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This study aims to investigate the difference on transmittance of four systems of dental all-ceramic zirconia materials which are at clinical required thickness,IPS e.max Press used as control.All-ceramic zirconia specimens containing Zenostar,Lava,Cercon and Upcera,are fabricated into discs with 10mm in diameter and 0.5±0.01mm in thickness.The transmittance of disc specimens are measured by using PR2650 spectrophotometer and the measurements are conducted statistical analysis with software SPSS13.Experimental results reveal that the transmittances of four systems of zirconia materials are significantly different.Their transmittances decrease in sequence of IPS e.max Press ,Zenostar,Lava,Cercon and Upcera zirconia.Zenostar and Lava Zirconia,which have good optical effects,possess ideal restorative materials for anterior teeth with higher transmittance.

This study aims to investigate the difference on relative translucency of four systems of dental all-ceramic zirconia materials which are all at clinical required thickness.All-ceramic zirconia specimens containing Zenostar,Lava,Cercon and Upcera are fabricated into discs with 10mm in diameter and 0.5±0.01mm in thickness.The relative translucency of specimens are measured with color difference meter,and the measurements are conducted statistical analysis with software SPSS13.Experimental results display that their relative translucency are significantly different,which decrease in sequence of Zenostar,Lava,Cercon and Upcera zirconia.Cercon zirconia with certain translucency could be used for relatively opaque posterior tooth.As for discolored teeth,Upcera Zirconia may be advisable.

The need for bone repair has increased as the population ages. However, currently, the bone grafts still have some disadvantages, such as low compressive strength and porosity, which limit their use. In order to solve these disadvantages, in this study, the porous beta-tricalcium phosphate (β-TCP) anorganic bone graft were prepared from healthy bovine cancellous bone by cell-free, defat and twice calcinations. X-ray diffraction (XRD) was used to investigate the chemical composition of the bone graft. And the morphology, porosity and mechanical strength of the bone graft were also evaluated. The results showed that most constituent of the bone graft was β-TCP. In addition, the bone graft scaffold exhibited the macro and micro porous structure and the porosity was 57.63%, just as the nature cancellous bone. The compressive strength was 4.47±0.63MPa. Above all, the porous β-TCP anorganic bone graft not only has similar chemical composites as the nature cancellous bone, but also it can effectively retain the porous structure of natural cancellous bone and provides optimal channels for the ingrowth of new bone and blood vessels.Therefore, the porous β-TCP anorganic bone graft is a potential biomaterial in bone tissue engineering.

The aim of this invitro study was to evaluate the fracture resistance of endodontically treated canines restored with one-piece milled zirconia post and core in the varying ferrule modes. Fifty recently extracted human maxillary canines were endodontically treated and randomly divided into 5 groups of 10 specimens each. According to the defect degree of ferrule, intact ferrule was classified as group A and served as control, 2 mm ferrule height without buccal ferrule was classified as group B, 2 mm ferrule height without mesial and buccal ferrule was classified as group C, 2 mm ferrule height without mesial, buccal and lingual ferrule was classified as group D, no ferrule preparation was classified as group E. All of the teeth were restored with one-piece milled zirconia post and core, and zirconia crowns. The teeth were prepared to standardized specifications. The restored teeth were loaded to fracture at a 135° angle to their long axis, at a cross-head speed 0.5 mm/min, and the load (N) at failure was recorded. Statistical analysis was performed by SNK pairwise multiple comparisons (α=0.05). The mean fracture resistance of five groups as follows: 1019.30±139.01N for group A, 861.20±105.67N for group B, 833.70±100.56N for group C, 733.20±96.91N for group D, 698.00±99.90N for group E. The fracture resistance of restored teeth between group B and group C, group D and group E had no statistically significant difference(P>0.05). The fracture resistance of the rest pairwise group comparisons had statistically significant difference(P

