Antibiotics are currently used in periodontology to specifically target the most pathogenic bacteria in subgingival biofilms and to improve treatments. The multiplicity of protocols / dosages tested and the variability of the results did not make it possible to reach an international consensus on antibiotic therapy and its cost / benefit ratio, in particular with regard to the significant side effects of taking antibiotics (resistance bacterial). The care environment as well as the clinical, biological and microbiological parameters can strongly influence the results in usual treatment.

Inclusion criteria:

• Patient over 18 years old
• Patient treated for periodontitis between 01/01/2012 and 07/31/2021
• Patient whose medical and periodontal file contains all the elements necessary for data analysis
• Subject not having expressed, after information, his opposition to the reuse of his medical data for the purposes of this research.

Exclusion criteria:

• Patient who expressed his opposition to participating in the study
• Patient without periodontitis
• Patient smoking more than 10 cigarettes / day
• Patient presenting a dilapidated oral state (untreated caries, unrestored teeth), oral infectious foci whose management requires antibiotic treatment during the initial treatment
• Impossibility of giving the subject informed information
• Subject under safeguard of justice
• Subject under guardianship or guardianship

Patient adult treated for periodontitis