Advanced Materials Research Vols. 105-106

Abstract: 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.

Abstract: 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.

Abstract: Zirconia ceramics are now widely used in dental restorations. The veneering porcelain chipping happens sometimes in zirconia-porcelain all-ceramic system. The objective of this study was to evaluate the bonding strength between the zirconia core and various commercial veneering ceramics. The shearing and bending methods were used to evaluate the bonding strengths of zirconia core and four veneering ceramics. Meanwhile, as surface treatment will play an important role for the bonding strength, the influence of 3 kinds of surface treatment was investigated. The results indicated that both the shearing and bonding strengths of Cercon ceram kiss is better. Moreover sand blasting is the most useful method of surface treatment.

Abstract: Calcium metaphosphate (CMP) fine powders were produced by a chemical precipitation method. In order to produce the powders, CMP was prepared by the mixing of two precursors, such as calcium oxide (CaO) and phosphate acid (H3PO4). Sparingly soluble chemicals, the Ca/P ratio of the mixture was set to be 0.50 to produce stoichiometric CMP, were chemical agitated in phosphate acid solution. At least 3 hours of pre-hydrolysis of phosphorus precursor were required to obtain CMP phase. The CMP powders were dried in a drying oven at 60°C for 72 hours and then heat-treated at various temperatures at a ramp of 1°C /min in air for various hours. The obtained powder was analyzed using XRD, XRF, FT-IR, SEM, TG-DTA, Zeta Potential Meter, Specific Surface Area, and Particle Size Analyzer. The results showed that obtained CMP powders have a significantly powder characteristics.

Abstract: 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.

Abstract: Mineralization is a powerful approach for fine inorganic minerals and organic/inorganic complexs with novel structure. The morphology of composites show the mineralized magnetite dispersed in chitosan hydrogel uniformly. The reason for uniform dispersion might be that the chitosan hydrogel restricted the moving ability of iron ions and the iron ions can only move to the nearest crystal nucleus. The magnetite content of magnetite/chitosan composite was approximately 12.6%. The mineralized magnetite have a significant interaction with chitosan which induced the magnetite/chitosan composite has a higher decomposition temperature than chitosan. After decomposition, the magnetite transformed into γ-Fe2O3 and α-Fe2O3, and a significant crystal growth happened.

Abstract: The bioactivity of HA has been tested by its osteoconduction ability in vivo. Nano HA has higher specific surface area and was presumed to have high bioactivity. In this paper, nano needle HA was synthesized by the microemulsion method. The properties of such nano materials were analyzed by the XRD and TEM. The impact of the nano HA on the expression of two hBMSCs’ genes, inhibitor differentiation 2 and ostopontin, and the ALP activity was researched in this paper.

Abstract: 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.

Abstract: 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.

Abstract: The objective of this study is to compare the degradation of three strontium-containing calcium phosphate cement (Sr-CPC) and one calcium phosphate cement without strontium (CPC) in vivo. Three Sr-CPCs, containing 1%, 5%, 10% strontium respectively, and a CPC without strontium were tested in this study. The specimens in rod-shape (2 mm  6 mm) were prepared, and were implanted in the erector spine muscle of 15 New Zealand rabbits. After 4, 8 and 12 weeks, 5 rabbits were sacrificed respectively and the specimens were taken out, cleaned, dryed and weighed. The weight losses of the specimens were calculated and the data were analyzed by ANOVA. The results showed that the CPC containing 5%, 10% strontium showed obviously higher degradation rates at the three observation periods than that containing 1% strontium and that without strontium (P<0.05). Addition of 1% strontium into CPC did not increase degradation rate (P>0.05), and the CPC containing 5% and 10% strontium showed no difference in degradation rate at the three observation periods (P>0.05).