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What causes dental fluorosis?

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A labeled diagram of the periodic table entry for fluorine, showing its atomic number 9, symbol F, atomic weight 18.998, electron configuration, and indicating it is a halogen and a gas at room temperature. — fluorine Properties of fluorine.

Dental fluorosis is caused by the chronic overexposure to fluoride during the early years of life when teeth are developing.12

While fluoride is beneficial for dental health in optimal amounts—typically around 0.7 parts per million (ppm)—ingesting levels greater than 1.5 ppm over a prolonged period can lead to this condition. This overexposure results in the appearance of white streaks, dark spots, or mottling on the tooth enamel. In many regions, including the United States, instances of dental fluorosis are generally considered mild and are regarded primarily as an aesthetic issue rather than a health concern.1342

Chronic exposure to high levels of fluoride can occur in areas where groundwater naturally contains elevated concentrations of the element, or through the misuse of dental products and other sources of fluoride.412