3D-Printed Nanocomposite Denture-Base Resins: Effect of ZrO2 Nanoparticles on the Mechanical and Surface Properties In Vitro

Abstract

Due to the low mechanical performances of 3D-printed denture base resins, ZrO2 nanoparticles (ZrO2NPs) were incorporated into different 3D-printed resins and their effects on the flexure strength, elastic modulus, impact strength, hardness, and surface roughness were evaluated. A total of 286 specimens were fabricated in dimensions per respective test and divided according to materials into three groups: heat-polymerized as a control group and two 3D-printed resins (NextDent and ASIGA) which were modified with 0.5 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% ZrO2NPs. The flexure strength and elastic modulus, impact strength, hardness, and surface roughness (µm) were measured using the three-point bending test, Charpy’s impact test, Vickers hardness test, and a profilometer, respectively. The data were analyzed by ANOVA and Tukey’s post hoc test (α = 0.05). The results showed that, in comparison to heat-polymerized resin, the unmodified 3D-printed resins showed a significant decrease in all tested properties (p < 0.001) except surface roughness (p = 0.11). In between 3D-printed resins, the addition of ZrO2NPs to 3D-printed resins showed a significant increase in flexure strength, impact strength, and hardness (p < 0.05) while showing no significant differences in surface roughness and elastic modulus (p > 0.05). Our study demonstrated that the unmodified 3D-printed resins showed inferior mechanical behavior when compared with heat-polymerized acrylic resin while the addition of ZrO2NPs improved the properties of 3D-printed resins. Therefore, the introduced 3D-printable nanocomposite denture-base resins are suitable for clinical use.

Keywords: 3D printed resin; ZrO2 nanoparticles; denture base PMMA; mechanical testing; reinforcement.

Figure 1

FTIR spectra of ASIGA and NextDent groups at different ZrO₂ concentrations (0, 0.5, 1, 3, and 5 wt.%). The FTIR spectrum of pure PMMA specimen is also shown.

Figure 2

Flexural strength values and comparison between tested groups.

Figure 3

SEM images of ASIGA group at different concentrations of ZrO₂NPs (0, 0.5, 1, 3, and 5 wt.%). (A) pure PMMA, (B) 0 wt.% ASIGA, (C) 0.5 wt.% ASIGA, (D) 1 wt.% ASIGA, (E) 3 wt.% ASIGA and (F) 5 wt.% ASIGA. The scale bars are 100 μm.

Figure 4

SEM images of NextDent group at different concentrations of ZrO₂NPs (0, 0.5, 1, 3, and 5 wt.%). (A) pure PMMA, (B) 0 wt.% NextDent, (C) 0.5 wt.% NextDent, (D) 1 wt.% NextDent, (E) 3 wt.% NextDent and (F) 5 wt.% NextDent. The scale bars are 100 μm.

Figure 5

Elastic modulus values and comparison between tested groups.

Figure 6

Impact strength values and comparison between tested groups.

Figure 7

Hardness values and comparison between tested groups.

Figure 8

Surface roughness values and comparison between tested groups.