In this article a new microradiographic approach for measuring the mineral content after various demineralization stages of the same enamel section and of the same area is described. Repositioning errors are smaller than 3 μm. The method described uses thick sections (up to 300 μm can be used). The error in mineral content is of the same order (3% by volume) for thick sections as for thin sections. The experiments with this method showed that the first stage in demineralization is a surface-softening process; later on a surface layer was observed. A linear least-square fit of the cube of the lesion depths found shows a high correlation (r = 0.99). This is also valid for the cube of the microhardness indentation lengths made perpendicular to the surface (r = 0.96). The results described in this study indicate that the new microradiographic method is suitable for repeated measurements of mineral distribution