Green staining may occur on baby or permanent teeth and can signal an underlying health condition. Teeth can turn green from the inside out (intrinsic staining) or from the outside in (extrinsic staining). Intrinsic staining happens deep within a tooth’s inner layer and is uncommon. It may be caused by a lack of nutrients or certain health conditions. Extrinsic staining occurs on the tooth’s outer layer and is usually caused by a buildup of bacteria or fungi. Dark foods, drinks, tobacco, and certain medications can also contribute to greenish stains. Conditions like jaundice, Rh incompatibility, ABO incompatibility, sepsis, and hemolytic anemia can cause green baby teeth. Some antibiotics may also cause greenish hues. Extrinsic stains can be caused by poor oral hygiene. Treatment depends on the cause and whether the staining is on baby or permanent teeth. Intrinsic green stains on baby teeth can’t be removed at home and shouldn’t be whitened professionally. These teeth will eventually fall out and be replaced by permanent teeth. Intrinsic stains on permanent teeth are tough to eliminate completely but can be treated with professional whitening. Extrinsic stains often respond well to at-home treatment or professional cleaning.