Children with black gums may be related to dental caries, pigmentation, heavy metal poisoning and other reasons. 1. Dental caries: The hard tissues of the teeth are destroyed due to bacterial infection and other factors, which may result in food impaction and darkening of the teeth. 2. Hyperpigmentation: if children eat chocolate and other heavily pigmented foods, pigmentation may appear on the gums, manifested as black gums. 3. Heavy metal poisoning: If a child suffers from lead poisoning, it can lead to the formation of light gray or blue-black pigmentation on the edge of the gums in the form of bands or lines. It is recommended that parents take their children to the hospital in time to clarify the cause of the disease and standardize the treatment under the guidance of the doctor to avoid delaying the condition.