Fluoride is a naturally occurring element. In some locations it is found at unusually high concentrations in the water. People who live in those locations may consume inappropriately large doses of fluoride by drinking the water. Teeth which have received excess fluoride during their development may have a blotchy to marbled appearance, with chalky white to brownish spots or streaks.
The severity of fluorosis is highly variable. In some cases, it may be noticeable only on close inspection of the teeth. In severe cases, the tooth enamel may be pitted, darkened, and obvious. Usually, the increased enamel density associated with fluorosis helps protect the tooth against cavities, but the condition may be considered visually unappealing by the patient.