title: In vitro activity of photoactivated disinfection using a diode laser in infected root canals.
abstract: OBJECTIVE
  To investigate the lethal activity of photoactivated disinfection (PAD) on Enterococcus faecalis (ATCC 29212) and mixed populations of aerobic or anaerobic bacteria in infected root canals using a diode laser after the application of a photosensitizer (PS).
  
  
  METHODS
  First, the bactericidal activity of a low power diode laser (200 mW) against E. faecalis ATCC 29212 pre-treated with a PS (toluidine blue) for 2 min were examined after different irradiation times (30 s, 60 s and 90 s). The bactericidal activity in the presence of human serum or human serum albumin (HSA) was also examined. Second, root canals were infected with E. faecalis or with mixed aerobic or anaerobic microbial populations for 3 days and then irrigated with 1.5% sodium hypochlorite and exposed to PAD for 60 s.
  
  
  RESULTS
  Photosensitization followed by laser irradiation for 60 s was sufficient to kill E. faecalis. Bacteria suspended in human serum (25% v/v) were totally eradicated after 30 s of irradiation. The addition of HSA (25 mg/ml or 50 mg/ml) to bacterial suspensions increased the antimicrobial efficacy of PAD after an irradiation time of 30 s, but no longer. The bactericidal effect of sodium hypochlorite was only enhanced by PAD during the early stages of treatment. PAD did not enhance the activity of sodium hypochlorite against a mixture of anaerobic bacteria.
  
  
  CONCLUSIONS
  The bactericidal activity of PAD appears to be enhanced by serum proteins in vitro, but is limited to bacteria present within the root canal.
authors.affiliation: Center for Oral and Dental Medicine, Department of Restorative and Preventive Dentistry, University Center Hamburg-Eppendorf , Hamburg , Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schiffner
authors.forename: Georg
authors.initials: G
authors.lastname: Cachovan
authors.forename: Jochen
authors.initials: J
authors.lastname: Bastian
authors.forename: Anton
authors.initials: A
authors.lastname: Sculean
authors.forename: Sigrun
authors.initials: S
authors.lastname: Eick
mesh_terms: D039903:Actinobacteria / Q000187:drug effects; D000190:Actinomyces / Q000187:drug effects; D016470:Bacteremia / Q000188:drug therapy; D058491:Bacterial Load / Q000187:drug effects; D001644:Bifidobacterium / Q000187:drug effects; D001770:Blood Bactericidal Activity; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000382:microbiology*; D004203:Disinfection / Q000379:methods*; D013293:Enterococcus faecalis / Q000187:drug effects*; D006801:Humans; D054023:Lasers, Semiconductor / Q000627:therapeutic use*; D028022:Low-Level Light Therapy / Q000295:instrumentation; D008422:Materials Testing; D010462:Peptostreptococcus / Q000187:drug effects; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D012388:Root Canal Irrigants / Q000627:therapeutic use; D012709:Serum Albumin / Q000494:pharmacology; D020592:Shewanella / Q000187:drug effects; D012973:Sodium Hypochlorite / Q000627:therapeutic use; D013997:Time Factors; D014048:Tolonium Chloride / Q000627:therapeutic use
chemical_list: D017319:Photosensitizing Agents; D012388:Root Canal Irrigants; D012709:Serum Albumin; D014048:Tolonium Chloride; D012973:Sodium Hypochlorite
keywords: Enterococcus faecalis; diode laser; human serum albumin; photoactivated disinfection; root canal infection