fa Oral medicine Oral medicine Original article Original article Photodynamic therapy (PDT) is a comparatively novel therapeutic method involving a safe light source and a light-sensitive substance, termed as photosensitizers (PSs), such as methylene blue (MB), toluidine blue (TBO), sulfonated aluminum phthalocyanine, chlorine derivatives, nontoxic indocyanine green (ICG), and curcumin (CUR). (1) The combination of a nontoxic PS with low-intensity visible light in the presence of oxygen develops reactive oxygen species (ROS) that are toxic and can cause oxidative damage to microorganisms and tumor cells. (2-4) PSs do not induce cytotoxicity but are activated by laser irradiation at a proper wavelength and develop ROS. (5,6) 1 3 http://jrdms.dentaliau.ac.ir/browse.php?a_code=A-10-25-4&slc_lang=fa&sid=1 A Azizi drarashazizi@yahoo.com 10031947532846008023 10031947532846008023 Yes Professor, Oral Medecine Dept, Faculty of Dentistry,Tehran Medical Sciences, Islamic Azad University, Tehran, Iran SH Lawaf 10031947532846008024 10031947532846008024 No Associate Professor, Prosthodontics Dept, Member ship of Dental Material Research Center, Faculty of Dentistry,Tehran Medical Sciences