[Transmission electron microscopic observations on dentin structures stained with silver].

The purpose of this study was to investigate the ultrastructure of silver deposit regions on human dentin. Three kinds of silver stained specimens were used in this study, the decalcified celloidin section stained with silver, the frozen section of decalcified tooth stained with silver, and the decalcified section of undecalcified tooth treated by the silver iontophorese method. After light microscopic observation of the specimens, these were embedded again in epoxy resin and ultra thin sections were made. Then these ultra thin sections were observed under transmission electron microscope, and the results were as follows: 1. By observing the decalcified celloidin section stained with silver, a deposition of silver particles was found on the surface and inside of the hypocalcified collagen fibrils. 2. By observing the section of decalcified tooth stained with silver, a deposition of silver particles was found on the hypercalcified collagen fibrils. According to the findings, it was concluded that the interglobular net and the dark-line of mineralized striation in dentin are hypercalcified regions. 3. By using the silver iontophorese method, large silver particles were found deposited among the hypocalcified collagen fibrils. 4. It was confirmed that the degree of mineralization of collagen fibrils in hard tissue can be estimated indirectly observing the morphological change of collagen fibrils in a decalcified section.