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The first step of the DRM reaction is just the decomposition of CH4 into CH4−x (x = 1–4). The next step comprises two steps, namely the oxidation of CH4−x into syngas (by CO2) and the self-polymerization of CH4−x species. The earlier one is known as dry reforming of methane (DRM), and the latter one generates carbon deposits over the catalyst surface. In this study, we investigated the impact of 1–3 wt% Sr over Ni-based catalysts on a ZrO2-WO3 support on the catalytic activity and coke deposit. Various characterization techniques such as thermogravimetric analysis, X-ray diffraction, Raman spectroscopy, temperature-programed oxidation, temperature-programed reduction, and temperature-programed desorption were used to assess the physicochemical properties of the fresh and spent catalysts. The addition of 2wt% Sr promoter significantly improves the catalyst's basicity in strong basic sites region through Sr2+ mediated interaction of CO2 species as well as inhibits the deposition of carbyne type carbon. Enhanced CO2 interaction results into the potential oxidation of carbon deposit and the highest CH4 conversion, reaching 60% up to 470 min TOS at a reaction temperature of 700 ℃. [ABSTRACT FROM AUTHOR]

Peri-implantitis continues to be one of the major reasons for implant failure. We propose a new approach to the incorporation of MTA into zirconia implant surfaces with Nd:YAG laser and investigate the biological and the microbiological responses of peri-implant cells. Discs of zirconia stabilized with yttria and titanium were produced according to the following four study groups: Nd:YAG laser-textured zirconia coated with MTA (Zr MTA), Nd:YAG laser-textured zirconia (Zr textured), polished zirconia discs, and polished titanium discs (Zr and Ti). Surface roughness was evaluated by contact profilometry. Human osteoblasts (hFOB), gingival fibroblasts (HGF hTERT) and S. oralis were cultured on discs. Cell adhesion and morphology, cell differentiation markers and bacterial growth were evaluated. Zr textured roughness was significantly higher than all other groups. SEM images reveal cellular adhesion at 1 day in all samples in both cell lines. Osteoblasts viability was lower in the Zr MTA group, unlike fibroblasts viability, which was shown to be higher in the Zr MTA group compared with the Zr textured group at 3 and 7 days. Osteocalcin and IL-8 secretion by osteoblasts were higher in Zr MTA. The Zr textured group showed higher IL-8 values released by fibroblasts. No differences in S. oralis CFUs were observed between groups. The present study suggests that zirconia implant surfaces coated with MTA induced fibroblast proliferation and osteoblast differentiation; however, they did not present antibacterial properties. [ABSTRACT FROM AUTHOR]

Background: Determination of the eligibility of several tooth analog materials for use in crown fracture testing. Methods: A standardized premolar crown preparation was replicated into three types of resin dies (C&B, low modulus 3D printed resin; OnX, high modulus 3D printed resin composite; and highest modulus milled resin composite). 0.8 mm zirconia crowns were bonded to the dies and the maximum fracture load of the crowns was tested. Twelve extracted human premolars were prepared to a standardized crown preparation, and duplicate dies of the prepared teeth were 3D printed out of C&B. Zirconia crowns were bonded to both the dies and natural teeth, and their fracture load was tested. Results: There was no statistical difference between the fracture load of zirconia crowns bonded to standardized dies of C&B (1084.5 ± 134.2 N), OnX (1112.7 ± 109.8 N) or Lava Ultimate (1137.5 ± 88.7 N) (p = 0.580). There was no statistical difference between the fracture load of crowns bonded to dentin dies (1313 ± 240 N) and a 3D-printed resin die (C&B, 1156 ± 163 N) (p = 0.618). Conclusions: There was no difference in the static fracture load of zirconia crowns bonded to standardized resin dies with different moduli or between a low modulus resin die and natural dentin die. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the optical properties and the relative translucency parameter of Ceramill ZI White (3Y‐TZP) and Ceramill Zolid FX White (5Y‐PSZ) zirconia ceramic systems and compare them with those of the bovine dentin and enamel/dentin structures. Materials and Methods: 3Y‐TZP and 5Y‐PSZ zirconia ceramic systems were evaluated. A 0.5‐mm‐thick 3Y‐TZP (3Y‐NC.5), 0.5‐mm‐thick (5Y‐NC.5), and 1.4‐mm‐thick (5Y‐C.14) were used. A 0.5‐mm‐thick dentin specimens and 1.4‐mm‐thick enamel/dentin specimens (n = 5) were obtained from anterior bovine maxillary teeth. Scattering, absorption, transmittance, and albedo coefficient were calculated using Kubelka–Munk's model. Data were statistically analyzed using Kruskal–Wallis and Mann–Whitney tests (p < 0.001), and goodness‐of‐fit coefficient (GFC). Relative translucency parameter differences were evaluated using translucency thresholds. Results: Reflectance, scattering, absorption, and transmittance properties were wavelength dependent. Good matches (GFC ≥ 0.999) in spectral reflectance were observed between 0.5‐mm‐thick dentin and 1.4‐mm‐thick enamel/dentin, and 3Y‐NC.5 and 5Y‐NC.5. Scattering was the main optical extinction process during light interaction with zirconia and dental structures, as indicated by albedo coefficient. Translucency differences were acceptable only for 3Y‐NC.5 and the dentin structure, and 5Y‐C.14 and the enamel/dentin structure. Conclusions: Optical properties of 3Y‐TZP and 5Y‐PSZ dental zirconia differed from each other and from bovine dental structures. Nevertheless, 3Y‐TZP showed similar relative translucency parameter to bovine dentin. Clinical Significance: To achieve the best esthetic results in restorative dentistry, it is crucial for clinicians to know about the optical properties of 3Y‐TZP and 5Y‐PSZ and to be able to compare these properties with those of dental structures. [ABSTRACT FROM AUTHOR]

There is a growing interest in field‐assisted fast ceramic processing and long‐term service of electrochemical devices under harsh operation conditions. These extreme redox conditions can make some conventionally thought slow ions highly mobile in electrochemical materials and devices and greatly accelerate the microstructural evolution. Experimental observations for enhanced slow ion diffusion that controls mass transport include accelerated grain growth in zirconia and ceria under atmospheric and electrochemical reduction above 1000°C and lattice cavitation of high‐voltage Li‐rich layered cathodes of lithium‐ion batteries at room temperature. These observations cannot be explained by altered defect concentrations under defect chemistry arguments. Instead, they support hugely enhanced slow ion mobility. My colleagues and I recently proposed a new mechanism resulted from strong electron–phonon interactions and dynamic electronic relaxations at the saddle point of an ion hopping event, which significantly lowers the ion migration barrier. In this perspective article, the theory and its experimental and computational supports shall be discussed. Such an electronic effect holds even in nominally ionic ceramic materials with wide bandgaps and is expected to be general in many transition metal oxides. It rationalizes a variety of intriguing experimental observations and offers an electronic perspective on the redox enhancement of slow ion kinetics in structural, functional, and energy ceramics. [ABSTRACT FROM AUTHOR]

