Children 12 years old teeth black, mainly caused by pigmentation or caries, must be pigment removal or caries filling treatment. 1. Pigmentation: poor oral hygiene or taking dark-colored drugs (such as iron, etc.) can lead to melanin deposition on the surface of the teeth, resulting in black teeth; must seek medical treatment for pigmentation of the cleaning (such as scaling or sandblasting) in order to effectively remove the pigmentation, and must be done to take good care of the oral cavity, as far as possible, to avoid eating dark-colored food or drugs. 2. Dental caries: Bacteria in dental caries will secrete melanin and other substances, which will make the teeth appear black cavities; we should seek medical treatment for filling and repairing dental caries, grinding out the black carious part and filling and repairing it, in order to effectively treat the above symptoms. Children twelve years old teeth black recommended to consult a doctor for a clear diagnosis and symptomatic treatment, in order to avoid delaying the condition.