ABSTRACT Background: Color changes that are detectable to human eye can affect the esthetic appearance of ceramic veneers. The purpose of this study was to evaluate and compare the effect of artificial accelerated aging on the color of ceramic veneers cemented with different resin cements. Materials and Methods: Sixty discs were prepared with 0.5 mm thickness, 30 discs made from IPS e.max press (Ivoclar Vivadent) and 30 discs were made from VITA Enamic (VITA Zahnfabrik). The discs were cemented with three resin cements: Variolink Veneer MV 0 shade (Ivoclar Vivadent), Rely X veneer Translucent shade (3M ESPE) and NX3 Nexus Clear shade (Kerr Corporation) with 0.1 mm thickness. The spectrophotometer Easyshade Advance was used to measure the color parameters (Lightness, axis a* of chroma and axis b*of chroma) immediately after cementation, after 150 and 300 hours of aging. The specimens were subjected to artificial accelerated aging in Accelerated Weathering Tester. Color change greater than 3.3 was considered unacceptable. One-way ANOVA, paired t-tests and Bonferroni adjusted t-test were used for statistical analysis (p <0.05). Results: Artificial aging caused high significant color change in both ceramic types, but there were non-significant difference in color change among the three resin cements used. The color change was between1.997-14.8 after 150 hours and it was between 2.179-15.68 after 300 hours. The color change of e.max discs after aging were within acceptable limit<3.3 whereas Vita Enamic specimens had shown unacceptable color change >3.3 after aging. Conclusions: The majority of color change after aging related to veneering materials while resin cement have only slight effect on color change after aging. IPS e.max had shown an acceptable color change after aging, so it is suitable for fabrication of restorations in esthetic zone while Vita Enamic should not be used in esthetic zone since it has poor color stability according to the results of this study.
In this paper the reinforced materials manufactured from steel continues fibers are used in Aluminum matrix to build a composite material. Most of researches concentrated on reinforced materials and its position in the matrix according to its size and distribution, and their effects on the magnitude of different kinds of the stresses, so this paper presents and concentrate on the geometrical shape of reinforced material and its effects on the internal stresses and strains on the composite strength using FEM as a method for analysis after loaded by certain force showing the deference magnitudes of stresses according to the different geometrical shapes of reinforced materials.
Academic Entitlement (AE) is the expectation by students to receive high grades or preferential treatment without significant effort. Exploring AE from faculty perspective has not been investigated in Arab colleges of pharmacy. The aim of this study was to explore experiences and perceptions towards student AE among pharmacy faculty in the Arab World. A cross-sectional, self-administered, anonymous, electronic survey was sent to pharmacy faculty across pharmacy colleges in Arab countries. The survey collected demographic data, an AE measure including 17 items reflecting seven AE components, and faculty perceptions and perceived reasons for AE. A total of 345 responses were collected. The AE level wa
Abstract In light of the changing conditions that prevail in society, and the intense competition that institutions and countries are forced to face, especially after the opening of markets, and the transformation of the world into what is called a small village, entrepreneurship has emerged as an important tool for dealing with the developments of societies, whether it is related to individual business projects or Economics for national business, leadership was the key to any driving force towards achieving growth. Today, women are no longer captive to a specific orientation, but rather all horizons and fields of work have been opened to them, and they have been able to occupy the most important economic, voluntary, service, and
... Show MoreBanks are considered the main basis of financial sector ,so they must be submitted to sound and strict regulatory system and so as to ensure their operations and according to instructions and regulations , in order to maintain the integrity of the banking sector and financial sector in general .One of the importance regulatory tools that are adopted by the Iraqi Central Bank to control over the banks an financial and periodic statements that are provided by the banks in accordance with planned schedules .The financial statements of the banks must reflect clearly and accurately financial situation and the result of their activities during the period in which they represent to achiveing its purposes.So it has the goal of Search is statemen
... Show MoreBackground: The size of the nasopharyngeal airway was believed to have an important role in the development of the dentofacial structure. This study was carried out to test the relation between the nasopharyngeal dimensions with some dento-cranial measurements in class I and II jaw relationship. Materials and Methods: This study was done on 60 subjects (30 males and 30 females) at age range 18-25 years. Cephalometric radiograph has been taken to each subject and the measurements were recorded. The sample was divided into two groups, class I skeletal relationship (15 males and 15 females) and class II skeletal relationship (15 males and 15 females). Comparisons between the different study groups were undertaken. Results: In class I skeletal
... Show MoreA reliable and environmental analytical method was developed for the direct determination of tetracycline using flow injection analysis (FIA) and batch procedures with spectrophotometric detection. The developed method is based on the reaction between a chromogenic reagent (vanadium (III) solution) and tetracycline at room temperature and in a neutral medium, resulting in the formation of an intense brown product that shows maximum absorption at 395 nm. The analytical conditions were improved by the application of experimental design. The proposed method was successfully used to analyze samples of commercial medications and verified throughout the concentration ranges of 25–250 and 3–25 µg/mL for both FIA and batch procedures, respecti
... Show MoreLately great interests have emerged to find educational alternatives to teach and improve motor skills according to modern educational methods that take into account individual differences and speed in learning for the learner through individual learning that the learner adopts by teaching himself by passing through various educational situations to acquire skills and information in the way he is The learner is the focus of the educational process and among these alternatives the interactive video, the researchers noted through the educational training units at the Model Squash School of the Central Union, and that most of the methods and methods used in learning basic skills take a lot of time in the educational program and do not involve
... Show MoreMonetary sterilization policies are one of the modern trends of monetary policy in rentier countries, specifically to confront the positive shocks in foreign assets flowing into the national economy and the impact of these shocks on monetary and real variables. And that the Central Bank contains these emergency increases in foreign exchange with the aim of avoiding the impact of this increase on the official local currency through its three main monetary tools, which are the rediscount rate, the legal reserve, and open market operations. As well as the relationship between the central bank and the objective of external balance, which is reflected in the balance of payments balance, the central bank resorts to managing the exchange rate
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