Teeth with green color like mildew may be due to pigmentation, calculus, dental caries and other reasons. 1. Pigmentation: If patients consume a lot of green food or vegetables, and do not clean their teeth in time, it may lead to green pigmentation on the surface of the teeth in the long term. 2. Dental calculus: If the patient suffers from dental calculus, the saliva in the mouth and the minerals in the calculus may cause calcification, appearing green like mold, in addition, if the consumption of a large number of green plants, may also cause the surface of dental calculus pigmentation. 3. Dental caries: If the patient has dental caries, the early dental caries may be lighter in color and may appear as green like moldy spots. It is recommended that patients should maintain good oral hygiene, diligent brushing and rinsing, can help the health of the teeth, such as physical symptoms, should go to the hospital in a timely manner, consult a physician for treatment.