Dental stains can be either extrinsic or intrinsic. Extrinsic stains are on the outside of the tooth and come from substances such as tobacco, coffee, tea, or food. They're usually removed by polishing the teeth with an abrasive prophylaxis paste. Intrinsic stains come from the injestion of certain materials or chemical substances during tooth development, or from the presence of caries. These stains are permanent and cannot be removed.