The most cities which their inhabitants are suffering from fluorosis, located in plain regions or margins of seas. However; there are some other cities located in high and mountainous regions with high prevalence of the fluorosis. Fluoride is not entered to the body only through drinking water, but it could also enter through food products especially teas and sea foods. The high level of fluoride in some food products, in a region, may be due to the high level of fluoride in drinking or agricultural waters and soil of the region or both. Excessive amount of fluoride in air may also cause fluorosis and this is especially true for cities that are located near Volcanoes, coal mine or Aluminium factory. Studies have shown in cities that are located in high regions and fluoride in drinking and agriculture waters is higher than normal range, severity of fluorosis is more than cities with the same level of fluoride in waters but located in lower-high areas. It seems living in high regions is caused relative hypoxia in the tissues as a result of decreased oxygen pressure; therefore there would be more fluoride retention in the tissues. The studies have shown in areas with high fluoride in waters and/or food products, the fluorosis is more prevalent in the rural regions than neighbour urban regions. It seems malnutrition and nutritional deficiencies are more prevalent in rural regions than urban regions. In the tooth formation process, nutritional deficiencies (particularly proteins, vitamins A, B deficiencies) are result in a weak enamel matrix which is more touched by high levels of fluoride consumed. In these cases, the final result is dental fluorosis with high severity. 

Keywords: Fluoride; Fluorosis; Drinking Water