Radiotherapy Reduces Microhardness and Mineral and Organic Composition, and Changes the Morphology of Primary Teeth: An in vitro Study

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/mm(2)) when compared to baseline (323.6 +/- 59.5 kgf/mm(2)) (p = 0.045). For dentin, the surface hardness decreased after 1,080 cGy (34.9 +/- 11.4 kgf/mm(2)) and 2,160 cGy (26 +/- 3.5 kgf/mm(2)) when compared to baseline (56.5 +/- 7.7 kgf/mm(2)) (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/mm(2), 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/mm(2), respectively) and 2,160 cGy (1,0071 +/- 2,547, 7,746 +/- 1,916, and 8,280 +/- 2,079 kgf/mm(2), respectively) and a reduction after 3,060 cGy (6,782 +/- 2,175, 3,558 +/- 1,884, and 3,565 +/- 1,867 kgf/mm(2), 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. (C) 2018 S. Karger AG, Basel