The Inorganic Constitution of Bone

Abstract

The composition of the unit structure for the apatite compound of human bone is approx. [Ca8.5oMgo.25Nao.19][(P04)5.o7(C03)1.24](H20)2.o. The Ca ions may be replaced by Na. The approximate formula of dentine is [Ca8.38Mg,0.45Nao.16][(P04)5.34(C03)o.88](H20)2.o and that of human enamel is [Ca9.45Mgo.18Nao.11] [(PO4)5.97 (COa)o.45](OH)1.54(H20)o.46. Available evidence seems to indicate that bone contains a hydrated tricalcium phosphate type of compound rather than hydroxyapatite and that Na and carbonate are essential constituents.