Abnormal tooth color and its cosmetic (color change) treatment There are many reasons for abnormal tooth color, which can be congenital or acquired. Tooth coloring caused by congenital causes is manifested as symmetrical color change of most of the teeth at the time of tooth eruption, and the common ones are fluorosis, tetracycline, and enamel underdevelopment. Acquired causes of tooth coloring manifested in the teeth when the eruption of normal color, adverse stimuli, individual teeth color gradually change, such as dental caries or after trauma. Dental fluorosis is the staining of tooth surface caused by excessive fluoride intake during the developmental stage of teeth. The more fluorine is ingested, the more serious the staining is, which is in the order of chalky, yellow, light brown, dark brown, and the staining range can be part of the tooth surface and all the tooth surface, and in serious cases, the tooth surface can be seen as a pit-like defect, which affects both the aesthetics and the quality of the teeth. Fluorine only damages the developing teeth, so before the age of 6~7 years old, living in areas with high fluoride content in drinking water for a long period of time, even if you move to other places later, you can not avoid the involvement of permanent teeth erupting in the future, on the other hand, after the age of 7 years old to move into high fluoride areas, there will be no dental fluorosis. Tetracycline is a tooth coloration caused by taking tetracycline group drugs during tooth development. The extent to which tetracycline affects tooth coloration is related to the type of tetracycline family drug, the dose, and the period of administration. It can appear as cadmium yellow, lemon yellow, or dark gray. Tetracycline drugs can enter the placenta through the mother’s blood circulation to affect the fetus, so the mother’s pregnancy or infants and young children themselves taking tetracycline can cause staining of milk teeth, permanent teeth. Tetracycline only affects the developing teeth. Generally speaking, administration of the drug after the age of 6~7 years will not cause significant tooth coloration. In order to prevent the occurrence of tetracycline teeth, the Ministry of Health stipulated in 1983 that tetracyclines should not be used by pregnant and breastfeeding women, as well as children under the age of 8 years. Enamel hypoplasia is a disorder of enamel development of permanent teeth caused by systemic diseases, nutritional disorders, or localized lesions of milk teeth in pregnant women and infants during tooth development. For example, severe malnutrition, high fever such as measles, pneumonia and sepsis in infants, and rubella and toxemia in pregnant women. Periapical infection of individual milk teeth can lead to hypoplasia of permanent teeth in that tooth position. Enamel hypoplasia is often characterized by chalky transverse stripes, or bands and fossae of substantial defects on the enamel surface, with exposure of the dentin at the defects showing a yellowish color. Enamel defects are also prone to hyperpigmentation and caries. Enamel development, such as systemic factors, the affected teeth tend to be symmetrical, such as the root of the permanent teeth due to periapical infection of the milk teeth, the development of underdevelopment, manifested in the crown of the tooth is small, irregularly shaped, and often grayish-brown coloring. Poor tooth color can affect facial aesthetics. The main treatments for poor tooth color are Decoloration bleaching The application of oxidizing agents or acid etching agents to eliminate the staining and discoloration layer of the teeth, so as to achieve the purpose of bleaching the teeth. However, bleaching is not effective for everyone, and should be strictly selected by specialized doctors for the indications, and the oral mucosa should be protected during operation to prevent the gums from being burned. Decolorizing bleaching can be divided into two types: external bleaching and internal bleaching. External bleaching is mainly used for the decolorization of fluorosis and tetracycline teeth without defects. Internal bleaching is mainly used for discoloration of anterior teeth, pulpless teeth or severe tetracycline discoloration. Composite resin coating restoration A technique that has been gradually developed since the 1980s. The polymer composite resin is bonded to the surface of the affected teeth to cover the discolored teeth or repair tooth defects. Dental veneer is mainly used for the front teeth to change the color and cosmetic restoration of teeth that are straight, complete and without caries damage. There are resin veneer, porcelain veneer, cast ceramic veneer, new plastic hard resin veneer. Casting Ceramic and Porcelain Crowns Casting ceramic and porcelain crowns are close to natural teeth in form, color, transparency and luster, making them ideal for restoration and aesthetics. To make a full crown, it is necessary to grind away 1-2mm of the tooth’s circumference, and sometimes it is also necessary to remove the nerve of the tooth. As far as color is concerned, all-ceramic crowns have the best shade.