Influence of printing orientation on the mechanical and surface characteristics of a novel 3D-printed definitive resin-based composite.

This study evaluated the effects of different printing orientations on the mechanical properties and surface roughness of a 3D-printed definitive resin-based composite (RBC) material. Bar shaped samples were fabricated from a 3D-printed RBC (VarseoSmile TriniQ) using three different build orientations (0°, 45°, and 90°) and lithium disilicate ceramic (IPS e.max CAD). Flexural strength and elastic modulus were evaluated using a three point bending test. Surface microhardness was assessed with a Vickers hardness test, and surface roughness was measured using a contact profilometer. Following mechanical testing, the sample surfaces and fractured regions were further examined by scanning electron microscopy (SEM) for topographic and fractographic evaluation. Statistical analysis was performed at α = 0.05 using one way ANOVA, with post hoc comparisons conducted using the Tamhane test. Significant differences were observed among the tested materials for all evaluated parameters (p < 0.001). IPS group demonstrated superior mechanical properties and lower surface roughness compared to the 3D-printed RBCs. Within the 3D-printed groups, the 0° build orientation exhibited higher flexural strength, whereas the 90° orientation showed increased surface hardness. Elastic modulus and surface roughness were not significantly influenced by printing orientation (p > 0.05). SEM analyses supported the quantitative findings by revealing a homogeneous and compact microstructure in IPS group and orientation-dependent surface and fracture features in the 3D-printed RBC groups. IPS e.max CAD demonstrated superior mechanical performance. The 0° orientation improved flexural strength, while the 90° orientation enhanced surface hardness, suggesting that build orientation should be selected according to the intended clinical function.