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How does fluoride help reduce tooth decay?

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A labeled cross section illustration of an adult human molar shows the tooth's crown and root, with layers including enamel, dentin, and pulp, as well as gum, cementum, blood vessels, periodontal ligament, lateral canals, and nerve. — tooth Cross section of an adult human molar.

Fluoride helps reduce tooth decay through two primary mechanisms that protect and strengthen tooth structure:

Remineralization: Fluoride is attracted to calcium-rich tissues like enamel. At the tooth surface, it facilitates the attachment of calcium and phosphate ions, promoting the formation of fluorapatite crystals. This process effectively remineralizes and strengthens the enamel.1
Inhibition of Bacteria: Fluoride present in saliva blocks the activity of specific enzymes within bacteria that contribute to tooth decay. By reducing the growth and adhesion of these bacteria, fluoride decreases the production of acid that would otherwise erode the tooth surface.1

By combining these actions, fluoride helps prevent or reduce the formation of dental caries, making it a significant tool in maintaining oral health.21