The most effective and economical method of protecting the teeth against decay. Their effectiveness against decay was discovered in the beginning of the last century. Initially it was used in the form of fluoridated water. Subsequently it has been developed into forms such as topical fluoride, fluoride supplements, fluoride rinses and fluoridated toothpastes. They are a large group of chemical compounds formed when fluorine combines with other elements. Their presence is felt in soil, air, water, as well as plants and animals in minute quantities. Thus we end up consuming about 0.3 mg of fluoride daily through intake of food and drinks.
Fluoride is a mineral that occurs naturally in many foods and water. Every day, minerals are added to and lost from a tooth's enamel layer through two processes, demineralization and remineralization. Minerals are lost (demineralization) from a tooth's enamel when acids - formed from plaque bacteria and sugars in the mouth - attack the enamel. Minerals such as fluoride, calcium and phosphate are redeposited (remineralization) to the enamel from the foods and waters consumed. Too much demineralization without enough remineralization to repair the enamel layer leads to tooth decay.
Fluoride enhances the tooth remineralization process. Fluoride found in a person's saliva will absorb onto the surface of a tooth where demineralization (tooth decay formation) has occurred. The presence of this fluoride in saliva in turn actually attracts other minerals (such as calcium), thus helping to speed up the rate or degree to which remineralization (reformation of tooth mineral) will occur.
To receive the benefit of this process fluoride must be present in a person's saliva. This is why drinking fluoridated tap water throughout the day would be a better choice (in regards to cavity prevention) than unfluoridated bottled water. This is also a reason why brushing with a fluoride toothpaste three times a day would be better than brushing just once a day.