Relationships between chronic oral infectious diseases and systemic diseases.

There are over 300 species of bacteria forming populations of several hundred billion in the human oral cavity. The number of bacteria reaches a thousand billion when the mouth is not sufficiently cleaned. Using saliva and gingival crevicular fluid as their main nutrients, these bacteria create their ecological niches on tooth surfaces, gingival crevices, saliva, dorsum linguae, and buccal and pharyngeal mucosa, threatening oral and systemic health. It is known that primary lesions of these chronic bacterial infections secondarily cause nephritis, rheumatoid arthritis, and dermatitis. Further, it has been demonstrated in recent years that bacteria inhabiting the oral cavity can cause bacterial pneumonia and endocarditis and that the periodontal-disease-associated bacteria become causative agents for pregnancy troubles and are involved in blood circulation problem and coronary heart disease. Dentistry reviewed the theme of World Health Day, Oral Health for a Healthy Life, in 1994. The 8020 campaign to promote tooth care is also becoming established in Japan; however, the authors emphasized that this achievement is not the goal of dental health care. In this article, we explain the bases supporting the concept that oral health care, primarily mouth cleaning, is important for not only oral disease but also a healthy life.