Periodontal health is a public health issue because of the frequency of periodontal disease (more than 50% of the French population suffers from severe periodontitis (Bourgeois, Bouchard and Mattout 2007)), its negative impact on patients' quality of life, speech, self-confidence and well-being, and its association with the development of chronic pathologies (diabetes, metabolic syndrome, rheumatoid arthritis, cardiovascular disease).

Gingivitis is a reversible inflammatory disease of the superficial tissues supporting the teeth. If left untreated, this inflammation will become chronic and spread apically to the deep tissues supporting the tooth, evolving into periodontitis with irreversible damage. The aetiopathogenic phenomena that lead to the onset of periodontal disease are complex, but one of the main aetiopathogenic factors is the bacterial biofilm found in the form of dental plaque.

Maintaining correct oral hygiene remains the main means of preventing periodontal disease (Chapple et al. 2018). Plaque control is achieved by the dental surgeon through scaling and resurfacing at intervals appropriate to the patient, but also by the patient themselves. Mechanical removal of plaque by brushing prevents it from accumulating and prevents the onset of these diseases. This control by the patient is essential to the effectiveness of periodontal treatments and the maintenance of periodontal health.

Plaque control by the patient using a toothbrush is not sufficient and must be supplemented by the use of interdental hygiene (Lindhe and Koch 1967). To date, the most effective interdental hygiene tools for reducing gingival inflammation and the plaque index are interdental brushes (Sälzer et al. 2015). However, their effectiveness requires professional calibration to enable adaptation to all sites, which can then reduce patient compliance through the need to use multiple tools.

Oral irrigator were developed in the 1960s and in 2001 the American Academy of Periodontology recognised their value in reducing gingival inflammation. The oral irrigator Sonicare HX8432 Ultra, Philips® was developed recently, combining water and air. Its pulsatile action is considered to be more conservative of gingival soft tissue and qualitatively modifies the composition of dental plaque.

The advantage of this tool is that, unlike interdental brushes, it does not require calibration and is simpler to use.

The main objective of this study was to evaluate the benefit of using oral irrigator Sonicare HX8432 Ultra, Philips® in patients with gingivitis on the reduction of the interproximal plaque index (API, Lange, 1975) after 12 weeks of use compared to the use of calibrated interdental brushes.

The secondary objectives of this study were to assess the benefit of using oral irrigator Sonicare HX8432 Ultra, Philips® in patients with gingivitis compared with using calibrated interdental brushes :

• reduction in the plaque control record (PCR) (O'Lheary et al., 1972) after 12 weeks' use
• reduction in Bleeding on probing (BOP) index (Ainamo & Bay, 1975) after 12 weeks' use
• on improvement in oral health-related quality of life (GOHAI - Geriatric Oral Health Assessment Index) after 12 weeks' use

Inclusion Criteria:

• with gingivitis (according to the International Classification of Periodontal Diseases; Chapple et al., 2018 i.e. a BOP greater than 10%).
• with at least 10 pairs of antagonistic teeth
• able to carry out oral hygiene procedures independently
• able to understand the instructions for using interdental devices
• fluent in French
• adults
• affiliated to a social security scheme
• agreeing to take part in the study

Exclusion Criteria:

• daily use of one of the study devices (hydropulper, whatever the model, or calibrated interdental brushes)
• with a medical history that could compromise the protocol (psychiatric, medical or pharmacological disorders such as the use in the week prior to inclusion of anti-inflammatory drugs, antibiotics or any compound that could alter or modify the inflammatory response)
• with eating disorders
• with ongoing orthodontic treatment
• protected by law (guardianship, curatorship, safeguard of justice)
• pregnant or breast-feeding women
• refusing to take part in the study