This study aims to identify new biomarkers that indicate the resilience of individuals to developing oral disease. An 'experimental gingivitis' model will be employed in which subjects will refrain from oral hygiene in one quadrant of their mouths for 3 weeks, and will then restore oral hygiene. Gum inflammation will be monitored by clinical measures throughout the trial and samples will be collected for analysis of microbial DNA and RNA.

This project will employ an extended experimental gingivitis model to monitor changes in the oral metagenome and metatranscriptome during progression to gingivitis and recovery to oral health. The study will employ a 'split-mouth' design whereby one half of each individual's mouth is protected from oral hygiene while the other half acts as an internal control. Oral health status will be monitored through clinical measurements of dental plaque accumulation and gingival index. Plaque samples will be collected for DNA (metagenome) and RNA (metatranscriptome) sequencing. Using statistical modelling, genes and functional pathways will be identified that associate with resistance and resilience to gingivitis.

Inclusion Criteria:

• have read, understood and signed an informed consent form
• be adults of age 18 years or over
• have a minimum of 20 natural teeth (excluding third molars)
• be willing and able to comply with study procedures
• be a non-smoker and non-user of e-cigarettes or other oral intake nicotine replacement therapy (or have quit smoking/e-cigarettes/oral intake nicotine replacement therapy at least 2 years previously)
• healthy participants: good oral (no sites with interproximal attachment loss, GI ≥ 2.0 in ≤ 10% sites, %BOP scores ≤ 10%) and good general health.
• Covid-19 negative by LFT and fully vaccinated

Exclusion Criteria:

• infectious or systemic diseases that may be unduly affected by participation in this study
• extensive crown or bridge work and/or rampant decay at the discretion of the examiner
• wear removable partial dentures, a fixed/removable orthodontic appliance
• diabetes
• history of xerostomia, salivary gland disease, head and neck radiotherapy, Sjögren's syndrome, mucocutaneous disorders of the oral cavity, vesicobullous disorders of the oral cavity
• smoking or use of e-cigarettes within the last 2 years
• current use of prescription or over-the-counter medications that could affect salivary flow, at the discretion of the examiner
• lack of capacity to be able to consent to the research project and/or inability to follow study instructions
• pregnant by medical history or nursing
• currently undergoing or requiring extensive dental, orthodontic or implant treatment, or treatment for peri-implantitis
• treatment with antibiotics for any medical or dental condition within 4 weeks prior to enrolment
• scale and polish within 4 weeks prior to enrolment
• long term use of antibiotics or non-steroidal anti-inflammatory drugs (prophylactic low dose aspirin is permitted though)
• evidence of drug induced gingival overgrowth
• participation in a dental research study within the previous 20 days.
• Unilever personnel and personnel in the University department performing the study

Gingivally healthy participants

Anonymised participant demographics will be linked to the data: Year of birth, sex, ethnicity.