Teeth black generally have three reasons: 1, extrinsic coloring: in simple terms, it is smoke stains, tea stains, coffee stains or eat Chinese medicine caused by scaling as well as quit smoking, quit tea, quit coffee, while brushing correctly, it is recommended that 1 year scaling 1-2 times; 2, intrinsic coloring: due to mothers taking certain medications during pregnancy, or toddlers to adolescents in contact with some of the special substances caused by the period, such as tetracycline, fluoride, etc., can be whitened by bleaching teeth or take dental restoration; 3, dental caries: mainly due to acid production by bacteria to demineralize the teeth, broken. The teeth can be whitened or restored by bleaching; 3, dental caries: mainly caused by bacterial acid production that demineralizes and breaks down the teeth. If you want to know the cause, it is recommended to go to the stomatology clinic for relevant examinations to clarify the cause of the disease and then carry out symptomatic treatment.