Effect of glazed and polished 3Y-TZP and 5 mol% yttria-stabilized partially stabilized zirconia on fibroblast behavior: In vitro study

To evaluate and compare the viability, proliferation, and adhesion of HGFs on glazed and polished surfaces of 3 mol% yttria-stabilized tetragonal zirconia (3Y-TZP) and 5 mol% yttria-stabilized partially stabilized zirconia (5Y-PSZ). This in vitro experimental study was conducted to evaluate the viability, proliferation, and adhesion of HGFs on zirconia discs with different compositions (3Y-TZP and 5Y-PSZ) and surface treatments (glazed and polished). The study employed a comparative design with four groups based on the combination of material type and surface finish. Sixty-four zirconia discs (n = 16/group) were prepared in four groups: 3Y-TZP glazed, 3Y-TZP polished, 5Y-PSZ glazed, and 5Y-PSZ polished. HGFs were cultured on each specimen. Cell viability was assessed using MTT assay at 24 h and 7 days. Cell morphology and adhesion were analyzed using the scanning electron microscope (SEM). Statistical analysis was performed using the two-way analysis of variance (ANOVA) and Tukey's post hoc test. All groups showed >70% cell viability at both time points, indicating noncytotoxicity. Polished zirconia surfaces exhibited significantly higher cell viability than glazed surfaces at 7 days (P < 0.05), with 5Y-PSZ polished showing the highest viability (95.4%). SEM revealed better fibroblast spreading and filopodia formation on polished surfaces. Two-way ANOVA indicated significant effects of material type and surface finish on cell viability (P < 0.05). Polished zirconia surfaces, irrespective of yttria content, enhanced HGF viability and adhesion compared to glazed surfaces. These findings suggest that polishing promotes superior soft-tissue integration and may contribute to the long-term biological success of zirconia restorations.