The dentinoenamel junction

Abstract

The dentinoenamel junction (DEJ) is the border where five different structures meet: the cervical enamel, two superficial outer dentin layers (Tomes’ granular and Hopewell-Smith hyaline layers), located over the inner circumpulpal dentin, and cementum (afibrillar acellular cementum and fibrillar cellular cementum). The DEJ is a complex scalloped structure associating at least two calcified tissues and preventing the propagation of cracks from enamel to dentin. It constitutes a biomimetic model of a structure uniting dissimilar materials. Its composition includes type I collagen, phosphorylated (SIBLINGs) and non-phosphorylated proteins (e.g., small leucine-rich proteoglycans (SLRPs), and some extracellular matrix molecules taking origin from the blood serum. Enzymes, metalloproteinases, and lipoproteins participate in its formation. Altogether they contribute to the DEJ mineralization, human enamel rod presenting anisotropic and nanotribological properties. Gradient of mineralization influences abfraction formation (Cuy et al. Arch Oral Biol 47:281-91, 2002; He and Swani J Dent 35:431-7, 2007; Imbeni et al. Nat Mater 4:229-32, 2005). The mechanical properties of the cervical zone of the teeth are functions of microstructural orientation of the mineral and organic matrix.