[Fracture resistance in two marginal designs of chamfer and shoulder in IPS emax restorations]

One of the problems of all ceramic restorations is their risk of fracture due to occlusal loads.The aim of the present study was to compare the effect of two marginal designs [shoulder and chamfer] on the fracture resistance of IPS-emax all ceramic restorations.One extracted maxillary first premolar received chamfer 50' marginal preparation [0.8 mm].Twenty impressions were made using poly vinyl siloxane. Then, chamfer was converted to shoulder 90'[1mm]. Afterimpression, epoxy resin dies were fabricated. Impressions of each epoxy resin die were made and poured with diestone. Twenty Press crowns and twenty ZirCAD crowns were made on stone dies and cemented on resin dies. Then,samples underwent a fracture test in a universal testing machine. Data were analyzed by one-way ANOVA.The mean fracture resistance was 1426N for the chamfer ZirCAD samples, 1361.3N for the shoulder ZirCADsamples, 1059.9N for the chamfer Press samples and 1295.8N for the shoulder Press samples. One-way ANOVA revealed no difference among groups. [p=0.095].After porcelain application, marginal design does not affect fracture resistance of single IPS-emaxposterior crowns. Fracture resistance was approximately the same in Press and ZirPress groups probably due to porcelain application, because in ZirCAD group fractures occurred in the porcelain prior to the core

[Comparison of the effect of feldspathic porcelain and zirconia on natural tooth wear]

Enamel wear is among the main disadvantages of ceramic restorations. Recently, use of full zirconia crowns without dental porcelain has been suggested. The aim of this study was to compare the effect of feldspathic porcelain and zirconia on the wear of natural teeth. In this experimental study, 22 zirconia specimens were fabricated; out of which, 11 specimens were polished and chosen as zirconia specimens while the remaining 11 were used to fabricate porcelain specimens. A total of 22 natural human teeth were also obtained. The natural teeth were photographed by a stereomicroscope in a fixed position and the distance from the cusp tip to a reference point was measured. Next, 11 teeth opposed zirconia and the remaining 11 opposed porcelain specimens in a chewing simulator and subjected to 120,000 masticatory cycles. The teeth were photographed again and the greatest difference between the before and after values was recorded. The mean [ +/- standard deviation] wear rate was 153.8 +/- 95.68 and 306.3 +/- 127.74, in the zirconia and porcelain groups, respectively; and the two groups had a statistically significant difference in this respect [P=0.007]. The mean wear was significantly lower in teeth opposing zirconia than in those opposing feldspathic porcelain

comparison between shear bond strength of VMK master porcelain with three base-metal alloys [ni-cr-t3, verabond, super cast] and one noble alloy [x-33] in metal-ceramic restorations

Statement of Problem: The increase in the use of metal-ceramic restorations and a high prevalence of porcelain chipping entails introducing an alloy which is more compatible with porcelain and causes a stronger bond between the two. This study is to compare shear bond strength of three base-metal alloys and one noble alloy with the commonly used VMK Master Porcelain

Materials and Method: Three different groups of base-metal alloys [Ni-cr-T3, Super Cast, and VeraBond] and one group of noble alloy [X-33] were selected. Each group consisted of 15 alloy samples. All groups went through the casting process and change from wax pattern into metal disks. The VMK Master Porcelain was then fired on each group. All the specimens were put in the UTM; a shear force was loaded until a fracture occurred and the fracture force was consequently recorded. The data were analyzed by SPSS Version 16 and One-Way ANOVA was run to compare the shear strength between the groups. Furthermore, the groups were compared two-bytwo by adopting Tukey test

Results: The findings of this study revealed shear bond strength of Ni-Cr-T3 alloy was higher than the three other alloys [94 MPa or 330 N]. Super Cast alloy had the second greatest shear bond strength [80. 87Mpa or 283.87 N]. Both VeraBond [69.66 MPa or 245 N] and x-33 alloys [66.53 MPa or 234 N] took the third place

Conclusion: Ni-Cr-T3 with VMK Master Porcelain has the greatest shear bond strength. Therefore, employment of this low-cost alloy is recommended in metalceramic restorations

Comparison of FEV1 and PEF values in cough variant asthma during methacholine challenge test

Asthma is one of the most common chronic diseases with an increasing prevalence. The cough variant of asthma [CVA] is a latent form of the disease. The aim of this study is to compare the decreasing rates of FEV1 and PEF during the methacholine challenge test. In this study, we tested a total of 120 patients [14-65 years old], whom were referred to the respiratory clinic with complaints of chronic cough, using normal chest and sinus x-ray and spirometry. Also other causes of chronic cough were ruled out. Spirometry and Peak Flowmetry were done during the methacholine challenge test, then FEV1 and PEF were recorded. From 120 patients, 47 patients [39.2%] were male and 73 [60.8%] were female. Thirty three [27.5%] patients showed a >/= 20% decrease in FEV1, while 35 patients [29.2%] had a >/= 20% decrease in PEFp. Decreasing values of FEV1 and PEFp with r=0.49 and P-value<0.000l were significant. Normalization for age, sex, and occupation shows that these factors have no effects on the decrease observed for FEV1 and PEFp. Based on the correlation ratio for PEFp in comparison with spirometry's FEV1, we suggest using peak flowmetry instead of spirometry for diagnosing CVA. According on the ROC curve, we recommend a >/= 15.5% decrease in the level of PEFp with 79% sensitivity and 69% specificity

