The reasons for baby teeth having black spots are as follows: a. When baby takes Chinese medicine preparation or drinks dark color, a large amount of exogenous pigment will be deposited on the surface of teeth, forming black spots or patches. Second, if the baby who likes to eat sweet food does not pay attention to oral hygiene cleaning, a large amount of food residues and soft scale can form acidic metabolic substances on the tooth surface, causing enamel demineralization and producing caries damage, brown patches or cavities can appear on the tooth enamel layer, and X-rays show that the density of black area is obviously reduced. Third, when suffering from fluorosis or tetracycline teeth, the teeth are affected by drugs, and yellow-brown or black-brown patches appear in the enamel layer, which will cause substantial defects in serious cases.