The goal of endodontic treatment is to debride and clear the root canal system of infected pulp tissue so that the canal space can be shaped and prepared to be filled with an inert material, thereby preventing or minimizing any chance of reinfection. However, failure occurs when endodontic treatment does not meet clinical standards and principles. Two approaches have been proposed to solve this problem. In the first approach, residual bacteria are eliminated or prevented from repopulating the canal system by inserting a dressing into the root canal, in an additional visit, generally falling into the following categories: phenolic derivatives (eugenol, paramonochlorophenol camphorate, phenol camphorate, metacresyl acetate , creosote from beech wood), aldehydes (formocresol), halogens (potassium iodide), calcium hydroxide, antibiotics or other combinations. The decision on the treatment tactics remains at the choice of the dentist, depending on the clinical condition, the general condition of the patient, the technical possibilities and the materials at his disposal, as well as his experience.