What mineral is commonly found in fluoridated water and toothpaste?

Fluoride is the mineral commonly found in fluoridated water and toothpaste. The primary purpose of adding fluoride to these products is to help prevent dental caries (cavities) and to strengthen tooth enamel. Fluoride works by remineralizing weakened enamel and making it more resistant to acid attacks from bacteria in the mouth. This mineral is specifically chosen for its proven benefits in promoting oral health, particularly in reducing the incidence of cavities, and is an essential part of many dental care regimens.

Calcium, iron, and magnesium are important minerals with various health benefits, but they do not have the specific role in cavity prevention that fluoride does, making fluoride the correct answer in this context.