title: Monitoring the effectiveness of photodynamic therapy with periodic renewal of the photosensitizer on intracanal Enterococcus faecalis biofilms.
abstract: OBJECTIVE
  Photodynamic therapy (PDT) can eliminate microorganisms in a root canal. However, the parameters for disinfection remain undefined. This study assessed the effectiveness of a PDT protocol against intracanal Enterococcus faecalis biofilms.
  
  
  METHODS
  Root canals were contaminated with E. faecalis for 21 days. The instrumentation was associated to irrigation with 0.85% saline or an alternate irrigation (AI) with 5.25% NaOCl and 17% EDTA. Complementary treatments included saline/PDT and AI/PDT. Four PDT cycles were performed using a diode laser (660nm, 40mW) delivered through a tapered optical fiber. In each cycle, the root canal was filled with 1.56μM/mL methylene blue and irradiated for 150s. Microbiological samples were collected before (S1) and after (S2) instrumentation; after PDT (S3); and daily over the course of 14 days (S4-S17). Colony-forming units (CFUs) were counted, positive cultures verified, and data subjected to parametric and proportion's tests.
  
  
  RESULTS
  The highest bacterial load reduction was observed in S2. In regard to S3, Saline/PDT reduced 1.3 log(10) CFU counts (p=0.000 for S2) and no CFUs were recovered after AI/PDT treatment. All canals were CFU-free on the 14th day for saline/PDT, AI and AI/PDT. Positive cultures were observed in 60% of saline-irrigated canals on the 14th day, whereas the saline/PDT, AI and AI/PDT treatments resulted in germ-free canals after 10, 5 and 2 days, respectively.
  
  
  CONCLUSIONS
  Our findings suggest immediate and delayed antibacterial effects using the PDT protocol tested.
authors.affiliation: Department of Dentistry, Federal University of the Jequitinhonha and Mucuri Valleys, Diamantina, Minas Gerais, Brazil. Electronic address: janirsoares@msn.com.
authors.forename: Janir Alves
authors.initials: JA
authors.lastname: Soares
authors.affiliation: Department of Dentistry, Federal University of the Jequitinhonha and Mucuri Valleys, Diamantina, Minas Gerais, Brazil.
authors.forename: Suelleng Maria Cunha
authors.initials: SMC
authors.lastname: Santos Soares
authors.affiliation: Department of Dentistry, Federal University of the Jequitinhonha and Mucuri Valleys, Diamantina, Minas Gerais, Brazil.
authors.forename: Carlos Augusto
authors.initials: CA
authors.lastname: Santos César
authors.affiliation: Department of Microbiology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Maria Auxiliadora Roque
authors.initials: MAR
authors.lastname: de Carvalho
authors.affiliation: Department of Dentistry, State University of Montes Claros, Montes Claros, Minas Gerais, Brazil.
authors.forename: Manoel
authors.initials: M
authors.lastname: Brito-Júnior
authors.affiliation: Faculty of Administrative Studies, FEAD, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Gerdal Roberto
authors.initials: GR
authors.lastname: de Sousa
authors.affiliation: Department of Microbiology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Betânia Maria
authors.initials: BM
authors.lastname: Soares
authors.affiliation: Department of Microbiology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Luiz
authors.initials: L
authors.lastname: de Macêdo Farias
mesh_terms: D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development*; D003786:Dental Pulp Cavity / Q000187:drug effects / Q000382:microbiology*; D004203:Disinfection / Q000379:methods; D004334:Drug Administration Schedule; D013293:Enterococcus faecalis / Q000187:drug effects*; D006801:Humans; D066298:In Vitro Techniques; D008751:Methylene Blue / Q000008:administration & dosage*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000008:administration & dosage; D012388:Root Canal Irrigants / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D017319:Photosensitizing Agents; D012388:Root Canal Irrigants; D008751:Methylene Blue
keywords: Chemomechanical preparation; Endodontic treatment; Enterococcus faecalis; Methylene blue; Photodynamic therapy