As endodontics advances into new horizons, Photodynamic Therapy (PDT) has emerged as a significant approach. The use of lasers is a new technique for eliminating microorganisms in root canal systems. However, the antibacterial effects of many of these lasers depend on dose-dependent heat generation, which can lead to charring of dentin, ankylosing roots, melting cementum, and causing root resorption and periapical necrosis. The disadvantages can be overcome by the use of PDT, which has recently been employed to target microorganisms in the root canals. Photodynamic therapy utilizes three simple components, namely: light, photosensitizer, and oxygen. The photosensitizer is introduced into the root canal and is activated by light. The sensitizer causes biochemical changes of the oxygen molecules into "reactive oxygen species.