The burden of oral disease: challenges to improving oral health in the 21st century.

Dental caries and periodontal diseases have historically been considered the most important part of the global burden of oral diseases. At present, the distribution and severity of oral diseases vary in different parts of the world and within the same country or region. Dental caries is still a major public health problem in most industrialized countries, affecting 60–90% of schoolchildren and the vast majority of adults. It is also a prevalent oral disease in several Asian and Latin American countries, while it appears to be less common and less severe in most African countries. It is expected, however, that the incidence of dental caries will increase in the near future in many developing countries of Africa, as a result of growing consumption of sugars and inadequate exposure to fluorides. The significant role of sociobehavioural and environmental factors in oral disease and health is demonstrated in a large number of epidemiological surveys. The current pattern of dental caries reflects primarily distinct risk profiles across countries (related to living conditions, lifestyles and environmental factors) and the implementation of preventive oral health systems. In some industrialized countries there has been a positive trend in the reduction of tooth loss among adults in recent years, though the proportion of edentulous persons in the elderly population is still high in some countries. In most developing countries, access to oral health services is limited and teeth are often left untreated or are extracted because of pain or discomfort. Tooth loss and impaired oral function are therefore expected to increase as a public health problem in many developing countries. Tooth loss in adult life may also be attributable to poor periodontal health. Severe periodontitis, which may result in tooth loss, is found in 5–15% of most populations. In industrialized countries,