OBJECTIVETo compare the retention of selected cores to all-ceramic posts in post-and-core system, in which the ceramic core was combined with the post by direct sintering, adhering, and the composite resin core was formed onto the post.

METHODSA total of 15 all-ceramic post fabricated by alumina-zirconia nano-composite infiltrated ceramics were divided into three groups. In group A, forming and combining the ceramic core with the post by direct sintering. In group B, combining the ceramic core with the post by adhering. In group C, forming composite resin core onto the post. Each specimen was placed into a special jig along the post axis and subjected to a load on INSTRON 4302 universal testing instrument until failure.

RESULTSThere was a statistically significant difference between the groups (P < 0.01). Group A showed a significantly higher retention which was 3.04 and 2.88 times as high as group B and C respectively (P < 0.01). There was no significant difference between adhering and composite resin core (P> 0.05).

CONCLUSIONA reliable retention of the core to the post can be achieved when the alumina-zirconia nanocomposite infiltrated ceramic core is formed and combined with the post by direct sintering, which offers significantly higher retention than adhering and forming composite resin core onto the post.

Aluminum Oxide ; Ceramics ; Composite Resins ; Dental Porcelain ; Dental Restoration Failure ; Humans ; Materials Testing ; Post and Core Technique ; Zirconium

OBJECTIVETo investigate the cyclic fatigue modes of Vita mark II machinable ceramics under Hertzian's contact.

METHODSHertzian's contact technique (WC spheres r = 3.18 mm) was used to investigate the cyclic fatigue of Vita mark II machinable ceramic. All specimens were fatigued by cyclic loading in moist environment, furthermore, surviving strength was examined by three point test and morphology damage observation.

RESULTSIn homogeneous Vita mark II machinable ceramics, two fatigue damage modes existed after cyclic loading with spheres under moist environment, including conventional tensile-driven cone cracking (brittle mode) and shear-driven microdamage accumulation (quasi-plastic mode). The latter generated radial cracks and deeply penetrating secondary cone crack. Initial strength degradation were caused by the cone cracks, subsequent and much more deleterious loss was caused by radial cracks.

CONCLUSIONCyclic fatigue modes of Vita mark II machinable ceramics includes brittle and quasi-plastic mode.

Ceramics ; Dental Porcelain ; Humans ; Materials Testing ; Surface Properties

OBJECTIVEThe objective of the present study was to investigate the feasibility and reliability of sintering alumina and zirconia-based all-ceramic materials through a recently introduced microwave heating technique. The variation of crystal phases, the growth of grain sizes and microstructural features of these materials were evaluated after sintering.

METHODSFour different groups of powder (l00%Al2O3, 60%Al2O3+40%ZrO2, 40% Al2O3+60%ZrO2, 100% ZrO2) were respectively press-compacted to fabricate green disk samples, 5 specimen of each group were prepared. All the samples were surrounded by refractory materials for heat containment and processed at 1 600 degrees C in a domestic microwave oven (850 W, 2 450 MHz), 1 600 degrees C/5 min for heating rate, 10 min for holding time. After sintering, the phase composition and average grain size of these ceramics were examined using X-ray diffraction (XRD). Their microstructure characteristics were studied by scanning electron microscopy (SEM).

RESULTSAll the specimens were successfully sintered with the application of microwave heating system in combination with a suitable thermal insulator. No phase change was found in alumina while monoclinic-zirconia was found to be transformed to tetragonal-zirconia. A little grain size growth of Al2O3 and ZrO2 has been observed with Al2O3 24.1 nm/before and 51.8 nm/after; ZrO2 25.3 nm/before and 29.7 nm/after. The SEM photos indicated that the microwave-sintered Al2O3-ZrO2 ceramics had a uniform crystal distribution and their crystal sizes could be maintained within the range of nanometers.

CONCLUSIONIt is expected that in the near future microwave heating system could be a promising substitute for conventional processing methods due to its unparalled advantages, including more rapid heating rate, shortened sintering time, superfine grain size, improved microstructure and much less expensive equipment.

Aluminum Oxide ; Ceramics ; Hot Temperature ; Materials Testing ; Microscopy, Electron, Scanning ; Microwaves ; Reproducibility of Results ; Surface Properties ; Zirconium

OBJECTIVETo investigate the effects of luting agent on the final color of glass infiltrated alumina ceramic restorations.

METHODS12 plate-shaped specimens with 12.5 mm in diameter and 0.5 mm thickness were fabricated from GI-II (color IG2). Vitadur alpha veneering porcelain (color A2) with 1.0 mm thickness was fired to GI- II glass/alumina composite. 12 plate-shaped background specimens simulating the metal alloy post-and-core 12.5 mm in diameter and 2 mm thickness were also made from Ni-Cr alloy. All-ceramic specimens were luted to the metal alloy by Zinc Phosphate cement, glass ionomer cement and composite resin. The color shifts of the specimens were measured by colorimeter.

