Darkening of 2-year-old baby’s teeth may be related to hyperpigmentation, dental caries, dental dysplasia and other reasons. 1. Hyperpigmentation: Babies can produce pigment when eating certain medicines or dark-colored foods as well as special bacteria in the mouth, all of which can easily lead to hyperpigmentation on the teeth, thus leading to black teeth of 2-year-old babies. 2. Dental caries: if the baby often eat sweets such as candy, chocolate, etc., or feeding habits are not good, such as sleeping with a bottle, eating at night, etc. can cause dental caries, which will lead to 2-year-old baby teeth black. 3. Dental dysplasia: If the baby’s teeth are not well developed, such as poor enamel mineralization, it will make the teeth appear black spots, which will lead to 2-year-old baby teeth black. It is recommended that the patient go to the hospital in time to see a doctor, to clarify the cause of the disease and then correctly treated.