Comparison of Clinical Effects of Au-Pt Based and Ni-Cr Based Porcelain Crowns

Objective To compare the long-term clinical effects of two kinds of crowns and bridges made of porcelain fused to Au-Pt alloy and Ni-Cr alloy. Methods A total of 131 teeth (64 patients) were rehabilitated using porcelain-fused-to-metal crowns, among which 59 were rehabilitated with Au-Pt alloy metal ceramic crown and 72 with Ni-Cr alloy metal ceramic crown. The porcelain fracture, shade, marginal adaptation, gingival discoloration, and gingival status after finishing restoration and 36 months of follow-up were evaluated. Results After 36 months of restoration, porcelain fused to Au-Pt alloy crown showed better clinical effects than porcelain fused to Ni-Cr alloy crown in shade, marginal adaptation, gingival discoloration, as well as gingival status (all P<0.05). Conclusion The Au-Pt alloy ceramic crown is superior to Ni-Cr alloy ceramic crown in long-term clinical effects.

Solidification of Be-free Ni-based dental alloy

A novel, Nb- and Si-rich and Be-free Ni-based alloy was cast by two methods of investment casting and continuouscasting to study the microstructure evolution during solidification and its mechanical properties. The solidification of the alloy startedwith the primary crystallization of FCC-γ, followed by a binary eutectic reaction, with the formation of a heterogeneous constituent：FCC-γ＋G-phase, which replaced the low-melting eutectic （FCC-γ＋NiBe） in the Be-bearing alloys. AlNi6Si3 and γ′ formed during theterminal stages of solidification by investment casting, while the formation of AlNi6Si3 was suppressed by continuous casting. TheScheil solidification model agreed very well with the experimental results.

International Financial Investments, Double Taxation of Dividends and ＂Effective Taxation＂ in the Portuguese Tax System

The purpose of this paper is to analyze the tax treatment of dividends established in the Portuguese corporate income tax code. The tax code aims at eliminating double taxation, if certain conditions are met. However, if dividends received were not previously subject to effective taxation, the elimination of double taxation no longer applies. The meaning of effective taxation is not defmed nor quantified in the code. But it is of great importance to firms＇ tax planning. In this context, it is a quite important concept, and the paper will discuss it. The methodological approach is based on using a hypothetical situation where a group of finns＇ faces different dividend flows, from diverse origins, and how taxes affect the overall tax burden of the group. The paper highlights the negative implications of a legal void in a very important tax topic regarding dividend policy in holding companies. It shows a tax induced level of uncertainty in designing dividend policy, and how it hinders financial management of groups of firms. The main conclusion is that the lack of a legal or quantitative definition of what constitutes effective taxation is an important factor of tax complexity in planning intercompany dividend policy, and the concept should be revised in legal terms.

Antibacterial activity of nanostructured Ti-45S5 bioglass-Ag composite against Streptococcus mutans and Staphylococcus aureus

Mechanical alloying and annealing at 1150 °C for 2 h under an argon atmosphere were used to prepare Ti-45S5 bioglass nanocomposites. Ti-45S5 bioglass material was chemically modified by silver. The antibacterial activity of Ti-10% 45S5 bioglass nanocomposite containing silver against Streptococcus mutans and Staphylococcus aureus was studied. Nanocomposites were characterized by X-ray diffraction, scanning electron microscopy equipped with an electron energy dispersive spectrometer and transmission electron microscopy to evaluate phase composition, crystal structure and grain size. In vitro bacterial adhesion study indicated a significantly reduced number of Streptococcus mutans and Staphylococcus aureus on the bulk nanostructured Ti-45S5 bioglass-Ag plate surface in comparison to that on microcrystalline Ti plate surface. Nanostructured Ti-based biomaterials can be considered to be the future generation of dental implants.

Chemical constituents isolated from the aerial parts of Swertia pseudochinensis and their potential neuroprotective effects

Objective:Swertia pseudochinensis,an annual herb of the genus Swertia in the family Gentianaceae.Some constituents and extracts from the Swertia genus have been recently reported to possess neuroprotective effects,suggesting their potential utility in the prevention and treatment of Parkinson disease(PD).The aim of this work is to identify the chemical constituents and evaluate the potential biological activists of Swertia pseudochinensis.Methods:The phytochemicals from the aerial parts of S.pseudochinensis were isolated and purified by silica gel,Sephadex LH-20 gel,semi-preparative high-performance liquid chromatography,and identified by the spectroscopic methods.All compounds were evaluated for their potential neuroprotective effects against 1-methyl-4-phenylpyridinium-induced apoptosis in the SH-SY5Y human neuroblastoma cell line using the 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide assay.Then,we performed an enrichment analysis using the Database for Annotation,Visualization,and Integrated Discovery and investigated the mechanisms by which bellidifolin regulates neurodegenerative disease.Results:Two new anthraquinone,1,5,6-trimethoxy-2-hydroxy-3-methy-anthraquinone(1)and 1,5,6,8-tetramethoxy-2-hydroxy-3-methyanthraquinone(2),together with nine known including 7-O-b-d-glucopyranosyl-1,8-dihydroxy-3-methoxyxanthone(3),gentisin(4),swertianolin(5),bellidifolin(6),gentiacaulein(7),norswertianolin(8),5-O-b-d-glucopyranosyl-1,3,8-trihydroxyapatone(9),1-hydroxy-3,5,8-trimethoxyxanthone(10),and aurantio-obtusin(11),were isolated and compounds 6–8 and 10 exhibited neuroprotective effects at a concentration of 50mmol/L.Among them,bellidifolin showed significant protective activity,and might have potential as a neuroprotective agent for the treatment of PD,possibly by acting on oxidative damage and reactive oxygen species.Conclusions:These findings indicate that further research on the genus Swertia and its bioactive constituents toward neurodegenerative disorders could be extremely rewarding.

