Evaluating the impact of print orientation and layer thickness on mechanical properties of three-dimensional-printed...

Layer thickness and print orientation are important printing considerations that influence the mechanical performance of additively manufactured denture base resins. However, evidence regarding their combined effects remains limited. The study investigated the influence of print orientation and layer thickness on the flexural strength, fracture toughness, surface roughness, and impact strength of an additively manufactured digital light processing (DLP) denture base resin.

In vitro comparative study.

Using a DLP-based three-dimensional printing system, 384 denture base resin specimens were manufactured with three build orientations (0°, 45°, and 90°) and four printing layer heights (25, 50, 75, and 100 µm). Flexural strength and elastic modulus were assessed using a three point bend test, fracture toughness using a pre-notched three point bending test, and Izod impact tester was used to estimate the impact strength. Surface roughness was evaluated with a stylus profilometer, and fractured surfaces were examined using scanning electron microscopy.

Two-way analysis of variance and Bonferroni adjusted post hoc comparisons.

Both layer thickness and print orientation significantly influenced all tested properties ( P < .001). The highest flexural strength (127.71 ± 1.83 MPa), fracture toughness (1.49 ± 0.02 MPa·m 0 · 5 ), and impact strength (10.58 ± 0.15 kJ/m 2 ) were observed at 25 µm and 45° orientation, whereas the lowest values were recorded at 100 µm and 90°. Surface roughness increased with increasing layer thickness, with the smoothest surface at 25 µm and 0° (Ra = 0.33 ± 0.01 µm) and the roughest at 100 µm and 90° (Ra = 0.95 ± 0.02 µm).

Fabrication at 25 µm layer thickness and 45° print orientation provided the most favorable mechanical performance for the additively manufactured DLP denture base resin.