title: Application of laser scanning microscopy for the analysis of oral biofilm dissolution by different endodontic irrigants.
abstract: BACKGROUND
  Multi-specie biofilms are highly resistant to antimicrobials due to cellular interactions found in them. The purpose of this study was to evaluate, by confocal laser scanning microscopy, the biofilm dissolution effectiveness of different irrigant solutions on biofilms developed on infected dentin in situ.
  
  
  METHODS
  A total of 120 bovine dentin specimens infected intraorally (30/group) were treated by the following solutions: 2% of chlorhexidine digluconate, 1%, 2.5% and 5.25% of sodium hypochlorite (NaOCl). The solutions were utilized for 5, 15 and 30 min with 2 experimental volumes 500 μL and 1 mL. All the samples were stained using an acridine orange and the biofilm thickness before (control group) and after the experiments were evaluated, utilizing a confocal microscope at ×40. The Mann-Whitney U and the nom-parametric Kruskal-Wallis Dunns tests were utilized to determine the influence of the volume and to perform the comparisons among the groups respectively. The significance level was set at P < 0.05.
  
  
  RESULTS
  Statistical differences were not found among the control and the 2% chlorhexidine digluconate groups at any experimental period (P > 0.05). The biofilm dissolution treated with 1% NaOCl was directly proportional to the exposure time (P < 0.05). The higher values of biofilm dissolution were found in 2.5% and 5.25% NaOCl groups (P > 0.05).
  
  
  CONCLUSIONS
  The higher exposure times and concentrations of NaOCl were not sufficient to dissolve 100% of the biofilm. However, all NaOCl solutions were more effective than 2% chlorhexidine digluconate to dissolve organic matter.
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Aldo
authors.initials: A
authors.lastname: Del Carpio-Perochena
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Clovis Monteiro
authors.initials: CM
authors.lastname: Bramante
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Marco Antonio
authors.initials: MA
authors.lastname: Hungaro Duarte
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Flaviana Bombarda
authors.initials: FB
authors.lastname: de Andrade
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Bruno Cavalini
authors.initials: BC
authors.lastname: Cavenago
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Marcelo Haas
authors.initials: MH
authors.lastname: Villas-Bôas
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Ronald
authors.initials: R
authors.lastname: Ordinola-Zapata
authors.affiliation: Department of Dentistry, Endodontics and Dental Materials, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.
authors.forename: Pablo
authors.initials: P
authors.lastname: Amoroso-Silva
keywords: Biofilm; chlorhexidine; confocal laser scanning microscopy; dentin; sodium hypochlorite