Bone mineral dissolution is a highly complex process due to large chemical and structural heterogeneity of bone tissue. To better understand this process, we have studied in detail the demineralization of different avian bone types (cortical and medullary bone) that have large differences in bone mineral chemistry, organic matrix composition and structure. We have followed chemical and structural changes occurring during demineralization using optical and electron microscopy, two-dimensional (2D) X-ray diffraction, and infrared spectroscopy. During demineralization, there was a selective dissolution of poorly crystalline bone mineral rich in labile carbonate that is associated to less mature and highly reactive bone tissue. Medullary bone mineral, which is poorly organized and has lesser crystallinity, dissolves much more rapidly than cortical bone mineral, which is highly organized and has a greater crystallinity. Differences in crystallinity cannot explain alone the extremely large differences in the solubility of the mineral in these two types of bone. Bone organic matrix composition and its structural relationship with the mineral in medullary bone could explain its greater solubility. The information obtained in this study can help to better understand the dynamics of bone chemistry during remodeling as well as bone mineral alteration processes in natural environments.

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