RESULTSLuting agents had effect on the final color of restorations. The influence of composite resin was least, followed by glass ionomer cement and Zinc Phosphate cement. The color difference between with and without Zinc Phosphate cement could be identified by the eye.

CONCLUSIONTo reduce the effect of luting agents, composite resin is recommended to all-ceramic restorations' adhesion.

Aluminum Oxide ; Ceramics ; Color ; Composite Resins ; Dental Cements ; Dental Porcelain ; Glass Ionomer Cements ; Humans ; Resin Cements

OBJECTIVETo investigate the long-term integrity and the biological function of interface between the bioadhesive peptide modified implant surface and peri-implant tissue.

METHODSA short bioadhesive peptide containing Glycine-Tyrosine-Arginine-Glycine-Asparticacid-Serine (GYRGDS) sequence was immobilized onto the titanium implant surface by means of sol-gel coating technique and self-assembled monolayers (SAM). The chemical composition and organic functional groups on the titanium surfaces were characterized using XPS (X-ray photoelectron spectroscopy) and FTIR (Fourier transform infrared spectrometer). The adhesive strength and stability of osteoblasts on various implant surfaces were compared under flow condition.

RESULTSThe results showed that alkali/hot water aging treatment could apparently improve the content of -OH functional groups of titanium surface. The chemical reactive Ti-O-Ti bonding at the surface of titanium played a vital role in inducing the formation of organosilane SAM. GYRGDS peptide can be covalently grafted onto the surface of titanium by SAM technique. The resistance of freshly adherent osteoblasts to detachment by flow was shear time dependent. When the four groups were compared under the same flow stress condition (2.05 Pa) at three specific time spans (30 min, 1 h, 2 h), the cells retention rates in GYRGDS-grafted groups were 93.0%, 54.4%, 34.4% respectively and were much higher than those in non-coated groups.

CONCLUSIONSIt was suggested that GYRGDS might have positive effects on maintaining stability and adherence of cells onto the substrates under flow condition.

Dental Cements ; Osteoblasts ; physiology ; Peptides ; pharmacology ; Prostheses and Implants ; Surface Properties ; Titanium

OBJECTIVETo compare the difference in strength degradation and morphology damage of brittle dental ceramic after static load and cyclic fatigue.

METHODSHertzian's contact technique with a tungsten carbide sphere was used to investigate the response of feldspathic dental porcelain to static load and cyclic fatigue. All specimens were subjected to static or cyclic loading in moist environment. Furthermore the surviving strength of specimens was examined by the three-point test and the morphology damage was observed. Statistical analyses were performed with ANOVA and a P-value less than 0.05 was considered to be significant.

RESULTSOuter cone crack and associated strength degradation simultaneously occurred both after the first cyclic loading and static loading. Up to 1,000 cycles, the specimens showed inner cone cracks and strength degradation was aggravated. No significant difference in the strength degradation among all static loading specimens and no inner cone cracks occurred in static loading specimens.

CONCLUSIONSBoth static and cyclic fatigue influence dental ceramic strength, but cyclic fatigue is more deleterious.

Compressive Strength ; Dental Porcelain ; Materials Testing

Objective: To explore the intrinsic mechanism of emotional intelligence and trait anger in the association between childhood psychological abuse and aggressive behavior among middle school students,and to provide a theoretical basis for intervention of aggressive behaviors. Methods: By using the multi-stage stratified random sampling method, 2 458 middle school students in Guizhou Province were selected, and group tests were carried out using psychological abuse scale, attack behavior scale,emotional intelligence scale and characteristic anger scale. Results: Agressive behavior, trait anger and emotional intelligence differed significantly by gender(t=2.19，5.12，-2.34，P<0.05), and there were significant differences in aggressive behavior, psychological abuse, emotional intelligence and trait anger among middle school students of different student origins by residence(t=-18.77，-6.04，9.10，-9.94，P<0.05). Childhood psychological abuse (r=0.41), temperamental trait anger (r=0.52) and reactive trait anger (r=0.49) were significantly positively correlated with aggressive behavior（P<0.05）. Emotional intelligence was significantly negatively correlated with aggressive behavior (r=-0.33, P<0.05). The test of multiple mediation effects showed that emotional intelligence, temperamental trait anger and reactive trait anger played multiple mediation roles between psychological abuse and aggressive behavior in childhood. Conclusion Childhood psychological abuse could not only directly affect the aggressive behavior of middle school students, but also further affect the aggressive behavior through emotional intelligence and trait anger. Emotional intelligence and idiosyncratic anger are important internal mechanisms by which childhood psychological abuse affects aggressive behavior.

