Tooth discoloration falls into two main categories: extrinsic and intrinsic stains. Extrinsic stains are caused by food, drink, medication and bad habits, like smoking cigarettes. These stains are easy to remove and can be prevented by following healthier lifestyles. Intrinsic stains, however, appear due to genetics or health problems which affect the inner structure of your teeth. Extrinsic stains are harder to treat and remove.\r