The project (PlanPerioMed) is a register-based study evaluating the associations and patterns of health care delivery between periodontitis and medical diseases using data from the Danish dental record system Dentalsuite (Plandent A/S) and national Danish health care registries with three overall hypotheses/ aims:

• Determine the extent to which periodontitis in registry data is associated with more odontological treatment services and treatment frequency.
• Determine if patients with systemic diseases attend dentists more frequently and receive more treatment services per patient than the population without these diseases.
• Determine to which extent periodontitis and received periodontal treatment affects the risk of medical diseases.

The study will focus on association and trajectories of periodontitis and its treatment with three medical diseases, namely, Type 2 Diabetes Mellitus (Type 2 DM), Cardiovascular Diseases (CVD) and Rheumatoid Arthritis (RA). The dataset consists of approximately 4,000,000 people aged between 18 and 99 years attending private practice in Denmark. The results from PlanPerioMed study are likely to have ramifications for treatment guidelines for other periodontitis comorbidities, e.g. CVD and DM, and will thereby improve the quality of life for a wide range of patients and reduce long-term societal health care expenses related to periodontitis and its comorbidities.

Inclusion Criteria:

• Subjects with clinical registrations of DMFT, periodontal status and corresponding treatment codes
• Self-reported systemic diseases including Diabetes Mellitus Type 2, Cardiovascular Diseases and Rheumatoid Arthritis
• Subjects with Clinical Attachment Loss>=3mm, Probing Depth >= 3mm and bleeding on probing (as defined by World Workshop 2017- criteria for periodontitis) in clinical examination will be included in the study population.

Exclusion Criteria:

• Subjects with more than 32 teeth
• Subjects with no clinical registrations

The study population will include people who are clinically diagnosed with periodontal diseases and private practice dental care attenders in Denmark.