Zirconia implants with improved attachment to the gingival tissue.

Gingival tissue attachment is known to be important for long-term prognosis of implants. This in vitro study evaluated the gingival attachment to zirconia implants and zirconia implants modified with sol-gel derived TiO2 coatings. Zirconia endodontic posts (n = 23) were used to function as implants that were inserted into the center of full-thickness porcine gingival explants (n = 31). The tissue/implant specimens were then individually placed at an air/liquid interface on a stainless-steel grid in cell culture wells containing a nutrient solution. The tissue cultures were incubated at 37°C in a 5% CO2 environment and at days 7 and 14, the specimens were harvested and analyzed by dynamic mechanical analysis (DMA) measurements under dynamic loading conditions mimicking natural mastication. Specimens were also analyzed by immunohistochemical staining identifying the laminin (Ln) γ2 chain specific for Ln-332, which is known to be a crucial molecule for the proper attachment of epithelium to tooth/implant surface. Tissue attachment to TiO2 -coated zirconia demonstrated higher dynamic modulus of elasticity and higher creep modulus, meaning that the attachment is stronger and more resistant to damage during function over time. Laminin γ2 was identified in the attachment of epithelium to TiO2 -coated zirconia. Both DMA and histological analysis support each other, so the gingival tissue is more strongly attached to sol-gel derived TiO2 -coated zirconia than uncoated zirconia. Immunohistochemical staining showed that TiO2 coating may enhance the synthesis and deposition of Ln-332 in the epithelial attachment to the implant surface.