AIMTo evaluate and compare the translucency of various commercially available zirconium oxide ceramic systems, i.e., Ceramill® Zolid Classic, Ceramill® Zi, and DD Bio ZX²71 by using a dual beam ...UV-visible spectrophotometer. MATERIALS AND METHODSThe present study comprised of 21 disk-shaped samples of zirconia for every group, i.e., group I-Ceramill® Zolid Classic, group II-Ceramill Zi®, and group III-DD Bio ZX²71. Furthermore, each group was split into three subgroups and every subgroup had seven samples each one of 0.7, 0.8, and 0.9 mm thickness. The samples were prepared by computer-aided design/computer-aided manufacturing (CAD/CAM) system devised by Amann Girrbach AG in accord with the steps provided by the manufacturer. The entire sample was designed having 10 mm in diameter with 0.7, 0.8, and 0.9 mm thickness for every group. The UV-visible dual beam spectrophotometer equipped with D2 lamp and W lamp was used for the measurement of absorbance and transmittance in order to assess the translucency of the fabricated zirconia samples. RESULTSThe mean value of transmittance % for Ceramill® Zi at 0.8 mm came out to be 0.849 ± 0.024, i.e., the least among all, whereas the mean value of Ceramill® Zolid Classic was 1.408 ± 0.033, being the highest for the same thickness. DD Bio ZX²71 had an intermediate value of 1.274 ± 0.012. The mean value of absorbance for Ceramill® Zi at 0.8 mm came out to be 2.086 ± 0.013, i.e., the maximum among all, whereas the mean value of Ceramill® Zolid Classic was, being the lowest for the same thickness. DD Bio ZX²71 had an intermediate value of 1.902 ± 0.004. CONCLUSIONThe present study data suggest that all the materials subjected to evaluation exhibited a substantial translucency. We attempted to study few of the desirable properties, these materials should possess when used for prosthetic rehabilitation with esthetic contentment a clinical setup. There has been an ambiguous distinction that Ceramill® Zi Zirconia supersedes the Ceramill® Zolid Classic and DD Bio ZX²71. Furthermore, 0.8 mm thickness substantiates to be the most ideal among 0.7, 0.8, and 0.9 mm. CLINICAL SIGNIFICANCEThe desired outcome of the procedure becomes dependent solely on the clinician's judgment to opt for the material whose properties are most fitting as per the demands of the esthetics. While a clinician should always be ambitious, but a good clinician should also bear in mind that the success of any treatment procedure not only depends on the assortment of properties of these materials but also the host response and satisfaction evoked by these materials.
Abstract Objectives To evaluate the effect of different chemo-mechanical surface treatments of zirconia ceramic in the attempt to improve its bonding potential. Methods Sintered zirconium oxide ...ceramic discs (Lava™ Ø10 mm × 1 mm height) were treated with ( n = 4): (1) airborne particle abrasion with 125 μm Al2 O3 particles; (2) 9.5% HF acid etching; (3) selective infiltration etching (SIE); (4) experimental hot etching solution applied for 10, 30 and 60 min; (5) no treatment. Ceramic discs surfaces were analyzed by atomic force microscopy (AFM) recording average surface roughness measurements of the substrate. Data were statistically analyzed by Kruskall–Wallis analysis of variance and Mann–Whitney tests ( α = 0.05). The same discs were used for bi-dimensional zirconia ceramic surface characterization with scanning electron microscope (SEM). Results Ceramic surface treatments significantly influenced surface topography and roughness ( p < 0.001). Bi-dimensional changes in ceramic surface morphology were assessed on a nanometric scale. The experimental hot etching solution improved surface roughness, independently from the application time. Conclusion Zirconia conditioning with the experimental hot etching solution may enhance ceramic roughness and improve the surface area available for adhesion allowing the formation of micromechanical retention. The influence of this surface treatment with regard to bond strength of zirconia needs to be addressed.
Abstract Objectives To evaluate the hydrolytic stability of different dual-cure resin cements when luted to zirconia ceramic. Methods Eighteen cylinder-shaped zirconia blocks (Cercon Zirconia, ...Dentsply) were conditioned with: Group 1, no treatment; Group 2, sandblasting (125 μm alumina–Al2 O3 -particles); Group 3, tribochemical silica coating (50 μm silica-modified Al2 O3 particles). Ceramic blocks were duplicated in composite resin (Tetric Evo Ceram, Ivoclar-Vivadent). Composite disks were luted to pre-treated ceramic surfaces using: (1) Clearfil Esthetic Cement (CEC; Kuraray); (2) Rely X Unicem (RXU; 3M ESPE); (3) Calibra (CAL; Dentsply Caulk). After 24 h, bonded samples were cut into microtensile sticks (1 mm2 ). Half of the sticks were loaded in tension until failure (cross-head speed of 0.5 mm/min). The remaining half was tested after 6 months of water storage at 37 °C. Data was analyzed with three-way ANOVA and Tukey’s test ( P <0.05). Fractographic analysis was performed by SEM. Results After 24 h, bond strength of CEC to zirconia was significantly higher than that of RXU and CAL, independently from the ceramic pre-treatment ( P <0.001). Using CAL, all samples failed prematurely except when luting to sandblasted surfaces. After 6 months of water aging, bond strength of CEC significantly decreased. RXU did not significantly alter bond strengths. Adhesion of sandblasted specimens luted with CAL fell over time. Micromorphological alterations were evident after water storage. Significance Resin–ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. CEC and RXU were both suitable for luting zirconia. Water aging played an important role in the durability of zirconia-to-composite chemical bonds.
