Photodynamic action of the red laser on Propionibacterium acnes.

Background: Photodynamic therapy is a therapeutic modality that has consolidated its activity in the photooxidation of organic matter, which arises from the activity of reactive oxygen species.

Objective: To evaluate the effect of red laser 660nm with the photosensitizer methylene blue on Propionibacterium acnes in vitro.

Method: The experimental design was distributed into four groups (1 - control group without the application of light and without photosensitizer, 2 - application of light, 3 - methylene blue without light, and 4 - methylene blue with light).