Published online by Cambridge University Press: 15 March 2011
We have studied the polarized hydroxyapatite (HAp) whose surface was negatively or positively charged. In this study, we assessed the interfaces in vitro and in vivo periodically. As in vitro experiment, samples were immersed in simulated body fluid for 7 days and the surface was examined by scanning electron microscope (SEM). As in vivo experiments, cortical bone defects were created on the femoral trochanters and the condyles of the six Japanese white rabbits and the samples were implanted. The rabbits were sacrificed at 1, 2 and 4 W after the operation to analyze the surfaces by the SEM and the optical microscopy. In this study, a new thick apatite layer was formed on the negatively charged surface (N-surface) after 1week immersion in SBF in vitro. Besides, significant new bone formation was found at 2 weeks after the operation on N-surface in vivo, which was earlier than positively charged or non-polarized HAp surface. From this study negatively charged HAp surface by polarization accelerated the HAp crystal growth or the new bone formation. Thus, this N-surface will be promising for earlier fixation of the prosthesis or better recovery of the bone defect.