The enamel (substantia adamantina) covers the crown of the tooth and is the hardest known substance in the body. This hardness is necessary to survive the powerful forces exerted on the tooth surface during chewing. Enamel is composed predominantly by calcium salts, with less than five percent of its weight being due to organic tissues. Since no cells or vessels penetrate into the enamel, it is not considered living tissue. Because of this, damage to the enamel of a tooth (as in the case of a dental cavity) cannot repair itself.