Microbial Biofilm Formation as a Dental-fouling Microorganisms Attachment Phenomenon in Oral Cavity Environment

DMFP （Dental microbial fouling phenomenon） of OCE （oral cavity environment） was studied in the local dental labs. Multi-smears of mature supra gingival plaques were randomly collected from fifty persons in dental labs that had different cultures, ages, sex and different scientific levels. Rapid microbial identification method was used to identify of these multi-smears by using vitek-2 compact instrument. The most frequent and appearance species of bacteria was Pantoeae spp., then Klebsiella pneumonia. Total species of microbial fouling in supra gingival plaques were included sixteen species： Staphyllococcus aureus, Klebsiella pneumonia, Pantoeae spp., Aercococcus viridians, Leuconostoc mesenteroides cremorise, Granuli.adiacens, Streptococcus sanguinis, Staphyllococcus sciuri, Stenotrophomonus maltiphilia, Kocuria varians, Gememlla morbillorum, Granulicatella adiacens, Nonreac biopattern, Kocuria kritinae, Kocuria rosea and Nonreac.biopattern while six fungal species were Tricoderma viride, Aspergillus flavus, Tricoderma harzianum, Cladosporium macrocarpum, Penicillium citrinum and Verticillium lecanii in addition to two yeast species were recorded Candida dubliniensis and Candida glabrata. The results were detected the most appearance of bacteria Pantoeae sp., then Klebsiella pneumonia, then Staphyllococcus aureus. These results of study suggest that adhesive strength conjugated with the biofilm layers presence in OCE may vary across different from one to other persons and mark a new path of inquiry for dental Microbial-fouling phenomenon research.

Design principle for parameters and interferences of tungsten carbide insert interface on roller bits

The lifetime of roll-bits with inserted tooth will be obviously decreased while drilling in strata and the tungsten carbide can be integrally separated from the roll-cone,which will need more trip out time to replace the roller bit.This study provides an entire analysis on stress as well as strength for teeth and tooth holes in loaded conditions.Qualities of tooth drop from matrix within roller bit.The optimized interferences of teeth inserted into the bit can be reasonably obtained by the critical interference derived from some relevant influence factors on the tooth-fixing quality of roller bits.

金牙 木盆 老花镜

记忆是蒲公英，岁月是风。蒲公英被风吹着在空中飘来飘去，我抬手拦住了它。在阳光下，透过这缥缈的蒲公英，我好像看到了你嘴里的那颗金牙，

Effects on cytotoxicity and antibacterial properties of the incorporations of silver nanoparticles into the surface coating of dental alloys

The aim of this study was to research the changes in cytotoxicity and antibacterial properties after silver nanoparticles （AgNPs） were incorporated into the surface coating of dental alloys. AgNPs were attached to cobalt chromium alloys and pure titanium using a hydrothermal method, according to the reaction： AgNO3＋NaBH4-, Ag＋1/2H2＋1/2B2H6＋NaNO3. A 3-（4,5-dimethylthiazol-2-yl）-2,5-diphenyl tetrazolium bromide （MTT） assay was used to evaluate the cytotoxicity of the alloys when in contact with osteogenic precursor cells （MC3T3-E1） from mice and mesenchymal stem cells （BMSC） from rats. The antibacterial properties of dental alloys incorporating three different concentrations （10, 4, and 2 μmol/L）of AgNPs were tested on Staphylococcus aureus （SA）and Streptococcus mutans （MS）. High cytotoxicity values were observed for all dental alloys that contained 0% of AgNPs （the control groups）. The incorporation of AgNPs reduced cytotoxicity values. No significant difference was observed for antibacterial performance when comparing dental alloys containing AgNPs to the respective control groups. The results demonstrated that the cobalt chromium alloys and pure titanium all had cytotoxicity to MC3T3-E1 and BMSC and that the incorpo- ration of AgNPs could reduce this cytotoxicity. The concentrations of AgNPs adopted in this study were found to have no antibacterial action against SA or MS.

Neuroprotective effects of xanthone extract from Swertia punicea Hemsl against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine(MPTP)-induced mouse model of Parkinson's disease

As a widely used traditional Chinese medicine （TCM）, Swertia punicea Hemsl has exhibited effects on anti-hepatitis B virus （HBV）, liver protection, hypoglycemic activity and cholecystitis. In this study, we confirmed that xanthone extract from Swertia punicea Hemsl （XSPH） improved the motor deficit, increased the levels of striatal dopamine （DA） and homovanilic acid （HVA）, and alleviated the loss of tyrosine hydroxylase （TH）-positive neurons located in substantia nigra pars compacta （SNpc） in MPTP-induced mouse model of Parkinson＇s disease （PD）. In conclusion, the present results indicated that XSPH offered neuroprotective effects against the neurotoxicity of MPTP and it might be a potential treatment for PD.

Toxicity testing of four silver nanoparticle-coated dental castings in 3-D LO2 cell cultures

To address the controversial issue of the toxicity of dental alloys and silver nanoparticles in medical ap- plications, an in vivo-like LO2 3-D model was constructed within polyvinylidene fluoride hollow fiber materials to mimic the microenvironment of liver tissue. The use of microscopy methods and the measurement of liver-specific functions optimized the model for best cell performances and also proved the superiority of the 3-D LO2 model when compared with the traditional monolayer model. Toxicity tests were conducted using the newly constructed model, finding that four dental castings coated with silver nanoparticles were toxic to human hepatocytes after cell viability assays. In general, the toxicity of both the castings and the coated silver nanoparticles aggravated as time increased, yet the nanoparticles attenuated the general toxicity by preventing metal ion release, especially at high concentrations.