An explanation for the "two fiber axes" problem in human enamel by x-ray diffraction.

Since Thewlis found the "two fiber axes" patterns on x-ray diffractograms of human enamel in 1934, many investigators have studied this problem. However, a definite answer has not yet been obtained. The present detailed x-ray diffraction study showed that the "two fiber axes" patterns in human enamel were caused by reflections from the two zones of the Hunter-Schreger bands being recorded simultaneously on x-ray film, because we used an x-ray beam far larger in size than the width of the Hunter-Schreger bands.