Effect of Printing Orientation and Postcuring Time on the Flexural Strength of 3D‐Printed Resins

Abstract

To evaluate the effect of printing orientation combined with different postcuring times on the flexural strength of 3D-printed resins. Materials and methods: A total of 480 rectangular specimens with the dimensions of 64×10×3.3 mm were designed and fabricated from two 3D-printed acrylic resins and one heat-polymerized resin (HP). 3D-printed groups were divided into 3 groups according to printing orientations (0-, 45-, 90-degree); each group was subdivided into 4 groups according to postcuring time (30, 60, 90, 120 min.). All specimens were subjected to thermal cycling (10,000 cycles) before testing flexural strength. Fractured surfaces were examined under a scanning electron microscope (SEM). ANOVA and Tukey's post hoc tests were used for data analysis (α = 0.05). Results:The result of this study showed that the highest flexural strength values of 3D-printed resin (NextDent, and ASIGA) were in 0-degree groups. Also, the flexural strength values increased when postcuring time was increased, regardless of the printing orientation; the highest flexural strength was recorded at 120 minutes postcuring time in all orientations. SEM analysis showed a rougher surface with irregular lamellae which represented a ductile fracture confirming that high energy is required for crack propagation and these features markedly increased as postcuring time increased. Conclusion:The results showed that the 0-degree orientation groups showed higher flexural strength compared to other groups. Similarly, with increased postcuring time, the flexural strength increased.

Fracture Load of 3D-Printed Interim Three-Unit Fixed Dental Prostheses: Impact of Printing Orientation and Post-Curing Time

“…In the 45° orientation, the printing layers are in an oblique direction instead of parallel, which may also explain the increased fracture load [ 38 , 40 ]. This finding is in agreement with previous studies [ 38 , 46 , 47 , 48 ]. Turksayar et al [ 38 ] reported the highest fracture strength in the 0° orientation (1094.80 N), which is close to the 30 min groups with all printing orientations.…”

Strength and Wear Behavior of Three-Dimensional Printed and Prefabricated Denture Teeth: An In Vitro Comparative Analysis

“…In this study, the printing parameters were standardized for all printed resins like 50µm layer thickness and 0-degree printing orientations. 35 In previous studies, 35,36 vertical or horizontal printing orientation were suggested. However, 0 degree was recommended by the manufacturer to make the load applied perpendicular to printing layer orientations as the specimens (full printed teeth no plate or disc specimens) placed on the testing machine with the same printing direction (►Fig.…”

“…While other orientations (45 and 90 degrees) made the load parallel to the printing layer directions which maybe results in layer separations that affect teeth properties. 36 However, this explanation could be considered with cautions as there are no studies that investigated the effect of printing orientations on denture teeth properties.…”

Comparative Evaluation of Surface Roughness and Hardness of 3D Printed Resins

“…For heat-polymerized (HP) denture base resin, specimens were prepared using a water bath conventional method as detailed in a previous study [ 29 ]. For 3D-printed resins, the disc specimen was designed virtually and then exported as standard tessellation language (STL) files to 3D printing systems (ASIGA and NextDent printers) [ 30 ]. The study design, including printing parameters and specifications, are listed in detailed in Figure 1 .…”