Abstract Objective To evaluate the effect of different chemo-mechanical surface treatments on the morphology of three recently marketed dental zirconia ceramics. Materials and methods Ceramic discs ...(Ø 10 mm × 1 mm height) were obtained from three sintered zirconia ceramics (Lava™, Cercon® , and Aadva Zr) and treated with: (1) airborne particle abrasion with 125 μm Al2 O3 particles (S); (2) selective infiltration etching (SIE); (3) experimental hot etching solution applied for 30 min (ST); (4) no treatment (C). Five discs per group were used for surface roughness analysis using an atomic force microscope (AFM). Data were statistically analyzed by Kruskall–Wallis analysis of variance and Mann–Whitney tests ( α < 0.05). The same discs were evaluated under SEM for surface topography analysis. Three discs per group were cemented to a composite overlay (Paradigm MZ100) with a total-etch resin luting agent (Calibra) and cross-section interfacial analysis was performed under SEM. Results and Significance Airborne particle abrasion improved the average surface roughness of Cercon® and Lava ( p < 0.05) while SIE induced significant changes on Lava and Adava Zr. Statistical differences in surface roughness were recorded after selective infiltration etching when compared to no treated group, independently from the zirconia type. SEM and AFM analyses revealed changes in surface topography for all the tested ceramics and intergrain spaces opening, especially after ST. The effectiveness of the tested chemo-mechanical surface treatments depends on the zirconia type. The hot experimental etching solution increased the surface roughness of all the tested ceramics creating retentive micro-spaces that may potentially improve zirconia/resin cement interfacial strengths.
The present study evaluated the durability of bond strength between zirconia and 3 different resin cements. Thirty stabilized tetragonal zirconium-dioxide blocks were duplicated in dual-curing resin ...core build-up material specimens. Resin blocks were randomly luted to zirconium surfaces using 1) Clearfil Esthetic Cement (CLF), 2) RelyX Unicem Aplicap (RELX), or 3) Multilink Automix (MLA). After 24 h, half of the specimens from each of the 3 groups were loaded in tension until fracture (0.5 mm/min). The remaining half were tested after 6,000 thermal cycles (5 to 55°C). Data were analyzed using 2-way ANOVA and the Tukey test (α = 0.05). Fractographic analysis was performed using a stereomicroscope. Tensile bond strength values were significantly affected by the luting agent system employed and by thermal aging (P < 0.001). The highest tensile bond strength values in non-thermal-aged groups were observed for specimens from the RELX and CLF groups. In contrast, in the thermal-aged groups, the highest tensile bond strength values were for the MLA and RELX groups. Moreover, while thermocycling significantly affected bond strengths in the RELX and CLF groups, the mean strength of the MLA group did not significantly change after aging. There was little difference in the distribution of failure modes in any group. (J Oral Sci 52, 425-430, 2010)
Background
Telescopic prostheses are an evidence‐based treatment modality, and conical zirconia crowns and electro‐formed gold copings have been used for dentures supported by teeth and/or implants.
...Purpose
We aimed to evaluate the survival rates of zirconia‐based tooth/implant restorations.
Materials and Methods
A total of 126 telescopic overdentures, all retained by conical zirconia crowns and electro‐formed gold copings, were retrospectively evaluated and failures analyzed for abutment configurations. Survival rates and modifying factors were evaluated by Kaplan‐Meier analysis, log‐rank testing, and Cox regression analysis.
Results
We evaluated observation periods of up to 11.5 years (mean: 45.25 ± 25.11 months). Five‐year prosthesis survival was 96.9 ± 2.2% (95% CI: 92.6‐100). Six dentures had been lost, and these failures were significantly associated with specific abutment configurations.
Conclusions
Within the limitations of this retrospective study, the concept of conical zirconia telescoping into electro‐formed gold provides a viable alternative to other telescopic designs used for removable dental prostheses. The concept is well suited especially for tooth/implant‐supported prosthetic rehabilitation.
