Effects of radiotherapeutic X-ray irradiation on cervical enamel

Therapeutic radiation used for head and neck cancers mainly affects the cervical region of the tooth. To better understand the impact of therapeutic radiation on tooth, we aimed to examine the crystallinity, micro-morphology, and elemental composition of the cervical inner enamel located adjacent to the dento-enamel junction.

Ninety-one specimens obtained from 16 impacted third mandibular molars were randomly divided into seven groups (0, 10, 20, 30, 40, 50, and 60 Gy irradiation groups). Energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were performed after the irradiation by 6 MV photon energy. The X-ray diffraction (XRD) were conducted in every group before and after irradiation. Elemental compositions, and Ca/P, P/N, Ca/N atomic ratios were subjected to the Shapiro-Wilk normality test. All of the elements except Mg showed a normal distribution and were compared by the one-way ANOVA. The non-normally distributed Mg data and Ca/P, P/N, and Ca/N ratios were compared by the Kruskal-Wallis test.

The results showed that widening in the interprismatic spaces were observed in the experimental groups subjected to 30 Gy and the following increased doses. In addition, there were no significant differences in C, O, Ca, P, N percentages between irradiated and non-irradiated groups (p > .05). An increase in atomic ratio of the Mg was detected after samples conducted by 60 Gy radiation dose (p < .05). The stoichiometric Ca/P, Ca/N, and P/N atomic ratios did not change by irradiation (p > .05). The XRD peaks of the inner enamel crystalline phase showed a slight decline in the 60 Gy radiation dose group.

Radiation effects begin to be seen after 30 Gy radiation dose groups. The widen interprismatic spaces seen obviously in 50 Gy and 60 Gy dose groups. Besides Mg ratio showed an increase in the 60 Gy dose group. But it should be thought that radiation caries is a multi-factorial disease that is in collaboration with various radiation-induced side effects.