Laser etching may be an alternative to acid etching of enamel and dentin. Several characteristics of irradiated dental hard tissues have been considered advantageous, microscopically rough surfaces without demineralization, open dentinal tubules without smear layer production and dentin surface sterilization. The aim of this study is to determine and compare histology the microleakage in class V cavity restored with a light cured composite after conditioning the samples(tooth surface) with 1-acid etching, 2-Q-switched Nd:YAG Laser etching and finally 3- acid and laser etching. Materials and methods: Twenty four non carious human extracted teeth were used in this study. The samples were equally grouped into four groups of six teeth each. A class V cavity was prepared. In group I, tooth surface was etched with a 37% phosphoric acid gel. In group II, the tooth surface was conditioned using a pulsed Nd:YAG Laser alone with a wavelength of 532 nm. The parameters were of pulse energy 60 mJ, pulse repetition rate 6Hz and energy density was 0.48 J/cm2. In group III, the tooth surface was treated with Nd: YAG Laser and then was etched with phosphoric acid. In group IV, the surface was treated with 37% phosphoric acid then irradiated with Nd: YAG Laser; with the same parameters and concentration mentioned in group I and II. The samples immersed in 1% basic fuschin dye to mimic the normal stains in oral cavity and the sections were examined by a stereomicroscope and the readings were scored. Results: The results showed that group IV, in which the surface was treated with 37% phosphoric acid and then irradiated with Nd: YAG Laser) recorded the least microleakage of the four groups, where group III, in which the tooth surface was treated with Nd: YAG Laser and then was etched with phosphoric acid)recorded reasonable results better than group I (group I tooth surface was etched with a 37% phosphoric acid gel) or group II , in which the tooth surface was conditioned using a pulsed Nd:YAG Laser alone) Conclusion: The use of Q-switched Nd:YAG laser in etching the tooth surface was so effective that it can be used in treating or conditioning the tooth surface to enhance bonding and the best parameters among the tested samples were pulse energy of 60mJ, pulse repetition rate of 6Hz and energy density 0.48 J/cm2.
The process of doing many kinds of industries , crafts , professions around Islamic Arabian State , they enable us to say that Arab Muslims over their homelands had been occupied various types of crafts and manufacturing before emergence Islam . Moreover Islam encouraged to work within manufacture field . And These matters were clarified through verses of the Holy Qur’an and honored prophetic guidance ( Sunna ) . Whereas Arab Muslims applied principle “ Free of Business “ . They admitted to different social groups such as pact – fellows people to profession or craft which they desire to work . We have to not forget that Arab Muslims had broken all restraints and shackles which had restricted the worker bef
... Show MoreBased on Lyapunov exponent criterion, the aircraft lateral-directional stability during critical flight cases is presented. A periodic motion or limit cycle oscillation isdisplayed. A candidate mechanism for the wing rock limit cycle is the inertia coupling between an unstable lateral-directional (Dutch roll) mode with stable longitudinal (short period) mode. The coupling mechanism is provided by the nonlinear interaction of motion related terms in the complete set equations of motion. To analyze the state variables of the system, the complete set of nonlinear equations of motion at different high angles of attack are solved. A novel analysis including the variation of roll angle as a function of angle of attack is proposed. Furthermore
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The research dealt with the study of animal drawings in the fresco, during the Umayyad period, especially in Qusayr Amra and Qasr al-Hayr al-Gharbi. Many imagesto different animals and birds were found and used in various subjects, most notably the hunting and predation scenes.
In the second millennium BC, the international community change at the ancient Near East, There has been a significant developments with the appearance of five kingdoms (Babylon, Assyria, Mitanni, Egypt, and Hatti) called themselves the (Great Powers) and their kings named (Great King), and Correspondence among themselves on behalf of (the brothers), to differentiate themselves from the small kingdoms Minor of them.
دور المراكز البحثية في الحياة السياسية وصنع القرار السياسي الخارجي الامريكي
The research addresses a pattern of imagery which is regarded a Prominent feature of Abi Tamaam's Poetry (the image of implicit simile) which is based on the hidden signified and the signifier which can be deduced out of context . The investigation requires a study whose proof is based on imagery which is of three types: natural proof , human proof and Quran proof . After handling the realistic structures of this image, the researcher has shifted attention to its types and has dealt with the psychological domain , dividing it in two types: the sensory image and the mental image. The research is directed towards studying the implicit sentence regarding its styles of expression : declarative expression and composition expression . The
... Show Moreيتطلب تحقيق تمايز الوحدة الاقتصادية في ظل استعمال تقنيات الأعمال الحديثة وازدياد المنافسة وعالمية الأعمال ضرورة الاهتمام بمستوى نوعية المنتجات وما تتطلبه هذه النوعية من كلف والتي تسمى بكلف النوعية، إذ ان العديد من الشركات العالمية قد قامت بدراسة وتحليل هذه الكلف ووضع برامج خاصة بها بهدف تخفيضها إلى أدنى حدٍ ممكن وبما يكفل تحقيق العديد من المنافع والتوفيرات في هذه الكلف وبما يرشد عملية اتخاذ القرارات
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Federal Russia remains the central player in the space of post-Soviet Union,
particularly in the regions of Middle Asia and the Caucasus , which set standard for
the local transformations of the two regions.
The Russian concern continued about the shift of power in the
world, as long as Russia is concerned with limiting the action of the United States
in the area in which Russia sees as vital area to its national interests. Russia's
nationalists play a main role in reviving Russia's influence in Middle Asia as a vital
area and the natural ally of Russia, but without resorting to the old ways of using
the threat of military force.
The idea of the return of Russia as a superpower in the global arena in
Middle
The book of Alphendidad is considered as an important part of the holy book of
Avesta in the Zoroastrian religion. It is a religious and urbanization book that consists of a
number of chapters dealing with the creation. The book includes 22 chapters, mostly edited
as a dialogue between Ahuaramzda the god of goodness and his prophet Zoroaster. The
biggest chapter deals with the rules of purification of vices of the devil and dismissing it of
the places around, hence it is the book of law of Zoroastrian about the important animals,
birds , insects, and reptiles and their categorization according to their creation; creatures of
the spirit of goodness and creatures of the spirit of evilness.
Some of these creatures ar
In this paper, an approach for object tracking that is inspired from human oculomotor system is proposed and verified experimentally. The developed approach divided into two phases, fast tracking or saccadic phase and smooth pursuit phase. In the first phase, the field of the view is segmented into four regions that are analogue to retinal periphery in the oculomotor system. When the object of interest is entering these regions, the developed vision system responds by changing the values of the pan and tilt angles to allow the object lies in the fovea area and then the second phase will activate. A fuzzy logic method is implemented in the saccadic phase as an intelligent decision maker to select the values of the pan and tilt angle based
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