HRTEM Study of the Mineral Phases in Human Cortical Bone

Although bone minerals have been widely studied by various techniques in previous studies, crystal structures and morphology of bone minerals remained as controversy. In this study, bone minerals were extracted from human cortical bone with ethylenediamine tetraacetic acid solution (pH 7.4, ambient temperature) and examined by high‐resolution transmission electron microscopy. The results showed that the majority of bone minerals were flake‐like and a few were needle‐like. Most of flake‐like minerals were less than 100 nm in their largest dimension and the needle‐like minerals have a width of ∼10 nm. Hydroxyapatite structure was identified in relatively thick bone minerals. However, octacalcium phosphate structure was identified in relatively thin flake‐like bone minerals. Moreover, central dark line defect similar to that reported in dentin and enamel crystals was observed in some of needle‐like bone minerals.