Scanning electron microscopy of attrited dentinal surfaces and subajacent dentin in human teeth.

– Attrited dentinal surfaces and subjacent dentin were examined in the scanning electron microscope. In a central area of the exposed surfaces the dentinal tubules were occluded, whereas peripherally most tubules were open. Deposits, apparently dental plaque, were observed on the exposed dentin as uneven, but often continuous, layers covering whole areas of the surfaces. Loss of dentin within delimited areas of the surfaces was observed. The resulting defects could hardly be related to attrition, and it seemed that they were caused by erosive or caries-like processes. The dentin subjacent to the attrited surfaces was characterized by mineralized inclusions in the dentinal tubules. The inclusions consisted of irregularly rod-shaped crystals forming a meshwork on the tubule walls. Other crystals were formed as prisms, seemingly rhombohedrons. Crystals which were hexagonal in cross-section were also seen. The exposure of the dentin also seemed to have influence on the organic content of the tubules. Thus, it appeared that ground substance was removed from the intratubular fibers permitting the observation of cross-banding typical of collagen at their surfaces. In some tubules the fibers seemed to be covered by mineral.