In an ageing society, the relationships between periodontitis and general diseases will play an increasingly important role. Research has shown, among other things has shown that periodontitis therapy can improve vascular function, reduce the wall thickness of the carotid artery and reduce pulse wave velocity. Effective periodontitis therapy can also reduce blood sugar in type 2 diabetes. The activity of rheumatoid arthritis can also be improved by periodontal treatment. However, there is only contradictory evidence that periodontal treatment can reduce the risk of preterm birth. The lecture is dedicated to the consequences that arise from the relationships between periodontal and systemic diseases for the medical history, diagnosis, patient education, therapy and further care of patients with periodontal disease.