Influence of 3D printed surface micro-structures on molding performance and dental bonding properties of zirconia
Cunliang Zhang1, Jiali Meng2, Li Zhang1
1Department of Prosthodontics, Nanjing Stomatological Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China.
Objectives:
To investigate the influence of the 3D printed micro-structured surfaces on the bond strength of zirconia to resin cement.
Methods:
Zirconia specimens were divided into five groups based on manufacturing technique and surface preparation: (1) milled zirconia (M group); (2) milled zirconia airborne abraded (MA group); (3) printed zirconia (M group); (4) printed zirconia airborne abraded (PA group); and (5) printed zirconia with micro-structured surface (PM group). The surface morphology, cross-sectional morphology, and elemental composition were observed using a scanning electron microscope (SEM). Surface roughness was measured using a laser scanning confocal microscope (SLCM). Shear bond strength (SBS) was measured using a universal testing machine after bonding resin cement (n = 10). The failure modes of the bonded fracture interfaces were observed and counted using a stereomicroscope and a SEM. In addition, boundary dimensional accuracy (n = 10) and micro-structural dimensional accuracy (n = 20) of printed zirconia specimens with micro-structured surfaces were measured using digital calipers and Fiji software. The crystalline phase changes before and after surface treatment were investigated using X-ray diffractometry. Data was analysed using one-way ANOVA and Tukey HSD post-hoc tests (α = 0.05).
Result:
The surface micro-structures of the PM group had regular morphology and no obvious defects. The surface roughness results showed that the PM group had higher Sa (42.21±1.38 um) and Ra (21.25±1.80 um) values than the other four groups (p < 0.001). The SBS test showed that the bond strength of the PM group reached 11.23 ± 0.66 MPa, which was 55.97% (p < 0.001) higher than that of the P group (7.20 ± 1.14 MPa). The boundary dimensional accuracy of the PM group was proficient (diameter: 99.63 ± 0.31%, thickness: 98.05 ± 1.12%), and the actual fabrication dimensions of the hexagonal micro-structures reached 77.45%-80.01% of the original design. The micro-structured surface did not affect the crystalline phase of zirconia.
Conclusions:
The current study illustrates that 3D-printed microstructured surfaces effectively improve the bond strength of zirconia to resin cements.
Clinical Significance:
With the advantage of 3D printing, this study provides a new idea for improving the bonding properties of zirconia.
