X-ray diffraction studies of bone apatite under acid demineralization

The analysis of the X-ray diffraction line broadening used to determine bone apatite crystallite size and lattice microstrain can provide information about the substructure of the bone mineral under differing real or simulated conditions. The paper discusses modifications in the bioapatite crystals observed in the bone subjected to demineralization in a 0.1 N HCl solution. Planar oriented specimens of mature bone with the analyzed surface normal to the longer bone axis were treated for varied immersion times. The crystallite size and the lattice microstrain were determined simultaneously by Fourier analysis of the X-ray diffraction line profiles. Both were observed to decrease during the acid demineralization. These findings support the idea that the distribution of lattice imperfections in the bulk of bioapatite crystals is highly nonuniform, with crystallite surface regions richer in imperfections dissolving more readily. In addition, an approach is proposed suitable for rough estimation of the reaction front advancement by demineralization-induced variations in the integrated intensity or shift in the position of the (002) and (004) diffraction lines. (C) 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.