Effect of Azithromycin on Failure Proportion of Severe Periodontitis Non-surgical Treatment

Inclusion Criteria: * Patient with severe generalized chronic periodontitis (loss of attachment ≥ 5mm at \> 30% sites) (AAP classification 1999) and periodontal pockets \>5mm on at least 5% of sites * presence of bleeding on probing (≥ 30%) * male or female subject older than 35 Years * patient with at least 15 teeth including at least 2 molars (excluding wisdom teeth) * patient with social assurance * voluntary patient who signed informed consent Exclusion Criteria: * Patient with contraindications to treatment with azithromycin or its excipient: absolute contraindications are the history of allergy to macrolides or one of the excipients used in this study, association with ergot derivatives Rye, Cisapride, colchicine, and severe hepatic deficiencies. Other contraindications are for patients at risk of cardiac arrhythmia (diagnosis of QT interval prolongation and/or concomitant treatments, electrolytic disorder (hypokalemia, hypomagnesemia, cardiac arrhythmia, heart failure), severe renal failure, and drug associations (Antivitamin K, statins) * Patient with aggressive periodontitis (AAP classification 1999) * Patient smoking more than 10 cigarettes/day * Patient with endocarditis risk or requiring antibiotic prophylaxis * Patient with antibiotic treatment within 6 months prior to periodontal examination * Patient with anti-inflammatory treatment in the month preceding periodontal examination and/or anti-inflammatory treatment of more than 3 consecutive days in the 3 months preceding periodontal examination * Patient following or having followed a drug treatment (cyclosporine and other anti-rejection drugs, antiepileptic, calcium inhibitor) influencing periodontal status * Patient with pathologies influencing periodontal status and/or systemic or local inflammatory response, such as diabetes, infectious stomatitis or not, diseases inflammatory and autoimmune, immuno-depression * Patient with prolonged oral hygiene disability (physical/psychic impossibility of brushing teeth) * Patient with impaired oral condition (untreated cavities, non-dental teeth rehabilitated), dental infections whose management requires antibiotic treatment within 6 months * Patient having specialized periodontal treatment, root planning, or a periodontal surgical treatment in the year prior to the examination * Pregnant woman or breastfeeding * Patient with repeated chronic infections (more than 3 times per year) requiring antibiotic treatment * Patient who had oral antiseptic treatment in the previous month * Patient included in another intervention research protocol or in periods of exclusion (participation in an observational study remains possible) * Patient with high bleeding risk and/or INR \> 4. * Patient under guardianship and under protection of justice * Patient unable to cooperate or understand the instructions related to the study and care