Histomorphometric and Microbiological Assessment of Photodynamic Therapy as an Adjuvant Treatment for Periodontitis: A Short-Term Evaluation of Inflammatory Periodontal Conditions and Bacterial Reduction in a Rat Model

Objective: The aim of this study was to investigate the short-term effects of photodynamic therapy (PDT) in periodontal tissue when it is used as an adjuvant treatment for periodontitis. Background data: PDT has been used as an adjuvant in the combat of local infections, such as periodontitis, and combines a photosensitizer (PS) with a light source to induce reactive oxygen species (ROS) and kill microbial cells. Methods: Fifty healthy male rats were used in this study. Periodontitis was induced by placing a cotton ligature around the upper left second molar in a subgingival position. Posterior maxillas were removed and histologically prepared with hematoxylin \& eosin (H\&E) staining techniques. PDT was performed with a diode laser (lambda = 660 nm) with an output power of 100mW. Methylene blue aqueous solution (100 mu M) was used as the PS while control group used phosphate buffered saline (PBS). Collagen organization, inflammatory infiltrate, and bone loss were evaluated. Bacterial samples were collected before and immediately after treatment to determine bacterial reduction. Results: The experimental group that was treated with PDT presented better periodontal healing, as measured by collagen organization, inflammatory infiltrate, and bone loss. Significant bacterial reduction was achieved following treatment with or without PDT compared to control, with a higher microbial reduction observed in the PDT group. Conclusions: PDT used as an adjuvant treatment showed effective short-term control of periodontitis infection. (AU)