Characterization and In Vivo Evaluation of Trace Element-Loaded Implant Surfaces in Ovariectomized Rats

Purpose: The purpose of this work was to investigate the effect of a hydroxyapatite (HA) coating doped with zinc (Zn), magnesium (Mg), or strontium (Sr) on implant osseointegration in ovariectomized rats. Materials and Methods: The HA coating doped with trace elements was produced by electrochemical deposition. Surface properties were tested by field emission scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and measurement of ionic release. A total of 36 ovariectomized rats were randomly divided into four groups: the HA coating group, the Zn-HA coating group, the Mg-HA coating group, and the Sr-HA coating group. The corresponding implants were then inserted into the tibiae. Histomorphometric analysis was performed after 4, 8, and 12 weeks. Results: HA coatings doped with 2.5% Zn, Mg, or Sr by electrochemical deposition showed almost identical surface morphologies. Bone-implant contact (BIC) in the Zn-HA group was significantly greater than that in the HA group for all time periods. BIC values in the Sr-HA group significantly exceeded those in the HA group at 8 and 12 weeks after implantation. Bone ingrowth area values of both the Zn-HA and Sr-HA groups were statistically significantly different from those in the HA group after 8 and 12 weeks. Conclusion: The Zn-HA and Sr-HA coatings have the potential to improve implant osseointegration in osteoporosis. Keywords: electrochemical deposition, hydroxyapatite, osseointegration, trace elements