title: Evaluation of Nd:YAG and Er:YAG irradiation, antibacterial photodynamic therapy and sodium hypochlorite treatment on Enterococcus faecalis biofilms.
abstract: OBJECTIVE
  To compare the antimicrobial efficacy of two-high power lasers (Nd:YAG and Er:YAG) and two commercial antimicrobial photodynamic therapy (aPDT) systems with that of sodium hypochlorite (NaOCl) action on Enterococcus faecalis biofilms grown on dentine discs.
  
  
  METHODS
  Enterococcus faecalis biofilms were grown on dentine discs in a microtiter plate, incubated for 24 h and subjected to the following treatments: aPDT (Denfotex and Helbo system), Er:YAG laser irradiation (2940 nm, 50 mJ or 100 mJ, 15 Hz, 40 s), Nd:YAG laser irradiation (1064 nm, 2 W, 15 Hz, 40 s) and immersion in 2.5% (w/v) NaOCl for 1, 5, 10 and 30 min. Surviving bacteria were harvested, and the number of CFU per disc was determined by plate counting.
  
  
  RESULTS
  Significant reductions (anova, P ≤ 0.05) in viable counts were observed for aPDT (Helbo) (2 log(10) reduction), Er:YAG irradiation using 100 mJ pulses (4.3 log(10) reduction) and all NaOCl treatments (>6 log(10) reduction). NaOCl (2.5%) for 5 min effectively eliminated all bacteria. aPDT (Denfotex), Er:YAG irradiation using 50 mJ pulses and Nd:YAG treatment caused a reduction in the viable counts of <1 log(10) unit; these results were not significantly different from the untreated controls.
  
  
  CONCLUSIONS
  Within the limitations of this particular laboratory set-up, NaOCl was the most effective in E. faecalis biofilm elimination, while Er:YAG laser treatment (100 mJ pulses) also resulted in high reductions in viable counts. The use of both commercial aPDT systems resulted in a weak reduction in the number of E. faecalis cells. Nd:YAG irradiation was the least effective.
authors.affiliation: Department of Operative Dentistry and Endodontology, Dental School, Ghent University, Gent, Belgium.
authors.forename: M A
authors.initials: MA
authors.lastname: Meire
authors.forename: T
authors.initials: T
authors.lastname: Coenye
authors.forename: H J
authors.initials: HJ
authors.lastname: Nelis
authors.forename: R J G
authors.initials: RJ
authors.lastname: De Moor
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001422:Bacterial Adhesion / Q000187:drug effects / Q000528:radiation effects; D058491:Bacterial Load / Q000187:drug effects / Q000528:radiation effects; D001431:Bacteriological Techniques; D018441:Biofilms / Q000187:drug effects* / Q000528:radiation effects; D018533:Biomass; D003131:Combined Modality Therapy; D003804:Dentin / Q000382:microbiology; D013293:Enterococcus faecalis / Q000187:drug effects* / Q000528:radiation effects; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D028022:Low-Level Light Therapy / Q000379:methods*; D008422:Materials Testing; D050296:Microbial Viability / Q000187:drug effects / Q000528:radiation effects; D008855:Microscopy, Electron, Scanning; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology; D011829:Radiation Dosage; D012388:Root Canal Irrigants / Q000494:pharmacology*; D012973:Sodium Hypochlorite / Q000494:pharmacology*; D013997:Time Factors; D014048:Tolonium Chloride / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D017319:Photosensitizing Agents; D012388:Root Canal Irrigants; D014048:Tolonium Chloride; D012973:Sodium Hypochlorite