title: Improvement of Antibacterial Efficacy Through Synergistic Effect in Photodynamic Therapy Based on Thiazinium Chromophores Against Planktonic and Biofilm-Associated Periodontopathogens.
abstract: OBJECTIVE
  Aim of the study was to improve the antibacterial efficacy of toluidine blue (TBO)/methylene blue (MB)-mediated photodynamic systems with light-emitting diode (LED) or laser irradiation administered to planktonic and biofilm-associated periodontopathogens.
  
  
  BACKGROUND
  Antibacterial photodynamic therapy (PDT) is a common, noninvasive adjunctive clinical method to inactivate microorganisms. So far, the disadvantage of this method has been its limited effectiveness in eliminating pathogens.
  
  
  METHODS
  An anaerobic cocktail consisting of six representative periodontal pathogens was prepared as initial culture for planktonic samples and biofilms grown on human tooth slides. Both types of microbial samples were exposed to three commercial photodynamic systems (PDT1: TBO, 630 nm LED, PDT2: TBO, 635 nm laser, PDT3: MB, 665 nm laser) in conventional and a new modified approach (PDTplus) based on the use of an oxygen supplement (photosensitizer+hydrogen peroxide). The microbial viability was characterized by bacterial growth [colony forming units (CFU)], total bacterial cell counts, and microbial vitality. Statistical data analysis was performed using 95% confidence intervals (ANOVA) and post hoc Tukey's test (p < 0.05).
  
  
  RESULTS
  The modified PDTplusshowed the highest statistically significant synergistic antimicrobial activity for TBO-based systems evidenced by a CFU reduction of 9 log10units to 0 for planktonic pathogens and a 4 log10CFU reduction for biofilm bacteria. The MB-based PDTpluswas superior mainly against biofilm pathogens. By comparison, the default TBO-based PDT achieved colony growth reductions of 2 and 1 log10units concerning planktonic and biofilm cells.
  
  
  CONCLUSIONS
  Compared to conventional PDT, PDTplusshowed superior antibacterial efficacy based on its synergistic effect, promising vast application possibilities.
authors.affiliation: Department of Conservative Dentistry and Periodontology, Center of Dentistry, Oral Medicine, and Maxillofacial Surgery, University Hospital , Tübingen, Germany .
authors.forename: Eva-Maria
authors.initials: EM
authors.lastname: Decker
authors.affiliation: Department of Conservative Dentistry and Periodontology, Center of Dentistry, Oral Medicine, and Maxillofacial Surgery, University Hospital , Tübingen, Germany .
authors.forename: Valentin
authors.initials: V
authors.lastname: Bartha
authors.affiliation: Department of Conservative Dentistry and Periodontology, Center of Dentistry, Oral Medicine, and Maxillofacial Surgery, University Hospital , Tübingen, Germany .
authors.forename: Christiane
authors.initials: C
authors.lastname: von Ohle
mesh_terms: D000704:Analysis of Variance; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects* / Q000528:radiation effects; D015169:Colony Count, Microbial; D016001:Confidence Intervals; D004357:Drug Synergism; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000528:radiation effects; D006801:Humans; D066298:In Vitro Techniques; D008751:Methylene Blue / Q000494:pharmacology*; D050296:Microbial Viability; D010519:Periodontium / Q000382:microbiology; D010778:Photochemotherapy / Q000379:methods*; D010933:Plankton / Q000187:drug effects* / Q000528:radiation effects; D012016:Reference Values; D014048:Tolonium Chloride / Q000494:pharmacology*; D014081:Tooth Extraction
chemical_list: D000900:Anti-Bacterial Agents; D014048:Tolonium Chloride; D008751:Methylene Blue
keywords: PDT; modified PDT; periodontal pathogens