The causes of yellow teeth are as follows: 1, and the light yellow teeth with uniform color are normal teeth color; 2. The color is uneven, and dark yellow or brownish yellow pigments appear on the tooth surface, which is called dental fluorosis. Patients who live in areas with high fluoride content in drinking water for a long time are prone to dental fluorosis. Clinically, it is necessary to grind a layer of teeth and then treat them with veneer or porcelain. 3. Long-term smoking will lead to the yellow substance in tobacco adhering to teeth, which can be treated by washing teeth clinically.