To evaluate the effect of accelerated firing on 3D-printed zirconia. To check if formulae provided by ISO 6872 can be extended to thin samples, finite element analyses were carried out in advance of fabricating 3-mol% yttria-stabilized tetragonal zirconia polycrystal discs by milling and by 3D-printing. Four groups (n = 38 each) of 3D-printed specimens were produced with two nominal thicknesses (0.6 mm and 1.2 mm) and two firing strategies (long: 51 h, accelerated: 14.5 h). In the milled group (thickness 1.2 mm, n = 30), a standard firing program (9.8 h) was selected. Biaxial flexural strength tests were applied and mean strength, characteristic strength, and Weibull modulus were calculated for each group. Differences were analyzed using Welch ANOVA and Dunnett-T3 post-hoc tests. Maximum tensile stresses occurring during biaxial strength testing can be calculated according to ISO 6872 for thin samples with b > 0.3 mm. Variability of measured strengths values was smaller for milled zirconia compared with 3D-printed zirconia. The 1.2-mm-thick 3D-printed samples had significantly decreased strength after accelerated firing than after long firing. However, for the 0.6-mm-thick samples, comparable mean biaxial strength values of about 1000 MPa were measured for both firing protocols. At the moment, long fabrication time for zirconia restorations is a major drawback of 3D-printing when compared with milling technology. This investigation showed that the strength of 0.6-mm-thick zirconia discs fabricated by 3D-printing was not impaired by accelerated firing. Thus, overnight firing of thin-walled 3D-printed zirconia restorations could be possible. • For thin disks (b=0.6 mm), both firing times led to high mean strengths (≈1000 MPa). • Lowest mean strength (805 MPa) was given for fast fired thick samples (b=1.2 mm). • About half of the fast-fired thick samples (b=1.2 mm) had strength values < 500 MPa. • Milled zirconia was more reliable than 3D-printed zirconia. • ISO 6872 formulae can be extended to samples with thicknesses 0.3 mm

This study evaluated the effect of an experimental borosilicate glass on the mechanical and optical behavior of 5Y-PSZ zirconia and comparing it to commercial glaze and as-sintered. Disc-shaped specimens of a 5Y-PSZ (Zpex Smile) were prepared and sintered (1550 °C, 2 h). The zirconia discs were randomly divided according to the surface treatment: as-sintered (C), commercial glaze (G), and experimental borosilicate glass (SL). Glaze and experimental glass powders were mixed with building liquids and applied to zirconia with a brush. G specimens were fired at 950 °C and SL at 1200 °C. An extended dwell time of 20 min was applied to both groups. Biaxial flexural strength, roughness (Ra and Rz), translucency (TP 00), color alteration (ΔE 00), Vickers hardness, fracture toughness, residual stresses, and x-ray diffraction analyses were conducted. Statistical analyses were performed with Weibull statistics, Kruskal-Wallis, or ANOVA tests (α = 5%). SL yielded the highest flexural strength (799.35 MPa), followed by G (662.34 MPa), and C (485.38 MPa). The fracture origin of SL specimens was in the bulk zirconia, while G and C showed fractures starting at the surface. As-sintered reached the highest fracture toughness and hardness. Glaze and borosilicate glass provided surface compressive stresses. Borosilicate glass application led to phase transformation (t→m). SL and G showed the lowest roughness. TP 00 and ΔE 00 were similar among groups. Borosilicate glass improved strength without harming the optical properties of third-generation zirconia. Toughness and roughness provided by the experimental glass were similar to those from commercial glaze. • Experimental borosilicate glass improved the flexural strength of 5Y-PSZ. • Borosilicate glass application led to phase transformation (t→m) of 5Y-PSZ. • Glaze and borosilicate glass produced similar translucency and color alteration. [ABSTRACT FROM AUTHOR]

Dental implants are regularly employed in tooth replacement, the good clinical outcome of which is strictly correlated to the choice of an appropriate implant biomaterial. Titanium-based implants are considered the gold standard for rehabilitation of edentulous spaces. However, the insurgence of allergic reactions, cellular sensitization and low integration with dental and gingival tissues lead to poor osseointegration, affecting the implant stability in the bone and favoring infections and inflammatory processes in the peri-implant space. These failures pave the way to develop and improve new biocompatible implant materials. CERID dental implants are made of a titanium core embedded in a zirconium dioxide ceramic layer, ensuring absence of corrosion, a higher biological compatibility and a better bone deposition compared to titanium ones. We investigated hDPSCs' biological behavior, i.e., cell adhesion, proliferation, morphology and osteogenic potential, when seeded on both CERID and titanium implants, before and after cleansing with two different procedures. SEM and AFM analysis of the surfaces showed that while CERID disks were not significantly affected by the cleansing system, titanium ones exhibited well-visible modifications after brush treatment, altering cell morphology. The proliferation rate of DPSCs was increased for titanium, while it remained unaltered for CERID. Both materials hold an intrinsic potential to promote osteogenic commitment of neuro-ectomesenchymal stromal cells. Interestingly, the CERID surface mitigated the immune response by inducing an upregulation of anti-inflammatory cytokine IL-10 on activated PBMCs when a pro-inflammatory microenvironment was established. Our in vitro results pave the way to further investigations aiming to corroborate the potential of CERID implants as suitable biomaterials for dental implant applications. [ABSTRACT FROM AUTHOR]

Ensuring a secure bond between a framework structure and layering composite resin veneer is essential for a long-lasting dental restoration. A variety of primer systems are available to facilitate the adhesive bonding. Nevertheless, the growing preference for efficiency and simplicity in dentistry has made the one-bottle universal primers a desirable option. This study aims to compare the effectiveness of universal primers on the shear bond strength (SBS) of base metal alloy (BMA) and zirconia to layering composite resin. Each 160 BMA and zirconia 20 × 10 × 5 mm test specimen was fabricated. Eight different primers (SunCera Metal Primer, Metal Primer Z, Reliance Metal Primer, Alloy Primer, MKZ Primer, Monobond Plus, ArtPrime Plus, and Clearfil Ceramic Primer Plus) were applied to 20 specimens in each group. Subsequently, a 5 × 2 mm composite resin build-up was applied. SBS tests were performed after 24 h of water storage and after thermocycling (25,000 cycles, 5–55 °C). On BMA, after water storage for 24 h, the bond strength values ranged from 26.53 ± 3.28 MPa (Metal Primer Z) to 29.72 ± 2.00 MPa (MKZ Primer), while after thermocycling, bond strength values ranged from 25.19 ± 1.73 MPa (MKZ Primer) to 27.69 ± 2.37 MPa (Clearfil Ceramic Primer Plus). On a zirconia base, after 24 h, the bond strengths values ranged from 22.63 ± 2.28 MPa (Reliance Primer) to 29.96 ± 2.37 MPa (MKZ Primer) and from 23.77 ± 3.86 MPa (Metal Primer Z) to 28.88 ± 3.09 MPa (Monobond Plus) after thermocycling. While no significant difference in bond strength was found between the primers on the BMA base, five primer combinations differed significantly from each other on zirconia (p = 0.002–0.043). All primers achieved a bond strength greater than 23 MPa on both framework materials after thermocycling. Thus, all primers tested can be applied to both framework materials with comparable results. [ABSTRACT FROM AUTHOR]

Objectives: This in vitro study aimed to compare the adhesion strength of the adhesives of four modified cement-retained methods (MCRMs) that affect the retention of two types of materials (Zirconia and hybrid ceramic/VITA Enamic). Methods: In this in-vitro study, four cement-retained methods were used: the first is an occlusal hole with a diameter (1mm) with lateral hole with a diameter (1mm) (OLH), the second is an occlusal hole with a diameter (2mm) for screw access (OH), the third is a lingual hole for releasing the excess adhesive (1mm) (LH), and the last one is a control group (no holes). twenty-eight crowns (n=7) were fabricated for test with CAD-CAM system. The retention strength was examined by mechanical tensile experiments (MTE) in vitro using a universal testing machine, pull-off test. Results: A statistically significant difference is seen in each material's retention strength (zirconia and hybrid ceramic). The OLH group in zirconia (257.4286 N), and in ceramic (213.5714 N). had the highest values among the other groups, subsequently, the LH groups had slight differences from the other OH and control groups. (P=0.05). Conclusions: The use of modified cement methods had a remarkable effect on retention. In this study, the use of occlusal-lateral with (1 mm) hole (OLH) modification is more retentive than the other groups. [ABSTRACT FROM AUTHOR]

