Objective: We aimed to evaluate whether radiotherapy causes changes in the mineral composition, hardness, and morphology of enamel and dentin of primary teeth. Materials and Methods: Thirty specimens of primary teeth were subjected to radiotherapy. At baseline and after 1,080, 2,160, and 3,060 cGy, the specimens were subjected to microhardness, FT-Raman spectroscopy, and scanning electron microscopy (SEM) analysis. The pH of artificial saliva was determined, as were the calcium and phosphate concentrations. The data were subjected to the Shapiro-Wilk normality test, showed a nonnormal distribution, and were compared by the Kruskal-Wallis test. Results: The results showed that the microhardness of the enamel surface decreased after 2,160 cGy (281.5 ± 58 kgf/mm²) when compared to baseline (323.6 ± 59.5 kgf/mm²) (p = 0.045). For dentin, the surface hardness decreased after 1,080 cGy (34.9 ± 11.4 kgf/mm²) and 2,160 cGy (26 ± 3.5 kgf/mm²) when compared to baseline (56.5 ± 7.7 kgf/mm²) (p < 0.0001). The mineral and organic contents of phosphate (p < 0.0001), carbonate (p < 0.0001), amide (p = 0.0002), and hydrocarbons (p = 0.0031) of enamel decreased after 3,060 cGy (5,178 ± 1,082, 3,868 ± 524, 999 ± 180, and 959 ± 168 kgf/mm², respectively). For dentin, we noticed a growing increase in phosphate v2, amide, and hydrocarbon content after 1,080 cGy (8,210 ± 2,599, 5,730 ± 1,818, and 6,118 ± 1,807 kgf/mm², respectively) and 2,160 cGy (1,0071 ± 2,547, 7,746 ± 1,916, and 8,280 ± 2,079 kgf/mm², respectively) and a reduction after 3,060 cGy (6,782 ± 2,175, 3,558 ± 1,884, and 3,565 ± 1,867 kgf/mm², respectively) (p < 0.0001). SEM images showed cracks on enamel and degradation of peritubular dentin. Conclusion: We concluded that radiotherapy caused a reduction in surface hardness, changed mineral and organic composition, and promoted morphological changes on the enamel and dentin of primary teeth.

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Background Gamma radiation turns the primary enamel more susceptible to demineralization. Aim 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. Design 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. Results Fluoride dentifrice alone, APF‐gel application alone, and their combination were not effective in inhibiting mineral loss of irradiated primary enamel. Conclusion The combination of fluoride dentifrice and APF‐gel was not effective in inhibiting the progression of mineral loss of gamma‐irradiated primary teeth.