The darkening of a three-year-old child’s teeth may be due to physiological factors or pathological factors such as dental caries, etc. Treatment includes lifestyle adjustment and treatment of the primary disease. 1. Lifestyle adjustment: If a three-year-old child eats chocolate and dark-colored food for a long time, the pigmentation on the surface of the teeth will cause the teeth to turn black. At this time should correct the bad habits, usually should try to eat less chocolate, etc., to reduce the pigmentation in the food, usually also hard to brush the teeth, meal logistics rinse mouth. 2. Treatment of primary disease: three-year-old child teeth black may also be caused by dental caries, at this time you can remove the decayed tissues, local tooth filling and repair, such as inlay restoration, composite resin filling. Three-year-old child teeth blackened if the disease is caused, should be timely to the hospital, under the guidance of the doctor to deal with.