title: Effect of endodontic irrigants on biofilm matrix polysaccharides.
abstract: OBJECTIVE
  To specifically investigate the effect of endodontic irrigants at their clinical concentration on matrix polysaccharides of cultured biofilms.
  
  
  METHODS
  Saccharolytic effects of 3% H2O2, 2% chlorhexidine (CHX), 17% EDTA, 5% NaOCl and 0.9% saline (control) were tested using agarose (α 1-3 and β 1-4 glycosidic bonds) blocks (n = 3) in a weight assay. The irrigants were also applied to three-species biofilms (Streptococcus mutans UAB 159, Streptococcus oralis OMZ 607 and Actinomyces oris OMZ 745) grown anaerobically on hydroxyapatite discs (n = 6). Glycoconjugates in the matrix and total bacterial cell volumes were determined using combined Concanavalin A-/Syto 59-staining and confocal laser-scanning microscopy. Volumes of each scanned area (triplicates/sample) were calculated using Imaris software. Data were compared between groups using one-way anova/Tukey HSD, α = 0.05.
  
  
  RESULTS
  The weight assay revealed that NaOCl was the only irrigant under investigation capable of dissolving the agarose blocks. NaOCl eradicated stainable matrix and bacteria in cultured biofilms after 1 min of exposure (P < 0.05 compared to all groups, volumes in means ± standard deviation, 10-3mm3per 0.6 mm2disc; NaOCl matrix: 0.10 ± 0.08, bacteria: 0.03 ± 0.06; saline control matrix: 4.01 ± 1.14, bacteria: 11.56 ± 3.02). EDTA also appeared to have some effect on the biofilm matrix (EDTA matrix: 1.90 ± 0.33, bacteria: 9.26 ± 2.21), whilst H2O2and CHX merely reduced bacterial cell volumes.
  
  
  CONCLUSIONS
  Sodium hypochlorite can break glycosidic bonds. It dissolves glycoconjugates in the biofilm matrix. It also lyses bacterial cells.
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: P N
authors.initials: PN
authors.lastname: Tawakoli
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: K T
authors.initials: KT
authors.lastname: Ragnarsson
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: D K
authors.initials: DK
authors.lastname: Rechenberg
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.|Department of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Zurich, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Mohn
authors.affiliation: Clinic for Preventive Dentistry, Periodontology and Cariology, Center for Dental Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Zehnder
mesh_terms: D018441:Biofilms / Q000187:drug effects*; D004708:Endodontics; D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite / Q000494:pharmacology
chemical_list: D012388:Root Canal Irrigants; D012973:Sodium Hypochlorite
keywords: NaOCl; biofilm; glycosidic bond; matrix