Peri-implant bone formation of non-thermal atmospheric pressure plasma-treated zirconia implants with different surface roughness in rabbit tibiae.

OBJECTIVES: The aim of this study was to evaluate and compare the osseointegration of powder-injection molded (PIM) zirconia implants in rabbit tibiae with or without He plasma treatment. MATERIAL AND METHODS: Twenty-five rabbits received 4 types of external hex implants with identical geometry in the tibiae: PIM zirconia implants, roughened PIM zirconia implants, plasma-treated PIM zirconia implants, and plasma-treated roughened PIM zirconia implants. The contact angles of the four types of implants were evaluated. Removal torque tests and histomorphometric analyses were performed. RESULTS: The plasma treatment markedly enhanced the hydrophilicity, but did not seem to change the surface topography of the PIM zirconia implants. There were statistically significant differences in the bone-to-implant contact (BIC) ratios, bone volume (BV/TV), and removal torque values (RTQ) among the tested implant types (P < 0.001). The plasma-treated implants exhibited significantly higher BIC and BV/TV values than the untreated implants. However, the removal torque values favored the rough surface. CONCLUSIONS: The He plasma treatments on PIM zirconia implants made the surface more hydrophilic and enhanced the osseointegration of the implants without changing the micro-topography.