Acceleration and Deceleration of Bone-Like Crystal Growth on Ceramic Hydroxyapatite by Electric Poling

摘要

The electric properties of HAp have long since been investigated for the understanding of its bioactive characteristics from the viewpoint of materials science. The mass transport mechanism was first studied by a complex impedance method for the crys-tallographical analysis of tooth caries, and the ion transport through the HAp structure has been attributed to the exchange of lattice positions of OH~- ions with lattice defects thereafter. An important hypothesis was also made based on the piezoelectric effect, that osteogenesis occurs by an ionic process driven by mechanical stress applied to bones; some studies have attributed the piezoelectricity of bones to incorporated water and fibrous collagens. Further analysis has thereafter been made through a series of thermally stimulated current studies, which have revealed that the polarizability of HAp originates from the reorienta-tion of the dipole moments between O~(2-) and H~+ of lattice OH~- ions. We have very now discovered the acceleration and deceleration of bone-like crystal growth on polarized ceramic HAp, depending on the electric polarization conditions.