Characterization of Temporary and Permanent 3D-Printed Crown and Bridge Resins

Abstract

3D-printing opens new possibilities for workflow and materials in restorative dentistry. The aim of this study was to evaluate mechanical, surface and optical properties of two 3D-printed crown and bridge resins, Temp PRINT (for temporary restorations) and CROWNTEC (for permanent restorations). Additionally, the study assessed the effects of printing orientation and accelerated hydrothermal aging on their mechanical properties. Specimens were 3D-printed using DLP technology. The evaluated mechanical properties were flexural strength, compressive strength and fracture toughness. Surface hardness and two-body wear were evaluated. Translucency parameter, light penetration and gloss were the evaluated optical properties. Scanning electron microscopy was used to analyze the microstructure of the materials. Data were analyzed using ANOVA and Tukey’s post-hoc. Hydrothermal aging, printing orientation and material type significantly affected the flexural strength values (p<0.05). Temp PRINT showed superior mechanical properties compared to CROWNTEC. The inherent layered structure of a 3D-printed specimen was found to compromise its strength in hydrothermal aging. There was a statistically significant difference in translucency between the materials. There was no significant difference in gloss after polishing. With the temporary material performing mechanically better than the permanent material, the classification of these materials by their manufactures can be questioned. However, CROWNTEC showed greater translucency, and could thus be considered more aesthetically pleasing. Printing orientation affected flexural strength but didn’t have an influence on fracture toughness.