title: Effect of photoactivated disinfection with a light-emitting diode on bacterial species and biofilms associated with periodontitis and peri-implantitis.
abstract: BACKGROUND
  To determine the effect of photoactivated disinfection (PAD) using toluidine blue and a light-emitting diode (LED) in the red spectrum (wave length at 625-635 nm) on species associated with periodontitis and peri-implantitis and bacteria within a periodontopathic biofilm.
  
  
  METHODS
  Sixteen single microbial species including 2 Porphyromonas gingivalis and 2 Aggregatibacter actinomycetemcomitans and a multispecies mixture consisting of 12 species suspended in saline without and with 25% human serum were exposed to PAD. Moreover, single-species biofilms consisting of 2 P. gingivalis and 2 A. actinomycetemcomitans strains and a multi-species biofilm on 24-well-plates, grown on titanium discs and in artificial periodontal pockets were exposed to PAD with and without pretreatment with 0.25% hydrogen peroxide. Changes in the viability were determined by counting the colony forming units (cfu).
  
  
  RESULTS
  PAD reduced the cfu counts in saline by 1.42 log₁₀ after LED application for 30s and by 1.99 log₁₀ after LED application for 60s compared with negative controls (each p<0.001). Serum did not inhibit the efficacy of PAD. PAD reduced statistically significantly (p<0.05) the cfu counts of the P. gingivalis biofilms. The viability of the A. actinomycetemcomitans biofilms and the multi-species biofilms was statistically significantly decreased when PAD was applied after a pretreatment with 0.25% hydrogen peroxide. The biofilm formed in artificial pockets was more sensitive to PAD with and without pretreatment with hydrogen peroxide compared with those formed on titanium discs.
  
  
  CONCLUSIONS
  PAD using a LED was effective against periodontopathic bacterial species and reduced viability in biofilms but was not able to completely destroy complex biofilms. The use of PAD following pretreatment with hydrogen peroxide resulted in an additional increase in the antimicrobial activity which may represent a new alternative to treat periodontal and peri-implant infections thus warranting further testing in clinical studies.
authors.affiliation: Department of Periodontology, School of Dental Medicine, University of Bern, Freiburgstrasse 7, CH-3010 Bern, Switzerland. sigrun.eick@zmk.unibe.ch
authors.forename: Sigrun
authors.initials: S
authors.lastname: Eick
authors.forename: Giedre
authors.initials: G
authors.lastname: Markauskaite
authors.forename: Sandor
authors.initials: S
authors.lastname: Nietzsche
authors.forename: Oliver
authors.initials: O
authors.lastname: Laugisch
authors.forename: Giovanni E
authors.initials: GE
authors.lastname: Salvi
authors.forename: Anton
authors.initials: A
authors.lastname: Sculean
mesh_terms: D018407:Bacterial Physiological Phenomena / Q000187:drug effects* / Q000528:radiation effects*; D018441:Biofilms / Q000187:drug effects / Q000528:radiation effects; D002460:Cell Line; D004203:Disinfection / Q000379:methods; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D008029:Lighting / Q000295:instrumentation*; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D057873:Peri-Implantitis / Q000188:drug therapy / Q000382:microbiology*; D010518:Periodontitis / Q000188:drug therapy / Q000382:microbiology*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D012666:Semiconductors; D014048:Tolonium Chloride / Q000008:administration & dosage*
chemical_list: D017319:Photosensitizing Agents; D014048:Tolonium Chloride