Photodynamic Therapy

Photodynamic therapy (PDT) is a promising treatment for cancer and other nonmalignant conditions, which involves the administration of a photosensitizing agent followed by exposure of the tissue to visible nonthermal light. PDT has been developed as a therapy for several diseases such as tumors, periodontitis, other oral lesions, and premalignant diseases, involving the application and retention of an applied photosensitizing agent in target tissues. PDT is defined as an ¿oxygen-dependent photochemical reaction that occurs upon light-mediated activation of a photosensitizing compound that leads to generation of cytotoxic reactive oxygen species, predominantly singlet oxygen.¿ This therapy can be applied topically into a periodontal pocket, hence avoiding overdoses. Other advantages of PDT include reducing the probability of side effects associated with the systemic administration of antimicrobial agents and minimizing bacterial resistance.