The processes occurring in the simultaneous contact of ZrO2 ceramics with two metal melts, inert (Cu, Cu–Ga, Ge, Cu–Ge) and active (Cu–Ga–Ti, Cu–Ti), were studied. The experiments were conducted in a high vacuum using thin ZrO2 ceramic plates, with one side in contact with a droplet of active melt and the opposite side with a droplet of inert melt. In the simultaneous interaction of active and inert metal melts with zirconium dioxide, the interface processes showed mutual influence: oxygen-deficient zirconium dioxide (ZrO2–x) was formed through the absorption of oxygen from ZrO2 by the active melt. This contributed to the dissolution of zirconium from the solid oxide in the inert melt, thereby activating it and increasing its adhesion to the substrate. At the same time, the dissolution of zirconium in the inert melt reduced the oxygen deficiency in zirconium dioxide, i.e., restoring its stoichiometry and promoting further absorption of oxygen by the active melt. Thus, with the simultaneous contact of active and inert melts with ZrO2, a larger amount of oxygen dissolves in the active melt, which leads to the saturation of the active melt with oxygen. This results in effects such as the loss of metallic luster and spherical shape of droplets in the active melt, delamination of the active melt, and increase in the thickness of the transition layers at the interface between the active melt and ZrO2. The results are significantly influenced by the amounts of inert and active melts in contact with ZrO2 and by the concentration of the active component (titanium) in the system. The results can be used in the development of methods for brazing and metallization of ceramic materials and techniques for the manufacture and use of refractories and high-temperature electrochemical devices. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the effects of multiple firings on the translucency, crystal structure, and mechanical strength of highly translucent zirconia. Four types of highly translucent zirconia (LAVA Esthetic, LAVA Plus, KATANA Zirconia STML, and KATANA Zirconia HTML) were fired three times at three different temperatures, and the translucency, crystal structure, and flexural strength were evaluated before and after firing. The translucency was statistically compared using repeated-measures analysis of variance; the zirconia phase composition was assessed using X-ray diffraction followed by Rietveld analysis; and the biaxial flexural strength was assessed using Weibull analysis. The translucency of LAVA Esthetic and KATANA Zirconia HTML decreased significantly after firing, and the crystal composition of LAVA Plus and KATANA Zirconia HTML changed after multiple firings, whereas multiple firings did not affect the biaxial flexural strength of any samples. Thus, multiple firings may affect the optical properties of highly translucent zirconia [ABSTRACT FROM AUTHOR]

In this study, we investigated the effects of surface treatment on the fracture strength of porcelain-veneered zirconia. Highly translucent 4 mol% yttria-stabilized zirconia disks (KATANA HT, Kuraray Noritake Dental) were divided into three surface-treatment groups: 1) as-sintered, 2) alumina sandblasted, and 3) ground. Crystallographic and surface-roughness analyses were conducted for each group. Veneering ceramics (Cerabien ZR, Kuraray Noritake Dental) were applied to the zirconia surfaces. The fracture strengths of the porcelain-veneered zirconia disks were measured using biaxial flexural-strength tests. Crystallographic analysis revealed that grinding and sandblasting increased the fractions of the monoclinic and rhombohedral zirconia phases. The ground specimens had a higher surface roughness than the sandblasted specimens. Weibull analysis showed no significant differences in biaxial flexural strength among the three groups. The results suggest that these surface treatments do not affect the fracture strength of porcelainveneered zirconia. [ABSTRACT FROM AUTHOR]

This study aimed to assess and contrast the effects on the vertical marginal fit of full contour CAD/CAM-generated monolithic zirconia crowns at pre- and post-cementation levels with various occlusal reduction schemes (planar and flat) and cements. Forty sound human maxillary first premolars were sampled for this study. The samples were divided into two main groups with twenty samples in each group according to the occlusal reduction scheme as follows: Group A included a chamfer finishing line design with a planar occlusal reduction scheme and Group B included a chamfer finishing line design with a flat occlusal reduction scheme. Each group was sampled into two subgroups (n = 10) based on the type of cement as follows: resin-modified glass ionomer cement (Fuji Plus) for subgroups A1 and B1, and a universal adhesive system (Duo Estecem II) for subgroups A2 and B2. Marginal gaps were tested in four indentations using a Dino light stereomicroscope (230×). Paired T-tests and Student's t-tests were used to analyze the data. Before cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, while subgroup B2 scored the highest mean; following cementation, subgroup A1 scored the lowest mean of vertical marginal gap values, and subgroup B2 scored the highest mean of vertical marginal gap values. A chamfer finishing line design with a planar occlusal reduction scheme could be a preferable occlusal reduction scheme. [ABSTRACT FROM AUTHOR]

The materials used in dentistry for the fabrication of all-ceramic restorations have undergone great and rapid developments over the last two decades. Among the most common ceramic materials in dentistry are those based on zirconium and lithium disilicate. Due to the properties of these materials, they are in great demand in the field of dental restoration production. Thus, dental restorations that will use those materials are commonly machined in CAD/CAM systems, which offer the possibility of manufacturing all-ceramic dental restorations in a very short period of time. This article reviews the modern materials in the field of all-ceramic dental restorations, their manufacturing processes, as well as what determines which ceramic materials are used for the production of CAD/CAM blanks and their production technology. [ABSTRACT FROM AUTHOR]

This article reviews promising studies on the design, manufacturing, microstructure, properties, and applications of glass‐ceramics containing ZrO2 and relevant glass‐ceramic matrix composites. After the addition of ZrO2 to a glass‐ceramic composition, it can persist in the residual glassy phase, facilitate nucleation, and/or precipitate as ZrO2 or another zirconate crystalline phase. Also, ZrO2‐reinforced or ZrO2‐toughened glass‐ceramics can be designed as composites. In this article, the term "ZrO2‐containing glass‐ceramics" encompasses all these scenarios in which ZrO2 is present. Such glass‐ceramics offer a wide range of applications in modern industries, including but not limited to architecture, optics, dentistry, medicine, and energy. Since S. Donald Stookey's discovery of glass‐ceramics in the early 1950s, the most important scientific efforts reported in the literature are reviewed. ZrO2 is commonly added to glass‐ceramics to promote nucleation. As a result, the role of ZrO2 in structural modification of residual glass and stimulating the nucleation in glass‐ceramic is first discussed. ZrO2 can also be designed into the main crystalline phase of glass‐ceramics, contributing achieving super high fracture toughness above 4 MPa·m0.5. Experimental and computational studies are reviewed in detail to elucidate how the transformation toughening and other mechanisms help to achieve such high values of fracture toughness. Sintered and glass‐ceramic matrix composites also show promise, where ZrO2 contributes to improved stability and mechanical properties. Finally, we hope this article will provoke interest in glass‐ceramic materials in both the scientific and industrial communities so that their tremendous technological potential in developing, for example, tough, thermally stable, transparent, and biologically compatible materials can be realized more widely. [ABSTRACT FROM AUTHOR]

In this study, the long-term resistance of Ce-TZP/Al2O3 specimens to hydrothermal treatment is evaluated in terms of their microstructure. Treatment of the specimens is carried out in an autoclave with water at 134°C for up to 360 h. The biaxial strength and Weibull modulus of the specimens remains unchanged after 120 h of hydrothermal treatment, and their pseudo-plasticity is preserved. However, after 360 h of hydrothermal treatment the biaxial strength decreases by 12% and the Weibull modulus is also decreased. The transformation surface layer is observed through scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The thickness of the transformation layer can be estimated only through TEM analysis, revealing minimal microcrack formation at the surface layer. For comparison, several Y-TZP specimens are also prepared. After 24 h of hydrothermal treatment, the monoclinic phase content in the Y-TZP specimen reached 60%, resulting in a 40% decrease in strength. This strength decrease can be attributed to microcrack formation in the surface layer. [ABSTRACT FROM AUTHOR]

