Two-year-old baby teeth black may be dental caries, oral iron or poor oral hygiene habits and other reasons. 1. dental caries: two-year-old baby long time without brushing the teeth, may lead to acidic substances on the enamel caused by the destruction of dental caries, caused by dental caries, then the baby teeth can appear black as well as cavities and other symptoms. 2. Oral iron: two-year-old babies such as oral iron, may lead to the performance of the teeth black, generally can be relieved after stopping the drug. 3. poor oral hygiene habits: two-year-old baby oral hygiene habits in daily life is poor, can lead to food debris stays on the surface of the teeth, under the influence of bacteria, can also have an impact on the tooth enamel, causing the above symptoms. Two-year-old baby teeth black, should be timely to the hospital, scientific treatment.