The study aims to investigate the genetic cause of the variability between individuals seen in the development of the gum disease, gingivitis. This will be carried out through a 3 week programme where all oral hygiene is ceased, allowing 'experimental gingivitis' to develop, followed by a period of recovery when tooth cleaning is restored. Clinical assessments and biological samples will be taken during the course of the study for further analysis.

The purpose of the project is to investigate the factors which influence the oral disease, gingivitis. Gingivitis is the inflammation (swelling, redness, pain) of the gums, caused by the build-up of bacteria in the mouth. Research shows that the severity, extent and rate of development of gingivitis varies considerably between individuals. The aim of this project therefore is to investigate if an individual's DNA contributes to this range in outcomes and what impact it has on the human and bacterial cells in the mouth. This will be investigated through a period where all tooth brushing and oral hygiene will cease, and the changes in the mouth measured as the temporary 'experimental gingivitis' develops. Clinical measurements will include plaque build-up, levels of inflammation and bleeding scores, while samples of blood, saliva and plaque will be used to quantify changes in inflammatory markers and bacterial community composition.

Inclusion Criteria:

• Age 18 to 35

• Caucasian

• No history of periodontitis/periodontal treatment (based on self-reported history)

• Medical history clear of cardiovascular disease, diabetes, cerebrovascular disease, kidney or liver disease, cancer, HIV, Tuberculosis and Hepatitis C (self-reported)

• Never smoker, e-cigarettes or nicotine gum use (self-reported). Individuals who rarely socially smoked more than 5 years ago would be permitted to participate.

• Minimum of 24 teeth present

• Be willing and competent (verbally and cognitively) to give written informed consent and complete a medical history form

• Be willing and physically able to carry out all study procedures

• Not have had a scale and prophylaxis in the previous month or have one scheduled prior to the end of the study

• Participant in good periodontal health, based on:

  1. absence of interproximal probing pocket depths (PPD) and clinical attachment level (CAL) > 3mm (with the exception of distal surfaces of third molars in the presence of impacted third molars) at the screening visit.
  2. bleeding on probing (BOP) < 30% at the Screening visit and BOP <10% at Day -7.

Exclusion Criteria:

• Currently taking part in other clinical trials
• Pregnant or breastfeeding women
• Taking medications including systemic anti-inflammatory medication within 3 months of the study (NSAIDs, no more than once per week and not in the week before sample collection, is permitted)
• Systemic antibiotic intake within 6 months
• Psychiatric conditions affecting participation in the study
• The participant is also a member of staff who is part of the study team
• Current orthodontic treatment
• Regular consumption of alcohol exceeding the government recommended levels
• Denture wearer/presence of dental implants/bridges
• Have oral piercings
• Obvious signs of untreated caries
• Taking dietary supplements (e.g. multivitamins; antioxidants; fish oils)

Gingivally healthy young adults

A data sharing agreement is in place with a funder of the project, Unilever plc. Anonymised participant demographics will be linked to the data, such as year of birth and sex.