title: Bactericidal effects of a high-power, red light-emitting diode on two periodontopathic bacteria in antimicrobial photodynamic therapy in vitro.
abstract: OBJECTIVE
  Light-emitting diodes have been investigated as new light activators for photodynamic therapy. We investigated the bactericidal effects of high-power, red light-emitting diodes on two periodontopathic bacteria in vitro.
  
  
  METHODS
  A light-emitting diode (intensity: 1100 mW/cm(2) , peak wavelength: 650 nm) was used to irradiate a bacterial solution for either 10 or 20 s. Bacterial solutions (Porphyromonas gingivalis or Aggregatibacter actinomycetemcomitans) at a concentration of 2.5 × 10(6) c.f.u./mL were mixed with an equal volume of either methylene blue or toluidine blue O (0-20 μg/mL) and added to titer plate wells. The plate wells were irradiated with red light-emitting diode light from a distance of 22 or 40 mm. The contents were diluted, and 50 μL was smeared onto blood agar plates. After 1 week of culturing, bacterial c.f.u. were counted.
  
  
  RESULTS
  The light-emitting diode energy density was estimated to be approximately 4 and 8 J/cm(2) after 10 and 20 s of irradiation, respectively. Red light-emitting diode irradiation for 10 s from a distance of 22 mm, combined with methylene blue at concentrations >10 μg/mL, completely killed Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans.
  
  
  CONCLUSIONS
  High-power, red light-emitting diode irradiation with a low concentration of dye showed effective bactericidal effects against two periodontopathic bacteria.
authors.affiliation: Department of Hard Tissue Engineering, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan Division of Oral and Maxillo Facial Surgery, National Center for Global Health and Medicine, Tokyo, Japan Department of Research and Development, J. Morita Manufacturing Corporation, Kyoto, Japan Department of Pharmacy, Tokyo Medical and Dental University Hospital, Faculty of Dentistry, Tokyo, Japan International Research Center for Molecular Science in Tooth and Bone Diseases, Tokyo Medical and Dental University, Tokyo, Japan Institute of Advanced Biomedical Engineering and Science, Tokyo Women's Medical University, Tokyo, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Umeda
authors.forename: Akiko
authors.initials: A
authors.lastname: Tsuno
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Okagami
authors.forename: Fumito
authors.initials: F
authors.lastname: Tsuchiya
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Izumi
authors.forename: Isao
authors.initials: I
authors.lastname: Ishikawa
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects* / Q000528:radiation effects; D058491:Bacterial Load / Q000187:drug effects / Q000528:radiation effects; D001431:Bacteriological Techniques; D004203:Disinfection / Q000295:instrumentation*; D006801:Humans; D008029:Lighting / Q000295:instrumentation*; D008751:Methylene Blue / Q000494:pharmacology; D010778:Photochemotherapy / Q000295:instrumentation*; D017319:Photosensitizing Agents / Q000494:pharmacology; D016966:Porphyromonas gingivalis / Q000187:drug effects* / Q000528:radiation effects; D011829:Radiation Dosage; D013997:Time Factors; D014048:Tolonium Chloride / Q000494:pharmacology
chemical_list: D017319:Photosensitizing Agents; D014048:Tolonium Chloride; D008751:Methylene Blue
keywords: antimicrobial photodynamic therapy; methylene blue; periodontopathic bacteria; red light-emitting diode; toluidine blue O