The onset and progression of periodontal disease is closely associated with patients’ lifestyles and habits, such as smoking, diet, stresses, etc. ; it is therefore considered to be a lifestyle-related disease. It is now listed as one of the complications of diabetes mellitus, as well as disorders of the retina, kidney, nervous system, heart, and brain. In addition to the concept that lifestyles and lifestyle-related diseases are causative factors of periodontal disease, this disease has now been revealed to be involved in the onset and progression of other systemic diseases, such as diabetes, as well as atherosclerosis, which leads to ischemic heart and brain diseases. Proinflammatory cytokines produced in the inflamed gingivae locally and bacteremia induced through the periodontal ulcerative lesions have been suggested to connect the local and systemic disorders. Periodontal diseases can be controlled by adequate risk management and oral health promotion, and this, in turn, contributes to risk reduction for other life-threatening systemic diseases
