Photodynamic Therapy in Planktonic and Biofilm Cultures of Aggregatibacter actinomycetemcomitans

Abstract Objective: To evaluate the inactivation of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), responsible for causing aggressive periodontitis, using photodynamic therapy (PDT) by rose bengal (RB) as a model of a reactive oxygen species (ROS) generator, in planktonic and biofilm cultures. Materials and Methods: A. actinomycetemcomitans was grown in planktonic and biofilm cultures using tryptic soy broth medium. The sensibility (dark toxicity) to RB was determined, and its ideal concentration for PDT was established. Concentrations in the range from 0.01 to 50.0 μmol L−1 RB, with different light potencies and incubation times, were used. An odontological resin photopolymerizer that emits the adequate wavelength for absorption of the RB dye was applied. Bacterial viability was determined by colony- forming units (CFU). Results: RB photosensitizer dye in concentrations up to 0.1 μmol L−1 did not show toxicity per se toward A. actinomycetemcomitans cells. In a PDT study with photoirrad...