X-ray crystallographic studies as to the calcification in the Hunter-Schreger bands of human enamel.

By analyzing integrated intensities of X-ray diffraction patterns and X-ray diffractograms obtained from the two zones of the Hunter-Schreger bands, it was deduced that the ratio of the sums of the integrated intensities and the degree of preferred orientation of the crystal aggregates in both zones of the bands were almost the same in value, but the fiber axes of the two zones were oriented in different directions. From these experimental observations and a consideration of the effect of the orientation of the enamel prisms relative to the incident X-ray beam, it is concluded that the two zones of the bands were calcified evenly and the light and dark zones on the microradiographs were caused by the difference in the orientation of enamel prisms.