Abstract: Gamma radiation turns the primary enamel more susceptible to demineralization. To investigate if the fluoride dentifrice combined with acidulated phosphate fluoride gel (APF-gel) inhibits the progression of mineral loss of gamma-irradiated primary enamel. Specimens of demineralized primary enamel were randomized into eight groups (n = 13): Non-irradiated + Non-fluoride dentifrice (G1); Non-irradiated + Fluoridated dentifrice (G2); Non-irradiated + APF-gel + Non-fluoridated dentifrice (G3); Non-irradiated + APF-gel + Fluoridated dentifrice (G4); Irradiated + Non-fluoridated dentifrice (G5); Irradiated + Fluoridated dentifrice (G6); Irradiated + APF-gel + Non-fluoridated dentifrice (G7); and Irradiated + APF-gel + Fluoridated dentifrice (G8). Specimens of irradiated groups were submitted to 3060 cGy radiation dose. After APF-gel treatment, specimens were submitted to a pH cycling, with the respective dentifrice exposure, twice daily. The microhardness and polarized light microscopy analyses were performed to quantitatively and qualitatively assess the enamel mineral loss, respectively. Quantitative data of mineral loss were compared using the two-way ANOVA, followed by the Tukey test. Fluoride dentifrice alone, APF-gel application alone, and their combination were not effective in inhibiting mineral loss of irradiated primary enamel. The combination of fluoride dentifrice and APF-gel was not effective in inhibiting the progression of mineral loss of gamma-irradiated primary teeth Ver menos