Background: Crown preparation of vital teeth involve the removal of a sound tooth structure, and when enamel removed this lead to exposed dentin with an increase in the number of open dentinal tubules also the diameter of dentinal tubules will increase, furthermore lead to increase movement of fluids inside the tubules all that causes post preparation sensitivity. The aim of this study is to evaluate the effect of desensitizing by Er:Cr:YSGG laser on shear bond strength of prepared tooth and resin cement. Materials and methods: Thirty sound maxillary premolars, grouped into three groups(n=10). Group A is the control group, group B irradiated by Er:Cr:YSGG laser with (0.25 W, 20 Hz, 10%water and air), group C irradiated by Er:Cr:YSGG laser with (0.5 W, 20 Hz, 10% water and air). Results: SEM examination showed complete occlusion of opened dentinal tubules after laser irradiation of both groups that irradiated with laser. Statistical analysis showed significant increase in surface roughness in group B and C. SBS was significantly increase in group B with no significant increase in group C. Conclusion: Er:Cr:YSGG laser can occlude open dentinal tubules without and adverse effect on the retention of the restoration, on the contrary it increase bonding strength. And this increasing was significant in group B with (0.25W, 20 Hz, 10 % water and air). suggestion: so the parameters used in group B (0.25 W, 20Hz, 10 % water and air) is recommended for desensitizing prepared tooth and induce enhancement to the bonding strength of resin to tooth surface.
Transportability refers to the ease with which people, goods, or services may be transferred. When transportability is high, distance becomes less of a limitation for activities. Transportation networks are frequently represented by a set of locations and a set of links that indicate the connections between those places which is usually called network topology. Hence, each transmission network has a unique topology that distinguishes its structure. The most essential components of such a framework are the network architecture and the connection level. This research aims to demonstrate the efficiency of the road network in the Al-Karrada area which is located in the Baghdad city. The analysis based on a quantitative evaluation using graph th
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(فتح الرحمن بكشف ما يلتبس في القرآن ) لزكريا الأنصاري (ت 926 هـ ) مصنَّف مهم تبارت فيه علوم العربية لفكّ ما يثيره ظاهر آيات قرآنية من لبس لدى المتلقي ، فكان للبلاغة السطوة في ذلك ، ولأهميته طبع طبعات كثيرة ، خمس منها بتحقيق محمد علي الصابوني ، وهو التحقيق المهمين الشائع ، غيرأنه لم يستوفِ الأسلوب العلمي في اخراج النصوص، إذ بدت فيه مزالق كثيرة بينَ تغيير وسقط ووهم وتحريف وتصحيف ودمج مما استنهض فكرة هذا البحث ، للتنب
... Show MoreThis study aims to expand the traditional model in calculating the break-even point to include the cost of capital invested and the funds employed in industrial companies through a change in the traditional model and the effect of adopting the advanced model of the break point on the operational leverage in planning profits in industrial companies. Where, the analysis of the break-even point and the operational leverage of the tools important by the management, which is used in the field of planning profits. A parity analysis in its sophisticated model will help in planning profits and determine the optimal size of production that maximizes profits. For its part, the operational leverage helps to make decisions regarding the expansion of
... Show MoreThe aim of this research is to study the effect of using computer
techniques to increase students information at the experimenting the speed
control of dc motor by the magnetic field.
Simulation of the experiment has been used by implementing
“Electronics Workbench” software.
The random sample, included (30) second year electrical department
students, divided into two groups , experimental and control with pre-test and
post-test .
The results showed great advantages for the experimental group
through the use of computer program in the laboratory. The calculated (t) was
(10.6) which was significant and showed statistical differences between the
experimental and control group.
According to the result
تواجه الوحدات الاقتصادية في العراق منافسة قوية بسبب مشكلات خاصة بإرتفاع الاسعار وارتفاع تكاليف الانتاج وضعف الاهتمام بدراسة السوق وغيرها من المشاكل ، فضلاً عن استخدام نظام التكاليف التقليدي الذي لا يوفر معلومات ملائمة لقرارات التسعير الامر الذي يتطلب دراسة وتحليل تلك المشكلات ومعالجتها بالاعتماد على تقنيات حديثة بما يمكنها من المنافسة ولهذا جاء هذا البحث والذي يعتبر من المداخل الحديثة لتخفيض التكاليف وم
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