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1.
Oncogene ; 42(3): 169-183, 2023 01.
Artigo em Inglês | MEDLINE | ID: mdl-36385375

RESUMO

Metadherin (MTDH) is a well-established oncogene in various cancers including Hepatocellular Carcinoma (HCC). However, the precise mechanism through which MTDH promotes cancer-related signaling pathways in HCC remains unknown. In this study, we identified DDX17 as a novel binding partner of MTDH. Furthermore, MTDH increased the protein level of DDX17 by inhibiting its ubiquitination. We confirmed that DDX17 was a novel oncogene, with dramatically upregulated expression in HCC tissues. The increased expression of DDX17 was closely associated with vascular invasion, TNM stage, BCLC stage, and poor prognosis. In vitro and in vivo tests demonstrated that DDX17, a downstream target of MTDH, played a crucial role in tumor initiation and progression. Mechanistically, DDX17 acted as a transcriptional regulator that interacted with Y-box binding protein 1 (YB1) in the nucleus, which in turn drove the binding of YB1 to its target epidermal growth factor receptor (EGFR) gene promoter to increase its transcription. This in turn increased expression of EGFR and the activation of the downstream MEK/pERK signaling pathway. Our results identify DDX17, stabilized by MTDH, as a powerful oncogene in HCC and suggest that the DDX17/YB1/EGFR axis contributes to tumorigenesis and metastasis of HCC.


Assuntos
Carcinoma Hepatocelular , Neoplasias Hepáticas , Humanos , Carcinoma Hepatocelular/patologia , Neoplasias Hepáticas/patologia , Moléculas de Adesão Celular/metabolismo , Transformação Celular Neoplásica/genética , Receptores ErbB/genética , Receptores ErbB/metabolismo , Fatores de Transcrição/genética , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , RNA Helicases DEAD-box/genética
2.
Am J Chin Med ; 50(1): 313-332, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-34963428

RESUMO

18[Formula: see text]-glycyrrhetinic acid (GA) is the active ingredient of the traditional Chinese medicinal herb Glycyrrhizae radix et rhizoma. We previously demonstrated that GA inhibited tumor growth in hepatocellular carcinoma (HCC). However, the effect of GA on transforming growth factor-[Formula: see text] (TGF-[Formula: see text]-induced epithelial-mesenchymal transition (EMT) and metastasis were still unclear. In this study, in vitro transwell assays and immunofluorescence (IF) demonstrated that GA inhibited TGF-[Formula: see text]-induced migration, invasion and EMT of HCC cells. However, it had little effect on the inhibition of proliferation by TGF-[Formula: see text]. Moreover, we confirmed that GA suppressed the metastasis of HCC cells in vivousing an ectopic lung metastasis model. Furthermore, we found that GA inhibited TGF-[Formula: see text]-induced EMT mainly by reducing the phosphorylation of signal transducer and activator of transcription 3 (STAT3), which played an essential role in TGF-[Formula: see text]-induced EMT and cell mobility. Mechanistically, GA inhibited the phosphorylation of STAT3 by increasing the expression of Src homology 2 domain-containing protein tyrosine phosphatases 1 and 2 (SHP1 and SHP2). Therefore, we concluded that GA inhibited TGF-[Formula: see text]-induced EMT and metastasis via the SHP1&SHP2/STAT3/Snail pathway. Our data provide an attractive therapeutic target for future multimodal management of HCC.


Assuntos
Carcinoma Hepatocelular , Ácido Glicirretínico , Neoplasias Hepáticas , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/metabolismo , Linhagem Celular Tumoral , Movimento Celular , Transição Epitelial-Mesenquimal , Ácido Glicirretínico/farmacologia , Humanos , Neoplasias Hepáticas/patologia , Invasividade Neoplásica , Fator de Transcrição STAT3/metabolismo , Fator de Crescimento Transformador beta1/genética , Fator de Crescimento Transformador beta1/metabolismo
3.
J Tradit Chin Med ; 35(2): 234-7, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25975059

