1.Biaxial flexural strength and phase transformation of Ce-TZP/Al2O3 and Y-TZP core materials after thermocycling and mechanical loading.
Merve BANKOGLU GUNGOR ; Handan YILMAZ ; Cemal AYDIN ; Secil KARAKOCA NEMLI ; Bilge TURHAN BAL ; Tulay TIRAS
The Journal of Advanced Prosthodontics 2014;6(3):224-232
PURPOSE: The purpose of the present study was to evaluate the effect of thermocycling and mechanical loading on the biaxial flexural strength and the phase transformation of one Ce-TZP/Al2O3 and two Y-TZP core materials. MATERIALS AND METHODS: Thirty disc-shaped specimens were obtained from each material. The specimens were randomly divided into three groups (control, thermocycled, and mechanically loaded). Thermocycling was subjected in distilled water for 10000 cycles. Mechanical loading was subjected with 200 N loads at a frequency of 2 Hz for 100000 times. The mean biaxial flexural strength and phase transformation of the specimens were tested. The Weibull modulus, characteristic strength, 10%, 5% and 1% probabilities of failure were calculated using the biaxial flexural strength data. RESULTS: The characteristic strengths of Ce-TZP/Al2O3 specimens were significantly higher in all groups compared with the other tested materials (P<.001). Statistical results of X-ray diffraction showed that thermocycling and mechanical loading did not affect the monoclinic phase content of the materials. According to Raman spectroscopy results, at the same point and the same material, mechanical loading significantly affected the phase fraction of all materials (P<.05). CONCLUSION: It was concluded that thermocycling and mechanical loading did not show negative effect on the mean biaxial strength of the tested materials.
Spectrum Analysis, Raman
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Water
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X-Ray Diffraction
2.Mechanical properties of zirconia after different surface treatments and repeated firings.
Meryem Gulce SUBASI ; Necla DEMIR ; Ozlem KARA ; A Nilgun OZTURK ; Faruk OZEL
The Journal of Advanced Prosthodontics 2014;6(6):462-467
PURPOSE: This study investigated the influence of surface conditioning procedures and repeated firings on monoclinic content and strength of zirconia before cementation. MATERIALS AND METHODS: Sintered bar-shaped zirconia specimens were subjected to no surface treatment (control), air abrasion, or grinding (n=21). Their roughness was evaluated using a profilometer, and microscope analysis was performed on one specimen of each group. Then, 2 or 10 repeated firings (n=10) were executed, the monoclinic content of specimens was analyzed by X-ray diffraction, and a three-point flexural strength test was performed. Surface roughness values were compared using one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) tests, the monoclinic content values were tested using Kruskal-Wallis and Mann-Whitney U tests, and the flexural strength values were tested using two-way ANOVA and Tukey HSD tests (P=.05). Spearman's correlation test was performed to define relationships among measured parameters. RESULTS: Surface-treated specimens were rougher than untreated specimens and had a higher monoclinic content (P<.005), and the relationship between roughness and monoclinic content was significant (P<.000). Neither surface treatment nor firing significantly affected the flexural strength, but Weibull analysis showed that for the air-abraded samples the characteristic strength was significantly lower after the 10th firing than after the 2nd firing. CONCLUSION: After firing, a negligible amount of monoclinic content remained on the zirconia surfaces, and rougher surfaces had higher monoclinic contents than untreated surfaces. Multiple firings could be performed if necessary, but the fracture probability could increase after multiple firings for rougher surfaces.
Cementation
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Ceramics
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Fires*
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X-Ray Diffraction
3.Construction of nano-granule titanium film and study of its surface topography.
Yuan-yuan LIU ; Meng YOU ; Hu WANG ; Jing ZHANG ; Zhen-yu YANG ; Ying-Jie LIN ; Jing-wei MIAO
West China Journal of Stomatology 2009;27(4):455-458
OBJECTIVETo construct four different micro- and nano-phase titanium film models and investigate the characteristics of their surface micro-topography.
METHODSFour different titanium films were prepared on commercial titanium discs, by direct current magnetron sputtering, at ambient, 100, 250, 380 degrees C substrate temperature, respectively. Their surface topography and crystal sizes were investigated using atomic force microscope (AFM) and X-ray diffraction (XRD). The size of granule and surface roughness in different group was calculated and compared.
