BACKGROUNDThe low-temperature resistance aging performance of Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is the key effective factor that influences the long-term success rate of prosthesis. The objective of this study was to test and compare the aging performances for resisting low temperature of Lava Frame, Cercon Smart, and Upcera Yttria-stabilized zirconia core materials, via analyzing the micro and the crystal phases of the materials, and measure the three-point bending strength and the fracture toughness.

METHODSThe three zirconia green bodies were prepared as 60 test samples for three-point bending strength and as 60 test samples for fracture toughness. The test samples for three-point bending strength and fracture toughness were assigned to five groups and were treated respectively for 0, 5, 10, 15, and 20 hours to observe the micro and the crystal phases of the test samples. Then the three-point bending strength and fracture toughness were tested by X-ray diffraction (XRD).

RESULTSThe m phase content of Lava Frame was raised from 7.70% to 13.01%; the m phase content of Cercon Smart was raised from 4.95% to 8.53%; and Lava Frame is raised from 10.84% to 35.18%. The three-point bending strengths of the three zirconia core materials were higher than 1100 MPa and the fracture toughness was higher than 3 MPa·m(1/2). The three-point bending strength and the fracture toughness of Upcra zirconia decreased the most, followed by Lava Frame, and then by Cercon Smart.

CONCLUSIONThe aging resistance sequences of the three zirconia core materials are, from strong to weak, Cercon Smart, Lava Frame, and Upcera.

Ceramics ; chemistry ; Dental Porcelain ; chemistry ; Microscopy, Electron, Scanning ; Temperature ; X-Ray Diffraction ; Yttrium ; chemistry ; Zirconium ; chemistry

OBJECTIVETo investigate the effects of sintering temperature on the physical and mechanical properties of dental zirconia toughened ceramic (ZTC).

METHODS3 mol% yttria-stabilized zirconia compacts were prepared by dry press method and then sintered at 1,490 degrees C, 1,530 degrees C, 1,570 degrees C and 1,610 degrees C respectively. The physical properties and bending strength were then measured.

RESULTSThe result of the study indicated along with the rise of sintering temperature density and shrinkage of ZTC increased, but the pore structure decreased. It also showed the peak of bending strength was in 1,570 degrees C.

CONCLUSIONSIn terms of sintering temperature and bending strength among the selected temperature, the best sintering temperature of 3 mol% yttria-stabilized zirconia should be about 1,570 degrees C.

Dental Porcelain ; chemistry ; Hardness ; Temperature ; Tensile Strength ; Yttrium ; chemistry ; Zirconium ; chemistry

OBJECTIVETo evaluate the effect of Fe2O3 and CeO2 as colorants on yttria stabilized tetragonal zirconia poly-crystals (Y-TZP) powder.

METHODSThe spray granulation slurry of colored zirconia was prepared with different concentrations of Fe2O3 (0.15%) and CeO2 (4%), which were added in Y-TZP. Zirconia powder was made by spray granulation. The powder specimens were divided into three groups: uncolored zirconia, Fe2O3 (0.15%) zirconia, and CeO2 (4%) zirconia. The particle morphologies of the powder specimens were measured with a laser particle size analyzer and an optical microscope.

RESULTSThe differences in D50 among the three groups were statistically significant (P<0.05). Group Fe2O3 showed a significant difference from groups CeO2 and uncolored zirconia (P<0.05). Group uncolored zirconia showed no significant difference from group CeO2 (P>0.05). Mostly spherical powder was observed in the three groups.

CONCLUSIONFe2O3 as a colorant can affect particles, whereas CeO2 has no effect.

