Peri-implant tissues include all the soft and hard, bony tissues that surround a dental implant. They develop progressively, along with tissue healing, after implant placement in the bone and closure of the mucoperiosteal lobe. Although similar to periodontal tissues, the basic difference is in the direction of providing the connective tissue fibers, which in the case of implants extend parallel to their longitudinal axis. It is the main cause of faster and drastic progression of pathological conditions. Peri-implant diseases and conditions are first defined and introduced into the 2017 classification of periodontal diseases. Three levels, peri-implant health, peri-implant mucositis, and periimplantitis, depending on certain clinical parameters, have been described. Diseases are of infectious etiology, which is why therapeutic protocols are based on the removal of bacterial plaque. Therapy plan is carried out individually, but no single protocol has yet been described to guarantee success. There are two basic approaches to therapies, non-surgical and surgical, which are not mutually exclusive, but complement each other. To doctors of dental medicine a non-surgical approach is certainly closer, which is based on mechanical and chemical methods of removing dental plaque and on creating an adequate condition for maintaining personal oral hygiene. Considering that the literature already provides enough knowledge about the listed pathological conditions, it is extremely important to educate oneself about the diagnostics of the diseases, therapeutic possibilities and to provide patient durability of the new implantoprosthetic restoration.