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).

CONCLUSIONS

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.

CLINICAL SIGNIFICANCE: Radiopaque 3D-printed models are particularly valuable in CBCT-guided treatment planning and guided implant surgery. Adequate radiographic visibility enables accurate visualization of the printed model relative to the patient's anatomy, facilitating the assessment of implant position, angulation, and depth during virtual planning. Furthermore, radiopaque surgical guides allow verification of guide seating and sleeve alignment on CBCT images, reducing the risk of undetected misfit and subsequent surgical inaccuracies.