The buccal cavity presents microorganismes whose the number and composition vary with oral hygiene and medical context (pathologies and associated drug therapies) of the patient. More than 1200 bacterial species have been identified, and among them, 400 are inhabitants of the sub-gingival biofilm. Among all these microorganismes, only 20 species participate to the etiopathogenesis of periodontal diseases.Some are recognised as major periodontopathogens other play unclear role in this pathology. They belong respectively to the red and orange complex of Socransky et al. (1998).

Other microorganismes such as virures, yeasts and protozoans could potentially impact the emergence and development of periodontal diseases. The presence of protozoans in periodontitis have been investigated in this study.

Inclusion Criteria:

• Adults > 18 years-old
• Consulting in periodontal department of CHU, Nancy
• Patient with moderate to severe periodontitis
• At least 2 periodontal sites with PPD≥ 4mm and One healthy site
• No scaling root planning in the last 6 months
• Patients insured under the French social security system

Exclusion Criteria:

• Pregnant patients
• Patients with antibiotic therapy, and/or all medecines which could modify the buccal microbiota in the last 6 months
• Tooth with endodontic periapical lesion
• Patients having a scaling root planning in the last 6 months
• Patient with guardianship

Patients consulting in the periodontal department of CHU, Nancy.

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