Ultrastructure of the dento-epithelial junction

The dento‐epithelial junctions (DEJ) of Rhesus monkeys were examined by electron microscopy. Various fixation procedures were employed in this study. It was revealed that the basal lamina between the junctional epithelium and the tooth surfaces was composed of three layers: the lamina lucida, the lamina densa and the sub‐lamina lucida. Fine filaments often coursed through the lamina densa, lamina lucida and hemidesmosomes and combined them into a structural unit. An electron‐dense linear border, presumably derived from tissue fluid, was generally observed on the tooth surface at the DEJ except that composed of the fibrillar cementum. This border was helpful in distinguishing the afibrillar cementum from the dental cuticle. The existence of a sub‐lamina lucida between the lamina densa and the tooth surfaces is a newly defined layer. It is hypothetically considered to be an area of competetive electrostatic forces of repulsion and London Van der Waals forces of attraction.