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.
A long-span Prestressed Concrete Hunched Beam with Multi-Opening has been developed as an alternative to steel structural elements. The commercial finite element package ABAQUS/CAE version 2019 has been utilized. This article has presented the results of three-dimensional numerical simulations investigating the flexural behaviour of existing experimental work of supported Prestressed Concrete Hunched Beams with multiple openings of varying shapes under static monotonic loads. Insertion openings in such a beam lead to concentrate stresses at the corners of these openings; as a result, extensive cracking would appear. Correlation between numerical models and empirical work has also been discussed regarding load displacemen
... Show MoreIn this work, Soda Lime Glass (S.L.G.) powder was used ,as
fluxe in traditional porcelain instead of feldspar. Two ceramics
porcelain were compared; commercial or traditional porcelain that
content of 50wt % kaolin, 25wt % quartz, and 25wt % feldspar.
Feldspar mass was substituted by scraps soda lime glass yielding a
new porcelain composition, to determine the softening points and
then the effect of glass addition on porcelain firing process.
Eight samples, for each patch, were prepared and 8wt % water
was added. The resulting composite blends were then die pressed at
2N, to produce disk specimens with diameter of 1.5 cm, and then
they were sintered at (1000, 1100, 1200, 1250,1300,1350,1400 and
1450) ˚C,
Abstract :
The present study aims at identifying the status of the two research variables in the organization under study and specifying the relationship and impact of the authentic leadership with all its four branch dimensions of (self-awareness, transparent relations, balanced processing of information and the moral perspective) on business process reengineering.
The basic problem of the study lies in the attempt to present a new leadership style that is more responsive to the dynamic changes surrounding it based on the authentic leadership behaviors. This is because this pattern has an impact on the nature of the organization's work and its progress.
The research
... Show MoreArchitecture forms theoretical summaries and multi systems that have the essence of change, and that what distinguishes Architecture from other sciences and their systems. Architecture means way of life via its expressional products and that appears through its systems. These systems are based on formative and technological properties in form, structure, services and materials as well as
their moral forms. All these are associated with techniques and facilities in order to establish integrated system.
Architectural creation does not come from void but it depends on a conception base to create a new condition for creative architectural product. The general problem of the research concentrated on limited theoretical and practica
This research aims at clarifying the concept of social auditing, which is one of the most important reasons for its emergence is social responsibility accounting and its role in measuring the social performance of enterprises. The study also aimed to know how social auditing has an impact and its role in improving the social performance of business organizations, and the research refers to testing the hypotheses of an impact of social auditing on social performance through a commitment to social responsibility. The research sample consisted of 200 individuals from 20 Algerian business organizations and represented individuals who were researched in managers and em
... Show MoreThe sports field is one of the fields that are concerned with the various methods and methods because of their positive impact on the development of actual training, the investment of the exerted effort in time, and through the follow-up of the researcher in the field and academic field, I noticed that there is a weakness in explosive ability, which affects performance and skill level during training and competition Therefore, the researcher decided to prepare maximum physical exertion exercises according to the anaerobic threshold as a principle of development in many physical and skill variables because good physical performance leads to reaching the best achievements and since the skill of shooting by jumping high - either constitutes a
... Show MoreThe Strategy of employees' empowerment, organizational performance and total quality management represent three informative which were and still the hub of many studies and researches including the current study. The higher education is considered one of the most important services sectors and the main development as well as the civil progress in the society. It is the main source that provides the organizations with the human resources having scientific or practical professions. So Higher Education has been chosen especially Baghdad University as a sample of the study. The study problem is concentrated to find answers of the following questions: What the level of the powers mandate in the organization concerning the
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