抄録
By using a scanning electron microscope (SEM) fitted with a backscattered electron (BSE) detector, 'prismless' enamel was observed in the surface layers of permanent teeth. The composite images of the BSE can reveal prism shapes with no etchings because prism sheaths show a lower value of the BSE emission than prism bodies and tails or the interprismatic regions. Thus, the enamel showing a uniformal BSE image was identified as a 'prismless' structure. The surface 'prismless' enamel was classified into three different shapes containing indistinct and stunted prism structures as well as that of the secondary electron (SE) images by SEM following acid and EDTA etching; in addition, the subsurface 'prismless' zones connected with the surface 'prismless' enamel were clearly found.
