Effects of direct therapeutic radiation on pulpal surface of root dentin: an in vitro study

The aims of the study were to analyze the effects of therapeutic radiation on human root dentin samples from the aspect of possible alterations in crystallinity, micro-morphology, and composition. Fifty-six root dentin specimens were divided into seven groups (0, 10, 20, 30, 40, 50, and 60 Gy). Scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses were performed on pulpal surfaces of root dentin after being irradiated by 6MV photon energy. Mineral compositions, Ca/P, P/N, Ca/N ratios, and hydroxyapatite pikes were calculated. Some deuteriations on the dentin surface were observed in SEM images after 30 Gy and subsequent doses. One-way ANOVA revealed that there was no significant alteration in weight percentages of C, O, Mg, Ca, P, and N between groups. Radiation did not influence stoichiometric Ca/P, Ca/N, and P/N molar ratios. XRD analysis did not show a remarkable decline in hydroxyapatite pikes by the increasing doses. Radiotherapy changes the micromorphology of circumpulpal dentin but does not affect elemental composition and crystallinity.