Problem statement:This study investigated the changes in crystallinity and dielectrical properties (conductivity) that could be demonstrated in extracted human teeth (enamel and dentin) subjected to γ-radiation at the sterilization dose (25 kGy). Approach: Twenty human third molar teeth were used in the study. Teeth were prepared so forty enamel and dentin samples were obtained. The samples were divided into two groups. The first group contains twenty samples of enamels. The second ones contains twenty samples of dentins. Each group was further subdivided into two subgroups (10 samples each), one for control while the other for irradiated samples. The X-ray Diffraction Pattern (XDR) studies for the control and irradiated enamel and dentin samples were carried out by X-ray diffractometer. In addition, the microhardness test for the present samples were investigated. Results: The crystallinity in irradiated enamel samples was better than that in dentin where the average crystallite size in enamel was larger than that in dentin. Also, it was found that the dielectrical conductivity for dentin increased with frequency after exposure to γ-radiation. Accordingly, the number and mobility of charge carriers were increased. Conclusion: Exposure of human teeth to gamma radiation at the sterilization dose decreases the hardness of both enamel and dentin.