Observation of Cells on a Simulated Titanium Surface with Transparency.

The main driving force of osseointegration on titanium implants is believed to be the calcification caused by cellular activity. However, owing to the opacity of bulk titanium, live cells on titanium surfaces cannot be observed using an inverted microscope. To overcome this limitation, this study proposes a transparent titanium thin layer as a simulated titanium surface that allows live-cell observation from below. The titanium layer was fabricated on a polystyrene culture dish by magnetron DC sputtering using a pure Ti(JIS1) target. The titanium layer was characterized by transparency, composition, structure, and wettability. Osteoblast-like cells were cultured in the titanium-coated dishes. The cell culture was observed periodically using an inverted microscope, and the images were compiled into time-lapse videos. Cells on the titanium layer were characterized by movement speeds and doubling times. The titanium-coated dish was transparent gray, and its transmittance profile was consistent with that of the polystyrene dish. The titanium layer showed similarities to bulk titanium surfaces in terms of composition and structure; that is, it showed an oxidized titanium outermost layer and titanium metal basal layer. The wettability of the titanium layer was hydrophilic with mean contact angles of 67.52°. Osteoblast-like cells successfully adhered to the titanium layer and proliferated to confluence. The time-lapse videos demonstrated active movement of the cells on the titanium layer, which suggested the involvement of the titanium surface in cellular motility. The cell culture on the titanium layer can be considered cell culture on a titanium surface. In short, the titanium layer enabled the acquisition of information for living cells on titanium that has either been unknown or analogically understood based on cell culture on polystyrene dishes.

Preparation of hydroxyapatite-granule- implanted titanium alloy composites with a cylindrical shape.

For uniformly implanting hydroxyapatite (HA) granules into curved surfaces of titanium alloy implants such as dental roots, a new superplastic forming system was developed. By fixing PVA films with HA granules on a die's curved inner surface, HA granules are uniformly scattered and hold on the surface. The pressing system has a couple of wedges that enable press load to act on the both sides of a cylindrical titanium alloy sample arranged with its long axis perpendicular to the direction of the load in the die, and thereby the sample to expand in its radius direction. This technique could uniformly press HA granules into all the curved surface of titanium alloy. As a result, HA-granule-implanted titanium alloy composites with a cylindrical shape were formed under the conditions of 1023 K, 1 h, 1960 N in vacuo.