Forms bulk of tooth, is considered a vital tissue with the pulp providing nutrition, sensation, resistance to breakdown. Yellow in colour, perforated throughout by tubules, continuous from pulp to outer surface and is therefore porous. A resilient material with no preferential fracture lines.
Inorganic phase is hydroxyapatite, the organic is mainly collagen.
Dentine also divided into coronal and radicular , primary and secondary , intertubular and peritubular. The tubules are curved, both primary and secondary curvatures beeing seen. Their diameter varies and reduces with age by deposition of peritubular dentine until total blockage occurs and the dentine becomes sclerotic . Mineralisation and composition differs from intertubular dentine. Tubules branch throughout their length in varying amounts.