / Q000008:administration & dosage / Q000494:pharmacology*; D015169:Colony Count, Microbial; D004338:Drug Combinations; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000502:physiology; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D012388:Root Canal Irrigants / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D000891:Anti-Infective Agents, Local; D002593:Cetrimonium Compounds; D004338:Drug Combinations; D012388:Root Canal Irrigants; D002710:Chlorhexidine; D000077286:Cetrimonium