To test the efficacy of two calcium phosphate pastes compared to that of fluoride toothpaste on remineralizing artificial caries in situ, this study had a double-blind crossover in situ design, involving three experimental phases of 14 days each, with an 8-day washout period between phases. Nine healthy subjects participated in the study. The subjects wore removable palatal appliances mounted with six human enamel slabs with artificial caries lesions, and in each of the experimental phases, used one of the following methods two times/day: group A, brushing with 1.0 g of Colgate Regular Flavor, followed by applying 0.25 g of Tooth Mousse Plus; group B, brushing with 0.25 g of Clinpro Tooth Crème; and group C, brushing with 1.0 g of Colgate Regular Flavor. After 14 days, the enamel slabs (54 slabs/group) were embedded in resin, sectioned and examined with a polarized-light microscope, and the lesion areas were quantified using Image-Pro Plus. All experimental groups showed a significant reduction in lesion area compared to the initial lesion area (paired t-test, P<0.001). The mean reduction in lesion area of Groups A, B and C were (0.029±0.010), (0.030±0.009) and (0.027±0.009) mm2, respectively. There were no statistical differences between groups (Kruskal–Wallis test, P>0.05). All three groups remineralized the enamel slab lesions, indicating model sensitivity to fluoride. Given the differences in usage amounts and treated regimens, Clinpro Tooth Crème provided similar benefits to the fluoride toothpaste; however, no additional benefit of Tooth Mousse Plus was observed when used in conjunction with the fluoride toothpaste.