Y2O3 and SiO2 co-doped ZrO2 powders with various additions of SiO2 substitution Y2O3 have been prepared by co-precipitation method. The microstructure, phase and chemical composition, phase transformation process, and phase stability after repeated calcination at 1300 °C of these powders have been investigated. The main phase of all powders is t′-ZrO2. There is no phase transformation when the powders are heated from room temperature to 1400 °C. Increasing the ratio (1:4 to 4:1) of SiO2 substitution Y2O3 will reduce the tetragonality of the powder at 1300 °C. The amorphous SiO2 will inhibit the growth of grains to a certain extent during the calcination process. The increase of the substitution ratio of SiO2for Y2O3will lead to the m-ZrO2more stable and the t′-ZrO2more unstable. The relationship among the SiO2 substitution Y2O3 addition, phase composition, and high-temperature phase stability of the powders has been discussed. Highlight: The main phase of the Y2O3 and SiO2 co-doped ZrO2 powder is t′-ZrO2. Increasing the ratio of SiO2 substitution Y2O3 will reduce the tetragonality of the powder at 1300 °C. The amorphous SiO2 will inhibit the growth of grains to a certain extent during the calcination process. The increase of the substitution ratio of SiO2 for Y2O3 will lead to the m-ZrO2 more stable and the t′-ZrO2 more unstable. [ABSTRACT FROM AUTHOR]

The high toughness of zirconia is paving the way for the development of new materials for application in TBC for gas turbine blades. The main aim of this work was the obtainment of tetragonal zirconia polycrystalline (TZP) with high density, from mixtures of high-purity powder of zirconia, yttria, and niobia with different compositions (14.5 to 21 mol%), through the processes of cold pressing by uniaxial pressing and by isostatic pressing, followed by air sintering processes at 1550 °C for 1 h. The samples were characterized for phase composition by X-ray diffraction, Rietveld analysis, and morphology by transmission electron microscopy and energy dispersive spectroscopy analyses. Mechanical and tribological resistance was evaluated by fracture toughness and nanoindentation tests as well as Weibull statistics. The incorporation of yttria and niobia resulted in relatively denser ceramics with stabilization of the tetragonal phase which was confirmed by detailed X-ray diffraction analysis. Modified ceramics for TBC with 17.5 mol% of yttria and niobia showed higher hardness and fracture toughness, 16.16 GPa and 173.38 GPa, respectively. Through nano hardness measurements, it was possible to verify the effect of the samples' ferroelasticity. Thus, the addition of niobia and yttria to zirconia represents an opportunity for the development of new materials with increasing mechanical and tribological resistance for TBC application. [ABSTRACT FROM AUTHOR]

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It has been observed in recent years that zirconia (Zr) is being increasingly used for a wide range of clinical applications. There are several reasons for this, but the most significant one is its excellent mechanical properties, specifically its transformation toughening properties compared to other dental ceramics and its improved natural appearance when compared to ceramometal restorations. As a result of the advancement of chairside milling and developments in rapid-sintering technology, the fabrication of dental restorations has become more computerized, time-saving, and accurate over the past few decades. However, a main disadvantage of conventional Zr restorations is that they lack the translucency of glass–ceramics, although they are extremely strong. Recently, by increasing the yttrium %, changing the grain size, and reducing the impurities, the ultra-translucent monolithic zirconia "5-mol%-yttria-stabilized tetragonal zirconia polycrystals" has been introduced, with successful attempts to make translucent Zr an aesthetically attractive option for minimally invasive veneer restorations. It is important to note that veneer restorations do not possess the mechanical retentive features of the tooth preparations and rely primarily on bonding to resin cement. This presents a great challenge for the inert Zr since it does not bond chemically with resin cement, unlike glass–ceramic materials that establish chemical adhesion with resin cement, favoring their use for indirect veneer restorations. Taking this into account, this article aims to review the progressive development of ultra-translucent monolithic Zr materials as they are available today and, in the future, represents a concerted drive toward maximum translucency and strength, which renders them a viable treatment option for esthetic veneer restorations. [ABSTRACT FROM AUTHOR]

The aim of the research was to find a zirconia treatment method that would reduce or minimize the transformation from the tetragonal phase to the monoclinic phase. Background: Yttria-stabilized zirconia is increasingly chosen for the base of permanent prosthetic restorations. To achieve a good bond between the prosthetic cup and the veneer material, the material must be treated to achieve surface development. This is a mechanical process, during which an unfavorable transformation from the tetragonal into the monoclinic phase takes place, which leads to the weakening of the internal structure of zirconium dioxide, and later damages the prosthetic restoration. Methods: The tested material consisted of cylindrical samples of 3Y-TZP CeramillZi zirconium oxide, which were sintered after cutting out from the block. After sintering, the samples were subjected to the following types of processing: laser structuring, chemical etching and plasma etching. After the surface treatments, the samples were subjected to diffraction tests to determine the phase composition. Next, the wettability was tested to determine the surface free energy. Results: On the basis of the conducted tests, it was noticed that the applied treatments caused a phase transformation from the tetragonal to the monoclinic phase. After the process of chemical etching, the range of the monoclinic phase for the sample was 5%; after plasma etching, it was 8%, and after laser structuring, it was 2%. In addition, post-surface free energy studies have shown that zirconia is wetted better with an apolar than a polar liquid. Conclusions: The obtained results indicate that the transformation was minimized with the treatments we applied; that is why they are called non-invasive methods. According to the literature data, depending on the parameters of the sandblasting process, the percentage of the monoclinic phase in the treated surfaces ranges from 22% to 52%, which confirms the above-mentioned conclusion. [ABSTRACT FROM AUTHOR]

Since the discovery of ferroelectricity in doped HfO2 and ZrO2 thin films over a decade ago, fluorite‐structured ferroelectric thin films have attracted much research attention due to their excellent scalability and complementary metal‐oxide semiconductor compatibility compared to conventional perovskite ferroelectric materials. Although various factors influencing the formation of the ferroelectric properties are identified, a clear understanding of the causes of the phase formation have been difficult to determine. In this work, ZrO2 films deposited by atomic layer deposition and chemical solution deposition have resulted in films with completely different structural properties. Regardless of these differences, a general relationship between strain and phase formation is established, leading to a more unified understanding of ferroelectric phase formation in undoped ZrO2 films, which can be applied to other fluorite‐structured films. [ABSTRACT FROM AUTHOR]

Since the discovery of ferroelectricity in doped HfO2 and ZrO2 thin films over a decade ago, fluorite‐structured ferroelectric thin films have attracted much research attention due to their excellent scalability and complementary metal‐oxide semiconductor compatibility compared to conventional perovskite ferroelectric materials. Although various factors influencing the formation of the ferroelectric properties are identified, a clear understanding of the causes of the phase formation have been difficult to determine. In this work, ZrO2 films deposited by atomic layer deposition and chemical solution deposition have resulted in films with completely different structural properties. Regardless of these differences, a general relationship between strain and phase formation is established, leading to a more unified understanding of ferroelectric phase formation in undoped ZrO2 films, which can be applied to other fluorite‐structured films. [ABSTRACT FROM AUTHOR]

Objectives: To compare volumetric wear of lithium disilicate against different ceramic (3 mol% yttria‐stabilized (3Y) zirconia, 5 mol% yttria‐stabilized (5Y) zirconia, lithium disilicate, porcelain and enamel antagonists). Materials and Methods: Forty lithium disilicate (e.max CAD) specimens (n = 8/antagonist) were wet sanded to 1200grit SiC and mounted into a UAB wear device. Antagonist spheres (diameter = 4.75 mm) were made from polished 3Y zirconia, 5Y zirconia, lithium disilicate, porcelain and human enamel. A two‐body wear test was performed with 20 N load and 1.5 mm slide for 400,000 cycles at 1 Hz. 33% glycerin was used as a lubricant. Wear facets were measured with optical profilometry. Wear scar areas of antagonists were measured with digital microscopy. Scanning electron microscopy was performed on wear facets and scars. Vicker's microhardness was measured of all antagonist materials. All data were compared with 1‐way ANOVA and Tukey post‐hoc analysis. Results: Significant differences in lithium disilicate volumetric wear (mm3) occurred with various antagonist materials: 0.38 ± 0.01a (3Y zirconia), 0.33 ± 0.01b, (5Y zirconia), 0.16 ± 0.01c (lithium disilicate), 0.11 ± 0.03d, (enamel), and 0.07 ± 0.01e (porcelain). The lithium disilicate antagonist demonstrated a larger wear scar than other materials. Zirconia was the hardest material and enamel the least hard. Conclusions: Zirconia causes significant wear on lithium disilicate and lithium disilicate causes significant wear against itself. Clinical Significance: When selecting a material to oppose an existing lithium disilicate crown, a porcelain or lithium disilicate surface would cause significantly less wear to the existing crown. If an existing zirconia crown exists opposed to a prepared tooth, lithium disilicate may not be an ideal material selection to restore the tooth. [ABSTRACT FROM AUTHOR]

