Continuous Mineral Matrices in Bone and Dentine

Summary

The classical model of the mineral component of bone and dentine envisages the hydroxyapatite phase to be in the form of discrete needle or plate like crystallites ~10’s nm by 100’s nm. Some authors have argued that these crystallites are intimately linked with the collagen fibres and it has been suggested that in bone the mineral might occupy the gap region between tropocollagen molecules. Such a model is inconsistent however with the observed properties of bone which retains its mechanical integrity following denaturation of the collagen phase. Recent results from this laboratory have led to support for a revised model of the structure of the mineral component of bone and dentine. Scanning electron micrographs of polished surfaces from which the collagen component has been preferentially removed by a collagenase solution have revealed a continuous matrix composed of contiguous spheroidal units. The smallest units are ~10–20nm across and these coalesce to form larger spheroidal units ~100nm across. These units aggregate to produce the macro structure of the bone and dentine.