[Association of trichomonas vaginalis with low birth weight]

Available information suggests that pregnant women infected with Trichomonas vaginalis may be at increased risk of preterm delivery and low birth weight [LBW]. This study evaluated the association between T. vaginalis infection and the risk of LBW. In this cohort study, we evaluated 1000 pregnant women [gestational age>/=28 weeks] for trichomoniasis by using direct and culture methods at the time of delivery at two hospitals of Zanjan, Iran. All the infected women [33 cases] and non-infected women [107] who had been selected with purposive quota sampling were compared with each other. Questionnaires were used to collect demographic and obstetric parameters. Consequently, infants' weights were recorded using mothers files. The prevalence of T. vaginalis infection was 3.3% [33 cases]. Mean gestational age of the infected women at the time of delivery was significantly less than the non-infected [36.5 +/- 4.5 weeks vs. 39 +/- 1.9 weeks; P=0.009]. Higher parity, and living in city were significantly associated with the increased risk of vaginal trichomoniasis [P<0.05]. No significant association was found between the T. vaginalis infection and degree of education, type of delivery, family income, and frequency of LBW. The results of this study suggest that, T. vaginalis infection may be associated with low gestational age and higher parity at the time of delivery. However, no significant association was found between the T. vaginalis infection and LBW in the third trimester of pregnancy

[ comparison of impulsivity between responsive and non-responsive obsessive-compulsive patients to selective serotonin reuptake inhibitors]

In recent years, there has been a growing interest in the interrelationships among obsessive- compulsive disorder, impulsivity, and serotonin and previous studies produced mixed results. This study aimed at investigating the comparison of impulsivity between responsive and non-responsive obsessivecompulsive patients to selective serotonin reuptake inhibitors [SSRIs]. In an ex post facto design, using Sadock and Sadock's [2007] definition, and through convenience sampling, 27 Obsessive-Compulsive patients were divided into two groups [responsive and nonresponsive to SSRI] and were examined through 11th Barratt Impulsivity Scale, Yale-Brown Obsessive-Compulsive Scale [symptom checklist], and Structured Clinical Interview for DSM-IV. The mean scores of impulsivity and its components in responsive patients were higher in comparison with non responsive ones. Centroids of responsive and non responsive groups were significantly different regarding impulsivity, attentional, motor, and nonplanning impulsiveness [p< 0.009]. Among the four variables, there were significant differences only in impulsivity [p<0.01], attention [p< 0.01] and impulsiveness between responsive and non responsive groups [p <0.05]. The findings of this research shows that there is a significant difference in impulsivity level between responsive and non-responsive obsessive-compulsive patients to SSRIs, and the mean score of impulsivity in nonresponsive patients is higher. However, attending to some paradoxes in the literature, more researches are needed to provide a comprehensive theoretical explanation for the interrelationships among impulsivity, OCD, and responsivity to SSRIs

[Bioassay for toxicity assessment of zinc oxide and titanium oxide to escherichia coli ATCC 35218 and staphylococcus aureus ATCC 25923 bacteria]

This study was conducted to investigate the toxicity of Titanium Oxide [TiO2] and Zinc Oxide [ZnO] nanoparticles as two of most widely used nanoparticles. The result of this study can help to designing environmental standard and legislations for nanoparticles. Different concentrations of nano ZnO and TiO2 nanoparticles were added to nutrient Agar culture media. Then, definite numbers of Escherichia coli and Staphylococcus aureus bacteria were added to culture media and inhibition of these bacteria growth was measured in comparison to controls. Obtained data were analyzed to determine nanoparticles' EC50 and NOEC [No Observed Effect Concentration] using SPSS ver.16 and Probit standard test. 24-hours EC50 of nano ZnO using E. coli and S. aureus determined to be 5.47 mg/L and 2.38 mg/L respectively. In addition, 24-hours EC50 of nano TiO2 using E. coli and S. aureus determined to be 5366 mg/L and 3471 mg/L respectively. In the case of ZnO nanoparticles, no observed effect concentration determined to be 1.15 and 3.28 mg/L for E. coli and S. aureus respectively and in the case of TiO2 nanoparticles no observed effect level determined to be 1937 and 1184 mg/L for E. coli and S. aureus respectively. This study showed that acute toxicity of nano ZnO is by farmore than that of nano TiO2. Regarding the EPA acute toxicity criteria, nano ZnO is categorized as moderately toxic and nano TiO2 is categorized as practically non toxic. Hence, regarding the acute toxicity, in recommending exposure criteria and environmental disposal standards, compared to nano TiO2, nano ZnO requires more attention

[Effect of sodium hypochlorite gel on shear bond strength and bond durability of excite to dentin]

