Disturbances of the teeth and related structures often produce serious impairment of general health, since mastication and subsequent digestion may be reduced. Also bacteria or their products from a dental infection may invade other tissues, either by direct extension or by passing into the bloodstream. There is a strong positive relationship between general bodily health and that of the oral cavity and teeth.
Dental caries, or cavity formation, results from the Dental caries, or cavity formation, results from the gradual deterioration of the enamel, dentine, and finally the tooth pulp. It is due to many contributing factors. However, the action of microorganisms on fermentable carbohydrates contained within adherent accumulations on the tooth surface called plaques produce acids which appear to initiate the process. The ensuing bacterial invasion leads to continued destruction of the enamel, the dentine, and finally cavitation of the tooth.
Dentoalveolar abscesses are acute or chronic inflammations from bacterial infections that occur in the root canals of the jaws. Periodontal disease, or pyorrhoea, is an inflammation of the gum margin and tooth sheath (periosteum) from local irritation or infection. Infection of the teeth and gums is mainly caused by a bacterium Streptococcus mutans.
Toothache, or ondontalgia, is pain arising from stimulation of the dental nerves by any process such as inflammation. It may occasionally occur as a reflex stimulation of the nerve roots and fibres from a lesion between the teeth and the brain. Diseases of the jaws are intimately related to tooth disorders since the upper and lower jaws form series of pockets for the teeth and carry their blood and nerve supply.
It is common for 95% of a population to have 10 to 15 teeth per person showing evidence of attack by the age of 20. Periodontal or gum diseases are the second most important cause of poor oral health after tooth decay. They affect nearly 9 out of 10 adults in many countries. According to the latest data on caries prevalence, the incidence of oral disease in the world falls into three general categories: very low to low in most countries in Africa and parts of Southeast Asia and the Pacific; moderate in many countries in the eastern Mediterranean region and some countries in Asia; and high to very high in most of the industrialized nations. Superimposed upon the caries problem is that of periodontal disease; broadly speaking, this disease tends to be worse in developing populations, especially in Africa and Asia, and somewhat less so in Europe and the Americas.
The number of dental schools in the world rose from 320 in 1958 to 371 in 1963 and 478 in 1974, but an analysis of the dental manpower situation shows that in general the number of dentists has increased less rapidly than the population. The population per dentist in the world was 7310 in 1963 and rose to 7566 in 1975. The dentist/population ratio differs widely from country to country, ranging from 1 : 1,140 in Sweden to 1 : 1,150,000 in Niger. The overall figures for the world, even in 1975, were far from high and the increase in the number of dentists is tending to become less rapid than it was 20 years ago. The geographical distribution of dentists within countries varies considerably, rural areas almost everywhere having fewer dentists and a much higher population/dentist ratio. Although this is a universal problem, it is particularly serious in developing countries where the proportion of the population living in large cities is low. As an indication, the market for toothbrushes and toothpaste in the UK in 1986 was £121 million (plus a further £23 million for denture cleansers).