http://www.who.int/water_sanitation_health/publications/fluoride_drinking_water_full.pdf http://www.who.int/water_sanitation_health/publications/fluo... In sum

http://www.who.int/water_sanitation_health/publications/fluoride_drinking_water_full.pdf http://www.who.int/water_sanitation_health/publications/fluo... In summary: The beneficial and the detrimental effects of fluoride naturally present in water were well established by the early 1940s. High levels of fluoride present in concentrations up to 10 mg l–1 were associated with dental fluorosis (yellowish or brownish striations or mottling of the enamel) while low levels of fluoride, less than 0.1 mg l–1, were associated with high levels of dental decay (Edmunds and Smedley, 1996), although poor nutritional status is also an important contributory factor. Concentrations in drinking-water of about 1 mg l–1 are associated with a lower incidence of dental caries, particularly in children, whereas excess intake of fluoride can result in dental fluorosis. In severe cases this can result in erosion of enamel. The margin between the beneficial effects of fluoride and the occurrence of dental fluorosis is small and public health programmes seek to retain a suitable balance between the two (IPCS, 2002). The various in Basically: appropriate amounts of fluoride help your teeth to not decay.