Color ; Dental Stress Analysis ; Ferric Compounds ; Humans ; Materials Testing ; Yttrium ; chemistry ; Zirconium ; chemistry

Adolescent ; Ciliary Body ; pathology ; surgery ; Cysts ; surgery ; Glare ; Humans ; Male ; Neodymium ; chemistry ; Yttrium ; chemistry

Zirconia is widely used in the field of dentistry because of its superior mechanical and esthetic characteristics. However, the tetragonal zirconia polycrystal restorations commonly used in clinics will degrade at low temperatures in the oral environment, resulting in increased surface roughness, microcracks, and decreased mechanical properties. Low-temperature degradation of zirconia can be affected by grain size, stress, stabilizer content and type, surface treatment, sintering conditions, and other factors. Through a literature review and analysis, this review summarizes the research progress on the low-temperature degradation of zirconia in prosthetic dentistry to provide references for the improvement of zirconia in clinical and research applications.
Ceramics ; Dental Materials ; Esthetics, Dental ; Materials Testing ; Prosthodontics ; Surface Properties ; Temperature ; Yttrium/chemistry* ; Zirconium

Objective: To evaluate the effects of pre-sintering heating rate and powder size on dental recycled zirconia. Methods: Recycled zirconia powders were sieved to obtain the large (50 μm With the same particle size, the recycled zirconia pre-sintered at different heating rates showed no significant differences in the relative densities, and the open porosities (P>0.05). When the pre-sintering heating rates were 2 ℃/min, 5 ℃/min, and 8 ℃/min, the flexural strengths of the large-particle recycled zirconia were (421.2±54.7), (444.2±70.1) and (427.5±68.4) MPa, the flexural strengths of the small-particle recycled zirconia were (750.1±74.1), (777.2±95.5) and (746.7±73.0) MPa, respectively. The flexural strength of commercial zirconia was (988.4±129.8) MPa. The flexural strengths of the recycled zirconia were significantly lower than that of the commercial zirconia (P<0.05). At the same pre-sintering heating rate, the flexural strengths of the small-particle recycled zirconia were significantly higher than that of the large-particle recycled zirconia (P<0.05). Conclusions: Compared with the large particles, small-particle recycled zirconia powders can effectively improve the properties of recycled zirconia, while the pre-sintering heating rate has no effect on the properties of the recycled zirconia.
Ceramics ; Dental Materials/chemistry* ; Heating ; Materials Testing ; Powders ; Surface Properties ; Yttrium ; Zirconium

OBJECTIVETo explore the methods for labeling CDTPA-coupled CD45 monoclonal antibody (mAb) with yttrium-90 ((90)Y) for potential acute myeloid therapy.

METHODSCD45 mAb was labeled with (90)Y by CDTPA and the labeling rate, radiochemical purity, final specific activity, and immunological activity of the mAb were detected.

RESULTSWith the optimal molar ratio of CDTPA/Ab at 20:1, the labeling rate was 95%, radiochemical purity 99.8%, and final specific activity 1.9 mCi/mg. This conjugate was stable in vitro with comparable immunological activity in comparison with unlabeled CD45 mAb.

CONCLUSION(90)Y-CDTPA-CD45 mAb possesses good properties as an ideal targetting therapeutic agent for acute leukemia.

Anhydrides ; chemistry ; Antibodies, Monoclonal ; chemistry ; immunology ; Humans ; Immunoconjugates ; chemistry ; immunology ; Isotope Labeling ; methods ; Leukocyte Common Antigens ; immunology ; Pentetic Acid ; chemistry ; Radiopharmaceuticals ; chemical synthesis ; chemistry ; immunology ; Yttrium Radioisotopes ; chemistry

OBJECTIVETo study the effects of alumina content on sintered density, mechanical property and translucency of zirconia nanocomposite all-ceramics.

METHODSSpecimens of zirconia nanocomposite all-ceramics were divided into five groups based on their alumina content which are 0% (control group), 2.5%, 5.0%, 7.5% and 10.0% respectively. The sintered densities were measured using Archimedes' method. Specimens' bending strengths were measured with three-point bending test (ISO 6872). The visible light transmittances were measured with spectrophotometric arrangements and the fractured surfaces were observed using scanning electron microscope (SEM).

RESULTSThe control group of pure zirconia could be sintered to the theoretical density under pressure-less sintering condition. The bending strength was (1100.27 ± 54.82) MPa, the fracture toughness was (4.96 ± 0.35) MPa×m(1/2) and the transmittance could reach 17.03%. The sintered density and transmittance decreased as alumina content increased from 2.5% to 10%. However, the fracture toughness only increased slightly. In all four alumina groups, the additions of alumina had no significant effect on samples' bending strengths (P > 0.05). When the content of alumina was 10%, fracture toughness of specimens reached (6.13 ± 0.44) MPa×m(1/2) while samples' transmittance declined to 6.21%. SEM results showed that alumina particles had no significant effect on the grain size and distribution of tetragonal zirconia polycrystals.

