Both cavities and stains impact your enamel but in different ways. Enamel is the hard, outer layer of your teeth that protects the inner layers.1 A cavity, also known as tooth decay, permanently damages your enamel and starts as a small hole in your tooth that needs to be treated by your dental team.1 Stains can cause the surface of your tooth to become discolored and are usually caused by certain food and drink or lifestyle habits. Extrinsic stains—stains on the outside of the tooth—can usually be corrected.2