Tooth Decay is simply the degeneration of teeth by gradual loss of the hydroxyl-apatite (calcium phosphate) and organic components of teeth. Several species of bacteria that are normally resident in the mouths of probably all individuals have been implicated as major cause of tooth decay. The currently predominant germ theory of tooth decay asserts that the loss of calcium phosphate is caused by an out-of-control bacterial disease. Archaeological evidence suggests that caries has been with human beings for thousands of years and probably even predate the human species; but historical records indicate that caries infections increased tremendously in Western Europe about 250 years ago when table sugar became widely available. The increased amounts of sugar-based and other highly processed food in diets seemed to have led to higher incidences of bacterial tooth infections or to entire populations becoming more susceptible to these infections.
Inadequate oral hygiene leads to the adhesion and accumulation of bacteria on the surfaces of enamel and dentin tissues of the teeth. A biofilm is later formed by the accumulated bacteria. A biofilm is simply a living colony or layer that consists of numerous bacteria. The biofilm that forms on tooth surfaces is known as dental plaque. It is the acidic waste products of the numerous bacteria in the biofilm that dissolve the calcium phosphate and the small amount of proteins that constitutes the structure of tooth enamel and dentin, thereby causing the formation of a carious lesion on a tooth. The small-scale action of tiny amounts of bacterial acids (such as lactic acid) on tooth can be compared to the action of say, dilute hydrochloric acid, on a limestone block.
Good oral hygiene and proper nutrition reduces the number of bacteria in the mouth and helps increase bodily resistance against caries-causing bacterial infection. Good oral hygiene consists mainly of thorough and careful tooth-brushing, flossing, and tongue scraping after (ideally) every meal or consumption of sweet or acidic beverages. Regular (at least twice yearly) enamel and dentin cleaning is also advised. Proper nutrition consists of reduced consumption of processed foods that contain fermentable carbohydrates, particularly sugar-laden food and drinks.