To evaluate bond strength of veneering ceramics to a graded zirconia core. Two zirconia core ceramics (Y-TZP and graded zirconia) were fabricated and veneered with IPS e.max Ceram. A metal ceramic system (IPS d.SIGN, Ivoclar Vivadent, Liechtenstein) was used as a control group for the two all-ceramic test groups (n=20). Shear bond strength test and microtensile bond strength test were conducted by a universal testing machine. Fracture surfaces were also evaluated to determine the failure modes. Additionally, one-way ANOVA and Tukey's HSD tests were used to analyze the data. The shear bond strength test and microtensile bond strength test showed the familiar results. Graded zirconia exhibited the highest bond strength value (SBS: 31.01±2.01 MPa, MTBS: 40.95±1.95 MPa), significantly higher than that of Y-TZP (SBS: 28.14±2.28 MPa, 37.99±2.83 MPa). No significant differences were found between the metal core group and the two zirconia core groups. All test groups demonstrated cohesive failure within the veneer, as well as adhesive failure between the core and the veneer. Glass infiltration to zirconia may affect bond strength between zirconia core and veneering ceramics. A graded zirconia glass structure exhibits a benign bond to a veneering ceramics which could be similar to that of a metal ceramic system.

To assess the color stability of different resin cements after accelerated ageing. Four different resin cements were included in the study (1mm thickness). The resin cements were bonded to ceramic disks (0.5mm thickness) built with the VITABLOCS MARK-Ⅱ ceramic (n=7). All of the samples were stored in 37°C distilled water at dark. Then color measurement were determined using spectrophotometric before and after accelerated ageing in a weathering machine with a total energy of 150kJ/m2. Changes in color (ΔE) were obtained using the CIE Lab system coordinates where a ΔE data above 3 was accepted as visible discoloration. The ΔE of Superbond C&B, RelyX ARC, Variolink Veneer and Tetric Flow were 2.24±0.52, 2.47±0.28, 0.62±0.31 and 0.72±0.31 respectively. The Superbond C&B and RelyX ARC achieved significant higher ΔE than the other groups (P0.05). All of the resin cements assessed in this study show varying degrees of discoloration after accelerated ageing. However, the color change are not beyond the clinical aesthetic demand. And the Tetric Flow and Variolink Veneer demonstrate a higher color stability.

The purpose of this study was to compare the transmittance of four dental all-ceramic core materials at clinical recommendation thickness.Specimens with 10mm in diameter and 0.50.01mm in thickness,including IPS e.max Press,Zenostar Zirconia,Lava Zirconia and Upcera Zirconia,were fabricated.The transmittance of specimens were measured with PR2650 spectrophotometer and measurements were analysed statistically with SPSS13.0.Experimental results showed that they had significantly different transmittance.There was a decreasing order,IPS e.max Press Lava Zirconia Zenostar Zirconia Upcera Zirconia,which were 6.1136.750 for IPS e.max,1.6042.135 for Lava Zirconia,1.5782.117 for Zenostar Zirconia and 0.9951.265 for Upcera Zirconia.

This study aimed to compare the translucency of four veneered dental all-ceramic core materials,including IPS e.max Press,Zenostar,Lava Zirconia and Upcera Zirconia.All specimens were fabricated at 10mm in diameter and 1.00.01mm in thickness.The translucency of specimens were measured with color difference meter and measurements were statistically analysed with SPSS 13.0. Experimental results showed that their translucency had significant difference,the order of relative translucency from high to low was IPS e.max PressLava ZirconiaZenostarUpcera Zirconia.IPS e.max Press which has good optical effect may be preferable for restoring anterior tooth with higher translucent. As for relatively opaque posterior tooth,Upcera Zirconia may be advisable.

The spectral transmittance of six kinds of Vita In-Ceram and Cercon all-ceramic core materials after veneering ceramic was determined. Based on the production method recommended by the manufacturer, specimens of the same thickness are made. PERKIN ELMER Spectrophotometer is adopted to measure the spectral transmittance of In-Ceram AL2 slip-casting glass/alumina composite, AL2 electroformed alumina, Z21 slip-casting glass/zirconia composite, Z21 electroformed zirconia, Cercon base color zirconia and Cercon base zirconia all-ceramic core materials, after veneering ceramic. The results show that, after veneering ceramic, Cercon base Zirconia has the highest spectral transmittance, followed by AL2 Electroformed Alumina and Z21 Electroformed Zirconia, whereas the transmittance of Z21 slip-casting Glass/Zirconia composite has the lowest. Statistical data show that, among the groups, In-Ceram slip-casting Glass/Alumina composite (AL2), Electroformed Alumina (AL2), Cercon base color Zirconia and Cercon base Zirconia have significant differences between every group. On the other hand, there is no significant difference between In-Ceram slip-casting Glass/Zirconia composite (Z21) and Electroformed Zirconia (Z21). Therefore, we should choose all-ceramic restoration materials based on the spectral transmittance of all-ceramic core materials after veneering ceramic and transparency of the remaining natural teeth of patients.

