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.
The technical of Flame Thermal Spray had been used in producing a cermet
composite based on powders of stabilized zirconium oxide containing amount of
Yatteria oxide (ZrO2- 8Y2O3) reiforced by minerals powders of bonding material
(Ni-Cr- Al- Y) in different rates of additions (25, 35, 50) on stainless steel base type
(304) after preparing it by the way of Grit Blasting.
Before heat treatment, the coated cermet layers were characterized for porosity
and electric resistivity. All samples were heat treated in vacuum furnace at different
temperature and times. The physical tests had been operated after heat treatment
and gave best results especially porosity, which found to be reduced dramatically
and producing hig
In this work, ZnS thin films have been deposited by developed laser deposition technique on glass substrates at room temperature. After deposition process, the films were annealed at different temperatures (200ºC , 300 ºC and 400ºC ) using thermal furnace.The developed technique was used to obtain homogeneous thin films of ZnS depending on vaporization of this semiconductor material by continuous CO2 laser with a simple fan to ensure obtaining homogeneous films. ZnS thin films were annealed at temperature 200ºC, 300 ºC and 400ºC for (20) minute in vacuum environment. Optical properties of ZnS thin film such as absorbance, transmittance, reflectance, optical band gap, refractive index extinction coefficient and absorption coefficien
... Show MoreThis work targeted studying organogel as a potential floating system. Organgel has an excellent viscoelastic properties, floating system posses a depot property. Different formulations of 12-hydroxyoctadecanoic acid (HOA) in sesame oil were gelled and selecting F1, F3 and F5 HOA organogels for various examinations: tabletop rheology, optical microscopy, and oscillatory rheology studies. Also, the floating properties studies were conducted at in vitro and in-vivo levels. Lastly, the in-vitro release study using cinnarizine (CN) was to investigate the organogel depot property. Based on the results, the selected concentrations of HOA in sesame oil organogels showed temperature transitions fr
... Show MoreThe experiments were conducted in laboratory conditions of a temperature of 25± 2C and relative moisture of 40± 5 % to evaluate the effectiveness of the cinnamon, lavender and clove essential oils on some biological life aspects of cowpea beetle, C. maculates. Results of the obligative experiment for the effect of the oils on insect adult killing showed that the concentration of 5% caused a mortality percentage averaged 13.33% of the insect males. The mortality percentage of the insect females was 11.3% for the cinnamon and lavender oils. The lavender oil had the lowest effect on adult killing, not exceeding 0. For the effect of the oils on egg laying, clove oil affected the number of eggs highly at the concentration of 5%, result
... Show MoreThe experiments were conducted in laboratory conditions of a temperature of 25± 2C and relative moisture of 40± 5 % to evaluate the effectiveness of the cinnamon, lavender and clove essential oils on some biological life aspects of cowpea beetle, C. maculates. Results of the obligative experiment for the effect of the oils on insect adult killing showed that the concentration of 5% caused a mortality percentage averaged 13.33% of the insect males. The mortality percentage of the insect females was 11.3% for the cinnamon and lavender oils. The lavender oil had the lowest effect on adult killing, not exceeding 0. For the effect of the oils on egg laying, clove oil affected the number of eggs highly at the concentration of 5%, result
... Show MoreThe present work aims to study forward osmosis process using different kinds of draw solutions and membranes. Three types of draw solutions (sodium chloride, sodium formate, and sodium acetate) were used in forward osmosis process to evaluate their effectiveness with respect to water flux and reverse salt flux. Experiments conducted in a laboratory-scale forward osmosis (FO) unit in cross flow flat sheet membrane cell. Three types of membranes (Thin film composite (TFC), Cellulose acetate (CA), and Cellulose triacetate (CTA)) were used to determine the water flux under osmotic pressure as a driving force. The effect of temperature, draw solution concentration, feed and draw solution flow rate, and membrane types, were studied with
... Show MoreBackground: Enterococcus faecalis is emerging as an important endodontic pathogen, which can persist in the environment for extended periods after treatment and may cause endodontic failure. It is known to produce biofilms, a community of bacteria enclosed within a protective polymeric matrix. This study aimed to establish whether the biofilm formation by Enterococcus faecalis can be inhibited with steralium, co+steralium, and 5% sodium hypochlorite in the root surface environment. Materials and Methods: Extracted human teeth were biomechanically prepared, vertically sectioned, placed in the tissue culture wells exposing the root canal surface to E. faecalis to form a biofilm. At the end of the 3rd and 6th weeks, all groups were treated fo
... Show MoreThe different crises and financial collapses place in many companies, particularly in developed countries as a result of administrative and financial corruption return aspects of the task to the role of the company and the external auditor, both in their emphasis on honesty and fairness of financial statements and the Provisions of accounting information and on the contrary to the truth, you may have to the loss of the rights of stakeholders, particularly existing investors, and the loss of confidence of prospective investors in the accounting information contained in the financial statements of these companies, which led to a crisis of confidence and credibility in the profession of accounting and auditing where the wonder of ma
... Show MoreThe Noble Qur’an is the book of God, the Blessed and Exalted, in which is the teachings of God Almighty’s religion, which is Islam, in order for people to unite it and establish servitude to it. The individual and the society alike saw it appropriate to make my opinion alerting the seriousness of this matter, so the research was entitled (The Impact of Sins and Disobedience on the Individual and Society in the Holy Qur’an - Objective Study), knowing that we touched upon some of the effects, which we found it appropriate to mention in this research in the service of the good. Its details came in the Holy Qur’an without referring to others, noting their arrangement in the Holy Qur’an..