title: A method to study sustained antimicrobial activity of rinse and dentifrice components on biofilm viability in vivo.
abstract: OBJECTIVE
  To develop an improved method for quantitative assessment of antimicrobial efficacy and substantivity of mouth rinses and dentifrices on in vivo treated plaque.
  
  
  METHODS
  Nine- and 72-h-old plaques were formed in volunteers carrying out standardized hygiene using NaF-containing dentifrice. Plaques were collected before (baseline) in vivo treatment with dentifrices or chlorhexidine mouth rinse, immediately post-treatment and after 1 or 6 h, dispersed in demineralized water and stained with live/dead stain after which bacteria were enumerated. Dispersed baseline plaques were treated with dentifrices or chlorhexidine to determine antimicrobial efficacy against planktonic bacteria.
  
  
  RESULTS
  Baseline plaques revealed 56-41% viable organisms in 9- and 72-h-old plaques, respectively. Treatment of planktonic (dispersed baseline plaque) bacteria resulted in 1-4% viable organisms. Chlorhexidine mouth rinse and dentifrices produced strong immediate antimicrobial effects, but after 1 or 6 h, the proportion of viable organisms in 9-h-old plaques rebounded significantly with only chlorhexidine mouth rinse retaining significant efficacy. Seventy-two-hour-old plaques were less susceptible to antimicrobials, although dentifrices appeared more effective after 6 h than initially, whereas efficacy of chlorhexidine rinse continued to drop with time post-treatment.
  
  
  CONCLUSIONS
  The proposed method holds promise for assessment of both immediate and retained antimicrobial actions of oral treatments against dental plaque in vivo.
authors.affiliation: Department of Biomedical Engineering, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands. h.c.van.der.mei@med.umcg.nl
authors.forename: H C
authors.initials: HC
authors.lastname: van der Mei
authors.forename: D J
authors.initials: DJ
authors.lastname: White
authors.forename: J
authors.initials: J
authors.lastname: Atema-Smit
authors.forename: E
authors.initials: E
authors.lastname: van de Belt-Gritter
authors.forename: H J
authors.initials: HJ
authors.lastname: Busscher
mesh_terms: D000891:Anti-Infective Agents, Local / Q000494:pharmacology* / Q000627:therapeutic use; D018441:Biofilms / Q000187:drug effects*; D002710:Chlorhexidine / Q000494:pharmacology* / Q000627:therapeutic use; D003773:Dental Plaque / Q000382:microbiology / Q000517:prevention & control*; D003802:Dentifrices / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D050296:Microbial Viability / Q000187:drug effects*; D018613:Microscopy, Confocal; D009067:Mouthwashes / Q000494:pharmacology* / Q000627:therapeutic use; D017063:Outcome Assessment, Health Care / Q000379:methods; D012107:Research Design; D014002:Tin Fluorides / Q000494:pharmacology* / Q000627:therapeutic use
chemical_list: D000891:Anti-Infective Agents, Local; D003802:Dentifrices; D009067:Mouthwashes; D014002:Tin Fluorides; D002710:Chlorhexidine