Objective: To compare the effect of 4 remineralizing materials on the incipient artificial carious lesion and its proximal sound enamel when used with fluoride dentifrice. Study Design: Models mimicking proximal contact were made, each of which was placed with an artificial carious specimen in contact with a sound enamel specimen. Each carious specimen was treated with one of four materials: glass ionomer cement (GIC), resin modified glass ionomer cement (RMGIC), 5000 ppm sodium fluoride (F-gel), and casein phosphopeptide amorphous calcium phosphate (CPP-ACP). The GIC and RMGIC specimens were thermocycled. Then all specimens were pH-cycled for 5 days with twice a day soaking in 1,000 ppm NaF dentifrice solution. Specimens were examined by polarized light microscopy and lesion area quantified by image analysis. Results: RMGIC significantly yielded smaller areas of lesion than CPP-ACP and GIC (p<0.05). F-gel reduced more area of lesion than CPP-ACP significantly (p<0.05). In the associated contact, RMGIC significantly reduced the area of lesion better than CPP-ACP (p<0.05). Conclusions: The most effective remineralizing material in reducing the carious lesion areas was RMGIC followed by F-gel, GIC and CPP-ACP. The demineralization inhibitory effects on the associated sound contact enamel followed the same trend.