title: Characterization of antimicrobial photodynamic therapy-treated Streptococci mutans: an atomic force microscopy study.
abstract: Abstract Objective: The aim of the present study was to examine the size and shape of Streptococcus mutans bacterial cells of infected dentin substrate subjected to photodynamic therapy (PDT) using atomic force microscopy (AFM).
  
  
  BACKGROUND
  New trends in the application of AFM have been developed in the field of dentistry, making AFM a useful technique in high resolution imaging of biological structures and processes.
  
  
  METHODS
  PDT was completed using an efficient light-emitting diode source (LED - λ=620-660 nm) with total light dose of 94 J/cm(2) in the presence of the photosensitizer toluidine blue O (TBO). Dentin specimens were immersed in brain heart infusion (BHI) broth inoculated with S. mutans for 5 days to induce caries in vitro. After demineralization, the samples were subjected to a series of treatments in which carious dentin infected by S. mutans was exposed to 0.9% sodium chlorite (NaCl) solution (control) for 10 min, or subjected to PDT-TBO photosensitizer followed by light exposure (energy density of 94 J/cm(2)).
  
  
  RESULTS
  Three-dimensional (3-D) images and cross-sectional measurements showed rod and diplococcic cell shapes. Photoinactivated bacterial cells did not differ from the control with respect to their cross-sectional shape, but they did show a reduction in size.
  
  
  CONCLUSIONS
  Photodynamic therapy decreased the diameter of S. mutans cells and AFM may be used as a technique for bacterial cell analysis.
authors: Post-graduation Program, Faculty of Pharmacy, Dentistry and Nursing, Federal University of Ceará, Fortaleza, Ceará, Brazil.
authors: Mary Anne Sampaio
authors: MA
authors: de Melo
authors: Juliana Paiva Marques Lima
authors: JP
authors: Rolim
authors: Iriana Carla Junqueira
authors: IC
authors: Zanin
authors: Eduardo Bede
authors: EB
authors: Barros
authors: Erivelton Façanha
authors: EF
authors: da-Costa
authors: Lidiany Karla Azevedo
authors: LK
authors: Rodrigues
mesh_terms: D003731:Dental Caries / Q000188:drug therapy* / Q000382:microbiology; D003804:Dentin / Q000187:drug effects / Q000382:microbiology*; D006801:Humans; D018625:Microscopy, Atomic Force; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000494:pharmacology; D013295:Streptococcus mutans / Q000187:drug effects*; D014048:Tolonium Chloride / Q000494:pharmacology
chemical_list: D017319:Photosensitizing Agents; D014048:Tolonium Chloride