Evidence of noncentrosymmetry of human tooth hydroxyapatite crystals

Herein, we investigate human single hydroxyapatite crystals (enamel and dentine) by convergent-beam electron diffraction (CBED) and automated electron-diffraction tomography (ADT). The CBED pattern shows the absence of the mirror plane perpendicular to the c axis leading to the P63 space group instead of the P63/m space group considered for larger-scale crystals, this is confirmed by ADT. This experimental evidence is of prime importance for understanding the morphogenesis and the architectural organization of calcified tissues. Human single hydroxyapatite crystals (enamel and dentine; see figure) were investigated by convergent-beam electron diffraction (CBED) and automated electron-diffraction tomography (ADT). The CBED pattern shows the absence of the mirror plane perpendicular to the c axis leading to the P63 space group instead of the P63/m space group considered for larger-scale crystals. This is confirmed by ADT. This experimental evidence is of prime importance for understanding the morphogenesis and the architectural organization of calcified tissues. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim