Epithelial Cell Attachment on TiO₂ Modified Zirconia Surface

Objectives: Good cell adhesion is an important prerequisite for soft tissue attachment on implant abutment or crown surface. The aim of this study was to evaluate the adhesion and proliferation of human epithelial cells on sol-gel derived TiO₂ coated and non-coated zirconia.

Methods: Altogether 56 zirkonia discs (Z-CAD, Metoxit, Swizerland) were fabricated for the study. Half of the discs were provided with a sol-gel derived TiO₂ coating (MetAlive™, ID Creations, Turku, Finland). The rest of the discs were non-coated and formed the control group. The cell adhesion was tested by cultivating epithelial cells (20 000/cm²) on the experimental discs for 1, 3, 6 and 24 hours, after which the fluorescence of the samples was measured (Biotek synergy HT). The amount of cells was detected by comparing the fluorescence value to the standard curve. In addition, the proliferation was studied by growing epithelial cells (25 000/cm²) for 1, 3 and 7 days. The number of cells was calculated by defining the absorbance of the samples (Multiskan EX, Themo Labsystems), followed by a comparison with the standard curve. Finally, the samples were processed for light microscopy.

Results: The amount of epithelial cells was greater on TiO₂ coated discs than on controls after 24 hours (p<0.05). Regarding the cell proliferation, the difference was statistically significant (p<0.05) on the days three and seven. Light microscope evaluation confirmed viable cells, which were in immediate close contact with both substrate surfaces. The cell layers on the coated discs appeared to be more uniform and cell rich than the layers on non-coated discs.
Conclusions: This study indicated that TiO₂ –coating improves epithelial cell attachment and proliferation on zirconia surface. This has good potential to enhance formation of epithelial junction to the coated zirconia surfaces.