In Vivo Effect of Titanium Implants with Porous Zinc-Containing Coatings Prepared by Plasma Electrolytic Oxidation Method on Osseointegration in Rabbits

Purpose: The aim of this study was to confirm the in vivo effect of surface-modified titanium (Ti) implants with zinc (Zn) prepared by a plasma electrolytic oxidation (PEO) method on the process of osseointegration. Materials and Methods: Forty-five New Zealand white rabbits were used. Implants were divided into three groups due to different surface treatments (the PEO-Zn group, the PEO-calcium phosphorus [Ca/P] group, and the sandblasted [control] group) and were randomly inserted into rabbits' mandibles. The implant surface morphology and chemical state of the relevant elements were observed. The maximum push-out force, the bone-to-implant contact (BIC), and the mineral apposition ratio (MAR) were detected at 4, 8, and 12 weeks after implantation. Results: A two-layer structure, with a dense inner layer and a porous outer layer, was found in the PEO samples. In the PEO-Zn group, CaHPO4·2H2O (dicalcium phosphate dihydrate) was the main calcium compound, and ZnO was identified as the predominant form of Zn. More bone deposition was found on the top of the PEO-Zn implant, which was also confirmed by scanning electron microscope (SEM) afterward, and the shear strength reached a maximum value of 1.57 ± 0.26 MPa at 12 weeks compared with the sandblasted group and the PEO-Ca/P group. The BIC values and the MARs of the PEO-Zn group were significantly higher than the control group, especially at the early weeks (P .05), and first reached maximum values of 73.91% ± 9.01% and 4.89 ± 0.60 μm/d at 12 weeks, respectively. Conclusion: Implants with Zn coating by the PEO method could accelerate bone formation and bone remodeling, shorten the osseointegration period, and enhance bone-implant bonding force. Keywords: bone-to-implant contact, dental implant, mineral apposition ratio, osseointegration, plasma electrolyte oxidation, zinc