The black stains on the teeth of two-year-old babies may be caused by a variety of reasons, among which the pigmentation of the tooth surface is the most common cause of black stains on baby teeth, and dental caries may also lead to black stains on baby teeth. 1. Pigmentation of the tooth surface: for example, babies love to eat chocolate, sickness taking Chinese medicine or baby’s supplementary food using more soy sauce, such darker pigmented food will lead to pigmentation on the tooth surface. In this case, the teeth should be polished and cleaned. If the cleaning is not in place, there may be black stains on the teeth, you can choose swallowable toothpaste for your baby; 2, dental caries: due to the low degree of mineralization of the enamel of the milk teeth, it is easy to appear caries, especially after eating milk at night, it is easy to cause dental caries. The manifestation of tooth decay can be black spots on the surface of the teeth, in this case, it is recommended to go to the stomatology department as soon as possible, but the tooth decay is not necessarily black, it may also be yellow in color.