HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF AMORPHOUS CALCIUM-PHOSPHATE

''Amorphous'' calcium phosphate (ACP) from human tooth enamel and different synthetic materials has been analysed by high resolution electron microscopy (HREM). All the materials studied showed, in addition to a ''truly'' amorphous phase, other calcium phosphate phases such as poorly crystalline hydroxyapatite (OHAP), well crystallized OHAP and poorly crystalline CaO type phase. Such structural heterogeneities have not been observed before in ACP, and are only possible to be detected by HREM as this is the only technique able to analyse nanometre size materials in the real space.