Abstract
Objectives: This in vitro study evaluated whether the shear bond strength (SBS) of resin cement to 3D-printed zirconia can be improved by combining digitally customized surface textures with standard surface treatments, and compared these outcomes with conventional milled zirconia and lithium disilicate subjected to established bonding protocols. Methods: Sixty disk-shaped specimens were fabricated and divided into six groups: milled lithium disilicate (MLD), milled 3Y zirconia (MZ), additively manufactured 3Y zirconia without surface texture (AMZ-0), and 3D-printed zirconia with customized porosity patterns of 200 × 200 μm (AM-200), 100 × 100 μm (AM-100), and 50 × 50 μm (AM-50). All specimens were tested for SBS before and after thermocycling (5000 cycles; 5 °C-55 °C). Data were analyzed using two-way ANOVA and Tukey's post hoc test (α = 0.05), with descriptive statistics reported as mean ± standard deviation (SD). Results: A significant difference in SBS was observed among groups (p < 0.001). The MLD group exhibited the highest bond strength before and after thermocycling, followed by AM-200, which maintained high SBS values and moderate degradation after aging. MZ and AM-100 showed intermediate results, while AMZ-0 demonstrated the lowest bond strength across all conditions. Thermocycling significantly reduced SBS in all groups; however, specimens with optimized surface characteristics (AM-200) retained superior bond stability compared with unmodified zirconia. Conclusions: Both surface texture customization and material composition critically influence the adhesive performance of 3D-printed zirconia. Among the tested designs, the AM-200 configuration achieved the best balance between adhesion and thermal stability, rejecting the null hypothesis. Clinical significance: Digital tailoring of surface micro textures represents a promising strategy to enhance the long-term bonding reliability of 3D-printed zirconia restorations, potentially broadening their clinical applicability in fixed and conservative prosthetic treatments.