The temperature changes appearing while the usage of very hot and very cold food alternately result in cracking of enamel. Gnowing nuts, opening bottles with teeth are the reasons of occurance of its chips. The dentine which is less steady to influence of chemically aggressive factors--the acids getting into the mouth with food, allocated by bacteria during their lifetime exposes. The structure of teeth includes salts of calcium (phosphates and carbonates). The acid operates on them, transmitting in a solvable condition, washes them away. The teeth collapse, caries develops.

Protective properties of saliva.
The saliva itself possesses bactericidal property. It includes lysozyme - the enzyme which destroys a cellular side of bacteria. The water that is the part of saliva, begins to inpour freely inside the bacterium, which swells and bursts.

The saliva protects not only from bacteria, but also from acids allocated by them. It has been noticed, that some people have saliva with the higher level of acidity (it is more alkaline), than others, not much, very insignificantly, but higher. The acid allocated by bacteria, is neutralized, caries does not develop.

Acidity - a saliva of each person is individual.

It can be caused genetically.Besides, the salivary glands are known to have a secretory function in a small degree, they can allocate urea, salts of heavy metals, ions of hydrogen (acidity depends just on them). Thereforeacidity of the saliva changes depending on the structure of food which the person eats. The similar situation arises with the people working with acids. They have an original defeat of the teeth developed: the enamel collapses, the teeth become sensitive to cold.

Any diseases, which conduct to infringement of allocation of the saliva (reduction of quality and amount), favour to development of caries and compel such patients to attend the dentist more often. An example of such disease is Shegren's syndrome.

For the teeth's health.
To prevent the influence of bacterial acids on the teeth, it is necessary after meal to rinse the mouth with water, or, even better, dental elixir, to gnow an apple or a carrot. In this situation the rests of food which would serve as a nutrient environment to bacteria will be removed from the surface of the teeth.
While chewing a chewing gum with the carbamide occurs not only clarification of the teeth, but also neutralization of the acid.

Teeth with strong enamel are less exposed to influence of aggressive substances. The use of products containing calcium (milk, dairy products), can promote this. It is possible to accept the preparations containing calcium and vitamin D (calcium D3-nicomed, calcid), but it is better to do it after the consulting a doctor. Calcium which your teeth lose will be filled.