The hardest and calcified pa of tooth is known as

Enamel is the densely calcified white material covering the crown of the tooth. It is the hardest substance in the body and made up of crystalline prisms.The prisms lie at right angles to the tooth surface.Pulp is the inner core containing soft tissue, blood vessels, nerve, and lymphatics.Pulp is covered by a layer of tall columnar cells called odontoblasts. The space-occupying pulp is called pulp cavity.Dentine is a calcified material surrounding the pulp cavity. It forms the basis of the tooth and contains spiral tubulesradiating from the pulp cavity. Each tubule is occupied by a protoplasmic process from the odontoblast. In dentine, calcium and organic matter are in the same propoion as bone.Cementum is the bony covering over the neck and root of tooth. It commonly overlaps the lower pa of enamel.Reference: Textbook of anatomy, Head Neck, and Brain, Vishram Singh, 2nd edition, page no.184