This study aimed first to compare the shear bond strength between zirconia samples luted to enamel with a 10-MDP- containing resin cement (Panavia F2.0, Kuraray, Japan) and those luted with a resin cement using a separated 10-MDP monomer-containing bottle (Panavia V5, Kuraray, Japan). The second objective was to evaluate the bond stability after 150 days of aging in water, between enamel and zirconia ceramic surface enhanced with a glass-ceramic coating. 80 specimens composed of ceramic cylinders and enamel disks were obtained, within eight experimental groups (n = 10). 60 zirconia cylinders (Katana STML zirconia, Kuraray, Japan) were assigned to 3 groups according to their surface treatment: milled/sintered surface (ZRCT), tribochemical silica-coating (Cojet™ Sand, 3 M ESPE, Seefeld, Germany) (ZRTC), and glass-ceramic coating (IPS e.max Zirpress) (ZRZP). 20 cylinders of lithium disilicate had a milled surface (IPS e.max CAD, Ivoclar-Vivadent, Schaan, Liechtenstein) (ECAD). The cylinders of each group were further divided into two subgroups according to the resin cement used: Panavia F2.0 (-PF) and Panavia V5 (-PV). All specimens were stored in distilled water for 150 days before shear bond strength (SBS) tests. The fracture mode was analyzed, and data were statistically computed (two-way ANOVA, post hoc Tukey test, p < 0.05, SPSS, IBM, v26). The ECAD-PF group recorded the highest SBS values (31.75 ± 2.2), and the ZRCT-PF group recorded the lowest values (5.59 ± 1.1). The two-way ANOVA test showed that ceramic surface treatment had a statistically significant effect on SBS (F (3,72) = 38.95, p < 0.001) while the type of ARC did not (F (1,72) = 2.40, p = 0.126). Tukey's post hoc test revealed no statistical difference between the ZRZP and the ZRTC or ECAD groups. Within the limitations of this study, the PV resin achieved similar shear bond strength results between tribocoated zirconia and enamel compared to the one for glass-ceramic and enamel. Furthermore, a long-term durable bond, similar to the glass-ceramic one, was achieved with the heat pressed ceramic coated specimens. Thus, this new surface treatment could be recommended for anterior cantilever bridges for its fracture resistance and bonding ability. [ABSTRACT FROM AUTHOR]

To introduce a versatile fabrication process to fabricate zirconia/PMMA composites for chairside CAD/CAM dental restorations. These zirconia composites have nacre-like lamellar microstructures, competent and tooth-matched mechanical properties, as well as crack resistance behaviours. Bi-directional freeze casting was used to fabricate ceramic green bodies with highly aligned lamellar structure. Pressure was then applied to control the ceramic volume fraction. PMMA was infiltrated into the ceramic scaffold. Mechanical tests including 3-point bending, Vickers hardness, and fracture toughness were performed on the composites. The machinability of the composites was also characterised. Two types of nacre-like zirconia/PMMA composites, i.e., 3Y-YZP/PMMA and 5Y-PSZ/PMMA composites were fabricated. The microstructure created was similar to the 'brick and mortar' structure of nacre. Excellent flexural strength (up to 400 MPa and 290 MPa for 3Y-TZP/PMMA and 5Y-PSZ/PMMA composite, respectively), tuneable hardness and elastic modulus within the range similar to enamel, along with improved crack-resistance behaviour were demonstrated on both zirconia composites. In addition, both zirconia/PMMA composites showed acceptable machinability, being easy to mill, as would be required to produce a dental crown. Nacre-like zirconia/PMMA composites therefore exhibit the potential for use in the production of chairside CAD/CAM dental restorations. [Display omitted] • Bi-directional freeze casting is a versatile method for fabricating nacre-like ceramic/polymer composites. • 3Y-TZP/PMMA and 5Y-PSZ/PMMA composites showed competent strength for dental restorations and great crack resistance. • The mechanical properties of 3Y-TZP/PMMA and 5Y-PSZ/PMMA composites were tuneable to closely match to human enamel. • 3Y-TZP/PMMA and 5Y-PSZ/PMMA composites showed proper machinability for chairside CAD/CAM dental restorations. [ABSTRACT FROM AUTHOR]

The aim of the study was to evaluate the influence of surface polishing and printing layer orientation on the fatigue behaviour of 3 mol% yttria-stabilized zirconia (3Y-TZP) by stereolithography (SLA) in comparison with subtractive manufacturing. 60 experimental zirconia bar-shaped specimens were 3D-printed (P) via SLA, and 30 specimens were milled (M) from commercial zirconia block (Lava™ Frame, 3 M ESPE AG). All specimens had the same dimensions (1 mm × 1 mm x 12 mm) after sintering. The 3D-printed specimens were randomly divided according to printing orientations: parallel or perpendicular to the tensile surface in the fatigue test. The specimens were subsequently submitted to two surface finishing protocols (n = 15/gr): unpolished or polished. Their phase compositions were analysed by X-ray diffraction. The fatigue behaviour was evaluated by a stepwise approach. The milled and both 3D-printed groups showed similar phase compositions for the as-sintered condition. Considerable amounts of rhombohedral phase were detected after polishing. Milled unpolished samples presented significantly higher fatigue strength than 3D-printed unpolished samples. Polishing did not improve the fatigue strength for milled zirconia but was advantageous for the 3D-printed specimens. 3D-printed specimens with parallel printing-layer orientation were significantly stronger than specimens with perpendicular layers regardless of surface finishing. The manufacturing techniques had a significant influence on the fatigue strength of 3Y-TZP, but not on the phase compositions of the surface. The polishing protocol showed different effects on 3Y-TZP fatigue strength and induced phase transition of the 3Y-TZP from Tetragonal to Rhombohedral. The best fatigue strength was achieved through milling using an unpolished surface and SLA-printed layers that were parallel to the tensile surface, followed by polishing. • Manufacturing techniques affect fatigue strength. • Polishing protocol provokes phase transition of zirconia. • Printing layers parallel to the tensile surface achieves the best fatigue strength. [ABSTRACT FROM AUTHOR]

Objectives: To compare the strength and reliability of 3D-printed 3Y-TZP zirconia manufactured with various printing orientations and staining. Materials and methods: A total of one-hundred cylindrical zirconia specimens were designed and fabricated using 3D printing and processed according to ISO 6872 standards. Of these specimens, 80 were 3D printed using the new ZIPRO-D (ZD) 3D ceramic printer. In this ZD group, 60 specimens were printed in a vertical orientation and were either stained after debinding (ZD1, x-orientation, n = 20) or not stained (ZD2, x-orientation, n = 20; ZD3, y-orientation, n = 20) and the remaining 20 specimens out of n = 80 were printed in a horizontal orientation (ZD4). Further 20 specimens out of the entire sample N = 100 were printed vertically with the CeraFab7500 3D ceramic printer (LC). All completed specimens were loaded until fracture using a universal testing machine. Biaxial flexural strengths and Weibull parameters were computed for the ZD groups and for the LC group. Group and sub-group effects were evaluated using Welch ANOVA (alpha = 0.05). Results: The mean (standard deviation, SD) biaxial flexural strengths of vertically oriented ZD samples with (ZD1) and without (ZD2/ZD3) staining were 811 (197) and 850 (152) MPa, respectively (p > 0.05). The ZD4 (horizontally printed), 1107 (144) MPa, and LC (1238 (327)) MPa samples had higher mean (SD) flexural strengths than the ZD1–3 specimens. No difference was observed between the ZD4 and LC group (p > 0.05). Weibull moduli were between m = 4.6 (ZD1) and 9.1 (ZD4) in the ZD group and m = 3.5 in the LC group. Conclusions: All tested 3D-printed zirconia specimens exceeded the flexural strengths required for class 5 restorations according to ISO 6872 standards. While the flexural strengths of zirconia printed using the novel ZD device in the vertical orientation are lower than those of zirconia printed using the LC printer, the ZD printer shows at least comparable reliability. Clinical relevance: 3D-printing of zirconia is a new technology in dental application. Based on the presented strengths values, clinical application of 3D-printed zirconia for fixed dental protheses can be recommended. [ABSTRACT FROM AUTHOR]

