Adhesion Properties of Human Oral Epithelial-Derived Cells to Zirconia

Objectives: To evaluate the adhesion properties of zirconia materials for epithelial cell attachment and compare this with titanium and alumina.
Methods: Human oral epithelial cells were cultured on smooth-surfaced specimens of commercially pure titanium (cpTi), ceria-stabilized zirconia/alumina nano-composite (P-NANOZR), yttria-stabilized zirconia (Cercon) and alumina oxide (inCoris AL). The cell morphology, the cell viability and mRNA of integrin β₄, laminin γ₂, catenin δ₂ and E-cadherin was evaluated by SEM, Cell-Counting Kit-8, and real time PCR, respectively
Results: Morphology of cells attached to specimens was similar among all groups. The viable cell numbers on Cercon and inCoris AL after 24 hours culture were significantly higher than for cpTi. Integrin β₄, laminin γ₂ and catenin δ₂ mRNA expression was not different among all groups. However, at 3 and 24 hours after incubation, E-cadherin mRNA expression in the P-NANOZR group was significantly higher than for cpTi (P-NANOZR is 1.74- and 1.50- fold increase each compared with cpTi, P<0.05).
Conclusions: This study demonstrated that adhesion properties of epithelial cells for zirconia is comparable to Ti and alumina, and that zirconia is presumably capable of supporting the binding of epithelial cells through hemidesmosomes comparable to Ti, when used as an abutment and implant superstructure. Furthermore, P-NANOZR imparts resistance to exogenous stimuli through strong intercellular contacts with peri-implant mucosal cells.