Fig. 3

SEM micrographs of enamel, dentin, and the DEJ in the three groups. With the dose increasing, progressive destruction of interprismatic substance and enamel prism was revealed. Fragments of enamel prism were evident in the 30-Gy and 60-Gy groups, and the arrangement of the enamel prism was irregular. Fissures at the DEJ were obvious in the treated groups. In dentin, obliterated dentinal tubules, degeneration of the collagen network, and cracks on the tubular walls can be seen in the 30-Gy and 60-Gy groups