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.
This paper considers approximate solution of the hyperbolic one-dimensional wave equation with nonlocal mixed boundary conditions by improved methods based on the assumption that the solution is a double power series based on orthogonal polynomials, such as Bernstein, Legendre, and Chebyshev. The solution is ultimately compared with the original method that is based on standard polynomials by calculating the absolute error to verify the validity and accuracy of the performance.
The primary objective of the current paper is to suggest and implement effective computational methods (DECMs) to calculate analytic and approximate solutions to the nonlocal one-dimensional parabolic equation which is utilized to model specific real-world applications. The powerful and elegant methods that are used orthogonal basis functions to describe the solution as a double power series have been developed, namely the Bernstein, Legendre, Chebyshev, Hermite, and Bernoulli polynomials. Hence, a specified partial differential equation is reduced to a system of linear algebraic equations that can be solved by using Mathematica®12. The techniques of effective computational methods (DECMs) have been applied to solve some s
... Show MoreEvolution in the modern era Which led to the rapid change in the forms of industrial products For many reasons, So put current research into question the view (What are the design requirements that define the formal change in the Iron clothes)? To reach the aim of In the design cornerstonesUnderlying the formal changethe Iron of the clothes, In the first section shed light on the development stages of systems design lists the historic stages of development and energy operator devices irons and mechanism of action and internal components, while in the second part, which was entitled (The role of technology and the factors influencing the change formality of Iron) touched on the three topics which technology modern industrial and receiver,
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This work is considered the first study for the components of the Iraqi Leucaena leucocephala plant, where the different phytochemical compounds that present in the aerial parts were identified by using the gas chromatography/mass spectrometry technique (GC/MS). The type of the components and their concentration will differ according to the part of the plant used and the method of extraction (hot and cold). This study made a comparison in lupeol concentration that was identified and isolated from petroleum ether fractions of Leucaena leucocephala by using Gas Chromatography/Mass Spectrometry (GC/MS), High-performance thin-layer chromatography (HPTLC), and Preparative High-Performance Li
... Show MoreThe research dealt with the topic ' the aesthetics of design shape of interior spaces for the syndicate of physicians' as it reflects visions evolving to the level of tasting and positive interpretation for the space of work to be on a high design level.The research consisting of four chapters as follow; The first chapter examined the problem of the research contracted in the following question: Have the design shapes any role in achieving and showing the aesthetic side for the syndicate of physicians? so the goal of the research was showing the aesthetics of design shape of interior spaces for the syndicate of physicians, The chapter also included the objective spatial and temporal limits of research .Finally the terms were specified. T
... Show MoreInterested in this research shed light on the reality of foreign trade to Iraq Who suffers from a marked deterioration due to poor economic diversification of the country And increase the degree of economic exposure , Which creates a state of extreme caution towards the question of accession to the (WTO) , As controls Iraq's foreign trade commodity , a president of one oil As well as the contribution of this item , and by a large formation in GDP , And that such a large and dangerous decline in the degree of economic diversification will create negative effects On overall economic activity components&
... Show MoreThe objective of the current research is to identify the degree of awareness of the teachers of Arabic language with the requirements of sustainable development. The research sample consisted of (100) male and female teachers of the Arabic language. A 3-likert scale of (71) items grouped into practical and cognitive aspects, five trends for each aspect was designed by the researcher to explore the required data. The results showed that the level of awareness of teachers of the Arabic language was moderate of both the cognitive and practical aspects of sustainable education with means (1.69) and (1.48) respectively. The researcher presented a set of recommendations and suggestions.
Most of the big companies and especially the intillictual ones become a ware of an important fact, and That is, The intillictual capital in new global economy, is a new source for Them & This Valuable source exceed in importance. The other company's sources.
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... Show MoreIn the present work, the image and representation of Adela, the youngest daughter of the family of the Casa de Bernarda Alba, one of the most popular works of the Spanish author Federico García Lorca (1898-1936), will be analyzed. In this work, there are different themes, but what concerns us is to show the repression, oppression and rebellion of this character in a context of customs of the 1920s in Spain. They are revealing elements in that period in which women were relegated to the background, despite the fact that a feminist movement had already begun in Spain. By studying Adela, we seek to see how a single woman confronts her family and the society that surrounds her to fight for freedom, although its end is finally linked to
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