title: Effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilm in experimental primary and secondary endodontic infections.
abstract: BACKGROUND
  To determine the antibacterial effect of photodynamic Therapy on Enterococcus faecalis (E. faecalis) biofilms in experimentally infected human root canals in primary infections and endodontic retreatments.
  
  
  METHODS
  One hundred and sixty single-rooted extracted teeth with one root canal were prepared using ProTaper instruments. Seventy specimens were left without root canal filling and autoclaved. The root canals of another 70 specimens were filled with Thermafil and AH Plus and the root canal fillings were removed after 24 hours using ProTaper D files and plasma sterilized. The specimens were infected with a clinical isolate of E. faecalis for 72 hours. Samples were taken using sterile paper points to determine the presence of E. faecalis in the root canals. The specimens were randomly divided into groups according to their treatment with 20 teeth each and a control. In the PDT group the teeth were treated using PDT, consisting of the photosensitizer toluidine blue and the PDT light source at 635 nm. In the NaOCl (sodium hypochlorite) group the root canals were rinsed with 10 mL of 3% NaOCl. In the NaOCl-PDT group the root canals were rinsed with 10 mL of 3% of sodium hypochlorite and then treated with PDT. Samples were taken after treatments using sterile paper points. Additionally, remaining root canal filling material was recovered from the root canal walls. Survival fractions of the samples were calculated by counting colony-forming units. A one-way analysis of variance (ANOVA) was applied to the data to assess the effect of different treatment techniques.
  
  
  RESULTS
  Antimicrobial treatment of root canals caused a significant reduction of bacterial load in all groups. NaOCl irrigation eliminated E. faecalis most effectively. PDT alone was less effective compared to NaOCl irrigation and the combination of NaOCl irrigation and PDT. CFU levels recovered from the filling material after NaOCl irrigation of the root canals were 10fold higher compared to PDT and the combination of NaOCl irrigation and PDT.
  
  
  CONCLUSIONS
  Photodynamic therapy killed E. faecalis in experimental primary endodontic infections and retreated human root canals. PDT is an effective supplement in root canal disinfection, especially in endodontic retreatments.
authors.affiliation: Department of Operative Dentistry and Periodontology, University of Freiburg - Medical Center, Hugstetter Str, 55, 79106 Freiburg, Germany. Christian.tennert@uniklinik-freiburg.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Tennert
authors.forename: Katharina
authors.initials: K
authors.lastname: Feldmann
authors.forename: Edwina
authors.initials: E
authors.lastname: Haamann
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Ahmad
authors.forename: Marie
authors.initials: M
authors.lastname: Follo
authors.forename: Karl-Thomas
authors.initials: KT
authors.lastname: Wrbas
authors.forename: Elmar
authors.initials: E
authors.lastname: Hellwig
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Altenburger
mesh_terms: D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D003786:Dental Pulp Cavity / Q000382:microbiology*; D003804:Dentin / Q000382:microbiology; D004338:Drug Combinations; D013293:Enterococcus faecalis / Q000187:drug effects*; D004853:Epoxy Resins / Q000627:therapeutic use; D006171:Gutta-Percha / Q000627:therapeutic use; D006801:Humans; D050296:Microbial Viability / Q000187:drug effects; D008855:Microscopy, Electron, Scanning; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use; D019233:Retreatment; D012387:Root Canal Filling Materials / Q000627:therapeutic use; D012388:Root Canal Irrigants / Q000627:therapeutic use; D018915:Root Canal Preparation / Q000379:methods; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D014048:Tolonium Chloride / Q000627:therapeutic use
chemical_list: D004338:Drug Combinations; D004853:Epoxy Resins; D017319:Photosensitizing Agents; D012387:Root Canal Filling Materials; D012388:Root Canal Irrigants; C534916:epoxy resin-based root canal sealer; D014048:Tolonium Chloride; D006171:Gutta-Percha; D012973:Sodium Hypochlorite