Dentine s a calcified tissue of the body and, along with enamel, cementum, and pulp, is one of the four major components of teeth. It is usually covered by enamel on the crown and cementum on the root and surrounds the entire pulp.By volume, 45% of dentin consists of the mineral hydroxylapatite, 33% is organic material, and 22% is water. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel.Dentin rates approximately 3 on the Mohs scale of mineral hardness.