To evaluate the masking effect and color stability of resin infiltration treatment in demineralized (white spot lesion) and hypomineralized (molar incisor hypomineralization) enamel lesions of young permanent anterior teeth. Eighty-four (84) anterior teeth with molar incisor hypomineralization or white spot lesions were treated with resin infiltration. The CIE L*a*b* values of sound enamel and enamel lesions were assessed with spectrophotometer and digital image analysis at baseline, immediate postop, 1 week and 6 months. The difference in ΔL, Δa, Δb, and ΔE measurements between sound enamel and the enamel lesions was compared using the repeated analysis of variance (ANOVA) test at p < 0.05. The enamel lesions were clearly discernible from the sound adjacent enamel at baseline. After resin infiltration, there was a significant drop in ΔE values of sound enamel and enamel lesions compared to baseline, and this difference did not change for 6 months, indicating a durable masking effect. At baseline and after 6 months, there was no significant difference in the ΔE values of the test groups. The demineralized and hypomineralized enamel defects were effectively masked by resin infiltration, which remained clinically stable for 6 months.