Journal Article

Susceptibility of <i>Streptococcus mutans</i> biofilms to photodynamic therapy: an <i>in vitro</i> study

Iriana Carla Junqueira Zanin, Reginaldo Bruno Gonçalves, Aldo Brugnera Junior, Christopher Keith Hope and Jonathan Pratten

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 56, issue 2, pages 324-330
Published in print August 2005 | ISSN: 0305-7453
Published online June 2005 | e-ISSN: 1460-2091 | DOI:
Susceptibility of Streptococcus mutans biofilms to photodynamic therapy: an in vitro study

More Like This

Show all results sharing these subjects:

  • Medical Oncology
  • Critical Care


Show Summary Details


Objectives: The purpose of this study was to evaluate the antimicrobial effect of toluidine blue O (TBO), in combination with either a helium/neon (HeNe) laser or a light-emitting diode (LED), on the viability and architecture of Streptococcus mutans biofilms.

Methods: Biofilms were grown on hydroxyapatite discs in a constant depth film fermentor fed with artificial saliva that was supplemented with 2% sucrose four times a day, thus producing a typical ‘Stephan pH curve’. Photodynamic therapy was subsequently carried out on biofilms of various ages with light from either the HeNe laser or LED using energy densities of between 49 and 294 J/cm2.

Results: Significant decreases in the viability of S. mutans biofilms were only observed when biofilms were exposed to both TBO and light, when reductions in viability of up to 99.99% were observed with both light sources. Overall, the results showed that the bactericidal effect was light dose-dependent and that older biofilms were less susceptible to photodynamic therapy. Confocal laser scanning microscopy images suggested that lethal photosensitization occurred predominantly in the outermost layers of the biofilms.

Conclusions: Photodynamic therapy may be a useful approach in the treatment of dental plaque-related diseases.

Keywords: dental plaque; caries; Stephan curve; light-emitting diode; biofilm structure

Journal Article.  3970 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.