Objectives: This in vitro study aimed to evaluate the wear of natural teeth opposing 3 mol% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) with different surface conditions. Materials and methods: Sixty 3Y-TZP specimens were randomly assigned to six groups (n = 10), differing in surface condition. In three groups, the samples underwent glazing—with the glaze applied to roughened (i.e., 106-µm-grit diamond-finished), as-sintered, and polished zirconia. The three remaining groups consisted of unglazed specimens: solely polished samples and diamond-finished samples (106-µm-grit and 46-µm-grit) without further conditioning. Two-body wear was evaluated at extracted, non-carious molars (n = 60), which served as antagonists in chewing simulation (10,000 masticatory cycles, 49N load). As a control, natural teeth with intact enamel surfaces were tested against natural molars (n = 10). All samples were 3D-scanned before and after the chewing simulation (7 Series, Straumann). Volume loss was calculated (Inspect Software, GOM), and statistically analyzed (SPSS Statistics 24, IBM). Results: Volume loss of the natural antagonists decreased in the following order: 106-µm-grit diamond-finished zirconia (4.6 ± 2.5 mm3), glazed 106-µm-grit diamond-finished zirconia (3.8 ± 1.1 mm3), glazed as-sintered zirconia (3.5 ± 0.9 mm3), 46-µm-grit diamond-finished zirconia (1.7 ± 0.6 mm3), control (1.6 ± 0.7 mm3), glazed polished zirconia (1.4 ± 0.5 mm3), and solely polishing (0.4 ± 0.2 mm3). Even when polishing the surfaces before glazing, volume loss was not mitigated to the same extent as after polishing alone. Conclusions: The zirconia surface condition beneath the glazing influences antagonist wear. Although polishing before glazing resulted in acceptable levels of antagonist wear, this approach did not yield as favorable results as polishing alone. Clinical relevance: For operators favoring glazing, pre-polishing the zirconia surface could be advantageous to reduce wear. [ABSTRACT FROM AUTHOR]

It is widely acknowledged that electrochemical reduction occurs during DC flash sintering (FS) of YSZ. In situ experiments have shown the emergence of new phases during FS that disappear again when the current is switched off. In addition, it has recently been reported that YSZ flash sintered in the absence of oxygen has a high electrical conductivity at room temperature. In this investigation electrical loading of YSZ was conducted in Ar and N 2 and maintained as the furnace cooled down such that on removing the current, the sample was rapidly quenched, avoiding reoxidation or other diffusion-limited phase transformations. XRD showed that the tetragonality of the ZrO 2-δ phase was diminished and the volume of the unit cell increased, the effect of the electrochemical reduction being similar to an increase in Y 2 O 3 content. In addition, rocksalt structure Zr(O,N) with a lattice constant of 0.4580 nm was formed at the surface and retained at room temperature. This phase had a metallic lustre and electrical conductivity approaching those of metals. The results enable several recent results in the literature to be reconciled and the implications for flash sintering are briefly discussed. [ABSTRACT FROM AUTHOR]

Silane chemistry has emerged as a powerful tool for surface modification, offering a versatile means to enhance the properties of various substrates, such as dental implant abutment materials. In this study, we investigated the stability of the 3‐aminopropyldiisopropylethoxysilane (APDS) layer on yttria‐partially stabilized zirconia (Y‐TZP) surfaces after mechanical, acid, and thermal treatment in order to simulate fluctuations within the oral cavity. To accomplish that, the viability of human gingival fibroblasts on APDS‐modified surfaces after applied treatment strategies was assessed by live/dead staining. Moreover, the hydrolysis stability and enzymatic degradation resistance of crosslinked fibronectin to the APDS layer was examined by immunostaining and western blot. The results revealed that the applied modifications were not affected by the different treatment conditions and could withstand the fluctuations in the oral cavity. Furthermore, crosslinked fibronectin on silanized Y‐TZP was stable against hydrolysis over 21 days and enzymatic degradation. We thus can conclude that the proposed functionalization method has high potential to tolerate harmful effects within the oral cavity and remains unchanged on the surface. [ABSTRACT FROM AUTHOR]

Zirconia implants are gaining attention as a viable alternative to titanium implants due to their comparable osseointegration development, improved soft tissue adaptation, and enhanced aesthetics. An encouraging avenue for improving zirconia implant properties involves the potential application of bioactive coatings to their surfaces. These coatings have shown potential for inducing hydroxyapatite formation, crucial for bone proliferation, and improving implant mechanical properties. This study aimed to evaluate the effect of coating zirconia implants with two bioactive glasses, 45S5 and BioK, on osteogenesis in vitro and osseointegration in vivo. Zirconia samples and implants were prepared using Zpex zirconia powder and blocks, respectively. The samples were divided into three groups: polished zirconia (ZRC), zirconia coated with 45S5 bioglass (Z + 45S5), and zirconia coated with BioK glass (Z + BK). Coatings were applied using a brush and sintered at 1200°C. Chemical analysis of the coatings was carried out using x‐ray diffraction and Fourier Transform Infrared Spectroscopy. Surface topography and roughness were characterized using scanning electron microscopy and a roughness meter. In vitro experiments used mesenchymal cells from Wistar rat femurs, and the coated zirconia implants were found to promote cell viability, protein synthesis, alkaline phosphatase activity, and mineralization, indicating enhanced osteogenesis. In vivo experiments with 18 rats showed positive results for bone formation and osseointegration through histological and histomorphometric analysis and a push‐out test. The findings indicate that bioactive glass coatings have the potential to improve cell differentiation, bone formation, and osseointegration in zirconia implants. [ABSTRACT FROM AUTHOR]

Worn denture teeth continue to be a significant complication with implant‐supported prostheses. This article discusses a case report that used an intraoral scanning system to restore an existing maxillary implant‐supported prosthesis with significant posterior occlusal wear. IPS e.max (Ivoclar Vivadent, Schaan, Liechtenstein) restorations were fabricated and cemented to the prepared posterior denture teeth to re‐establish the occlusal vertical dimension and to help prevent further wear of the occlusal surfaces. [ABSTRACT FROM AUTHOR]

Despite the advancements in indirect monolithic restorations, technical complications may occur during function. To overcome this issues, intraoral repair using resin composite is a practical and low-cost procedure, being able to increase the restoration's longevity. This review aimed to evaluate the need for repair and suggest a standardized repair protocol to the main indirect restorative materials. For this, studies were surveyed from PubMed with no language or date restriction, to investigate the scientific evidence of indirect monolithic restoration repair with direct resin composite. A classification to guide clinical decisions was made based on the FDI World Dental Federation criteria about defective indirect restorations considering esthetic and functional standards, along with the patient's view, to decide when polishing, repairing or replacing a defective restoration. Based on 38 surveyed studies, different resin composite intraoral repair protocols, that included mechanical and chemical aspects, were defined depending on the substrate considering resin-based, glass-ceramic or zirconia restorations. The presented criteria and protocols were developed to guide the clinician's decisionmaking process regarding defective indirect monolithic restorations, prolonging longevity and increasing clinical success. [ABSTRACT FROM AUTHOR]

