Surface Characterization and Human Stem Cell Behaviors of Zirconia Implant Disks Biomimetic-Treated in Simulated Body Fluid

Purpose: This study investigated the effects of biomimetic deposition on a zirconia surface in simulated body fluid (SBF) and assessed the proliferation and differentiation of human bone marrow mesenchymal stem cells on the SBF-treated zirconia disks. Materials and Methods: Corrected SBF was prepared according to Kokubo's recipe. Eighty yttrium oxide-stabilized tetragonal zirconia polycrystalline disks were prepared and divided into two groups: (1) the test group with SBF-treated disks and (2) the control group with nontreated disks. Zirconia disks were soaked in SBF for 1, 4, 7, and 14 days at 36.5°C, and the hydroxyapatite (HA) precipitation was verified by analyzing the surface morphology. For more in-depth validation of HA formation, the surface roughness, composition, and crystallization of the 7-day treated disks were analyzed. Human bone marrow mesenchymal stem cells were used to further evaluate cell proliferation, alkaline phosphatase activity, and osteoblast gene expression on the 7-day treated zirconia disks. Results: Disks showed different surface morphologies after soaking for different time periods. As the SBF soaking time increased, the amount of HA coverage increased gradually, uniformly covering the disks by day 7. There was no difference in surface roughness between the two groups (P > .05). Cell proliferation was higher on the SBF-treated disks (P .05). At 9 days, alkaline phosphatase activity was higher on the SBF-treated disks (P .05). Alkaline phosphatase staining was significant on the SBF-treated disks (P .05). A gene study revealed that alkaline phosphatase and osteocalcin showed higher expression in SBF-treated disks (P .05); however, collagen type I and runt-related transcription factor 2 did not show significant differences between the two groups (P > .05). Conclusion: This study demonstrated that biomimetic deposition has an effect on the formation of HA on zirconia disks. The cell attachment, proliferation, and differentiation of SBF-treated zirconia disks was superior to that of nontreated disks, which indicates that SBF-treated zirconia implants have long-term clinical value. Keywords: cell proliferation, human mesenchymal stem cells, hydroxyapatite, osteoblast differentiation, simulated body fluid, zirconia implant