Flexural Strength and Surface Properties of 3D-Printed Denture Base Resins—Effect of Build Angle, Layer Thickness and Aging

A variety of printable resins for denture bases are available, without detailed instructions on print parameters. This study aimed to evaluate the effect of the printing build angle and the layer thickness of 3D-printed denture base resins before and after thermocyclic aging on flexural strength values and surface properties. The flexural strength, surface roughness (Ra, Rz) and hardness (HM, HV2) of two 3D-printed denture base resins (Formlabs (FL) and V-print dentbase, VOCO, (VC)) were therefore compared to a conventionally pressed cold-curing control material (PalaXpress (PP)). The specimens were printed at a 0°, 45° or 90° build angle and the layer thickness was varied for FL at 50 and 100 µm and evaluated before and after thermocyclic aging (N = 200; n = 10). Differences in flexural strength values were analyzed using multifactorial ANOVAs (α = 0.05). The build angle and aging significantly affected the flexural strength of the 3D-printed denture base resins (p < 0.05), while the layer thickness showed no effect for FL (p = 0.461). The required threshold value of 65 MPa defined by ISO 20795-1 was exceeded by PP (70.5 MPa ± 5.5 MPa), by FL when printed at 90° (69.3 MPa ± 7.7 MPa) and by VC at 0° (69.0 MPa ± 4.6 MPa). The choice of an appropriate build angle for each material and printing technology is crucial for the flexural strength and consequently the clinical longevity of a printed denture base.