ObjectiveThe study was designed to investigate the process of calcification during bone healing in a standardised rat calvarial bone defect model, measured by bone mineral density and the concentrations and distributions of calcium, phosphorus and carbon in the bone matrix.
Materials and methodsA standard defect was made on the parietal bone of 12-week-old rats under anaesthesia. The rats were fixed in weeks 1, 2, 4 and 8, and the calvaria were resected and examined with microcomputed tomography, then frozen and sectioned for histology and analysed with energy-dispersive X-ray spectroscopy (EDX). Parietal bone of 12-week-old control rats was processed similarly.
ResultsThe mineral density of healing bone increased with time. The healing bone became thicker and denser with time in histology. The distributions of Ca and P expanded over the bone matrix, whereas that of C became localised and complemented that of C and P. The Ca/P concentration ratio increased, whereas the C/Ca and C/P ratios decreased in the healing bone matrix.
ConclusionHealing bone is immaturely calcified initially and proceeds calcification gradually, that is, as the bone volume increases, mineral increases in density and matures in quality, while organic components decrease.