RESUMO

OBJECTIVE: To observe the effect of lit-moxa stimu- lating acupoint Guanyuan (CV 4) on lactic acid and super-oxide dismutase (SOD) in skeletal muscle after exercise exhaustion. METHODS: Twenty-eight adult male Sprague-Dawley rats were randomly divided into normal control group, exhausted control group, exercise group and moxibustion group using exercise training and mild heating with lit-moxa stick as treatment methods. The exhausted control group, moxibustion group and exercise group received an exhaustive swimming after 20 days of intervention. Swimming exhausted times were recorded. Lactic acid and SOD concentration in soleus muscle were detected and compared between every two groups. RESULTS: The swimming exhausted times of the moxibustion group and the exercise group were significantly increased compare to the exhausted control group (P < 0.05). The lactic acid of the exhausted control group was significantly increased comparing with the normal control group (P < 0.05), and the lactic acid of the moxibustion group and the exercise group were significantly lower than that of the exhausted control group (P < 0.05). The SOD level of the exhausted control group was significantly decreased comparing with the normal control group (P < 0.05), and the SOD level of the moxibustion group and the exercise group were significantly higher than that of the exhausted control group (both, P < 0.05). There was no statistical difference between the moxibustion group and the exercise group. CONCLUSION: With lit moxa stick, heat stimulating acupoint of Guanyuan (CV 4) decreased the levels of lactic acid and SOD in rat's skeletal muscle.


Assuntos
Tolerância ao Exercício , Ácido Láctico/metabolismo , Moxibustão , Músculo Esquelético/metabolismo , Superóxido Dismutase/metabolismo , Pontos de Acupuntura , Animais , Humanos , Masculino , Músculo Esquelético/enzimologia , Ratos , Ratos Sprague-Dawley
4.
ACS Appl Mater Interfaces ; 5(17): 8740-52, 2013 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-23937511

RESUMO

This article describes a CuInS2 quantum dot (QD)-sensitized solar cell (QDSSC) with a multilayered architecture and a cascaded energy-gap structure fabricated using a successive ionic-layer adsorption and reaction process. We initially used different metal chalcogenides as interfacial buffer layers to improve unmatched band alignments between the TiO2 and CuInS2 QD sensitizers. In this design, the photovoltaic performance, in terms of the short-circuit current density (JSC), open-circuit voltage (VOC), fill factor (FF), and power conversion efficiency (PCE), was significantly improved. Both JSC and VOC were improved in CuInS2-based QDSSCs in the presence of interfacial buffer layers because of proper band alignment across the heterointerface and the negative band edge movement of TiO2. The PCE of CuInS2-based QDSSCs containing In2Se3 interfacial buffer layers was 1.35%, with JSC=5.83 mA/cm2, VOC=595 mV, and FF=39.0%. We also examined the use of alternative CdS and CdSe hybrid-sensitized layers, which were sequentially deposited onto the In2Se3/CuInS2 configuration for creating favorable cascaded energy-gap structures. Both JSC (11.3 mA cm(-2)) and FF (47.3%) for the CuInS2/CdSe hybrid-sensitized cells were higher than those for CuInS2-based cells (JSC=5.83 mA cm(-2) and FF=39.0%). In addition, the hybrid-sensitized cells had PCEs that were 1.3 times those of cells containing identically pretreated In2Se3 interfacial buffer layers. Additionally, we determined that ZnSe served as a good passivation layer on the surface of CuInS2/CdSe hybrid-sensitized QDs, prevented current leakage from the QDs to electrolytes, and lowered interfacial charge recombination. Under simulated illumination (AM 1.5, 100 mW cm(-2)), multilayered QDSSCs with distinct architectures delivered a maximum external quantum efficiency of 80% at 500 nm and a maximum PCE of 4.55%, approximately 9 times that of QDSSCs fabricated with pristine CuInS2.


Assuntos
Cobre/química , Índio/química , Pontos Quânticos/química , Energia Solar , Compostos de Enxofre/química , Espectroscopia Dielétrica , Eletrodos , Titânio/química
5.
Chem Commun (Camb) ; 48(40): 4848-50, 2012 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-22498756

RESUMO

A Cu(2)S-CuInS(2)-ZnSe quantum dot (QD)-sensitized solar cell with cascaded energy gap structures has been fabricated. Under simulated illumination (AM 1.5, 100 mW cm(-2)), the best device is obtained with a Cu(2)S-CuInS(2)-ZnSe QD-sensitized solar cell, yielding a power conversion efficiency of 2.52%.