RESULTSAll samples were covered by a thin film consisting of dense round or ovaloid granules. The granules and crystals was growing as the substrate temperature increasing. The Ti substrate had greater effect on the surface topography of film compared with Si substrate. This kind of complex topography caused the surface roughness of Ti substrate group decreased as the granules growing.
CONCLUSIONIn our study, four different micro- and nano-phase titanium film models were constructed for our coming investigation of their topographical influence on biological reaction of proteins and cells. Basic data on surface features was obtained for next in vitro and in vivo experiment.
Surface Properties ; Titanium ; X-Ray Diffraction
4.Comparison of the optical properties of pre-colored dental monolithic zirconia ceramics sintered in a conventional furnace versus a microwave oven.
The Journal of Advanced Prosthodontics 2017;9(5):394-401
PURPOSE: The purpose of this study was to compare the optical properties of pre-colored dental monolithic zirconia ceramics of various thicknesses sintered in a microwave and those in a conventional furnace. MATERIALS AND METHODS: A2-shade of pre-colored monolithic zirconia ceramic specimens (22.0 mm × 22.0 mm) in 3 thickness groups of 0.5, 1.0, and 1.5 mm were divided into 2 subgroups according to the sintering methods (n=9): microwave and conventional sintering. A spectrophotometer was used to obtain CIELab color coordinates, and translucency parameters and CIEDE2000 color differences (ΔE 00) were measured. The relative amount of monoclinic phase (X(m)) was estimated with x-ray diffraction. The surface topography was analyzed by atomic force microscope and scanning electron microscope. Statistical analyses were conducted with two-way ANOVA (α=.05). RESULTS: There were small interaction effects on CIE L*, a*, and TP between sintering method and thickness (P<.001): L* (partial eta squared η(p)²=0.115), a* (η(p)²=0.136), and TP (η(p)²=0.206), although higher b* values were noted for microwave sintering regardless of thickness. Color differences between two sintering methods ranged from 0.52 to 0.96 ΔE(00) units. The X(m) values ranged from 7.03% to 9.89% for conventional sintering, and from 7.31% to 9.17% for microwave sintering. The microwave-sintered specimen demonstrated a smoother surface and a more uniform grain structure compared to the conventionally-sintered specimen. CONCLUSION: With reduced processing time, microwave-sintered pre-colored dental monolithic zirconia ceramics can exhibit similar color perception and translucency to those by conventional sintering.
Ceramics*
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Clothing
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Color Perception
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Methods
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Microwaves*
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Spectrophotometry
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X-Ray Diffraction
5.Structure and properties of colored dental tetragonal zirconia stabilized by yttrium ceramics.
Yuan-fu YI ; Chen WANG ; Ning WEN ; Yong-zhao LIN ; Jie-mo TIAN
West China Journal of Stomatology 2009;27(5):473-478
OBJECTIVETo investigate the structure, mechanical and low temperature aging properties of colored dental zirconia ceramics.
METHODS5 graded colored dental zirconia ceramics were made by adding colorants and their combinations into a 3Y-TZP (tetragonal zirconia stabilized by 3mol% yttrium) powder, the green body were compacted at 200 MPa, pre-sinter at 1,050 degrees C and maintained for 2 h, then densely sintered at 1,500 degrees C for 2 h. Specimens were cut from each of the 5 graded colored blocks. Physical, mechanical properties as well as chemical stability were tested, microstructure were observed, crystalline phase were identified by X-ray diffraction (XRD), aging properties were assessed by measurement of the relative content of monoclinic phase and bending strength testing.
RESULTSThe overall density of colored zirconia ceramics was over 99.7%, linear shrinkage was about 20%, while thermal expansion coefficient was about 11 x 10(-6) x degrees C(-1), the crystalline phase was tetragonal, bending strength was over 900 MPa which was slightly lowered than that of the uncolored zirconia, fracture toughness was slightly higher. Good chemical stability in acetic acid was observed. After aging treatment, tetragonal-to-monoclinic phase transformation was detected up to 40%, while bending strength was not significantly degraded.
CONCLUSIONThe results showed that colored 3Y-TZP ceramics presented good mechanical properties even after aging treatments, and was suitable for dental clinical use.
