Many years ago scientists started to notice that children who were born and raised in areas with natural fluoride in drinking water had fewer cavities than children in other areas. Fluoride absorbed by your body when teeth were forming (during mothers pregnancy to early childhood) integrates into the structure of enamel and makes it stronger.
After teeth eruption, fluoride found in your toothpaste, mouthwash, or in what your dentist places on your teeth still has a positive effect on your teeth. It strengthens the enamel and reduces the chance of tooth decay.
If you have children and live in an area that has no fluoride in its drinking water, you should consult your dentist and physician about fluoride tablets that are available for children.