Do the printing orientation angle and layer thickness influence the radiopacity of 3D-printed dental resins?

This in vitro study aimed to evaluate the effect of layer thickness, printing orientation angle, and resin type on the radiopacity of 3D-printed dental resins.

Three dental 3D-printed resins (VarseoSmile TriniQ, Crowntec, and Primeprint Temp) were investigated using two-layer thicknesses (50 and 100 µm) and three printing orientation angles (0°, 45°, and 90°). Clearfil Majesty Posterior and Clearfil Majesty Flow composites were used as control materials. Standardized specimens (10 × 10 × 2 mm³) were radiographed together with 2-mm-thick human enamel and dentin sections and an aluminum step wedge using digital periapical radiography. Mean gray values were obtained with ImageJ and converted into aluminum equivalent thickness (mm Al). Data were analyzed using three-way ANOVA and Tukey post hoc tests (α = 0.05).

All tested materials showed radiopacity values significantly lower than enamel (3.332 ± 0.125 mm Al) (p<0.001). Compared with dentin (1.712 ± 0.079 mm Al), Primeprint Temp and VarseoSmile TriniQ exhibited significantly lower radiopacity, whereas Crowntec showed significantly higher values. Crowntec demonstrated the highest radiopacity among the 3D-printed resins, while Primeprint Temp presented the lowest. Printing orientation angle and layer thickness had no significant effect on radiopacity. Significant differences were found between the 3D-printed resins and the control composite materials.

Radiopacity significantly differed among the evaluated 3D-printed resins; however, printing parameters such as layer thickness and printing orientation angle did not influence radiopacity. Conventional composite resins exhibited significantly higher radiopacity than all tested 3D-printed resins and natural dental tissues.