Ceramics ; Materials Testing ; X-Ray Diffraction ; Yttrium ; Zirconium
6.Liquisolid technique for enhancement of dissolution prosperities of tanshinone II(A).
Xiao-qian LIU ; Qing-ju MENG ; Xue-lin XU ; Jie ZHAO ; Hua YANG ; Hong YI
China Journal of Chinese Materia Medica 2015;40(24):4840-4846
The technique of liquisolid compress is a new technique developed in 1990s, which was considered to be the most promising technique to improve the dissolution of water-insoluble drugs. In this article, tanshinone II(A) and the extracts of the ester-solubility fractions were chosen as the model drugs to evaluate the effects of the liquisolid technique for enhancement of dissolution properties of tanshinone II(A). Several liquisolid tablets (LS) formulations containing different dosage of drugs and various liquid vehicle were pre-pared and for all the formulations, microcrystalline cellulose and silica were chosen as the carrier and coating materials to evaluate their flow properties, such as angle of repose, Carr's compressibility index and Hausner's ratio. The interaction between drug and excipients in prepared LS compacts were studied by differential scanning calorimetry(DSC) and X-ray powder diffraction (XRPD). The dissolution curves of tanshinone II(A) from liquisolid compacts were investigated to determine the technique's effect in improving the dissolution of tanshinone II(A) and its impacting factors. According to the results, the dissolution increased with the rise in the dissolution of the liquid-phase solvent. The R-value and drug dosage can significantly affect the drug release, but with less impact on active fractions. This indicated that liquisolid technique is a promising alternative for improvement of dissolution property of water-soluble drugs, and can make a synergistic effect with other ester-soluble constituents and bettern improve the release of tanshinone II(A). Therefore, the technique of liquisolid compress will have a better development prospect in traditional Chinese medicines.
Calorimetry, Differential Scanning
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Diterpenes, Abietane
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chemistry
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Solubility
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X-Ray Diffraction
7.Study on identification of traditional Chinese medicine Yangqishi and Yinqishi by X-ray diffraction.
Long CHEN ; Ming-yang YUAN ; Mi LEI ; Bi-sheng HUANG ; Ke-li CHEN
China Journal of Chinese Materia Medica 2015;40(18):3560-3566
The aim of this paper is to clarify the mineral origin of traditional Chinese medicine (TCM) Yangqishi and Yinqishi and guide identification of the both, by X-ray diffraction (XRD) Fourier patterns. Morphological identification and conventional physical and chemical analysis wee used to identify 22 batches of Yangqishi and Yinqishi. It used XRD Fourier patterns which has been collected from sample powders to analyze phase composition. It has been found experimentally that the mineral origin of Yinqishi is Talc schist and the mineral origin of Yangqishi is tremolite and actinolite. The results also showed that the method using XRD can get not only an accurate but also rapid identification of Yangqishi and Yinqishi. There are many differences in medicinal properties, efficacy, indications and composition of Yangqishi and Yinqishi, so be careful not to mix them up.
Asbestos, Amphibole
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chemistry
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Drugs, Chinese Herbal
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chemistry
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X-Ray Diffraction
8.Effects of prior freezing or drying on the swelling behaviour of the bovine cornea.
Yi-fei HUANG ; Keith M MEEK ; Li-qiang WANG ; Da-jiang WANG
Chinese Medical Journal 2009;122(2):212-218
BACKGROUNDFrozen or dried corneal grafts are commonly used for stromal transplantation such as lamellar keratoplasty (full or partial thickness), keratophakia, epikeratophakia. Structural properties are important for the final optical results of these surgeries but the effects of freezing/thawing and drying/rehydration on the properties of the stroma are known little compared with the corneal endothelium, mainly because of lack of non-invasive technique to evaluate the stromal structure. This study aimed to investigate the swelling and structural properties of the bovine corneal stroma following freezing or drying by X-ray diffraction which was a non-invasive technique and could give ultra-structural information in hydrated tissues.
