The dental tissues are anatomically divided into the crown, the neck, the root, and the pulp chamber in between. Histologically the dental tissues include the enamel, the hardest tissue on the outside of the crown, the dentin on the inside, the bone located in the alveolar sockets and on the surface of the roots, and the pulp chamber in the middle. The enamel is the hardest tissue, commonly known as enamel, and is shiny, hard, and very beautiful like a pearl. The dentin located in the middle is yellowish with internal nerve protrusions and can sometimes be felt as hot, cold, sour, or sweet, especially if the enamel is excessively worn causing dentin exposure, such as in patients with dental hypersensitivity. Dentin is loose on the surface of the tooth root, with 55% inorganic and more organic matter. Dentin inorganic matter contains 70% and enamel inorganic matter contains 96%, which is the structure of the tooth tissue. The pulp cavity contains blood vessels, nerves, lymph, fibroblasts, and restorative cells.