The purpose of this study is to observe and compare the dynamic change of artificially demineralized enamel by remineralization solutions of different degrees of saturation at pH 4.3. In this study, 30 enamel specimens were demineralized artificially by lactic acid buffered solution. Each of 10 specimens was immersed in pH 4.3 remineralization solution of three different degrees of saturation (0.22, 0.30, 0.35) for 10 days. After demineralization and remineralization, images were taken by a polarizing microscope (x 100). The density of lesion were determined from images taken after demineralization and remineralization. During remineralization process, mineral deposition and mineral loss occurred at the same time. After remineralization, total mineral amount and width of surface lesion increased in all groups. The higher degree of saturation was, the more mineral deposition occurred in surface lesion and the amount of mineral deposition was not much in subsurface lesion. Total demineralized depth increased in all groups.