Influência do envelhecimento e do glaze na resistência de placas oclusais impressas confeccionadas por métodos digitais

Resumo (EN)

Objective: To evaluate the influence of aging and glazing on the strength of 3D-printed occlusal splints fabricated using different digital manufacturing methods. Materials and Methods: A total of 180 bars (64 mm × 10 mm × 3.3 mm) were fabricated according to ISO 20795-1. The specimens were divided into 16 groups: milled resins (control): G1 (polished), G2 (polished and glazed), G3 (polished and aged), and G4 (polished, glazed, and aged); printed resins from an open system (PriZma): G5 (polished), G6 (polished and glazed), G7 (polished and aged), and G8 (polished, glazed, and aged); printed resins from a closed system (DMG): G9 (polished), G10 (polished and glazed), G11 (polished and aged), and G12 (polished, glazed, and aged). The specimens were subjected to a three-point bending test in a universal testing machine until fracture or final displacement. Shapiro–Wilk, Chi-square, and Wilcoxon tests were applied, considering the manufacturing method, printing system, surface treatment, and aging as factors, with flexural strength defined as a continuous dependent variable. Results: A significant difference was observed between manufacturing methods, with milled resins (117 ± 7 MPa) showing superior performance compared to printed resins (105 ± 22 MPa; p < 0.001). Among the printing systems, the open system (PriZma) (110 ± 24 MPa) exhibited higher flexural strength than the closed system (DMG) (99 ± 18 MPa), with a statistically significant difference (p = 0.006), as well as a significant difference in the occurrence of catastrophic fractures (3% vs. 55%, respectively; p < 0.001). Glazing significantly increased flexural strength (113 ± 18 MPa) compared to non-glazed specimens (105 ± 19 MPa; p < 0.001), without affecting the fracture rate (p = 0.6). Artificial aging significantly increased the fracture occurrence from 38% to 69% (p < 0.001), without altering the mean flexural strength (109 ± 12 MPa for the non-aged group and 109 ± 24 MPa for the aged group; p = 0.10). Printed groups exhibited higher coefficients of variation, reaching up to 28.84% for the open system (PriZma) and 20.63% for the closed system (DMG), whereas milled groups showed lower dispersion, with values up to 6.97%. Conclusion: The mechanical performance of the resins is strongly influenced by the manufacturing method and as a result of aging, with milled resins showing greater reliability. Dimensional standardization alone does not guarantee improved performance, while glazing increases flexural strength without reducing the occurrence of fractures.