A fusion gene CTB-PROIN, in which Proinsulin gene was fused to the 3' end of CTB gene by a hinge peptide 'GPGP', was constructed and cloned into pET-30a(+) to obtain a prokaryotic expression vector pETCPI. Subsequently the recombinant plasmid pETCPI was transformed into E. coli stain BL21 (DE3). After induced by IPTG, the expression product was analyzed by sodium dodecyl sulphate-polyacrylamide gel (15%) electrophoresis (SDS-PAGE), and its result indicated that the recombinant protein CTB-PROIN was expressed and accumulated as inclusion bodies. The recombinant CTB-PROIN protein accumulated to the level of 25% of total bacterial proteins. After inclusion bodies was denaturalized and refolded in vitro, significant assembly of monomers had occurred, and the recombinant protein represented assembled pentamers. The results of western blotting analysis also demonstrated that the fusion protein could be recognized by the anti-CT and anti-insulin antibody, respectively. In addition, the result of the CTB-PROIN-GM1 binding assay, that the protein could bind to monosialoganglioside specifically, showed it possesed biological activity in vitro. These results provided the possibility of developing a cheaper and more efficient oral vaccine for type I diabetes using such constructs.
Artificial Gene Fusion ; Cholera Toxin ; genetics ; Cloning, Molecular ; Escherichia coli ; genetics ; metabolism ; G(M1) Ganglioside ; metabolism ; Proinsulin ; genetics ; Recombinant Proteins ; biosynthesis ; genetics

AIM:To investigate whether Yiqi-Wenyang-Huoxue-Huatan formula ( YWHHF) attenuats brain injury induced by hypoxia-hypercapnia pulmonary hypertension ( HHPH) in the rats by inhibiting excessive endoplasmic re-ticulum stress response .METHODS:Healthy SPF male SD rats ( n=50 ) were randomly divided into 5 groups: control group, hypoxia-hypercapnia group, low-dose YWHHF group, middle-dose YWHHF group and high-dose YWHHF group. The rats in control group lived in normal environment , while the rats in other 4 groups were raised for 4 weeks in oxygen tank with low oxygen concentration and high CO 2 concentration .YWHHF was perfused in the rats of low-, middle-and high-dose groups at 0.15, 0.3 and 0.6 g/kg daily, respectively.The rats in hypoxia-hypercapnia group were given isomet-ric distilled water.The surgery was performed on the rats after 4 weeks, and the brain and lung tissues were quickly collect-ed to detect brain water content and observe the morphological changes after mean pulmonary artery pressure recording and heart perfusion .The caspase-3 activity and the apoptotic index of the brain cells were determined .The expression of c-Jun N-terminal kinase (JNK), caspase-12, C/EBP homologous protein (CHOP) and glucose-regulated protein 78 (GRP78) at protein and mRNA levels in brain tissues was detected by Western blot and RT-PCR.RESULTS:Compared with con-trol group, mean pulmonary artery pressure, brain water content, brain apoptotic index, caspase-3 activity, and the protein and mRNA levels of JNK, caspase-12, CHOP and GRP78 in the rest 4 groups were increased , and the brain and lung tis-sues had obvious damage under light microscope .Compared with hypoxia-hypercapnia group , mean pulmonary artery pres-sure, brain water content , brain apoptotic index , caspase-3 activity, and the protein and mRNA expression of JNK , caspase-12, CHOP and GRP78 in low-, middle-and high-dose YWHHF groups were decreased , and the pathological dam-age of the brain and lung tissues was obviously reduced under light microscope .These changes in middle-dose YWHHF group were the most significant .CONCLUSION:YWHHF effectively relieves the brain injury induced by HHPH in rats , which may be associated with inhibiting excessive endoplasmic reticulum stress response .

BACKGROUNDThe blood vessels of a transplanted organ are the interface between donor and recipient. The endothelium in the blood vessels is thought to be the major target for graft rejection. Endothelial cells of a transplanted organ can be of recipient origin after transplantation. In this study, we tested whether endothelial chimerism correlated with the graft rejection and cold ischemia.

METHODSWe studied the biopsy samples from 34 renal transplants of female recipients who received the kidney from a male donor for the presence of endothelial cells of recipient origin. We examined the tissue sections of renal biopsy samples by fluorescence in situ hybridization (FISH) for the presence of endothelial cells containing two X chromosomes using a biotinylated Y chromosome probe and digoxigenin labelled X chromosome probe, and then analyzed the relationship between the endothelial cell chimerism and the rejection and cold ischemia.

RESULTSEndothelial chimerism was common and irrespective of rejections (P > 0.05). The cold ischemic time of chimerism group was longer than no chimerism group ((14.83 +/- 4.03) hours vs (11.27 +/- 3.87) hours, P < 0.05).

CONCLUSIONSThere is no correlation between the percentage of recipient endothelial cells in vascular endothelial cells and the type of graft rejection. The endothelium damaged by ischemic injury might be repaired by the endothelial cells from the recipient.

Animals ; Biopsy ; Endothelial Cells ; pathology ; Female ; Graft Rejection ; Humans ; In Situ Hybridization, Fluorescence ; Kidney ; pathology ; Kidney Transplantation ; Male ; Mice ; Time Factors ; Transplantation Chimera ; Transplantation, Homologous