Fluoride helps reverse and prevent tooth decay in three ways: 1. Promoting Tooth Remineralization Acids can demineralize a tooth — that is, create a weak spot that develops into a cavity. Fluoride helps promote the opposite process, called remineralization, which can reverse the very early stages of tooth decay. 2. Helping Teeth Become More Resistant to Tooth Decay Fluoride actually strengthens teeth, giving them natural protection against future tooth decay. 3. Inhibiting Oral Bacteria’s Ability to Create Tooth-Attacking Acids Fluoride disrupts bacteria’s ability to metabolize sugars, the process that leads to the attack of tooth enamel.