Effect of changing the internal structure on the mechanical properties of three-dimensional-printed custom tray material: An in vitro study

The main challenges to the widespread clinical application of three-dimensional (3D)-printed customized trays include cost and time limitations. This study examined how changing the internal structure of 3D-printed materials used for customized trays affects flexural strength (FS), flexural modulus (FM), manufacturing time, and material weight. Specimens (64 × 10 × 3.3 mm) were printed using a light-sensitive liquid resin. The internal structures of control specimens were completely filled, whereas the internal structures of test groups comprised vertical bars spaced 1 mm (Test 1) or 2 mm (Test 2) apart. Specimens were weighed and then subjected to a three-point bending test to evaluate their FS and FM. Data were analyzed using one-way ANOVA and Tukey's test, with Weibull analysis applied to FS values. Control specimens had the highest FS (106 ± 4 MPa), while Test 2 specimens demonstrated the highest FM (6101 ± 1407 MPa). No significant differences were found between Test 1 and Test 2 specimens in FS or FM. Test 2 specimens had the lowest mean weight (1440 ± 42 mg). Manufacturing times were 80 min for control and Test 1 specimens and 60 min for Test 2 specimens. Including spaces in the internal structure of 3D-printed custom tray material saves material and manufacturing time while maintaining mechanical properties.