Ultrastructural observations on human coronal dentin

abstract – The incisal area of the coronal dentin of intact anterior teeth was studied by means of scanning and transmission electron microscopy. The great majority of the tubules were open regardless of age. A variety of fibrous structures with diameters between 50 nm and 0.7 μm were observed within dentinal tubules. The cross-banding typical of collagen was occasionally discernible in these fibers, but as a rule they had a smooth surface, probably due to masking of structural details by ground substance. Fibers with a tendency to arboresce were interpreted as nerve fibers. Disturbances in the mineralization were observed in a central area of the dentin between the pulp horn and the incisal edge. Especially the development of peritubular dentin was inconsistent. In adult teeth the tubules at this location were occluded by a fine-textured material. A varying amount of secondary dentin was present in the pulp horn of the teeth at an early age. The first formed tissue had an atubular appearance, whereas in an apical direction the structure became more regular with tubules and intertubular areas.