The causes of tooth decay:

The daily diet

The systematic use of carbohydrates (glucose, sucrose, fructose) in between meals. In the occurrence of cavities plays a role not so much the amount of sweets consumed as the frequency of their admission and their duration of stay in the mouth.
Found that the protein deficiency, deficiency of vitamins D, A, C, etc. do not affect the occurrence of dental caries. Only a very crude supply shortages for a long time may be associated with an increased caries lesions.
The influence of diet on the occurrence of dental caries is not limited to the influence of carbohydrates. Undisputed caries-preventive role of fluoride.
Even another 60 - 80 years ago, the food is not exposed to intense cooking. Being tougher, it had a pronounced cleaning effect, and the result is self-cleaning of the teeth. Currently, the food has increased the amount of carbohydrates, especially refined (not less than 40 kg per year per capita). We used the food softer and does not require intensive treatment, which does not provide a self-cleaning of the teeth. As a consequence, the formation of plaque on tooth surfaces. Add to this the systematic use of carbohydrates, it becomes clear why there is often damage the buccal cavities and contact surfaces of the teeth.

Effect of microorganisms

Normally, in the oral cavity of man there is a large number of microorganisms. Some of their views when entering the mouth of carbohydrates are able to produce adhesives and using them to bind to the surface of the teeth, forming plaque and dental plaque.
Over time, bacteria in dental plaque proliferate, it becomes thicker and more dense, becoming a mature and active dental plaque. In this case, a process of dissolution of enamel plaque at the site of adhesion to the tooth. Caries begins - a process of destruction of dental hard tissues, leading to the appearance of the cavity. Since the process of transforming into a mature plaque lasts for 18-28 hours, then carefully removing the plaque from your teeth twice a day (1 every 12 hours), you can significantly reduce the risk of tooth decay.

Past medical history

Under the influence of common diseases vary the conditions of formation and maturation of dental hard tissues and especially the enamel, which makes them less resistant to cariogenic factors.
Effect of common diseases (tuberculosis, rheumatic fever, etc.) on an already-formed tooth is not supported by convincing evidence. Enamel - highly mineralized tissue, which has no blood vessels and nerves, maintains its continuity through ion exchange with the saliva. Thus, one should not overestimate the value of the transferred cariogenic and related diseases in adults, because they have the formation and maturation of the tooth has long ended.
External effects on the body that cause tooth decay
Ionizing radiation.
Prolonged intense x-rays.