title: Antimicrobial photodynamic therapy: a promise candidate for caries lesions treatment.
abstract: BACKGROUND
  Antibacterial photodynamic therapy (aPDT) is a promising adjunctive therapy to the treatment of caries lesions, mainly in the minimally invasive approach to preserve dental tissue and favor its repair. Here we analyzed both the efficacy of aPDT in reducing the bacterial load in cariogenic biofilms and the indirect effect of noxious components produced by aPDT on the viability of dental pulp cells.
  
  
  METHODS
  The aPDT protocol was established using 0.025g/mL methylene blue (MB) and 5min pre-irradiation time. A continuous-wave diode laser (660nm, 0.04cm(2) spot size, 40mW, 60s, 60J/cm(2) and 2.4J) was used in punctual and distance modes to excite the MB. The protocol was first tested against Streptococcus mutans (U159) biofilms produced in 96-well microplates, and then evaluated on caries-like affected human dentin discs of three thicknesses. The number of colony forming units (CFU) was compared between groups. Discs were then assembled in metallic inserts to produce an artificial pulp chamber and allow investigation of the indirect effects of aPDT on dental pulp cells by the 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT) assay. Data were analyzed using Student's t test or one-way analysis of variance (ANOVA) followed by the Tukey's test at a significance level of 5%.
  
  
  RESULTS
  Bacterial load reduction was observed in biofilms produced both in the microplates (p<0.05) and on the caries-like affected dentin discs (81.01% or mean reduction of log21.010±0.1548; p=0.0029). The cell viability of aPDT and control group was similar (p>0.05).
  
  
  CONCLUSIONS
  aPDT may be considered a promise adjunctive therapy for deep carious lesions.
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Sao Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo 05508-000, SP, Brazil. Electronic address: ivanadiniz@usp.br.
authors.forename: Ivana Márcia Alves
authors.initials: IM
authors.lastname: Diniz
authors.affiliation: School of Engineering, Federal University of Minas Gerais (UFMG), Av. Antônio Carlos, 6627, Belo Horizonte 31270-901, MG, Brazil. Electronic address: ivaydinizhorta@gmail.com.
authors.forename: Ivay Diniz
authors.initials: ID
authors.lastname: Horta
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Sao Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo 05508-000, SP, Brazil. Electronic address: cynthiaazevedo@hotmail.com.
authors.forename: Cynthia Soares
authors.initials: CS
authors.lastname: Azevedo
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Sao Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo 05508-000, SP, Brazil. Electronic address: thais.elmadjian@usp.br.
authors.forename: Thaís Regina
authors.initials: TR
authors.lastname: Elmadjian
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Sao Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo 05508-000, SP, Brazil. Electronic address: bona@usp.br.
authors.forename: Adriana Bona
authors.initials: AB
authors.lastname: Matos
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences (ICB), University of Sao Paulo, Av. Prof. Lineu Prestes, 2415, São Paulo 05508-000, SP, Brazil. Electronic address: mrsimion27@gmail.com.
authors.forename: Maria Regina Lorenzetti
authors.initials: MR
authors.lastname: Simionato
authors.affiliation: Department of Restorative Dentistry, School of Dentistry, University of Sao Paulo, Av. Prof. Lineu Prestes, 2227, São Paulo 05508-000, SP, Brazil. Electronic address: mmmarques@usp.br.
authors.forename: Márcia Martins
authors.initials: MM
authors.lastname: Marques
mesh_terms: D058491:Bacterial Load / Q000187:drug effects; D018441:Biofilms / Q000187:drug effects*; D002470:Cell Survival; D003731:Dental Caries / Q000188:drug therapy*; D003786:Dental Pulp Cavity / Q000187:drug effects; D006801:Humans; D008751:Methylene Blue / Q000494:pharmacology*; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000494:pharmacology*; D013295:Streptococcus mutans / Q000187:drug effects*
chemical_list: D017319:Photosensitizing Agents; D008751:Methylene Blue
keywords: Antimicrobial photodynamic therapy; Dental caries; Dentin/pathology; Diode lasers; Methylene blue