Fluoride (from drinking water, supplements, tea, or dental products) is absorbed by the small intestine, and about half is excreted via the kidneys. Absorbed fluoride in the blood can bind with apatite in bone and teeth, becoming fluorapatite. Blood and bone concentrations of fluoride are in equilibrium and are impacted by bone remodeling activity and age.[1] Fluoride in toothpaste and mouthwash works locally in the mouth by getting integrated into the structure of the tooth, supporting remineralization of teeth (by speeding up uptake of minerals like calcium and phosphate from the saliva to make stronger crystals on the outer enamel), resisting demineralization by acidic substances in the mouth, and inhibiting the activity of plaque-forming bacteria.[2][3] Fluoride can also be professionally applied as a gel or varnish, allowing fluoride to be released when the mouth becomes acidic, thereby providing longer-term protection to the enamel.[4]