The unit research of UNICAM ODV, UNIPG and ADI-Vet executes a study on 9 dogs affected by periodontal disease (PD), of phase 2, 3 and 4, to evaluate the regenerative capacity of the nanohydroxyapatite in the periodontal tissue. The project lasts not more than 24 months. During this period the recruitment of the subjects and the record on the dental sheet relative to the periodontium conditions, supported by a radiographic and iconographic documentation, are effected. The half animals, divided in 3 homogeneous groups of 3 subjects in base on the level of the estimated PD, is subjected to a regenerative therapy of the periodontium (PD phase 2 and 3) and eventually to extraction and method by plant (PD phase 4). The dogs are subjected quarterly to clinical exams and other evaluations both instrumental (RX, TAC, RM, Echocardiography) and of laboratory (hemochrome and eventually hemoculture). The results are then analyzed with a statistical method.