Photodynamic therapy treatment (PDT) was introduced in 1900. Uses for it in dentistry have been considered in order to decrease the infection level of the root canal system. This therapy regained popularity in the last decade due to its effectiveness in treating endodontic microbial infections, particularly because the most commonly used chemical irrigations such as chlorhexidine and sodium hypochlorite are not always 100% successful in eradicating the microbial flora in the infected root canal. Understanding of the mechanism of microbes and a total microorganism eradication from the system of the root canal. The Pubmed, Embase, NCBI, and Cochrane databases were searched for studies of photodynamic therapy and its effects in endodontic treatments. Both clinical and laboratory studies as well as in vitro and in vivo studies were analyzed. In recent years, studies that were done showed PDTs’ antibacterial potential, however, most of them were unable to adequately confirm better disinfection when contrasted with regular chemomechanical formulation with NaOCl.