Biomechanical and histological studies of the effects of active zinc-coated implants by plasma electrolytic oxidation method on osseointegration in rabbit osteoporotic jaw

Abstract

The objective of this study was to fabricate an active zinc-containing coating on the surface of Ti implants by plasma electrolytic oxidation (PEO) method, and to explore its in vivo effects on osteogenesis at the sites of osteoporotic bone. Thread Ti implants treated by sandblasting and acid-etching were processed and divided into three groups according to different ions added into the electrolytes of the following PEO treatment: PEO-Zn/Ca/P, PEO-Ca/P and sandblasted (SLA) group (control). Surface morphology of the samples was observed by a field SEM with EDX spectrometer for elemental composition analysis. Ovariectomized animal models were established by using New Zealand white rabbits through bilateral ovariectomy. After ovariectomized outcomes were confirmed, different implants were inserted into ovariectomized rabbit mandibles. The result of pull-out test showed that maximum removal torque values of the PEO-Zn/Ca/P group were significantly larger than those of the control group at 2, 8, 10 weeks. Stereo microscope results suggested that the values of bone coverage in the PEO-Zn/Ca/P group were confirmed significantly larger than those of the other two groups at 2, 4, 12 weeks. Histological analysis indicated that maximum apposition ratio of the PEO-Zn/Ca/P group reached a peak value the earliest at 4 weeks, and the rates of bone implant contact ratio all presented as PEO-Zn/Ca/P > PEO-Ca/P > SLA at each time point. In conclusion, active zinc-coated implants by PEO method strengthened pull-out strength of implants, accelerated surrounding bone formation, and improved the amount of new bone formation in the rabbit model of osteoporosis.