The present paper probes into the effect of background color of different post-core materials on the core materials of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia, Cercon base color Zirconia, and Cercon base Zirconia. The spectrocolorimeter was used to measure colorimetric values of all groups of samples against the background of noble metal, nickel-chromium alloy, silver amalgam and resin, and to calculate the color difference among the groups. The result showed that the color difference of Cercon base color Zirconia viewed against different backgrounds was identifiable by human eyes (ΔE > 1.5). In contrast, the color differences of In-Ceram AL2 Electroformed Alumina, Z21 Electroformed Zirconia and Cercon base Zirconia viewed against different backgrounds were unidentifiable by human eyes (ΔE < 1.5). Based on this, it can be stated that Cercon base color Zirconia is significantly affected by background color. Thus, proper method to shelter the background color should be adopted. In addition, AL2 Electroformed Alumina, Z21 Electroformed Zirconia, and Cercon base color Zirconia are less influenced by the background color, thus it is not necessary to cover the background color.

Objective: to investigate glass infiltrating rates (depth/time) within dental CAD/CAM alumina at different temperatures. Methods: micron α-alumina powder was prepared with cold isostastic pressure at 250 MPa and sintered at 1450°C. The presintered alumina specimens were then infiltrated with special glass at 1150°C, 1200°C and 1250 °C. The infiltrating depths and time to form the infiltrate at the different temperatures were evaluated. Results: As the infiltrating temperature increased, the viscosity of the infiltrating glass decreased, and the infiltrating depth increased. A 1 mm infiltration depth into the presintered alumina at 1150°C, 1200°C and 1250°C required 95 min, 22 min and 8 min, respectively. Conclusion: An optimal infiltrating time required to reach a suitable infiltration depth into the presintered alumina was observed at 1200°C, an important finding for clinical applications at this commonly used furnace temperature.

Objective: to describe and demonstrate an oral mucosa irritation and a skin sensitivity test for evaluation of the biological safety of a colored alumina/glass composite (AGC). Methods: colored alumina/glass composite and control materials were sutured to mucine bilateral cheek pouch mucosa, in a position for gross observation and for histological and cytological examination; skin irritation activity of the composite was tested by intradermal injection of a guinea pig test solution, by inducing, enhancing, and stimulating the allergic response observed after local tissue exposure. Results: colored AGC in mouse cheek pouch mucosa stimulated the same reaction as the control, with no significant inflammatory reaction or infiltration of inflammatory cells. Guinea pigs showed no obvious erythema or edema from the irritation test, such that the assessment of colored AGC skin allergy response in mice was 0%. Conclusion: colored AGC was benign towards mouse oral mucosa and elicited no allergic skin inflammation response, indicating that in these aspects this material had good biological safety.

The purpose of this study was to investigate the structure, mechanical and low temperature aging properties of colored dental zirconia ceramics. Colored 3Y-TZP zirconia dental zirconia ceramics were made by mixing colorants and their combinations into a 3Y-TZP powder, the green body were compacted at 200MPa, presinter at 1050°C and densely sintered at 1500°C for 2h. Specimens were subjected to an accelerated aging test carried out in an autoclave in steam at 134°C, 2bar, for 4hs. XRD was used to identify the crystal phases, three-point bending strength were tested before and after aging according to the ISO 6872 standard, polished and aging specimens were observed by Atomic Force Microscopy (AFM) to evaluate surface microstructure. Tetragonal-to-monoclinic phase transformation was detected for both uncolored and colored specimens, the relative content of monoclinic phase was increased with the prolonged aging time. Aging had no significant negative effects on flexural strength on colored 3Y-TZP. The nucleation and growth of monoclinic phase were detected by AFM in surface of both colored and uncolored zirconia.

To study the influence of background color on 3 veneered all-ceramic core materials, the color of all veneered samples that were put on noble metal, Ni-Cr alloy, Ag-Hg alloy and resin background was measured with chromatism instrument (and the chromatic aberration value among groups was Calculated). Under different backgrounds, there was significant difference in the L, a and b values among Empress II samples, there was significant difference in a and b values among In-Ceram Alumina samples, and there was no difference in the L, a and b values among In-Ceram Zirconium samples. After veneered, the influence of background color on Empress II was clear, on In-Ceram Alumina was less clear, and on In-Ceram Zirconium was void.

