Most patients who complain about stains can be successfully treated with bleaching procedures like ZOOM! whitening. ZOOM! uses a special peroxide gel that lifts superficial stains and yellowing. But bleaching only works on extrinsic stains, or discoloration of the tooth enamel. Extrinsic stains are generally caused by things you put in your mouth: cigarettes, chewing tobacco, coffee, blueberries, and so on.
However, teeth can also suffer from intrinsic stains, or discoloration of the dentin (inner structure of the tooth). These stains are caused by internal processes, and do not respond to bleach. One of the most common causes is tooth trauma. When a tooth is hit really hard, it often turns gray. The color of the tooth enamel hasn’t changed; it’s the underlying tissue that’s the problem.
Other intrinsic stains happen as a side effect of medications; most commonly, the antibiotics tetracycline and doxycycline and certain chemotherapy drugs. Again, the enamel is fine; it’s the dentin which has discolored.
Fortunately, intrinsic stains are fairly rare. In the case of damage, the staining usually affects just one or two teeth. Though bleaching isn’t an option, treatments like veneers and porcelain crowns can give you the white smile you want.