Damage of pulp tissue usually begins in the coronal pulp. Its mistreatment or its lack of on time detection determines the progressive inclusion of the whole endodontic space in its evolution, opening the way of its expansion in the surrounding tissues of the tooth, and on the marginal apical tissue. Aim. The goal of this study was to highlight that the primary endodontic lesions with secondary periodontal implication healed and bone repair was obtained due to a proper disinfection and an adequate sealing of the endodontic system. In primary endodontic lesion with secondary periodontal involvement, endodontic treatment is required in the first stage followed by specific periodontal treatment. The prognosis is good if an appropriate endodontic approach is chosen, depending on the stage of the periodontal disease and the treatment response. The identification of the etiological factors is the most important to establish the appropriate treatment. In all clinical cases selected in this article, the healing tendency was noticed after an adequate disinfection and sealing of the endodontic system.