Dental zirconium oxide restorations are milled from pre-sintered blocks or disks which are produced either with high isostatic pressure (HIP) or, simpler, a slurry technique. The objective was to ...perform a fatigue test and an in vitro wear simulation of two ceramics, yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramic and a hybrid zirconium oxide-aluminum oxide ceramic, (ATZ) both produced either the classical way using high isostatic pressure (HIP, control) or with a slurry technique.
Ten discs/group were subjected to a cyclic biaxial fatigue test using a staircase approach under water at 37 °C in a dynamic universal testing machine. The 2-body wear test was performed on eight lapped 12 mm thick cylindrical samples subjected to spherical (ø 6 mm) leucite ceramic antagonists in a CS-4 chewing simulator at 49 N force and 0.7 mm lateral movement for 600 k cycles and 4167 thermal cycles (5–55 °C). Volumetric wear was calculated based on laser-scanned surfaces. Selected samples of both tests were viewed in SEM.
All the ceramic specimens produced using the HIP method survived up to 1.2 M cycles with the maximum load of the equipment (1000 N) loading the specimens up to 1527 MPa. The fatigue limit stress at 1.2 M cycles for the Slurry ATZ samples was 946 MPa. For the Slurry Y-TZP samples the fatigue limit stress at 1.2 M cycles was 658 MPa. At 600 k cycles, all zirconium oxide ceramics showed no measurable wear and had a highly polished appearance. The leucite ceramic antagonists wear developed in a linear way. There was no difference between the materials produced with the slurry and the HIP process. ATZ ceramic produced significantly more wear than 3Y- TZP ceramic.
The HIP method provided higher fatigue strength than the Slurry manufacturing method. All HIP ceramics surpassed the limit threshold (1527 MPa) of the testing machine. The tested ceramics did not show any measurable wear but had worn the leucite reinforced glass ceramic antagonists for a considerable amount.
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The dependence of the porosity, mechanical and surface properties of the obtained zirconium ceramics on the content of polylactide as a pore-forming agent was explored. It was shown ...that modification of ceramics with the polymer material leads to the improvement of mechanical properties and to the decrease in the cytotoxicity of materials.
Purpose: All‐ceramic crowns are subject to fracture during function, especially in the posterior area. The use of yttrium‐stabilized zirconium‐oxide ceramic as a substructure for all‐ceramic crowns ...to improve fracture resistance is unproven. The aim of this study was to compare fracture strength and fatigue resistance of new zirconium‐oxide and feldspathic all‐ceramic crowns made with computer‐aided design/computer‐aided manufacturing (CAD/CAM).
Materials and Methods: An ivorine molar was prepared to receive an all‐ceramic crown. Using epoxy resin, 40 replication dies were made of the prepared tooth. Twenty feldspathic all‐ceramic crowns (Vita Mark II) (VMII) and 20 zirconium‐oxide crown copings (In‐Ceram YZ) (YZ) were made using CAD/CAM technique (CEREC‐3D). The YZ copings were sintered and veneered manually with a fine‐particle ceramic (VM9). All crowns were cemented to their respective dies using resin cement (Panavia F 2.0). Ten crowns in each group were subjected to compressive fatigue loading in a universal testing machine (instron). The other ten crowns from each group were loaded to fracture at a crosshead speed of 1 mm/min. Data were statistically analyzed using independent t‐test and Fisher's exact test at α= 0.05.
Results: There was a significant difference between the survival rates of the two materials during the fatigue test (p < 0.001). All VMII crowns survived without any crack formation, while all YZ crowns fractured (40%) or developed cracks (60%). All the YZ crown fractures occurred within the veneering layer during the fatigue test. There was no significant difference in mean fracture load between the two materials (p= 0.268). Mean fracture loads (standard deviation) in N were: 1459 (492) for YZ crowns and 1272 (109) for VMII crowns.
Conclusions: The performance of VMII crowns was superior to YZ crowns in the fatigue test. The premature fractures and cracks of the YZ crowns were attributed to weakness in the YZ veneer layer or in the core/veneer bond.
Technology of thermal ceramic barriers (TBC) has been chiefly designed for materials with a single thermal barrier of the 7YSZ type. A high content of Y2O3 ensures a good phase stability of the YSZ ...material. In search for other alternative materials suitable for TBC, the material most often examined is modified zirconium oxide. The modification consists of stabilizing the ZrO2 powder with Y2O3 and doping it with La, Gd and Nd. This paper presents the results of studies on producing cathodic zirconium oxide-based ceramic targets intended for depositing refractory heat-resistant nano-crystalline TBC coatings. The targets are characterized by a high density (close to its theoretical value) and have a homogeneous phase and chemical structure.
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