Dentin

Dentin is a yellow, calcified tissue, comprised of 70% mineral hydroxylapatite, 20% organic material and 10% water, produced by odontoblasts that are arranged in a layer at the pulp cavity of the tooth. Dentin is covered by enamel on the crown and cementum at the root, and affects tooth color due to the transparency of enamel. Odontoblasts send cellular projections into the mineralized dentin tissue, where they become enclosed within the channels called dentinal tubules and extend towards the outer wall of the dental pulp. Dentinal tubules also contain fluid that is thought to participate in the mechanisms responsible for sensation of pain and hypersensitivity.