METHODSBovine corneas were either frozen at -40 degrees C or dried to constant weight in a dessicator over silica gel. Swelling was carried out by placing the corneas into dialysis tubing and equilibrating them against various concentrations of polyethylene glycol (PEG) to obtain a range of tissue hydrations. This method minimises the loss of soluble tissue components during the swelling process. Synchrotron X-ray diffraction was used to measure the average intermolecular spacing, the interfibrillar spacing and the fibril diameter as a function of hydration. Changes in light scattering were detected using a microdensitometer.
RESULTSFreezing and thawing of the cornea caused an increase in light scattering by 63.9% at tissue hydration (H) = 3.4, and by 50.0% at H = 4.9. Repeated freezing and thawing causes further increased by 38.9% at the second time and another 36.0% at the third time (P < 0.05). There was a tendency for both the frozen and the dried corneas to lose some swelling ability, achieving hydrations respectively of 10% and 18% below those of fresh corneas at 0 PEG. There were no changes in the fibril diameters, interfibrillar or intermolecular spacings as measured by X-ray diffraction in the equilibrated fresh, pre-frozen and pre-dried corneas.
CONCLUSIONSThe increase in light scattering and the loss of swelling ability after freezing and thawing probably results from structural changes following the close association of the collagen molecules and fibrils whilst the tissue is in the dry or frozen state. Some unknown changes in the extracellular matrix between the collagen fibrils may also play a role in the light scattering. The equilibration technique may improve the quality of rehydrated corneal graft or lenticules used for corneal surgeries.
Animals ; Cattle ; Cornea ; chemistry ; Desiccation ; Freezing ; X-Ray Diffraction
9.Application of tin ion-plating to the orthodontic appliance.
Korean Journal of Orthodontics 1991;21(1):7-16
To estimate the possibility of the application of TiN ion-plating to the orthodontic appliance, colorimetric properties, and characteristics of ion-plated film as well as adhesive strength of TiN film to the substrate and mechanical properties of ion-plated orthodontic appliance were investigated. The obtained results were as follows: 1) TiN ion-plated film had the colorimetric properties which were the hue of about 2.5 Y, the brightness of about 6, and the chroma of about 4 by the standard color chip of JIS. 2) TiN ion-plated film was 2micrometer in thickness and its deposition pattern was rather irregular. 3) TiN phase was confirmed on the X-ray diffraction pattern. 4) Critical load for delamination of ion-plated film from stainless steel band was 10N. 5) Tensile and yield strength of ion-plated specimen was increased about 10Kg,f/mm2 , while elongation was decreased 1% com pairing to the values of the non ion-plated specimen.
Adhesives
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Orthodontic Appliances*
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Stainless Steel
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Tin*
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X-Ray Diffraction
10.A comparative study of electroplating and electroless plating for diameter increase of orthodontic wire.
Jae Nam KIM ; Jin Hyoung CHO ; Young Eun SUNG ; Ki Heon LEE ; Hyeon Shik HWANG
Korean Journal of Orthodontics 2006;36(2):145-152
The purpose of this study was to evaluate electroless plating as a method of increasing the diameter of an orthodontic wire in comparison with eletroplating. After pretreatment plating of the 0.016 inch stainless steel orthodontic wire, electroless plating was performed at 90 degrees C until the diameter of the wire was increased to 0.018 inch. During the process of electroless plating, the diameter of the wire was measured every 5 minutes to examine the increasing ratio of the wire' diameter per time unit. And to examine the uniformity, the diameter at 3 points on the electroless-plated orthodontic wire was measured. An X-ray diffraction test for analyzing the nature of the plated metal and a 3-point bending test for analyzing the physical property were performed. The electroless-plated wire group showed a increased tendency for stiffness, yield strength, and ultimate strength than the electroplated wire group. And there was a statistically significant difference between the two groups for stiffness and ultimate strength. In the electroless-plated wire group, the increasing ratio of the diameter was 0.00461 +/-.00003 mm/5 min (0.00092 mm/min). In the electroplated wire group, it was 0.00821 +/-.00015 mm/min. The results of the uniformity test showed a tendency for uniformity in both the plating methods. The results of this study suggest that electroless plating of the wire is closer to the ready-made wire than electroplating wire in terms of the physical property. However, the length of plating time needs further consideration for the clinical application of electroless plating.
Electroplating*
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Orthodontic Wires*
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Stainless Steel
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X-Ray Diffraction