In France, two-thirds of adults over 35 years of age have at least a periodontal disease. The etiology is the accumulation of dental plaque, especially in interdental spaces. The cleaning of interdental spaces is particularly complex. This accumulation of dental plaque is at the origin of a modification of the bacterial flora in favor of periodontopathogenic bacteria. These pathogens can induce within the periodontal tissues an immune and inflammatory reaction that cause tissue degradation. The majority of studies focus on people over 30 years of age with gingivitis or periodontitis. However, young adults, in whom the initial or even reversible stages of periodontal disease are the most frequent, should be the preferred target of preventive measures for this pathology.

The main objective of this study is to quantify, in healthy patients, the evolution of the supragingival bacterial flora, in the interdental spaces, following the daily passage of brushes with the adapted diameter and single passage. The secondary objective is to evaluate the qualitative change in the bacterial flora (proportions of periodontal bacteria / commensal bacteria) following the interdental cleaning.

Inclusion Criteria:

• having teeth at the 4 interdental sites studied (15-16, 25-26, 35-36, 45-46),
• reporting a minimum of two daily toothbrushes,
• having a good understanding of the French language,
• accepting the terms of the study and signing written informed consent,
• in good general health (opinion of the investigator) without significant clinical abnormality and medical history.

Exclusion Criteria:

• Smoking patients (daily consumption greater than or equal to 1 cigarette),
• patients with pathologies: diabetic, haemophilia, anticoagulant, platelet antiaggregant, pregnant and lactating women,
• patients with a history of periodontal treatments,
• patients with mandibular fixed orthodontic appliances and or maxillary, masticatory coefficient less than 80%,
• patients who have taken antibiotics in the past 3 months,
• patients using interdental brushes on a regular basis (more than once a week) in addition to brushing teeth or mouthwash ,
• patients at risk for infectious endocarditis,
• patients unable to answer questions,
• non-cooperative patients,
• patients requiring geographic mobility compromising evaluation.

- Subjects aged from 18 to 35 years in good health