X-RAY POLE FIGURE ANALYSIS OF APATITE CRYSTALS AND COLLAGEN MOLECULESIN BONE

X-ray pole figure analysis was performed on apatite (AP) crystals in b one mineral and collagen molecules in the bone matrix. For AP in bone mineral, the (0002) plane (c-axis) and {21 (3) over bar 0} plane were examined. The diffraction peaks from both planes were well isolated fr om other diffraction peaks in the bone. To investigate the orientation of collagen molecules in the bone matrix, demineralized bone by EDTA treatment was used. For collagen, the diffraction peak from about the 0.3 nm period along the helix axis of the collagen molecule was invest igated. The c-axis of AP and the helical axis of the collagen molecule have strongly preferred orientations in a direction parallel to the b one axis. The c-axis of AP has an appreciable pole density peak in the radial and tangential direction of the bone, whereas collagen molecul es were almost uniaxially oriented in the bone axis direction though h aving an appreciable distribution. This suggests that there are more t han two types of morphology in the AP particle in bone mineral: one wi th the c-axis almost parallel to the bone axis and the other in which the c-axis is oriented almost perpendicular to the bone axis. The {21 (3) over bar 0} plane has isolated peaks of pole density in pole figur es in both radial and tangential directions. On the basis of the class ification of orientation for elongated polyethylene, the main portion of AP particles in bone is concluded to be biaxially oriented.