URPOSE. To investigate the effect of sintering programs and surface treatments on surface properties, phase transformation and flexural strength of monolithic zirconia. MATERIALS AND METHODS. Zirconia specimens were sintered using three distinct sintering programs [classic (C), speed (S), and superspeed (SS)] (n = 56, each). One sample from each group underwent scanning electron microscopy (SEM) and grain size analysis following sintering. Remaining samples were divided into five subgroups (n = 11) based on the surface treatments: control (CL), polish (P), glaze (G), grind + polish (GP), and grind + glaze (GG). One sample from each subgroup underwent SEM analysis. Remaining samples were thermally aged. Monoclinic phase volume, surface roughness, and three-point flexural strength were measured. Monoclinic phase volume and surface roughness were analyzed by Kruskal-Wallis and Dunn tests. Flexural strength was analyzed by two-way ANOVA and Weibull analysis. The relationships among the groups were analyzed using Spearman's correlation analysis. RESULTS. Sintering program, surface treatment, and sintering × surface treatment (P = .010) affected the monoclinic phase volume, whereas the type of surface treatment and sintering × surface treatment affected the surface roughness (P < .001). Type of sintering program or surface treatment did not affect the flexural strength. Weibull analysis revealed no significant differences between the m and so values. Monoclinic phase volume was positively correlated with surface roughness in the SGG and SSP groups. CONCLUSION. After sintering monolithic zirconia in each of the three sintering programs, each of the surface treatments can be used. However, for surface quality and aging resistance, G or GG can be recommended as a surface finishing method. [ABSTRACT FROM AUTHOR]

PURPOSE. This study aimed to evaluate the maximum vertical wear, volume wear, and surface characteristic of antagonist enamel, opposing monolithic zirconia or lithium disilicate crowns. MATERIALS AND METHODS. The study comprised 24 participants (n = 12), who were randomly allocated to receive either a 5 mol% Y-TZP or a lithium disilicate crown in positions which would oppose the natural first molar tooth. The contralateral first molar along with its antagonist was considered as the enamel opposing natural enamel control. Data collection was performed using an intraoral scanner and polyvinylsiloxane impression. The means of the maximum vertical loss and the volume loss at the occlusal contact areas of the crowns and the various natural antagonists were measured by 3D comparison software. A scanning electron microscope was subsequently used to assess the wear characteristics. RESULTS. The one-year results from 22 participants (n = 11) indicated no significant differences when comparing the zirconia crown's antagonist enamel (40.28 ± 9.11 µm, 0.04 ± 0.02 mm3) and the natural enamel wear (38.91 ± 7.09 µm, 0.04 ± 0.02 mm3) (P > .05). Also, there is no significant differences between lithium disilicate crown's antagonist enamel (47.81 ± 9.41 µm, 0.04 ± 0.02 mm3) and the natural enamel wear (39.11 ± 7.90 µm, 0.04 ± 0.02 mm3) (P > .05). CONCLUSION. While some studies suggested that monolithic zirconia caused less wear on opposing enamel than lithium disilicate, this study found similar wear levels to enamel for both materials compared to natural teeth. [ABSTRACT FROM AUTHOR]

The surface adhesion of bacterial cells and the in vivo biocompatibility of a new ceramic–metal composite made of zirconium dioxide and tantalum were evaluated. Within the framework of an in vitro study using the crystal violet staining and colony counting methods, a relatively similar adhesion of Streptococcus oralis to the 3Y-TZP/Ta biocermet (roughness Ra = 0.12 ± 0.04 µm) and Ti-Al6-V4 titanium alloy (Ra = 0.04 ± 0.01 µm) was found. In addition, in an in vivo preliminary study focused on the histological analysis of a series of rods implanted in the jaws of beagle dogs for a six-month period, the absence of any fibrous tissue or inflammatory reaction at the interface between the implanted 3Y-TZP/Ta biocermets and the new bone was found. Thus, it can be concluded that the developed ceramic–metal biocomposite may be a promising new material for use in dentistry. [ABSTRACT FROM AUTHOR]

Calcium phosphate (CaP) coating of zirconia and zirconia-based implants is challenging, due to their chemical instability and susceptibility to thermal and mechanical impacts. A 3 mol% yttrium-stabilized tetragonal zirconia polycrystal was subjected to femtosecond laser (FsL) irradiation to form micro- and submicron surface architectures, prior to CaP coating using pulsed laser deposition (PLD) and low-temperature solution processing. Untreated zirconia, CaP-coated zirconia, and FsL-irradiated and CaP-coated zirconia were implanted in proximal tibial metaphyses of male Japanese white rabbits for four weeks. Radiographical analysis, push-out test, alizarin red staining, and histomorphometric analysis demonstrated a much improved bone-bonding ability of FsL-irradiated and CaP-coated zirconia over CaP-coated zirconia without FsL irradiation and untreated zirconia. The failure strength of the FsL-irradiated and CaP-coated zirconia in the push−out test was 6.2–13.1-times higher than that of the CaP-coated zirconia without FsL irradiation and untreated zirconia. Moreover, the adhesion strength between the bone and FsL-irradiated and CaP-coated zirconia was as high as that inducing host bone fracture in the push-out tests. The increased bone-bonding ability was attributed to the micro-/submicron surface architectures that enhanced osteoblastic differentiation and mechanical interlocking, leading to improved osteointegration. FsL irradiation followed by CaP coating could be useful for improving the osteointegration of cement-less zirconia-based joints and zirconia dental implants. [ABSTRACT FROM AUTHOR]

In recent years, heterogeneous catalysts have led to environment‐friendly transformations with better yields and reusability. Pd, one of the initial metals employed in heterogeneous organic synthesis, suffered from limitations like its high cost. This justifies the need for development of catalysts with abundant, low‐cost metals, which has been receiving a lot of attention in the scientific community. In this work, a bimetallic oxide catalyst, CeO2–ZrO2, is synthesized by a sol–gel route. The structure and morphology of the catalyst are investigated using X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray analysis, thermogravimetric analysis, Brunauer–Emmett–Teller measurements, and temperature‐programmed desorption. It is utilized for obtaining quinoxaline derivatives at room temperature. 2,3‐Diphenylquinoxaline is obtained via a simple condensation reaction between 1,2‐diaminobenzene and 1,2‐diketones, catalyzed by CeO2(50)–ZrO2(50) with 87% yield in 15 min. Quinoxalines are known for their biological and therapeutic activities; hence, they are essential molecules. The biological activity of the synthesized quinoxaline derivatives has been evaluated against bacterial and fungal strains. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

In the present work, silver-doped zirconium oxide nanocomposites were synthesized by hydrothermal method and characterized by XRD, FTIR, FESEM and EDX techniques. The existence of zirconium and silver in the finished nanocomposites from the produced material is investigated using XRD and FTIR. The estimated particle diameter size range for crystallites is 10–16 nm. In addition, the obtained Ag/ZrO2 nanocomposites were analyzed the biocidal activity of two separate bacteria Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and two separate fungal Aspergillus niger (A. niger), Candida albecans, pure AgO, ZrO2 and Ag doped ZrO2 nanocomposites were also examined. This Ag doped ZrO2 (10 %) nanocomposites have a larger zone of inhibition than other human diseases, according to the results of the biocidal activity. [ABSTRACT FROM AUTHOR]

3Y-TZP ceramics are widely used in dental restoration materials due to their excellent biocompatibility, mechanical properties, and aesthetics. However, the low temperature aging characteristics seriously affect the service life of 3Y-TZP. This study aimed to investigate the mechanical properties, low temperature degradation properties and biocompatibility of a certain amount of alumina doped dental 3Y-TZP ceramics. The 3Y-TZP powder was produced by co-precipitation and then combined in a predetermined ratio with alumina powder. The fitting results of the Johnson-Mehl-Avramorow-Kolmogorow (JMAK) equation shows that the doping of alumina is beneficial to improve the low temperature degradation resistance of 3Y-TZP. The doped 3Y-TZP exhibited favorable biocompatibility, indicating its potential suitability as a dental restorative material. [ABSTRACT FROM AUTHOR]

