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 layer 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 layer from the foods and waters consumed. Too much demineralization without enough remineralization to repair the enamel layer leads to tooth decay.