In this study, the binding performance of a Cercon-based zirconia framework material and special Cercon Ceram S zirconia veneering porcelain is discussed. Rectangular 30 mm × 20 mm × 2 mm porcelain blocks were made from zirconia using the CAD/CAM system. The 2 mm veneering porcelain was then sintered onto blocks at a temperature of 850-800°C with a loading speed of l mm/min. The shear bond strength of the interface was tested. Sintering was studied by visual observation, scanning electron microscopy, energy dispersive spectroscopy (EDS), thermal shock test and other methods. Excellent sintering results of the zirconia framework material and veneering porcelain can be achieved. The cross-sectional morphology of the samples, observed by SEM, shows a uniform, fine, and smooth texture for the veneering porcelain, whereas that of the zirconia framework material shows a rough surface with a uniform and compact texture. EDS results indicate that a small amount of A12O3 and SiO2 is present in the zirconia area, and no ZrO2 or Y2O3 is detected in the veneering porcelain area. No interlayer radial crack or flaw is found throughout the entire thermal shock test of the samples at 60-240°C. Thus, the cracking temperature of the samples is pegged at T>240°C. The shear bond strength of the interface is 32.62±5.77 MPa. Chemical element infiltration exists between zirconia and the veneering porcelain, indicating the chemical bond between the two. An excellent match between the Cercon-based zirconia framework and the special veneering porcelain can be achieved, which can satisfy clinical requirements.

Objective: To study the relative translucency of 3 veneered and glazed all-ceramic systems core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium and Ivoclar Vivodent Empress. Methods: Under standard black and write background, the surface light reflectivity of 3 veneered all-ceramic systems core material was determined with contact color difference meter, and the ratio of Yb /Yw was calculated. Results: After veneered, the relative translucency of 3 core materials all declined, and ranged from 0.8880 of Empress II to 1.00 of In-Ceram zirconia, among of that Empress II was most transparent. Conclusion: The relative translucency of 3 veneered all-ceramic systems core material had significant statistical difference. There was a decreasing range as Vitadur Alpha dentin (standard) > Empress II (0.8 mm) > In-Ceram Alumina > In-Ceram Zirconia.

Objective: To study the relative translucency of 3 all-ceramics system core material, including Vita In-Ceram Alumina, Vita In-Ceram Zirconium and Ivoclar Vivodent Empress II. Methods: The visible light transmittance of all samples was determined with spectrophotometer. Results: The relative translucency of dentin and opaque dentin was between 0.5958 and 0.8336, that of 3 core ceramic ranged from 0.8089 of Emp ress II to 1.00 of In-Ceram Zirconium. Conclusion: The relative translucency of 3 core material was significantly different. There was a decreasing range as Empress II > In-Ceram Alumina and In-Ceram Zirconia.

The purpose of this study was to investigate the effect of different veneering porcelain types on the flexural strength of dental Y-TZP/porcelain layered structure. KAVO™ Everest zirconia ceramics were selected as substructure. To forming Y-TZP/porcelain bilayered structure, a leucite based veneering porcelain was fired on the zirconia substructures by slip-casting technique with dentin washbake, and two nano-fluorapatite based veneering porcelain was fired on the zirconia substructures either by slip-casting or pressed-on technique with or without liner coverage. Bending strength was tested according to ISO 6872 standard, and the veneered surfaces of fracture samples were analyzed by SEM. Experimental results showed that for covering KaVo™ zirconia core material, conventionally applied veneering slurry-porcelain combined with liner or wash firing has significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive.

Objective: To study the effects of presintering temperature and temperature rise speed on the physical and mechanical properties of alumina-glass-composite (AGC). Methods: AGC was prepared respectively under the condition that presintered at 1400°C and 1450°C as well as two kind of temperature rise speed. The properties were measured, including density, thermal expansion coefficient, three-point bending strength, fracture toughness, modulus of elasticity and Vicker’s hardness of AGC. Results: With the increasing of presentering temperature and the temperature rise speed, density of AGC decreased, bending strength, fracture toughness, modulus of elasticity increased markedly. There was no difference between three-point bending strength and fracture toughness of AGC that was made by two temperature rise speed to 1450°C. Bending strength of AGC that was made by lower temperature rise speed to 1400°C was the lowest. The Vicker’s hardness of the 1450°C groups was higher than that of the 1400°C groups. Conclusion: Both presintering temperature and the temperature rise speed can influenced the properties of AGC, but the effect of presintering temperature was the most.

