title: Blue light kills Aggregatibacter actinomycetemcomitans due to its endogenous photosensitizers.
abstract: OBJECTIVE
  The aim of this study was to demonstrate that the periodontal pathogen Aggregatibacter actinomycetemcomitans (AA) can be killed by irradiation with blue light derived from a LED light-curing unit due to its endogenous photosensitizers.
  
  
  METHODS
  Planktonic cultures of AA and Escherichia coli were irradiated with blue light from a bluephase® C8 light-curing unit with an emission peak at 460 nm, which is usually applied for polymerization of dental resins. A CFU-assay was performed for the analysis of viable bacteria after treatment. Moreover, bacterial cells were lysed and the lysed AA and E. coli were investigated for generation of singlet oxygen. Spectroscopic measurements of lysed AA and E. coli were performed and analyzed for characteristic absorption and emission peaks.
  
  
  RESULTS
  A light dose of 150 J/cm(2) induced a reduction of ≥5 log10 steps of viable AA, whereas no effect of blue light was found against E. coli. Spectrally resolved measurements of singlet oxygen luminescence showed clearly that a singlet oxygen signal is generated from lysed AA upon excitation at 460 nm. Spectroscopic measurements of lysed AA exhibited characteristic absorption and emission peaks similar to those of known porphyrins and flavins.
  
  
  CONCLUSIONS
  AA can be inactivated by irradiation with blue light only, without application of an exogenous photosensitizer.
  
  
  CONCLUSIONS
  These results encourage further studies on the potential use of these blue light-mediated auto-photosensitization processes in the treatment of periodontitis for the successful inactivation of Aggregatibacter actinomycetemcomitans.
authors.affiliation: Department of Operative Dentistry and Periodontology, University Medical Center Regensburg, Franz-Josef-Strauß-Allee 11, 93053, Regensburg, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Cieplik
authors.forename: Andreas
authors.initials: A
authors.lastname: Späth
authors.forename: Christoph
authors.initials: C
authors.lastname: Leibl
authors.forename: Anita
authors.initials: A
authors.lastname: Gollmer
authors.forename: Johannes
authors.initials: J
authors.lastname: Regensburger
authors.forename: Laura
authors.initials: L
authors.lastname: Tabenski
authors.forename: Karl-Anton
authors.initials: KA
authors.lastname: Hiller
authors.forename: Tim
authors.initials: T
authors.lastname: Maisch
authors.forename: Gottfried
authors.initials: G
authors.lastname: Schmalz
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000528:radiation effects*; D055117:Curing Lights, Dental; D004926:Escherichia coli / Q000528:radiation effects; D006801:Humans; D008027:Light; D010510:Periodontal Diseases / Q000382:microbiology; D026082:Singlet Oxygen; D013050:Spectrometry, Fluorescence
chemical_list: D026082:Singlet Oxygen