6.
Zhongguo Gu Shang ; 24(6): 517-20, 2011 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-21786562

RESUMO

OBJECTIVE: To evaluate the osteogenic ability of the three-dimensional interconnected porous titanium(TDIPT) coated with bonelike apatite, by the test of the culture of osteoblast in vitro. METHODS: The pure TDIPT was prepared by the high temperature insostatic pressing (HIP) and was divided into two groups. One group of TDIPT was dipped into the 1.5 simulated body fluid (1.5 SBF) and developed the TDIPT coated with bone-like apatite (The test group). Another group was control group (pure TDIPT). The porous titanium of the two groups were all made into standard parts (5 mm x 5 mm x 4 mm) and placed into the 24-hole plates. The osteoblasts were extracted from SD rat. After the primary culture and subculture of the osteoblast in vitro, the osteoblasts were inoculated into the samples in the 24-pole plate and cultured continually. MTT Cell Proliferation Assay was done on the 1st, 3rd, 5th, 7th and 9th day respectively after inoculating. The ALP activity was tested on the 7th, 14th and 21st day, respectively. The collected data were analyzed by use of the student t test. RESULTS: The MTT value and the ALP activity increased with the increasing of the culture time in the two group, but those of the test group was more significant than those of the control group (P < 0.05). Moreover, the osteoblast tachyauxesis and stable adhesion were observed in test group by SEM at the 7th day after culturing. CONCLUSION: The bioactivity of the TDIPT improves significantly after coating with the bone-like apatite onto the surface of the TDIPT.


Assuntos
Osteoblastos/fisiologia , Osteogênese , Titânio/química , Fosfatase Alcalina/metabolismo , Animais , Células Cultivadas , Feminino , Masculino , Microscopia Eletrônica de Varredura , Osteoblastos/ultraestrutura , Porosidade , Ratos , Ratos Sprague-Dawley
7.
Nan Fang Yi Ke Da Xue Xue Bao ; 30(10): 2281-3, 2287, 2010 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-20965825

RESUMO

OBJECTIVE: To investigate the effect of three types of veneering porcelain on the bending strength of KAVO Y-TZP/porcelain layered structure. METHODS: KAVO zirconia ceramics were used as the substructure. To form 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 porcelains were fired on the zirconia substructures by either slip-casting or pressed-on technique with or without liner coverage. The bending strength was tested according to ISO 6872 standard, and the veneered surfaces of the fracture samples were analyzed by scanning electron microscopy (SEM). RESULTS: For covering KAVO zirconia core material, the conventional veneering slurry-porcelain combined with liner or wash firing had significant higher bending strength than pressed-on porcelain. SEM showed that the main failure type at the interface was adhesive failure. CONCLUSION: Thin layer sintering using washbake program or liner on KAVO zirconia surface increases the surface wettability, and this procedure may be indispensable when veneering on the surface of dental zirconia.


Assuntos
Porcelana Dentária , Resistência ao Cisalhamento , Zircônio , Análise do Estresse Dentário
8.
Nan Fang Yi Ke Da Xue Xue Bao ; 30(5): 945-8, 2010 May.
Artigo em Chinês | MEDLINE | ID: mdl-20501363

RESUMO

OBJECTIVE: To investigate the effect of two methods of pigmentation on the flexural strength of dental Y-TZP/porcelain layered structure. METHODS: KaVo 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. RESULTS: In 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. CONCLUSION: Pigmentation 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.


Assuntos
Colagem Dentária , Porcelana Dentária/química , Análise do Estresse Dentário , Pigmentação , Ítrio/química , Zircônio/química , Materiais Dentários , Facetas Dentárias , Teste de Materiais , Resistência à Tração
9.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 27(5): 473-8, 2009 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-19927712

RESUMO

OBJECTIVE: To investigate the structure, mechanical and low temperature aging properties of colored dental zirconia ceramics. METHODS: 5 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. RESULTS: The 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. CONCLUSION: The results showed that colored 3Y-TZP ceramics presented good mechanical properties even after aging treatments, and was suitable for dental clinical use.