The purpose of this study was to investigate the effect of pigmentation on the flexural strength of dental Y-TZP/porcelain layered structure. KaVo™ Everest zirconia substructures was pigmented by dipping presintered blocks in coloring solution, and colored TZ-3YS zirconia substructures were fabricated by adding pigments before isostatically pressing. Specimens were made in monolithic or bilayered forms. The bending strength was tested. XRD and SEM with EDX were used to analyze the characteristics of the surface structure. Experimental results showed that there were significant differences of bending strength in both zirconia systems between white and colored monoclinic materials, which also in bilayered structures. Pigmentation has no apparent effects on the bonding strength between veneering porcelain and zirconia. Both coloring methods are appropriate when the concentration of pigments is under deliberate controlled.

Objective: to evaluate the biological safety of a colored alumina/glass composite in terms of cytotoxicity and hemolytic ability. Methods: the cytotoxicity of an alumina/glass composite was evaluated with molecular filtration method. Cytotoxicity by spectrophotometric responses of test material and responses of a fresh rabbit red blood anticoagulant solution was determined by spectrophotometer. Results: cell-coated filter paper in contact with the test material showed the appearance of intracellular blue dye as the same staining density as in control samples, leading to a toxicity rating of 0. Colored alumina/glass composite assayed at

This study aims to investigate the effect of background color on the chromatic value of four all-ceramic system core materials at clinically appropriate thicknesses. Disc specimens with 15 mm in diameter and thicknesses ranging from 0.5±0.01mm In-Ceram zirconia core, Cercon base zirconia core, and Cercon base color zirconia core) to 0.8±0.01mm (Empress II) were fabricated. A colorimeter (CIE- 1976-Lab) measured the chromatic value of all samples placed on a high-noble metal-ceramic alloy and a visible light-cured dental composite resin (A2 color) background, after which the color difference was calculated. The color difference of Empress II samples was more than 1.5 among different background color groups, while that of Zirconia was less than 1.5. The influence of background color on the Empress II dentin was visible, such that it could be used on a tooth color post. Meanwhile, the influence of background color was invisible for the three kinds of Zirconia core materia1s, such that the materials developed excellent color-masking abilities and could be adapted for use on any color background.

This study aims to investigate the effects of ceric oxide and ferric oxide on the color of alumina-glass-composite (AGC). Uncolored glass and colored glass powder with 4% ceric oxide and 0.5% ferric oxide were fabricated. Primary mixture powder were made by mixing the two colored glass powder with 0.1g interval, and then 81 kinds of colored mixture powder were gained by mixing uncolored powder with the primary mixture powder. Molten glass was infiltrated into presintered alumina blocks. The colored AGC and VITAPAN-3D-MASTER shade guide were measured with spectrophotometer. Experiment results showed that the Yxy value of VITAPAN-3D-MASTER shade guide distributed from (185,0.378,0.340) to (121,0.443,0.341) and the Yxy value of colored AGC distributed from (227,0.352,0.343) to (102,0.489,0.364). There were 37 kinds of samples in the color range of shade guide. The color range of 81 kinds of AGC covered that of the VITAPAN-3D-MASTER shade guide.

The surface microhardness and flexural strength of colored zirconia were examined. Two groups of zirconia disks (1mm thick, 20mm in diameter) within 5 disks each were shading with the same coloring liquids IL2 (Vita Classic-scale) when another group of 5 disks measured in no color. The shading time of one group was 3s and that of the other group was prolonged to 30s. The mechanical properties were tested after sintering at 1500°C. Data were evaluated using ANOVA analysis. Disks of shading 30s showed a lower strength 712  53 MPa. The value of 3s was 853  46 MPa. There were no significant difference on microhardness between the two shading time. Prolonged the shading time lowered the biaxial flexural strength of zirconia ceramic, but shading time did no effect on surface microhardness.