光動力療法（photodynamic therapy, PDT）是藉由低能量雷射（例如：Diode laser）照射在被光敏物質附著的特定細菌或病變組織上，而產生殺菌與破壞細胞的作用。近幾年來許多專家學者陸續發表PDT運用在牙周病治療的相關研究，除了能減少抗生素的使用外，PDT是否能取代傳統牙周病非手術性治療（SRP）或僅有輔助性效果一直大家所關注的話題，本文藉由文獻回顧介紹PDT的基本原理與探討其在牙周病治療的效果，期望能提供臨床醫師在使用雷射治療牙周病的參考依據。

Photodynamic therapy(PDT) is based on the principle that a photosensitizer binds to the target cells and can be activated by light of a suitable wavelength. Following activation of the photosensitizer through the application of light of a certain wavelength, singlet oxygen species and other very reactive agents are formed, which are cytotoxic, thereby mediating bacterial kill. In recent years, many experts publish the research about the usage of PDT on the treatment of periodontal disease. In addition to the reduced use of antibiotics, whether PDT can serve as a primary mode or only as an adjunct to non-surgical treatment is all topic of concern. This paper introduced by literature review and discussion of the basic principles and effect of PDT in the treatment of periodontal disease, hoping to provide clinicians with guideline of using laser in the periodootal therapy.