CONCLUSIONSAdditions of alumina to yttria-tetragonal zirconia polycrystals could influence its mechanical property and translucency. Additions of the other phase to zirconia ceramics should meet the clinical demands of strength and esthetics.

Aluminum Oxide ; chemistry ; Ceramics ; chemistry ; Dental Porcelain ; chemistry ; Dental Stress Analysis ; Elasticity ; Hardness ; Materials Testing ; Microscopy, Electron, Scanning ; Nanoparticles ; Pliability ; Surface Properties ; Yttrium ; chemistry ; Zirconium ; chemistry

OBJECTIVEThe effect of sandblasting on the bond strength between 3mol% yttrium-stabilized tetragonal zirconium polycrystal (3Y-TZP) zirconia framework and veneering porcelain was evaluated.

METHODSA total of 21 specimens [(25 ± 1) mm x (3 ± 0.1) mmx (0.5 ± 0.05) mm] were prepared according to ISO 9693. The specimens were then randomly divided into 3 groups. Sandblasting was performed on 2 meshes of Al₂O₃ particles: group A with mesh 110 and group B with mesh 80. Group C, which was not sandblasted, was the control group. The surface roughness of the zirconia framework, as well as the bond strength between 3Y-TZP zirconia framework and veneering porcelain, was measured. The interface microstructure was observed by scanning electron microscope (SEM), and elemental distribution was detected by energy dispersive spectroscopy (EDS).

RESULTSSurface roughness values were (1.272 ± 0.149) μm for group A, (0.622 ± 0.113) μm for group B, and (0.221 ± 0.065) μm for group C. Statistical significance were found among groups (P < 0.05). The bond strength values were (28.21 ± 1.52) MPa for group A, (27.71 ± 1.27) MPa for group B, and (24.87 ± 3.84) MPa for group C. Statistical significance was found between group A and group C (P < 0.05), whereas the other groups had no statistical significance (P > 0.05). Interface adhesion failure was the primary performance. SEM images showed the close interface bonding, and EDS showed that the interface had no obvious element penetration.

CONCLUSIONAl₂O₃ sandblasting can slightly enhance the bond strength between zirconia framework and veneering porcelain.

Aluminum Oxide ; chemistry ; Dental Bonding ; Dental Porcelain ; chemistry ; Dental Stress Analysis ; Dental Veneers ; Materials Testing ; Microscopy, Electron, Scanning ; Shear Strength ; Surface Properties ; Yttrium ; chemistry ; Zirconium ; chemistry

OBJECTIVETo investigate the effect of two methods of pigmentation on the flexural strength of dental Y-TZP/porcelain layered structure.

METHODSKaVo zirconia substructures were pigmented by dipping presintered blocks in the coloring solution VITA LL1 and LL5, and colored TZ-3YS zirconia substructures were fabricated by adding pigments before isostatic pressing. The colors No.1 and No.5 were used for the test. The specimens were made in monolithic or bilayered forms, and the flexural strength was tested. XRD and SEM with EDX were used to analyze the characteristics of the surface structure.

RESULTSIn KaVo group, no significant differences were found in the flexural strength between white and LL1 and LL5 colored monoclinic materials, nor in bilayered structures. While in TZ-3YS group, significant differences were noted in the flexural strength between color No.5 white and color No.1 monoclinic materials, but not between the latter two subgroups. The flexural strength was significantly lowered by veneering with porcelain in both zirconia groups, and similar findings were observed with the monoclinic materials. Only the tetragonal phase was detected in both of the zirconia groups.

CONCLUSIONPigmentation has no apparent effects on the bonding strength between the veneering porcelain and zirconia. Both coloring methods are appropriate when the concentration of the pigments is under deliberate control.

Dental Bonding ; Dental Materials ; Dental Porcelain ; chemistry ; Dental Stress Analysis ; Dental Veneers ; Materials Testing ; Pigmentation ; Tensile Strength ; Yttrium ; chemistry ; Zirconium ; chemistry