Assuntos
Cerâmica , Ítrio , Teste de Materiais , Difração de Raios X , Zircônio
10.
Hua Xi Kou Qiang Yi Xue Za Zhi ; 26(5): 556-9, 2008 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-19007085

RESUMO

OBJECTIVE: To obtain and investigate the chromaticity properties of colored dental 3Y-TZP ceramics with different colorant combinations. METHODS: Colorant combinations were mixed with TZ-3Y-S powder, then the mixtures were compacted at 200 MPa using cold isostatic pressure, densely sintered at 1500 degrees C for 2 h forming 5 graded colored dental zirconia ceramics. Specimen were sectioned into 10 mm x 10 mm x 0.5 mm and 10 mm x l0 mmx 1 mm slices from the sintered blocks. Color measurement was performed under black background using spectrophotometer. The chromaticity properties were compared with that of the VITA In-Ceram YZ shade guide. RESULTS: Five colored dental zirconia ceramics were obtained. The lightness decreased gradually, and the chroma value increased gradually. The color differences of the two thickness specimens were little. The parameters of the color space were L*: 67.76-77.78; a*: -2.19-3.80; b*: 12.13-25.01, which was similar with that of the VITA In-Ceram YZ shade guide, while the lowest value of lightness was relatively higher than that of the VITA In-Ceram YZ shade guide. CONCLUSION: Colored 3Y-TZP dental ceramics are suitable for clinical use. There is a need to develop more darkness shaded zirconia dental ceramics.


Assuntos
Cerâmica , Cor , Óxido de Alumínio , Porcelana Dentária , Humanos , Zircônio
11.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 43(3): 172-7, 2008 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-18788554

RESUMO

OBJECTIVE: To investigate the influence of in vitro low-temperature degradation (LTD) treatment on the structural stability of 5 kinds of Y2O3 stabilized tetragonal zirconia polycrystals (Y-TZP) dental ceramics. METHODS: TZ-3YS powder was compacted at 200 MPa using cold isostatic pressure and pre-sintered at 1050 degrees C for 2 h forming presintered blocks. Specimens were sectioned into 15 mm x 15 mm x 1.5 mm slices from blocks of TZ-3YS, Vita In-Ceram YZ, Ivoclar, Cercon Smart, and Kavo Y-TZP presintered blocks, 18 slices for each brand, and then densely sintered. Specimens were divided into 6 groups and subjected to an accelerated aging test carried out in an autoclave in steam at 134 degrees C, 0.2 MPa, for 0, 1, 2, 3, 4, and 5 h. X-ray diffraction (XRD) was used to identify crystal phases and relative content of monoclinic phase was calculated. Specimens for three-point bending test were fabricated using TZ-3YS ceramics according to the ISO 6872 standard and bending strength was tested before and after aging. The polished and aging specimens of TZ-3YS and Cercon Smart zirconia ceramics were observed by atomic force microscopy (AFM) to evaluate surface microstructure. RESULTS: Tetragonal-to-monoclinic phase transformation was detected for specimens of TZ-3YS, Vita In-Ceram YZ, Ivoclar, and Kavo zirconia ceramics except for Cercon Smart ceramics after aging, and the relative content of monoclinic phase was increasing with the prolonged aging time. TZ-3YS was the most affected material, Kavo took the second, and Vita and Ivoclar were similar. Aging had no significant negative effects on flexural strength of TZ-3YS with average bending strength being over 1100 MPa. The nucleation and growth of monoclinic phase were detected by AFM in surface of Cercon Smart zirconia in which monoclinic phase was not detected by XRD. CONCLUSIONS: The results suggest that LTD of dental Y-TZP is time dependent, but the aging test does not reduce the flexural strength of TZ-3YS. The long-term clinical serviceability of dental Y-TZP needs further observation.


Assuntos
Temperatura Baixa , Porcelana Dentária/química , Zircônio/química , Análise do Estresse Dentário , Teste de Materiais , Fatores de Tempo
12.
J Mater Sci Mater Med ; 17(9): 815-23, 2006 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-16932863

