AGE AND TEMPERATURE-RELATED CHANGES TO THE ULTRASTRUCTURE AND COMPOSITION OF HUMAN BONE-MINERAL

This X-ray diffraction (XRD) investigation of heat-treated human femor al bone showed that the main mineral phase of both unheated bone and b one heated to 600 degrees C resembled that of a poorly crystalline for m of hydroxyapatite, The rod-shaped apatite crystals in unheated bone persisted in bone heated up to 400 degrees C, Recrystallization at app roximately 600 degrees C, produced larger crystals, which either retai ned their original morphology or changed to tabular or equidimensional shapes. The size of the apatite crystals in unheated and heated bone specimens was dependent on both temperature and age, When heated above 600 degrees C the crystallinity of the bone mineral increased, and th e XRD pattern more closely resembled that of hydroxyapatite, partial d ecomposition of the hydroxyapatite phase to calcium oxide above 1000 d egrees C, and beta-tricalcium phosphate, alpha-tricalcium phosphate, a nd calcium oxide phosphate between 1200 degrees C and 1400 degrees C, indicated that the original apatite phase was both calcium deficient a nd contained carbonate, The relative peak intensities of the thermal d ecomposition products were related to some extent to the age of the de ceased person and reflected the compositional changes that occur durin g bone aging, Because the thermally induced changes to the composition and ultrastructure of bone mineral were influenced by the age of the individual, this investigation proposed that the heat treatment of bon e tissue may offer an alternative way of studying bone aging.