Characterization of temporary and permanent 3D-printed crown and bridge resins.

PURPOSE

The aim of this study was to evaluate the mechanical, surface, and optical properties of two 3D-printed crown and bridge resins (CROWNTEC and Temp PRINT). Additionally, the study assessed the effects of printing orientation and accelerated hydrothermal aging on their mechanical properties.

MATERIALS AND METHODS

Specimens were 3D-printed using digital light processing technology (Asiga MAX™). Mechanical properties, including flexural strength (FS), compressive strength, and fracture toughness (FT), were determined for each material following ISO standards. Three printing orientations (0°, 45°, and 90°) were used for fabricating 3-point bending specimens. Surface hardness was evaluated using a Vickers indenter. Two-body wear tests were conducted using a ball-on-flat configuration in a chewing simulator with 15,000 cycles, and wear depth was measured with a non-contact 3D optical profilometer. Disk-shaped specimens ( = 5/material) were prepared to measure translucency parameter, gloss and light penetration. For gloss measurement, specimens underwent laboratory-machine polishing (4,000-grit abrasive paper) and chairside two-step hand polishing (Top Dent DiaComposite). Posterior composite crowns ( = 10/material) were fabricated and subjected to cyclic fatigue aging (5,000 cycles at Fmax = 150 N) before quasi-static loading to fracture. The microstructure of each material was analyzed using scanning electron microscopy (SEM). Data were statistically analyzed using ANOVA and Tukey's HSD test.

RESULTS

Hydrothermal aging, printing orientation, and material type significantly affected the FS values ( < 0.05). Temp PRINT showed superior FS (129 MPa) and FT (1.3 MPa m) compared to CROWNTEC (102 MPa, 0.9 MPa m), particularly at 0° orientation. Gloss measurements revealed no significant differences between materials ( > 0.05) across used polishing systems. SEM analysis demonstrated differences in microstructure between the materials.

CONCLUSION

Temp PRINT demonstrated superior mechanical performance compared to CROWNTEC, which exhibited higher translucency values. The printing orientation was identified as a critical parameter influencing the mechanical properties and overall performance of 3D printed restorations.