Synthetic polymer gels have been examined as decalcifying media for the preparation of artificial carious lesions in tooth enamel. Enamel specimens were demineralized in lactic acid/calcium phosphate buffers containing 0.1–0.5% (w/w) polyacrylic acid (Carbopol C907, MW = 450,000 daltons) to act as a surface-protective agent. The rate, histology and physical characteristics of lesions were characterized by surface microhardness, polarized light, and microradiographic analyses. Following demineralization, selected lesions were remineralized in solutions supersaturated with respect to fluoroapatite. The results show that polyacrylic acid is extremely useful and effective as a surface-protective agent for artificial carious lesion preparation. The histology of lesions formed in C907 gels can be carefully controlled by adjusting the undersaturation of the demineralization medium with respect to tooth mineral salts. Lesions formed in C907 gels are extremely reactive towards remineralization and the rate and histology of mineral repair are not noticeably influenced by the resin content in solution. The use of synthetic polymer gels is recommended for the systematic reproducible preparation of artificial carious lesions in dental ename