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.
Background: Dental implants act as infrastructure for fixed restoration to look like as a natural tooth. Osseointegration is a biological events and considered as a base for success of dental implant. The aim of this study is to evaluate the bond strength between bone and Ti implant coated with mixture of nano hydroxyapatite-chitosan-collagen compared with Ti implants coated with nano hydroxyapatite implanted in rabbit tibia, after different period of implantation time (two and six weeks) by torque removal test. Material and methods: 36 screws of commercially pure titanium; 8mm in length and 3mm diameter , 18 screws coated with mixture of nano hydroxyapatite-chitosan-collagen and18 screws coated with nano hydroxyapatite by dip coating. St
... Show MoreA field experiment was carried out in Horticulture Department / Collage of Agricultur e/University of Baghdad to study influence of adding ascorbic acid(asa) and bread yeast extract in snap bean cv.primel under irrigation with saline water using sodium chloride salt (NaCl) during spr ing season of 2016 .A factorial experiment using Randomized Complete Block Design( RCBD) with three replications wereconducted . The first factor includes three treatments of salinity which were tap water ( S0), 4ds.m-1(S1) and 8ds.m-1 (S2) . The second factor includes three treatments which were control treatment without any adding (C) ,ascorbic acid 0.3g.l-1( A ) and yeast extract 12g.l -1( Y ). Results showed significant and gradually decreases in all studie
... Show MoreMeditationsuggetsthat the theatrical world and the receiptindicatethattherie a thread connection or relationshipbetweenthembecausetheateris an art thatfailsinto the abyss of the humanfield ,receivingis a practice thatisreffered to by corners of society and islocated in the context of thisfield. Thus, the relationshipbetweenalgeriantheater and the recepientissanctified by the nature of theaterwhichisbased on a social basis thatbuildsitsexistance and continuityfrom the recepient.Its impossible to imagine a real theaterthatwillbeestablishedunlessit’sassociatedwith an audience so one hand never claps to makesound. This connectionis the first phenomenonthatcanbecome accessible to all people and itremains the second phenomenonthatrequires th
... Show MoreThis research discusses one of the most important means of reducing corruption in public sector companies and government departments, a relationship of cooperation and coordination between the external auditor and internal auditor, in the light of ISA (610), the recommendations of the International Organization of Supreme Audit Institutions (INTOSAI) and the National Strategy to combat corruption. The research was based on two assumptions: the first was weak relationship of cooperation and coordination between the external auditor and internal auditor leads to weakne
... Show MoreThe aim of this research is to identify the impact of the effectiveness of digital transformation technology in improving the efficiency of the insurance service in the public insurance companies in Iraq through digital transformation technology in the insurance process "promotion of the insurance product, submission of insurance application, underwriting, settlement of losses" and to achieve this goal a questionnaire was designed A survey distributed in the surveyed community Which represents the decision makers in the researched companies under study, and one of the most important results of the research was the existence of a relationship between digital transformation and improving the efficiency of the insurance process, whether thr
... Show MoreThe aim of this work is study the partical distribution function g(r12,r1) for Carbon ion cases (C+2,C+3,C+4) in the position space using Hartree-Fock's Wave function, and the partitioning technique for each shell which is represented by Carbon Ions [C+2 (1s22s2)], [C+3 (1s22s)] and [C+4 (1s2)]. A comparision has been made among the three Carbon ions for each shell. A computer programs (MATHCAD ver. 2001i) has been used texcute the results.
Public-private partnership (PPP) has been used over the past 20-30 years by governments in developed countries to meet the public demand for infrastructural services. In Iraq, the PPP concept is comparatively new to the Government of Iraq (GoI), where the government has historically taken most of the responsibility for providing public services. There are few PPP projects in Iraq. However, the number is increasing. Recently the Iraqi market has experienced a number of attempts of PPP in different sectors, especially after the new investment law in 2006. The aim of this paper is to evaluate the investment environment in Iraq and to indicate the main factors affecting PPP in particular for infrastructure projects. Some literature review and
... Show MoreIraq economy suffered, nor , still many difficulties and problems , including oil derivatives crisis that emerged in 2004 and was the most prominent features of the inability of local production to meet the needs of the increasing growth of consumption, the crisis has cast a shadow on the growth of national in general, and citizen living in particular. Therefore, the real test of crisis and challenge to the capacity of government agencies to manage the crisis and control and reduce its harmful effects, which disappear in a region or sector, even begin to appear in another, given the multiplicity and complexity of third-party solution for remedying the negative consequences of deliberate.