Importance. Currently, endodontic dental treatment is a complex manual process that requires in-depth knowledge of the anatomy of the crown and root part of the tooth, all this is necessary, as is a three-dimensional assessment of the structure of the pulp chamber of the root canal system, using modern technologies. In other words, a favorable result of endodontic treatment can be achieved in case of correct formation of access to the root canals and the qualitative removal of any inflamed, infected, degeneratively altered and necrotized pulp tissues. Objectives ― the study of the antibacterial effect and the possibility of using a laser photodynamic system for antibacterial treatment of root canals containing fragments of endodontic instruments. Methods. Fifteen patients aged from 18 to 50 years with 20 root canals containing fragments of an endodontic instrument were selected for work, previously treated for chronic periodontitis. Three samples for microbiological examination were taken: before the start of treatment, the sampling of dentinal chips from the root canal with a sterile file (sample A), after the instrumental treatment, medical treatment with 2.25 % sodium hypochlorite solution and the sampling of dentinal chips from the channel wall (sample B). Further, a photosensitase solution was placed in the root canal for 60 sec., Exposure was carried out with a laser beam for 120 seconds (HELBO system, Austria), dentinal chips collected (Sample C). Results. In samples A, the infection level corresponded to 4 points (marked bacterial load); in samples B ― 2 (average); in samples C ― 0. Conclusions. The use of a laser photodynamic system in the root canals, provides a high therapeutic effect, accelerates the process of medical treatment of the canal canal, by removing the dentinal chips and smear layer.