This study evaluates the interaction between host immune cells and bacteria associated with periodontitis. It comprises biological material from donors with and without periodontal disease. Specifically, we collect a spit and blood sample to conduct in vitro stimulations and measurements of selected parameters related to periodontitis to clarify obscure areas in the immunologic pathogenesis of this disease.

Periodontitis is a prevalent, multifactorial inflammatory disease characterized by the interaction between microorganisms organized in biofilms on tooth surfaces and host immune cells, leading to an inflammatory destruction of the tooth-supporting tissues and - if left untreated - eventually tooth loss. Periodontitis affects up to 50% of the population in the United States of America, and is classified in an aggressive and a chronic form depending on genetic factors, age of onset, speed and severity of attachment loss.

The onset of periodontitis is caused by an immunologic imbalance between host immune cells and residing microorganisms in subgingival pockets. The host immune cells are capable of enhancing both a protective and a destructive inflammatory response towards the microorganisms through the release of inflammatory mediators e.i. proinflammatory and antiinflammatory cytokines.

The role of antibodies in periodontitis is also unclear. Some studies show an excessive antibody level against bacteria associated with periodontitis e.g. Porphyromonas gingivalis (P.g.).

In general, this study contributes to a profound understanding of the host immune cells role in the onset and pathogenesis of periodontitis by comparing healthy versus diseased donors immunologic responses toward pathogene and apathogene microorganisms and their genetic background.

Inclusion criteria for chronic periodontitis donors:

• 50-60 years of age.
• Interproximal attachment loss at minimum 3 teeth besides molars and incisors.
• Clinical attachment loss at minimum 10 sites identified by bleeding and pus upon probing.
• Visible radiographic bone loss.
• Medically healthy donors.

Inclusion criteria for aggressive periodontitis donors:

• 19-40 years of age.
• Interproximal attachment loss at minimum 3 teeth besides molars and incisors.
• Clinical attachment loss at minimum 10 sites identified by bleeding and pus upon probing.
• Visible radiographic bone loss.
• Medically healthy donors.

Inclusion criteria for healthy donors: (age: 19-40 years; 50-60 years)

• No sign of inflammatory conditions or other general systemic diseases.
• Medically healthy donors.

Exclusion criteria for all groups:

• Pregnant and breastfeeding.
• Antibiotic treatment within 6 months.
• Suffer from periodontal manifestations caused by systemic diseases e.i. genetic diseases, haematologic anomalies or syndromes.

This study includes 170 participants, which are legally competent e.i. above 18 years of age and general decision competent. The participants are divided into three groups: 1) Participants with chronic periodontitis (n=35), 2) participants with aggressive periodontitis (n=35) and 3) healthy participants without periodontal disease (n=100). The participants are recruited from the Department of Odontology, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark and assigned to a group in accordance with the periodontal disease classification system in 1999 American Academy of Periodontology.

IPD will not be available to other researchers in accordance with our approved Human Subjects Protection application in Denmark.