Inclusion Criteria:  Periodontitis stage III-IV Full-mouth plaque score (FMPS) < 25% at the 1-month re-evaluation Full-mouth bleeding score (FMBS) < 25% at the 1-month re-evaluation Signed informed consent  Exclusion criteria  Age < 18 yo Pregnancy or lactation Heavy smokers (>10 die) Conditions or diseases influencing periodontal healing Patients that cannot complete the 6 months follow-up