Influence of different post-washing solutions on the mechanical and surface properties of 3D-printed material for definitive restorations: An in vitro study.

OBJECTIVE

To assess the influence of three different wash solutions on the flexural strength (FS), elastic modulus (E), surface microhardness (VHN), surface roughness, water sorption (Wsp), and solubility (Wsl) of a 3D-printed glass-reinforced composite resin (3D-CR).

METHODS

VarseoSmile Crown Plus was printed at a 50 µm layer thickness and a 90° build angle. Three test groups were formed based on the ultrasonic bath wash solution: InovaPrint Wash (Group 1), 96 % ethanol (Group 2), and 90 % denatured ethyl alcohol (Group 3). Thirty bar-shaped specimens (25 × 2 × 2 mm3), ten per group, were produced to measure FS and E using a three-point bending test, while five disk-shaped specimens (Ø 15 × 3 mm2) per group were employed to evaluate VHN. Both tests were conducted under dry conditions. Additionally, another set of five specimens (Ø 15 × 3 mm2) per group was used to assess surface roughness before and after simulated toothbrushing, while five disk-shaped specimens (Ø 15 × 1 mm2) were utilized to determine Wsp and Wsl over 28 days. Kruskal-Wallis and Bonferroni post hoc tests were applied for statistical group comparisons.

RESULTS

The Kruskal-Wallis test showed a significant difference between the groups in terms of FS (p = .008), E (p = .004) and in VHN (p = .001). Variations among groups were notable in Wsp and Wsl at 21 and 28 days (p = .001). Regarding the surface roughness, the specimens exhibited values surpassing the clinical acceptability threshold (0.2 μm) before and after brushing.

CONCLUSIONS

These findings underscore the importance of selecting appropriate washing protocols to optimize the long-term performance of 3D-printed composite resins.

CLINICAL IMPLICATION: Optimizing the washing protocol can mitigate the degradation of mechanical and surface properties in 3D-printed composite resins. This is a critical consideration for ensuring the long-term success of definitive restorations.