One of the sad stories about what was considered to be a successful prevention of tooth decay is represented by fluoride supplementation of water and toothpastes. But even today, without knowing all the scientific reliable proofs, all the pieces of a very large puzzle, this action has many (especially in developing countries) promoters. That's why we considered that a well-documented review in this domain would be of large interest, especially because the deleterious effects are many, accompanied by a large number of threats for the health, and the benefits are lacking.