The most efficient way to prevent caries is by using fluoridated dental products. Fluoride can reduce enamel demineralization and promote enamel remineralization. In terms of prevention, the topical application of fluoride is accessible, which includes fluoride toothpaste, fluoride varnish, fluoride gel, and mouth rinse. Besides, the application of fluoride is systematical. In some countries, fluoride is added into water, salt, or milk. Fluoride is also used for the medical treatment of early dental caries. However, fluoride is a double-edged sword. Excessive fluoride intake will cause toxic reactions, and dental fluorosis is caused by a high intake of fluorides during tooth development.