Periodontitis and Inflammation in Children With Down Syndrome/Trisomy 21: Study on Biological Samples (NT21)

Inclusion Criteria: Common to all groups: Age: 3 to 12 Patient affiliated to a social security program, beneficiary not covered by the AME. Legal representatives who speak and understand French well enough to be able to read and understand the study information. Legal representatives giving written consent for their child's participation in the study. Specific: Case Group: Trisomy 21 patient with gingival inflammation (subgroup 1) Trisomy 21 patient with healthy gingiva on intact periodontium with no history of periodontitis (subgroup 2) Control Group: child meeting one of these criteria: Patient with psychomotor retardation with no known repercussions on the orofacial sphere or immunity, presenting gingival inflammation (subgroup 1) Patients with psychomotor retardation and no known repercussions on orofacial health or immunity, presenting gingival health on intact periodontium with no history of gingival inflammation (subgroup 2). Patients with no known general pathology and gingival inflammation (subgroup 3) Patients with no known general pathology and healthy gingiva on intact periodontium with no history of gingival inflammation (subgroup 4) Exclusion Criteria: Common to all groups: Patient having received antibiotic prophylaxis, antibiotic therapy or anti-inflammatory treatment in the 3 months prior to inclusion Patient included in another interventional research protocol or in a period of exclusion. Patient on AME Patients with a contraindication to the use of MEOPA: Patients requiring pure oxygen ventilation Intracranial hypertension Unevaluated head trauma New-onset, unexplained neurological abnormalities Pneumothorax Emphysema bubbles Gas embolism Diving accident Abdominal gas distension, occlusion Patient recently treated with ophthalmic gas (SF6, C3F8, C2F6) Known, unsubstituted vitamin B12 deficiency Specific to Trisomy 21 group: - Patient with no genetic diagnosis