1Bioengineering Department, Forsyth Dental Center, 140 Fenway, Boston MA USA
The relative magnitudes of mineral, organic and water contents of dense mammalian bone are calculated by a new theory based on recent findings
A computational model was developed based on the generalized packing model. It provides a unifying approach to explain many features of mineralized fibrous collagenous tissues. The results are presented as estimates of the mineralized collagen fibril density, the volume fraction of collagen in bone, the density of the extrafibrillar space, the fraction of the e.f. space occupied by mineral and the ratio of mineral within collagen to total mineral content, each expressed as a function of wet bone density.
A useful data base, available from previous studies, related mineral, organic and water weight fractions to wet bone density, for a density range from 1.7 g/cc for deer antler to 2.7 g/cc for porpoise petrosal. A second order polynomial was found for each weight fraction component, with bone density as the input variable, with a standard deviation less than 2% of total bone weight. This permits the bone properties to be related to a single variable, the wet bone density.
It is seen that compacting the collagen fibrils as well as reducing the organic component weight fraction are two important factors determining the structure of the mineralized osteoid. It was concluded that voids and pore spaces may occupy at least 5% of the bone volume.