Inclusion Criteria:  Common criteria for all patient groups  Patient > 18 years old Patient affiliated to a social security system, beneficiary or beneficiary of a right other than AME Patient who speaks and understands French well enough to be able to read and understand the study information note. Patient who does not object to his participation in the study  Specific criteria:  - Case: Patient with localized or generalized periodontitis, stage 3 or 4. The diagnosis of periodontitis is based on the elements found during the interview and clinical examination  -Control group: Patient with gingival health on intact or reduced periodontium with no history of periodontitis and requiring surgical care such as dental avulsion and pre-prosthetic periodontal corrective/aesthetic surgeries (coronal elongation, neck alignment.)  Exclusion Criteria:  Patients who have received antibiotic prophylaxis, antibiotic therapy, or anti-inflammatory treatment within 3 months prior to inclusion Pregnant or breastfeeding women Patient included in another interventional research protocol or in a period of exclusion. Patients under guardianship, curatorship or legal protection. Patient having expressed his opposition to participate in the research