The clinical manifestations of dental fluorosis are characterized by chalky to brown plaques on the enamel erupting at the same time and, in severe cases, are complicated by parenchymal defects of the enamel. It is often clinically classified into chalky (mild), stained (moderate) and defective (severe) types according to their mild, moderate and severe severity. Brown-black teeth Abnormal change in color of teeth with brown-black color. Intra-dental staining is the discoloration of teeth caused by structural or nutritional changes in the tissues of the teeth, commonly including pulpal necrosis, mottled enamel teeth and discoloration of teeth caused by drug deposition. Extradental staining is the pigmentation of the surface of the tooth. Yellowing of teeth Due to various different reasons, teeth appear yellow. Abnormal tooth color Because the surface of the tooth is covered with a layer of enamel, which is transparent or translucent, and its deeper part is dentin, which is light yellow. The color of the teeth is related to the degree of calcification of the enamel, the higher the degree of calcification, the more transparent the enamel, while the original color of the dentin in its deeper part makes the teeth pale yellow, abnormal tooth color is seen in various dental diseases. Black spots on teeth Some people drink or eat food with easy to stain for a long time, or long-term exposure to certain minerals, such as long-term period with potassium permanganate water rinse, silver nitrate treatment of oral diseases can be exposed to mercury, etc.. All can make the teeth black. Exposure to iron, sulfur and other substances can easily make the teeth appear black-green deposits. In addition, tooth enamel hypoplasia, dentin hypoplasia, hereditary milk light teeth, fluorosis, tetracycline teeth, dental caries, etc. can make the teeth appear yellow, brown, black. The clinical manifestation of hereditary papillary teeth is a translucent papillary color, which can be light yellow or brownish yellow, and the X-ray shows a large pulp cavity in the early stage, and after the enamel is worn away, the pulp cavity and root canal gradually become calcified and locked. The periodontal supporting tissues are normal. Sometimes a shell tooth (shel tooth) is seen, showing a large pulp cavity, thin dentin layer, and abnormally short roots, but no signs of root resorption.