dentinenamel

The dentin-enamel junction (DEJ) is the boundary between enamel, the tooth’s hard outer layer, and dentin, the underlying, more pliable tissue that forms the bulk of the tooth. Enamel is highly mineralized and largely acellular, composed mainly of hydroxyapatite crystals. Dentin is a living tissue with odontoblasts at the periphery of the dental pulp and a network of dentinal tubules that extend toward the DEJ, containing fluid-filled channels and cellular processes.

The DEJ itself is not a flat plane; it has a scalloped interface that creates interlocking folds between enamel and dentin. This irregularity increases the surface area at the junction and contributes to the mechanical bonding between the tissues. The development of the DEJ occurs during tooth formation as ameloblasts form enamel and odontoblasts form dentin, with the interface maturing as mineralization progresses.

Clinically, the DEJ influences how teeth respond to wear, trauma, and restorative procedures. When enamel is lost or dentin becomes exposed, dentin tubules can transmit stimuli, leading to sensitivity. In dentistry, bonding agents and restorative techniques aim to recreate a stable, integrated interface with the DEJ to resist fracture and ensure durable adhesion. The DEJ also plays a role in the propagation of cracks, with its interlocking pattern helping to deflect cracks and distribute stresses under load.