The nanostructure of an electrochemically deposited hydroxyapatite coating

The structure of an implant's coating can significantly affect its physical and chemical properties, and eventually its clinical performance. In this paper, the nanostructure of an electrochemically deposited hydroxyapatite (EDHA) coating was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The X-ray analysis showed that the coating consisted predominantly of the stoichiometric HA phase. However, SEM and HRTEM revealed that EDHA coating is composed of two distinct regions: the upper layer consisted of platelet crystallites preferentially grown perpendicular to the substrate surface, while the lower layer was dense and uniform and consisted of nano-sized crystallites of HA. The possible effects of these different microstructures on the implant's after-implantation behavior are discussed. (C) 2011 Elsevier B.V. All rights reserved.