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Post deposition thermal annealing of amorphous coatings improves optical properties of dielectric mirrors. However, excessive temperatures cause crystallization, resulting in a degradation of mechanical and optical properties. Therefore, annealing is limited to temperatures 'below' the crystallization threshold. The threshold is determined by x-ray diffraction (XRD) measurement which requires a significant amount of crystallized material for detection, yet it has been shown that a population of crystallites may exist in otherwise amorphous coatings below the threshold temperature. In this study XRD measurements show crystallites that grow during annealing within amorphous oxide coatings to a limited and predictable size predicated on the difference in density between the crystal and the surrounding amorphous phase and the average material's Young's modulus. These crystallites may be the point-like, extremely weak scatterers revealed in the LIGO test masses when imaged off-axis. [ABSTRACT FROM AUTHOR]

The aim of the current study was to present the clinical and radiological outcomes of monolithic zirconia superstructures compared to the metal–ceramic ones in the All-on-4 concept for the prosthetic rehabilitation of the maxillae. A total of 30 patients were subdivided into groups according to their superstructure type (metal–ceramic (n = 15) or monolithic zirconia (n = 15)). All implants were functionally loaded within 24 h after insertion with provisional acrylic superstructures. Prosthetic complications, marginal bone loss, plaque accumulation, probing pocket depth, bleeding on probing, and bite force were documented over a period of 5 years. Marginal bone loss around the implants of the ceramic group remained well over the five years (1.21 ± 0.23 mm). However, marginal bone loss was significantly lower around the implants in the monolithic zirconia group (0.22 ± 0.14 mm) (p < 0.001). Bleeding on probing, plaque accumulation, and probing pocket depth values were correlated with marginal bone loss. Among all evaluated parameters, no differences could be detected in terms of the angulation of the implants. Detachment or chipping was observed in seven cases in the metal–ceramic superstructure group. In all cases, dentures were removed and repaired in the laboratory. In the monolithic zirconia group, chipping was detected after one year in two cases, after two years in four cases, and after five years in one case and could be managed by polishing in situ. Monolithic zirconia superstructures presented superior results regarding the parameters evaluated. [ABSTRACT FROM AUTHOR]

Background: To determine what thickness of 5 mol% yttria zirconia (5Y-Z) translucent crowns cemented with different cements and surface treatments would have equivalent fracture resistance as 3 mol% yttria (3Y-Z) crowns. Methods: The study included 0.8 mm, 1.0 mm, and 1.2 mm thickness 5Y-Z (Katana UTML) crowns and 0.5 and 1.0 mm thickness 3Y-Z (Katana HT) crowns as controls. The 5Y-Z crowns were divided among three treatment subgroups (n = 10/subgroup): (1) cemented using RMGIC (Rely X Luting Cement), (2) alumina particle-abraded then luted with the same cement, (3) alumina particle-abraded and cemented using a resin cement (Panavia SA Cement Universal). The 3Y-Z controls were alumina particle-abraded then cemented with RMGIC. The specimens were then loaded in compression at 30° until failure. Results: All 5Y-Z crowns (regardless of thickness or surface treatment) had a similar to or higher fracture force than the 0.5 mm 3Y-Z crowns. Only the 1.2 mm 5Y-Z crowns with resin cement showed significantly similar fracture force to the 1 mm 3Y-Z crowns. Conclusion: In order to achieve a similar fracture resistance to 0.5 mm 3Y-Z crowns cemented with RMGIC, 5Y-Z crowns may be as thin as 0.8 mm. To achieve a similar fracture resistance to 1.0 mm 3Y-Z crowns cemented with RMGIC, 5Y-Z crowns must be 1.2 mm and bonded with resin cement. [ABSTRACT FROM AUTHOR]

The use of CO 2 -rich natural gas as feedstock in DRM is an attractive route of carbon dioxide utilisation due to the compositional advantage of these particular resources. The optimal operating conditions would potentially improve the overall thermal efficiency of the DRM process, especially when the temperature is lower than 800 °C. This study reports a catalyst with the demonstrated high performance and high coke-resistance, developed from ruthenium modified ceria-zirconia. Coprecipitation and hydrothermal methods were adopted to prepare the ceria-zirconia supports, and then impregnated with a very small amount of Ru (0.10 wt%). The structure-catalytic activity relationship of the catalyst was further investigated in DRM. High conversions of CH 4 and CO 2 , i.e., 44.0% and 57.4%, respectively, were achieved by using 0.1Ru1CZ5U-180 at low temperature of 600 °C. A significant reduction in the onset reaction temperature was observed from temperature programmed reduction (TPR) and this observation was related to the increased number of exchangeable oxygens in the presence of Ru. Nitrogen adsorption-desorption results suggested that the specific surface area and the total pore volume also improved the exchange of oxygen between adsorbed carbon dioxide molecules and the crystal lattice. It is evident that the presence of ruthenium accelerated the oxygen spillover process on the surface of the catalyst, and facilitated the dynamics of the oxygen exchange between the adsorbed carbon dioxide molecules and the ceria-zirconia, which ultimately contributed to the observed increase in catalytic activity at temperatures below 800 °C. Most importantly, no detectable carbon deposits were formed over the entire experimental period when the ruthenium modified ceria-zirconia catalyst was used. • A trace amount of Ru (0.10 wt%) was used to promote ceria-zirconia. • 0.10 wt% Ru significantly increased its reducibility and oxygen exchange dynamics. • Synthesis method showed a performance difference at temperatures between 400 and 850 °C. • 44% of CH 4 and 57.4% CO 2 were converted at 600 °C by 0.1Ru1CZ5U-180. • No observable carbon formation was detected from hydrothermally prepared samples. [ABSTRACT FROM AUTHOR]

This study investigates the influence of processing parameters when applying direct laser interference patterning (DLIP) on the morphology and microstructure of zirconia surfaces using a 10 ps‐pulsed laser source with 1064 nm wavelength. An experimental testing matrix is built with different values of laser fluence (5.7–18.2 J cm−2) and pulse overlap (66–98%). Surface morphology and microstructure are characterized by confocal microscopy and scanning electron microscopy. Homogeneous line‐like patterns with periodic spatial repetition of 5.0 µm, with varying depths, widths, and aspect ratio, are fabricated using proper processing parameters (5.7–7.6 J cm−2 and 92–96%). Structures with maximum depth of 1.5 µm and sharp edges are obtained (7.6 J cm−2 and 96% overlap). Ablated regions presented a morphology typical of photophysical ablation mechanism, with signs of molten material at the surface. Sub‐micrometric pores and nanodroplets are registered for all conditions, while sub‐micrometric cracks developed only for higher fluences. A processing window conducing to homogenous DLIP structures is set based on experimental data. Periodic structures with multiscale topographic features are successfully obtained on zirconia surfaces using DLIP technology in this study. These outcomes open new perspectives for fabrication of multifunctional zirconia surfaces for advanced biomedical and engineering applications. [ABSTRACT FROM AUTHOR]

Zirconium Oxynitrate Hydrate (ZrO(NO3)2·xH2O) prototype product from Kalimantan zircon sand, or hereafter we mention it as ZON, has been successfully synthesized. The ZrO2 content of 38.62 wt.% in the ZON analysis was higher than that of several commercial products. TENORM (Technologically Enhanced Naturally Occurring Radioactive Material) reduction was obtained from zircon raw materials containing ThO2 and U3O8 of 619.9 and 728.8 ppm, respectively, to become 121.1 and 0 ppm in the ZON. The ZON formation was indicated by the XRD and FTIR characterization. [ABSTRACT FROM AUTHOR]