dentina

Dentin, also known as dentine, is the calcified tissue that forms the main bulk of a tooth, lying beneath the enamel in the crown and beneath cementum in the root. It provides structural support to the tooth and protects the dental pulp, while facilitating the transmission of sensory stimuli to the nervous system.

Dentin is produced by odontoblasts from the dental pulp and remains metabolically active throughout life, forming primary dentin during tooth development and secondary dentin after eruption. A portion of the extracellular matrix is predentin, which subsequently mineralizes. Dentin contains dentinal tubules that extend from the pulp to the outer surface; around each tubule is peritubular dentin, with intertubular dentin found between tubules. Mantle dentin is the outermost layer near the enamel.

In composition, dentin is about 70% mineral (primarily hydroxyapatite), 20% organic matrix (mostly type I collagen), and 10% water. The organic matrix also includes non-collagenous proteins such as dentin sialophosphoprotein. The tubules house fluid and odontoblastic processes, contributing to the tissue’s permeability.

Dentin serves as a protective barrier for the pulp and plays a key role in tooth resilience. The hydrodynamic theory explains dentin sensitivity: fluid movement within tubules in response to thermal, osmotic, or mechanical stimuli can activate nerve endings in the pulp. Secondary and tertiary dentin development reduces tubule exposure and pulp chamber size over time.

Clinically, exposed dentin from enamel loss, abrasion, or recession can cause hypersensitivity. Treatments aim to seal tubules or reinforce dentin with restorative materials to reduce fluid movement and pain.