Although bonding mechanism is based on resin diffusion onto the demineralized dentin collagen fibers in most of dentin adhesive systems, it has been shown that the bond is going to degrade over time. The aim of this study was to determine the effect of sodium hypochlorite on shear bond strength and bond durability of Excite to dentin. In an experimental study, buccal and lingual surfaces of 36 intact human premolars were prepared and randomly assigned to 4 groups. In groups 1 and 3, specimens were etched and bonding procedures were accomplished according to manufacturer's directions. Then, composite resin was bonded to the dentin surfaces. In groups 2 and 4, AD Gel [10% sodium hypochlorite gel] was applied in order to remove the collagen fibers after acid conditioning. Then, the bonding procedure was followed as for groups 1 and 3. After 24 hours, water storage in groups 1 and 2 and 1 year water storage in groups 3 and 4, shear bond strength was evaluated and analyzed by one way analysis of variance. Variance test was used for data analysis due to normal distribution of data and homogeneity of variances. ANOVA test showed that shear bond strength of group 1 [28.2 +/- 7.0 MPa] was significantly higher than group 2 [17.6 +/- 8.6 MPa] [P=0.001]. The bond strength was also significantly higher in group 3 [29.4 +/- 4.7 MPa] than group 4 [21.3 +/- 8.0 MPa] [P=0.009]. No statistical significant difference was found between groups 1 and 3 and also between groups 2 and 4 in terms of shear bond strength. Shear bond strength of Excite to dentin decreased with using sodium hypochlorite gel. Shear bond strength of Excite did not show any significant difference after one year of water storage, with or without using sodium hypochlorite gel

[Evaluating the effects of globalization on poverty measures]

Globalization of economy is characterized by increasing movement of labor and capital, technology, increased international trade, integration of markets and communication. Liberalization and globalization lead to increased foreign investment and increased amount and type of goods and services traded by nations. One of the challenges in globalization literature is its impacts on living condition of income groups and more specifically on poverty and income distribution of different income groups. Some believe in a positive relation between poverty and trade liberalization. However, others have got a negative relation between them. In this study the effect of globalization on poverty was investigated using both of micro and macro frameworks. In macroeconomic lens, globalization effect on Poverty Headcount and Poverty Gap criteria was studied using a variable as foreign trade - gross domestic production ratio. In microeconomic lens the results obtained for Wheat market was used. The Wheat market contains equations of import, domestic production and domestic demand simultaneously. The results of the Wheat market obtained from Mousavi's [1385] study, conducted to predict the impact of globalization on Wheat market. In the microeconomic approach in addition to the Wheat market results, household expenditure, collected by Iranian Statistical Center, was also used. In the microeconomic approach the impact of different levels of increase in Integration of International Trade [LIT] criterion [as a mean indicating level of globalization] on Wheat [Bread] consumption was investigated. Two approaches were considered in order to investigate the impact of globalization on consumption. In approach one, the total changes in Wheat consumption was regarded as summation of changes in domestic supply and import. While in second one the changes in Wheat [Bread] domestic demand was regarded as consumption changes. Different levels of increase in Integration of International Trade criterion were also 10, 20, 30, 50 and 100 percent. In addition to the increased levels of the Integration of International Trade criterion, the impacts of increase in price of bread on selected households expenditure and poverty indices including Headcount, Poverty Gap and Severity of Poverty was studied. Based on findings, globalization has no considerable impact on the percent of urban poor, while 1% rise in globalization criterion can reduce urban poverty gap by 2.95%. Inflation index also reveled that increase in prices results in decreased poverty gap in urban Iran. In the case of rural households the findings showed that globalization results in a reduced poverty head count, but it raises poverty gap. In other words participation of Iran in global market will result in more undesirable condition of rural lower income poor, needing for more protection of the mentioned groups. The impact of agriculture sector growth on rural poverty is also interesting in that more growth of it lead to more poverty. Based on the results agriculture sector growth is expected to increase both of the poor number and poverty gap. The results of Headcount criterion revealed that 36.74% of urban and 25.43% of rural households are considered as poor. The results of micro lens evaluation that was also performed using coefficients obtained from Mousavi's [1385] study and household expenditure showed that globalization of wheat market individually, and increased bread price would not result in a considerable change in poverty Headcount, Gap, and Severity

[Frequency of yeasts and precipitating antibodies against Candida Albicans and Pityrosporum Ovale in patients with scalp psoriasis]

Background: psoriasis of scalp is a multi-factorial disease and one of the suggested theories is role of yeasts. Hence, current study has performed to determine the prevalence of yeast in culture of the scalp and anti-yeast antibody in serum of psoriatic patients in comparison with control population

Materials and methods: current study is a comparative cross-sectional survey among 80 subjects in two groups of 40 persons including psoriatic patients and control group. They were selected in a simple random manner among those attending to dermatology clinic of Imam-Khomeini Medical Center of Tehran during 2000

Results: 38 patients [95%] in psoriatic group and 5 subjects in control group had positive culture of scalp for yeasts [P=0.0001]. There was a significant difference between psoriatic and control group from point of antibodies against Candida Albicans and Pityrosporum Ovale [P=0.0001]

Conclusion: yeasts may have an important role in pathogenesis of psoriasis disease and therefore using anti-yeast agents may be therapeutic choice for scalp psoriasis