Tetragonal and Cubic Zirconia Multilayered Ceramic Constructs Created by EPD

Accuracy, fit, and marginal quality of advanced additively manufactured and milled zirconia 3-unit fixed dental prostheses

STATEMENT OF PROBLEM

Advanced additive manufacturing (AM) of zirconia is an emerging technology that can explore the limitations of traditional computer-aided design and computer-aided manufacturing (CAD-CAM) milling techniques. However, a comprehensive evaluation of their differences in producing zirconia restorations, especially multi-unit restorations, is lacking.

PURPOSE

The purpose of this in vitro study was to compare the accuracy, fit, marginal quality, and surface roughness of zirconia 3-unit fixed dental prostheses (FDPs) by using advanced AM and 2 CAD-CAM milling materials.

MATERIAL AND METHODS

Based on the same CAD model, 30 3-unit posterior FDPs (n=10) were manufactured by using AM and 2 CAD-CAM milling materials (VT and UP). The accuracies of the total, intaglio, occlusal, axial, and marginal regions were calculated separately by comparing the scanned model with the design model by using 3-dimensional (3D) deviation analysis. The silicone layer was scanned to evaluate the marginal and intaglio fit in 3 dimensions. A 3D laser microscope was used for surface roughness detection, marginal quality assessment, and marginal defect measurement. The data were analyzed using ANOVA and the Tukey post hoc test (α=.05).

RESULTS

Compared with CAD-CAM milling, the AM group had higher accuracy and smaller positive deviations on the axial and intaglio regions (P<.001). Different manufacturing methods showed no statistically significant effect on the mean intaglio fit (P>.05), and all were within the clinically acceptable range (<100 µm). The intaglio gap was significantly higher than the target parameter in the occlusal regions. AM-fabricated FDPs had significantly higher surface roughness than milled ones, yet showed better margin quality with fewer marginal defects CONCLUSIONS: Compared with CAD-CAM milling, the advanced additively manufactured zirconia 3-unit FDPs provided better accuracy, improved margin quality, and clinically acceptable fit, but higher surface roughness, and may be a promising alternative for clinical applications.

New trends in the development of electrophoretic deposition method in the solid oxide fuel cell technology: theoretical approaches, experimental solutions and development prospects

The key features and challenges of the use of electrophoretic deposition for the formation of functional layers of solid oxide fuel cells are considered. Theoretical models and experimental results of the studies of electrophoretic deposition are presented. The analysis covers the physicochemical deposition mechanisms, methods for preparing suspensions and conditions necessary for obtaining thin-film electrode and protective single- and multi-layers with both dense and porous structure for solid oxide fuel cells. The prospects of theoretical simulations of the method and its potential practical applications are evaluated.

The bibliography includes 282 references.

Enhanced Mechanical and Electrochemical Performances of Silica-Based Coatings Obtained by Electrophoretic Deposition

To solve the existing problems of silicon dioxide (SiO₂) coating fabricated by the sol-gel method, such as complicated process, long production cycle, uncontrollable quality, etc., an improved electrophoretic deposition (EPD) combined with the sintering process was proposed to prepare SiO₂ coating on a dark nickel (Ni)-coated Q235 steel substrate. Silica sol was prepared by basic catalysis, containing silica of ∼130 g L^-1 with viscosities below 4 mPa s. Silica sol powder was characterized by the differential thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. EPD was applied to prepare SiO₂ coating on the Ni adhesive layer, followed by the sintering process to improve the compactness. In addition, the effects of EPD and sintering parameters were also evaluated. Potentiodynamic polarization and electrochemical impedance spectra were utilized to assess the corrosion behavior of the coating. The results showed that the EPD coating demonstrated excellent wear resistance when deposited at 15 V for 40 s and sintered at 400 °C for 45 min, exhibiting ∼6 μm thickness and a compact morphology. It also showed superior corrosion resistance with i_corr of 1.02 × 10^-7 A cm^-2, which was 2 orders of magnitude lower than that of dip-coating. Combining the EPD and sintering processes could shorten the fabrication period of SiO₂ inorganic coating and also improve the mechanical and corrosion properties, providing guidance for inorganic ceramic fabrication and showing potential for practical applications.

Biocompatible hollow-strut, silica enriched zirconia foams

BACKGROUND

Porous ceramic biomaterials structures are accepted components in applied research in the field of tissue engineering due to their mechanical properties being closer to structural tissue like bone or other properties related to improved biocompatibility.

OBJECTIVE

Hollow-strut, silica enriched zirconia foams were made by replication of polyurethane via impregnation with a suspension of zirconia-particles in polysiloxane.

METHODS

Two-step heat treatment allowed conversion of the precursor structures into hollow-strut ceramic foams which were tested for their biocompatibility using an osteoblast cell line. Further, the material was characterized via different spectroscopic (Raman-spectroscopy, EDX) and imaging (SEM, μCT) methods.

RESULTS

The material shows open cell porosity with hollow struts and sufficient structural integrity for handling and an expected chemistry as investigated by Raman and EDX spectroscopy. The material further supported cell growth and overall good biocompatibility.

CONCLUSIONS

The investigated composite foam shows promising properties and is potentially interesting as candidate material for future bone tissue engineering applications.