Dental fluorosis is also known as plaque enamel. It is a common dental disease in daily life, which is related to the high fluoride content in drinking water, and its main cause is the water source, which is especially related to the local geographical environment, especially the quality of the local water source. The fluoride content in the water is too high, for example, in some mountainous areas, and drinking water with high fluoride content leads to the formation of dental fluorosis. It is difficult to treat dental fluorosis because it is very difficult to cure once it is formed. However, compared to the treatment of dental fluorosis, the prevention of dental fluorosis is really easier, but of course, we must first understand the causes of dental fluorosis in order to prevent dental fluorosis timely and effectively. Children who drink water containing too much fluoride during the calcification period of tooth development before the age of seven or eight may endanger the enamel cells of the tooth embryo, thus leading to incomplete enamel development. This is actually a sign of mild fluorosis, and severe fluorosis can cause fluorosis osteosclerosis (bone fluorosis) in the bones. Fluoride itself has a dual effect on the teeth. Dental fluorosis can occur if the fluoride content in drinking water is higher than 1ppm (1mg/L), and the incidence is 100% if it exceeds 3ppm (3mg/L). However, if there is a lack of fluorine in drinking water, the anti-cavity ability of teeth will be reduced. When the fluoride content of drinking water is 1ppm, it has both anti-caries effect and does not lead to the formation of dental fluorosis. In addition, the occurrence of dental fluorosis is also related to the local temperature, calcium and phosphorus intake and individual differences. For example, the water intake is relatively higher in areas with high temperature, and the fluorine intake is also higher accordingly, and the imbalance of vitamin A, D and calcium and phosphorus can increase the degree of fluorine hazard. Mild dental fluorosis, also called chalky type, is characterized by opaque plaque like white chalk on the surface of enamel, i.e. chalky plaque, but the enamel is still hard and shiny; moderate dental fluorosis, also called stained type, is characterized by yellowish brown or dark brown plaque on the enamel, most obvious on the upper front teeth, and the enamel is still smooth and hard; severe dental fluorosis, also called defective type, is characterized by yellowish brown plaque on most teeth and even on the whole mouth, along with linear, dotted or sulcus-like defects, deep staining in the depressions, and loss of luster on the tooth surface. Fluorosis is a specific and definite cause of enamel hypoplasia, which is different from what we usually call enamel hypoplasia. The staining and defects of enamel hypoplasia mostly show up on groups of symmetrical teeth. In contrast, dental fluorosis can occur on most teeth, most commonly on the maxillary anterior teeth, and people with dental fluorosis usually lived in a high fluoride area before the age of 7-8. These children can still show dental fluorosis after the eruption of permanent teeth even if they move to a non-high fluoride area later, because the calcification disorder of the teeth has already formed. If the child moves to a high fluoride area after the age of 7-8, the teeth may not show dental fluorosis at all. In addition, dental fluorosis mostly occurs in permanent teeth because enamel formation and calcification of milk teeth, mostly during embryonic and lactation periods, and the placenta has a limiting effect on fluoride, but still can lead to dental fluorosis in milk teeth if fluoride intake is excessive and exceeds its limited level. The most important thing for dental fluorosis is prevention. The most fundamental prevention method is to improve the water source and reduce the fluoride content in drinking water. In addition to drinking water, environmental fluoride pollution in the atmosphere and foods with too much fluoride should also be treated. Tooth fluorosis that has been formed should be treated according to the degree of damage. Mild cases usually do not require treatment. Moderate cases can be bleached and decolored, and moderate cases can be restored with composite resin or porcelain materials for cosmetic purposes.