title: Aggregatibacter actinomycetemcomitans biofilm can be inactivated by methylene blue-mediated photodynamic therapy.
abstract: BACKGROUND
  The purpose of this study was to evaluate the antibacterial effects of photodynamic action of methylene blue (MB) against Aggregatibacter actinomycetemcomitans organized on biofilm.
  
  
  METHODS
  After the biofilm growth in 96 flat-bottom well plate, the following groups were used: control group, untreated by either laser or photosensitizer (PS); MB group or dark toxicity group, which was exposed to MB alone (100μM) for 1min (pre-irradiation time); laser group, irradiated with laser for 5min in the absence of PS and three antimicrobial photodynamic inactivation (APDI) groups, with three exposure times of 1, 3 and 5min of irradiation, corresponding to fluences of 15, 45, and 75J/cm(2) respectively. The results were compared to the control group for statistical proposes. Scanning electronic microscope analysis was used to access structural changes in biofilm.
  
  
  RESULTS
  Red laser alone and MB alone were not able to inactivate bacterial biofilm. APDI groups showed differences when compared to the control group and they were dependent on the exposure time. No statistically significant differences were observed among the APDI groups at 1 and 3min of irradiation. On the other hand, 5min of APDI showed 99.85% of bacterial reduction (p=0.0004). In addition, the biofilm loose its structure following 5min APDI.
  
  
  CONCLUSIONS
  The results of this study suggest that A. actinomycetemcomitans biofilm can be inactivated by MB mediated APDI.
authors.affiliation: Dental Research Center, São Leopoldo Mandic, Campinas, Brazil.
authors.forename: Letícia Heineck
authors.initials: LH
authors.lastname: Alvarenga
authors.affiliation: Postgraduate Program in Biophotonics Applied to Health Sciences, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil; School of Dentistry, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil. Electronic address: pratesra@uninove.br.
authors.forename: Renato Araujo
authors.initials: RA
authors.lastname: Prates
authors.affiliation: Center for Lasers and Applications, Nuclear and Energy Research Institute IPEN-CNEN/SP, São Paulo, Brazil.
authors.forename: Tania Mateus
authors.initials: TM
authors.lastname: Yoshimura
authors.affiliation: Department of Biomedical Engineering, ABC Federal University (UFABC), Santo Andre, SP, Brazil.
authors.forename: Ilka Tiemy
authors.initials: IT
authors.lastname: Kato
authors.affiliation: Center for Lasers and Applications, Nuclear and Energy Research Institute IPEN-CNEN/SP, São Paulo, Brazil.
authors.forename: Luis Cláudio
authors.initials: LC
authors.lastname: Suzuki
authors.affiliation: Center for Lasers and Applications, Nuclear and Energy Research Institute IPEN-CNEN/SP, São Paulo, Brazil.
authors.forename: Martha Simões
authors.initials: MS
authors.lastname: Ribeiro
authors.affiliation: Postgraduate Program in Biophotonics Applied to Health Sciences, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil; School of Dentistry, Nove de Julho University (UNINOVE), São Paulo, SP, Brazil.
authors.forename: Luis Rodolfo
authors.initials: LR
authors.lastname: Ferreira
authors.affiliation: Dental Research Center, São Leopoldo Mandic, Campinas, Brazil.
authors.forename: Sílvio Antônio Dos Santos
authors.initials: SA
authors.lastname: Pereira
authors.affiliation: Dental Research Center, São Leopoldo Mandic, Campinas, Brazil.
authors.forename: Elizabeth Ferreira
authors.initials: EF
authors.lastname: Martinez
authors.affiliation: Dental Research Center, São Leopoldo Mandic, Campinas, Brazil.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Saba-Chujfi
mesh_terms: D016976:Aggregatibacter actinomycetemcomitans / Q000187:drug effects* / Q000502:physiology*; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development* / Q000528:radiation effects; D002470:Cell Survival / Q000187:drug effects / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D008027:Light; D008751:Methylene Blue / Q000008:administration & dosage*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use
chemical_list: D017319:Photosensitizing Agents; D008751:Methylene Blue
keywords: Antimicrobial photodynamic chemotherapy; Antimicrobial photodynamic inactivation; Periodontal disease; Periodontitis; Photosensitizer; Red laser