Killing of periodontopathogenic bacteria by photodynamic therapy

Background: The aim of this study was to evaluate a new approach for killing periodontopathogenic bacteria using photodynamic therapy (PDT). Methods: In this study, we investigated the photosensitizers chlorin e6, BLC 1010, and BLC 1014 by three different methods for their effect in PDT on the viability of periodontopathogenic bacterial species. The methods included examination of inhibition zones on agar plates, determination of colony-forming units (CFU), and the use of a bacterial viability kit. Results: Using the CFU method, we were able to demonstrate that the anaerobic bacteria Porphyromonas gingivalis, Fusobacterium nucleatum, and Capnocytophaga gingivalis can be photo-inactivated completely by illumination with an intensity of 5.3 J/cm(2) in the presence of 10 muM chlorin e6 and 10 muM BLC 1010. With the photosensitizers chlorin e6 and BLC 1010, we were able to induce zones of inhibition on agar plates. BLC 1014 failed to produce a zone of inhibition. The results of the bacterial viability test also showed that the photosensitizer BLC 1014 provides the lowest photodynamic effect in comparison to the others. Conclusion: The data collected to date suggest that photodynamic therapy with chlorin e6 and BLC 1010 is advantageous for suppressing periodontopathogenic bacteria.