Effect of build orientation on fracture load and surface roughness of three-unit provisional fixed partial dentures fabricated by digital light processing

OBJECTIVE: To evaluate the effect of build orientation on the fracture load and surface roughness of three-unit provisional fixed partial dentures (FPDs) fabricated by digital light processing (DLP). METHODS: In this in vitro study, standardized three-unit FPDs were designed and fabricated using a DLP 3D printer at three buccolingual angulations (150°, 180°, and 210°) and three mesiodistal angulations (0°, 15°, and 45°) (n = 12 per group). Surface roughness (Ra, µm) was measured using a profilometer, and fracture load (N) was determined using a universal testing machine. Surface roughness data were analyzed using three-way repeated-measures ANOVA, while fracture load data were analyzed using two-way ANOVA, followed by Tukey post hoc tests (α = 0.05). RESULTS: Buccolingual and mesiodistal angulations significantly affected surface roughness (p < 0.001) and fracture load (p < 0.001). The lowest surface roughness was observed at 210° buccolingual and 45° mesiodistal angulation, whereas the highest fracture load was recorded at 210° buccolingual and 0° mesiodistal angulation. The effect of location on surface roughness was not significant (p = 0.309). CONCLUSIONS: Build orientation significantly influences the surface and mechanical performance of 3D-printed provisional FPDs. The 210-degree buccolingual angulation showed favorable outcomes under specific mesiodistal conditions; however, the optimal mesiodistal angulation depended on the desired outcome, with 45 degrees improving surface smoothness and 0 degrees enhancing fracture resistance.