Effect of chair-side treatment with 172 nm vacuum ultraviolet light on the surface properties of three different implant materials

Abstract The establishment of an effective soft-tissue seal is crucial for the long-term stability of the implant-soft tissue interface. The surface properties of dental implants play a critical role in modulating early cellular responses, facilitating the formation of a stable soft-tissue seal. This study aims to investigate the effects of 172 nm vacuum ultraviolet (VUV) chair-side irradiation on the physicochemical properties of smooth surfaces of zirconia, pure titanium and titanium alloy (Ti6Al4V) implants. Furthermore, it explores how these changes influence the biological behaviors of human gingival fibroblasts (HGFs), including proliferation, adhesion, spreading and protein secretion. Implant materials were irradiated with VUV light for 20 s. Contact angle measurements, scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) assessed changes in hydrophilicity, surface morphology and elemental composition. The Cell Counting Kit-8 (CCK-8) evaluated HGFs proliferation, while SEM and immunofluorescence analyzed cell morphology, adhesion and spreading. The enzyme-linked immunosorbent assay (ELISA) measured the secretion of type I collagen (Col-I) and fibronectin (FN). VUV treatment effectively removed hydrocarbon contamination and improved hydrophilicity without altering surface morphology. After VUV irradiation, the contact angles decreased by 65.1% for zirconia, 54.5% for pure titanium and 67.7% for Ti6Al4V. XPS analysis revealed a decrease in carbon content by 47.56% for zirconia, 14.02% for pure titanium and 49.41% for Ti6Al4V, while oxygen content increased by 41.67% for zirconia, 17.02% for pure titanium and 72.28% for Ti6Al4V. Compared to untreated materials, VUV treatment enhanced HGFs proliferation after 3 days. In addition, cell adhesion and spreading significantly increased on treated surfaces, with cell area increasing by 44.7% for zirconia, 16.5% for pure titanium and 24.6% for Ti6Al4V at 24 h. At 12 h, SEM showed improved cell morphology with better spreading and attachment on VUV-treated materials. After 3 days, VUV-treated zirconia showed reduced Col-I and FN secretion, pure titanium exhibited reduced Col-I secretion, whereas Ti6Al4V showed increased FN secretion. These results indicate that VUV chair-side treatment improves both the surface properties and biological behavior of implant materials, potentially enhancing the soft tissue sealing effect around the implant necks.