Effect of the Printing Angle on Flexural Strength, Microhardness, and Surface Roughness of Three-Dimensionally Printed Resin for Provisional Restorations

Abstract

Objective: To evaluate the influence of three angles (0°, 45°, and 90°) on the mechanical properties and surface characteristics of the specimens produced by a 3D printer and resin for provisional restorations. Material and Methods: In this in vitro study, ten bars (4 × 2 × 10 mm) were produced for each experimental group (n = 10), designed in the Meshmixer software and printed on a 3D printer. The bars were tested immediately, without aging. They were subjected to a three-point bending test in a universal testing machine, and the surface roughness was measured by a contact profilometer. Microhardness was measured by a microhardness tester and the surface roughness of the specimens was evaluated with a scanning electron microscope. Results: The flexural strength of the 0° group (236.20 ± 29.73) was significantly higher than those of the 45° (155.80 ± 36.19) and 90° (138.70 ± 48.20) groups. Similarly, the surface roughness of the 0° group (0.10 ± 0.06) was significantly lower than the 45° (1.62 ± 0.55) and 90° (0.97 ± 0.22) groups. Microhardness was similar among the groups. Conclusion: The 0° angulation, with deposition of the layers on the printed object so that they are oriented perpendicular to the direction of application of forces, resulted in the best resistance to bending and lower roughness, which may contribute to better clinical behavior.

Keywords

• Printing, Three-Dimensional
• Flexural Strength
• Stereolithography