Children are prone to some dental problems, especially during the period of tooth replacement. When children have black stains on their teeth, the first consideration is directly related to pigmentation and poor oral hygiene. In addition, dental caries and dental fluorosis can also cause the phenomenon of black stains on children’s teeth. 1, pigmentation: some children like to eat some darker or more pigmented food, such as black chocolate, black rice porridge, etc., and often drink drinks containing pigment, and do not rinse their mouth after meals, which can lead to pigmentation on the surface of the teeth, forming black stains over time; 2, poor hygiene: when children Without good oral hygiene habits, food residues remain on the tooth surface, which can easily cause the growth of bacteria in the mouth, forming plaque or aggravating plaque, and the food residues are not cleaned in time, it is easy to calcify and form darker soft scale; 3, dental fluorosis: mainly due to the consumption of excessive fluoride-containing food and drinking water, resulting in colorful dental fluorosis. The tooth enamel surface will change color, yellowish brown or dark brown, and in serious cases, black-brown change will occur, that is, black dirt may appear on the tooth surface; 4, dental caries: it is an oral disease caused by bacterial infection, when the teeth are corroded by bacteria, there will be a change in tooth color, blackening and caries, this situation should be treated in time to avoid the lesion continues to develop to form cavities.