RESUMO

Three different porous scaffolds were tested. The first two were prepared by sintering bovine bone. The third scaffold was prepared using three-dimensional gel-lamination, a new rapid prototyping method, and was named as hydroxyapatite artificial bone. X-ray diffraction and Fourier transform infrared spectroscopy analysis confirmed that the samples were mainly highly crystalline hydroxyapatite ceramics. Scanning electron microscopy and mercury intrusion porosimetry measurement showed that the pores were interconnected and pore sizes ranged from several microns to hundreds of microns. Mouse osteoblast-like cells grown on the three scaffolds retained their characteristic morphology. Cell proliferation and differentiation, analyzed by methylthiazol tetrazolium (MTT) and alkaline phosphatase activity assays, were significantly higher on the hydroxyapatite artificial bone than on the other two scaffolds tested. All the scaffolds provided good attachment, proliferation and differentiation of bone cells. These results indicate that the scaffolds have a favorable interaction with cells, they support cell growth and functions, and therefore these scaffolds may have great potential as bone substitutes. The three-dimensional gel-lamination method is proven to be an attractive process to design and fabricate bone scaffolds with favorable properties, and therefore, has promising potential for bone repair applications.


Assuntos
Materiais Biocompatíveis/química , Substitutos Ósseos/química , Durapatita/química , Osteoblastos/metabolismo , Fosfatase Alcalina/metabolismo , Animais , Osso e Ossos/metabolismo , Bovinos , Diferenciação Celular , Camundongos , Microscopia Eletrônica de Varredura , Espectroscopia de Infravermelho com Transformada de Fourier , Sais de Tetrazólio/farmacologia , Tiazóis/farmacologia , Difração de Raios X
13.
Zhonghua Wai Ke Za Zhi ; 43(12): 807-11, 2005 Jun 15.
Artigo em Chinês | MEDLINE | ID: mdl-16083586

RESUMO

OBJECTIVE: To fabricate biomimetic biphasic calcium phosphate BCP ceramic scaffolds using three-dimensional (3D) gel-lamination technology and evaluated their structure with 3D parameters and related method. METHODS: Series two-dimensional images of femoral head's specimen of dogs were obtained by micro-computed tomography (Micro-CT). According to these images, porous biomimetic biphasic calcium phosphate (BCP) ceramic scaffolds with oriented trabecular structure were fabricated by three-dimensional (3D) gel-lamination technology. And then, the three-dimensional structure of the scaffolds were reconstructed by computer according to Micro-CT images of these scaffolds and evaluated by three-dimensional parameters. These parameters included bone volume fraction (BVF, BV/TV), bone surface/bone volume (BS/BV) ratio, trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular spacing (Tb.Sp) and structure model index (SMI). The biomechanical properties and biocompatibility of these scaffolds were also evaluated in the study. Six scaffolds, which were combined with BMCs (bone mesenchymal cells, BMCs), were planted into the bone defect of six dogs' femoral head respectively. RESULTS: There was no significant difference between trabecular samples and BCP scaffolds in BV/TV, Tb.Th, Tb.N, and Tb.Pf (P > 0.05). The trabecular system of the scaffold, which had some orientation, represented plate-like model. With a micro-porous porosity of 62%, the average compressive modulus and ultimate strength along the axis of the scaffolds reached (464.0 +/- 36.0) MPa and (5.6 +/- 0.8) MPa respectively. The results of animal test indicated that the trabeculae of these scaffolds were covered by a layer of new bone after 10 weeks of operation. CONCLUSION: Porous BCP scaffolds have been produced with oriented microarchitectural features designed to facilitate vascular invasion and cellular attachment and with initial mechanical properties comparable to those of trabecular bone.


Assuntos
Biomimética/métodos , Substitutos Ósseos/química , Fosfatos de Cálcio/química , Animais , Cães , Feminino , Masculino , Teste de Materiais , Implantação de Prótese , Relação Estrutura-Atividade , Engenharia Tecidual
14.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 38(4): 306-8, 2003 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-12930667

