The mineral in bone, dentin and tooth enamel

Abstract

AbstractDetailed knowledge about the constitution and the solubility behaviour of the mineral in calcified tissues is still lacking. This knowledge is important for the understanding of the behaviour of the mineral under physiological and pathological conditions. In this study literature data on the composition and particle size of the mineral are reviewed. Their predominantly apatitic nature goes back to hydroxyapatite as their prototype. However, other calcium phosphates, like whitlockite, are also important. The various analytical data on the content of Ca, P, Na, Mg and CO3 as the main components were analyzed for their consistency with a model of variable phase composition of the mineral. This analysis revealed that the probable phase composition of the mineral in dentin and bone is the same, but different from that in tooth enamel. Studies on the solubility behaviour indicate that near the physiological pH (7.4) all phases are solubility controlling simultaneously. This supports a physiological model according to which the body fluids are close to physicochemical equilibrium with bone mineral. Hence, changes in the chemical and phase composition of the mineral which occur under pathological conditions are related to changes in the activities of the relevant components in the surrounding body fluid. The latter depend mainly on cellular activity and organic transport activity. Attention is also paid to the anticariogenic effect of fluoride and the incorporation of that component in the mineral of fluorotic bone. This study is closed with some remarks about the use of synthetic analogues of biominerals as implants in dentistry and surgery.