A sample preparation technique to study the organic phase of tooth enamel under scanning electron microscopy

The study of the organic phase of heavily mineralized tooth enamel under scanning electron microscope is difficult primarily because of its partial dissolution in demineralizing agents and its instability after demineralization. In this study, enamel from human and rat teeth were treated first with hydrazine to remove the organic phase. A suitable epoxy resin was prepared and then embedded into the voids of deorganified enamel by vacuum impregnation as well as diffusion techniques. After polymerization of the resin samples, the enamel was treated with demineralizing agents such as EDTA, or Cr3SO4 or HCI for different times, which left a resin replica of the organic phase of enamel in each case. Slow and preferential etching of resin replica under a demineralizing agent enabled SEM examination of the larger structures in the deep layers of the enamel, which, otherwise, would be obscured by the dense network of finer structures.