RESUMO

OBJECTIVE: To study the bonding characteristic of Titanium and RG experiment porcelain. METHODS: 5 specimens with a size of 10 mm x 5 mm x 1.4 mm were cast from pure titanium. Then 1 mm of RG experiment opaque and body porcelain were fused on the surface of the titanium specimens. The interface of titanium and porcelain was analyzed with a scanning electron microscope with energy-despersive spectrometry; 6 metal specimens with the size of 25 mm x 3 mm x 0.5 mm were cast from Ni-Cr alloy and a uniform thickness of 1 mm of VMK 99 porcelain was veneered on the central area of 8 mm x 3 mm 18 metal specimens as the same size were cast from pure titanium. The uniform thickness of 1 mm of VITA TITANKERAMIK porcelain, of Noritake super porcelain Ti-22 and of RG experiment porcelain were veneered on every 6 specimens respectively in the central area of 8 mm x 3 mm. The specimens were subjected to a three-point bending test on a load-test machine with a span of 20 mm, then the failure loads were recorded and statistically analysised. The RG porcelain/titanium crown was fabricated by fusing RG opaque porcelain and body porcelain to cast titanium substrate crown. RESULTS: The SEM results show no porosity and crackle were found in the interface. The energy-dispersive spectrometry show that there are Si, Ti and O in the 1 micro m layer between porcelain and titanium, which suggesting titanium and experiment porcelain bonding well. The three point test showed the fracture force for the combinations of titanium/VITA TITANKERAMIK porcelain, titanium/Noritake super porcelain Ti-22 and titanium/RG experiment porcelain were (7.233 +/- 2.539) N, (5.533 +/- 1.199) N and (6.316 +/- 1.433) N respectively. There were not statistically significant differences among them (t test, P < 0.01). The fracture force for the Ni-Cr alloy/VMK99 porcelain combination (12.733 +/- 3.297) N was significantly greater than those of the cast titanium/porcelain (t test, P > 0.05). The crown was translucent with no crack. CONCLUSION: RG porcelain is well compatible with titanium.


Assuntos
Ligas Metalo-Cerâmicas/química , Titânio/química , Porcelana Dentária/química
15.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 38(2): 137-9, 2003 Mar.
Artigo em Chinês | MEDLINE | ID: mdl-12839652

RESUMO

OBJECTIVE: An intrinsically colored machinable glass-ceramic containing tetrasilicic fluormica as the predominant crystal phase was studied, which was used in molar crown in dental CAD/CAM system. METHODS: Orthogonal design analysis was used to select appropriate base formula, coloration and heat treatment process. RESULTS: Factors influencing the color appearance of mica glass ceramic were nucleation agent and the ratio of Mg(2+) to K(+) in base formula; Cerium oxide (CeO(2)) was used as the main coloration; The preferred heat treatment was 650 degrees C for 1 h and 1,000 degrees C or 1,050 degrees C for 3 h - 4 h. CONCLUSIONS: This mica glass-ceramic could provide 4 to 5 color appearance for dental use, it showed excellent machinability which was eminently suitable for use in dental CAD/CAM system.


Assuntos
Silicatos de Alumínio/química , Porcelana Dentária/química , Vidro/química , Cor , Desenho Assistido por Computador , Coroas , Dente Molar
16.
Dent Mater ; 18(3): 216-20, 2002 May.
Artigo em Inglês | MEDLINE | ID: mdl-11823013

RESUMO

OBJECTIVE: This study was conducted to investigate the effect of MgO additive to Al2O3 on the flexural strength, fracture toughness of glass infiltrated alumina for CAD/CAM application. METHODS: Alumina blanks with additive of 0.5 wt% MgO were prepared via isostatic pressing and sintering at 1400 degrees C for 2h, and then alumina-glass composites were fabricated by infiltrating the molten glass into the partially sintered alumina compact. Flexural strength and fracture toughness were determined using three point bending methods and a single edge notched beam method. The mechanism of crack propagation was observed under a field emission scanning electron microscope. RESULTS: The three-point flexural strength and fracture toughness of partially sintered alumina and alumina-glass composite were 210 MPa, 1.86 MPam(1/2), and 432.2 MPa, 5.12 MPam(1/2), respectively, and they were free of shrinkage during the processing of glass infiltration. The field emission SEM micrograph indicated that indentation caused a non-planar crack propagation including crack deflection and crack bowing. SIGNIFICANCE: MgO was used as an additive to alumina to improve the strength and fracture toughness of partially sintered alumina and alumina-glass composite. The high strength and toughness are related to toughening by the distribution of alumina with uniform particle sizes, crack bowing, crack deflection and the beneficial wetting properties of the particle surface.


Assuntos
Óxido de Alumínio/química , Desenho Assistido por Computador , Vidro/química , Óxido de Magnésio/química , Cerâmica/química , Temperatura Alta , Humanos , Teste de Materiais , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Maleabilidade , Pressão , Estresse Mecânico , Propriedades de Superfície , Molhabilidade
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