Assessment of cell compatibility and antibacterial activity of nano-ZrO2/carbon fibre-reinforced PEEK bioactive composite: an in vitro study.

BACKGROUND: The peri-implant seal established between a dental implant abutment and the surrounding gingival soft tissue, serves as the first line of defence against the oral environment. It is a critical determinant of the long-term stability and success of an osseointegrated implant. Carbon-fibre-reinforced polyetheretherketone (CFR-PEEK) is a promising alternative for metallic surgical implants. This in vitro study determined the optimal zirconia nanostructure on CFR-PEEK surfaces to enhance the response of human gingival fibroblasts (HGFs) and its antibacterial properties, thereby facilitating the peri-implant seal of gingival and dental implant abutments. MATERIALS AND METHODS: zirconium (Zr) ions were introduced into CFR-PEEK via plasma immersion ion implantation at different voltages and durations, denoted as Zr-1 (-15 kV, 2 h), Zr-2 (-30 kV, 2 h), and Zr-3 (-30 kV, 3 h). The materials were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). In vitro studies such as cell attachment assays, cytoskeleton morphology, wound healing assays, real-time PCR, and enzyme-linked immunosorbent assays were performed to evaluate HGFs compatibility. Standard plate counting assay, fluorescence staining, and real-time PCR of pathogenic genes expression were used to assess the samples’ antibacterial effects. RESULTS: SEM and XRD revealed the formation of ZrO2-embedded nanostructures on the CFR-PEEK surface. The contact angle test and AFM results demonstrated that the Zr-1, Zr-2 and Zr-3 exhibited slightly hydrophobic surfaces and Zr-1, Zr-2 and Zr-3 exhibited increased surface roughness. In vitro assays demonstrated that Zr-2 significantly enhanced HGF proliferation and migration than that of the CFR-PEEK, Zr-1, and Zr-3. HGFs on Zr-2 also exhibited HGF-related genes upregulation (FAK, ITGA2, ITGB1, VCL, FN1, COL-1A1), along with increased collagen secretion and higher FAK/p-FAK protein levels. Furthermore, Zr-2 effectively inhibited Porphyromonas gingivalis viability and downregulated its fimA gene expression. CONCLUSION: The Zr-2 surface optimally enhanced HGF adhesion, migration, proliferation, and collagen secretion, and its inherent antibacterial properties against P. gingivalis make it a compelling candidate for implant abutments.