Characterization and Biocompatibility of Zirconia Surfaces Coated with TiO2 Nanotubes

Purpose: Given the inconclusive research regarding the quality of osseointegration of zirconia as compared to Titanium, we proposed that surface modification of zirconia surfaces coated with titanium nanotubes (ZrO2-TNT) may enhance biocompatibility and long-term success, and may still result in improved esthetic outcomes as compared to titanium implants in cases of thin gingival biotype and gingival recession. Methods: An investigation of the surface characterization and biocompatibility of a novel implant surface was performed. Titanium was deposited on zirconia discs using electron beam evaporation deposition. Electrochemical anodization for 10 minutes, 20 minutes, and 30 minutes resulted in the fabrication of three hybrid nanotube surfaces, to be compared to roughened zirconia and the non-nanotubular hybrid ZrO2-TiO2 surface. All five groups were characterized using FESEM, FTIRS, and WCA, and hMSCs cultured to investigate cellular response. Results: While samples anodized for 10 minutes appeared grey in color and had shorter nanotubes, samples became lighter in appearance as anodization time increased to 20 and 30 minutes due to the visibility of the underlying ZrO2 surface as more titanium is converted to translucent nanotubes. As a result, the hybrid titanium nanotube surface had improved translucency and esthetic appearance after 20 and 30 minute anodization. The 20 and 30 minute samples had less metal remaining as titanium was converted to translucent nanotubes, resulting in decreased risk of metal allergenicity. Longer nanotubes were noted with the 20 and 30 minute anodized samples, as well, increasing surface area for cell anchorage and drug loading. There was significant increase in cellular response in all hybrid ZrO2-TNT samples from Day 0 to Day 6 as compared to ZrO2. ZrO2-TiO2 and the 10 minutes anodized sample had significantly improved cellular response as compared to the 20 and 30 minutes anodized samples. Conclusion: There was significant increase in cellular response in all hybrid samples from Day 0 to Day 6 as compared to ZrO2. ZrO2-TiO2 and the 10 minutes anodized sample had significantly improved cellular response as compared to the 20 and 30 minutes anodized samples. However, the 20 and 30 minutes anodized samples still had improved cellular response as compared to ZrO2 with the added benefit of transparent titanium nanotubes for improved esthetic appearance and longer nanotubes for increased surface area.