Optimizing dental resins radiopacity and surface properties via barium sulphate concentration and printing orientation.

OBJECTIVE: This study investigated 3D-printed models incorporated with silanized barium sulphate (BaSO₄) particles at varying concentrations, focusing on their radiopacity, surface roughness, and microhardness across different printing orientations. METHODS: BaSO₄ was incorporated into a 3D-printed model resin to create four groups: control, 5 wt%, 10 wt%, and 15 wt%. Each group was fabricated at three orientations (0°, 45°, and 90°) (n=10). Radiopacity was evaluated using cone-beam computed tomography (CBCT) through global histogram analysis. Surface roughness was measured with a contact profilometer, while microhardness was assessed using a Vickers hardness tester. Data were analyzed using two-way ANOVA and Tukey's post hoc test (α=0.05). RESULTS: Both BaSO₄ concentration and printing orientation significantly affected voxel intensity and distribution width (P < 0.001). Specimens printed at 0° consistently exhibited the highest modal intensity values, reaching 85.3% ± 1.9% of the grayscale spectrum and corresponding to the "Enamel" and "Metal" density ranges. Surface roughness was significantly influenced by all tested factors, with printing orientation showing the greatest effect (P < 0.0001, ηp² = 0.6). Microhardness increased with increasing BaSO₄ content regardless of printing orientation, with filler concentration exerting the strongest influence (P < 0.0001, ηp² = 0.8). CLINICAL SIGNIFICANCE: An integrated trade-off analysis indicates that a 10 wt% BaSO₄ concentration printed at 0° orientation relative to the scan plane provides the optimal clinical configuration. This configuration achieved the "Enamel" and "Metal" segmentation thresholds, produced a high-contrast modal density peak (85.3% ± 1.9%), maintained adequate microhardness, and minimized image noise, making it the most clinically favorable combination for CBCT-guided applications.