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.
مشكلة البحث :
إن القرآن الكريم هو النور المبين والذكر الحكيم يحتوي على الغاية الأسمى التي تهدف اليها الإنسانية ، فهو روح التربية الإسلامية وهو المنهج القديم الذي تستمد منه فلسفتنا التربوية واتجاهاتها ، (الزوبعي ، 1974: 18)
إن الدين الإسلامي هو نظام الهي
... Show MoreThe Qur'an was revealed with a clear Arabic tongue, and it seized minds, and was astonished by its eloquence and eloquence of tastes, so it was a new dawn, and a nucleus for the birth of a new literature inspired by the tolerant thought of Islam, its fresh words, and its delicate and revealing meanings
٠ اش١جخ ٗزفقث ٌٟبِ ٟجعبؾٌّا تٔبغٌا ٟف بقزخِ ٟئبنل ( ًئاضل بساحم ) توهم ىلع ءىضلا طٍلسحو بلارم ءادأ ىلع اهرٍثأحو تٍوهملا اهحاءارجإو تمذخخسملا اهحاٍومح ثٍح نم تٍئاضملا تبساحملا دبثبغؾٌا . اسبِٙٚ د ءبمٌلأ ٟمبٌّا ـؾف ٍٝػ ض١وشزٌا يلاخ ِٓ خ١ٔٛٔبمٌا سِٛلأبث خفشؼٌّا ءٛم ٟف دب٠شؾزٌا ًجمزغٌّا ٍٝػ حشظٔ ٌا خجعبؾٌّا ْا شؽبجٌا ظزٕزعاٚ ذٍجٌٍ ٞدبقزللاا َذمزٌا خٍغػ غفد ٟف ُٙغر خ١ئبنم ، خجعبؾٌّا ٟف خِذخزغٌّا خض٠ذؾٌا ت١ٌ
... Show MoreThe holy city of Najaf is a vital space that helps to bring people together within a particular context, thus strengthening intellectual communication, community participation and increasing opportunities to learn about different cultures
تحديات العولمة للهوية العربية و دور الجامعات العربية في مواجهتها
An automatic text summarization system mimics how humans summarize by picking the most significant sentences in a source text. However, the complexities of the Arabic language have become challenging to obtain information quickly and effectively. The main disadvantage of the traditional approaches is that they are strictly constrained (especially for the Arabic language) by the accuracy of sentence feature functions, weighting schemes, and similarity calculations. On the other hand, the meta-heuristic search approaches have a feature tha
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خليفة بن خياط بن خليفة الشيباني ألليثي العصفري البصري، أبو عمرو، ويعرف بشَبَابه، الفقيه، المُحدَث، الأديب، المؤرخ، النسَابة، وهو سليل أسرةِ اشتهر أبناؤها بالعلم، وأنجبت عدداً من العلماء الأفاضل، الذين عرفوا في ميادين مختلفة، فالجد والأب والحفيد، علماء محدَثون، وبرزوا في علوم عدة ، كان متقناً وعالماً بأيام الناس.
برزت الشخصانية في حقبة تاريخية كان فيها العالم و اوربا وفرنسا تشهد انتهاء حقبة حضارية امتدت من نهاية القرون الوسطى حتى اوائل القرن العشرين تميزت بكونها رأسمالية التركيب، ليبرالية المنهج، وبرجوازية القيم، جاءت الشخصانية ليس فقط محاولة للإجابة عن حقبة جديدة ولادة حضارة جديدة لاتزال غامضة المعالم فحسب انما ايضا كرد على المدرسة الماركسية المادية والوجودية الملحدة محددة هدفها الابعد بإعادة صنع النهضة
ان الداسات القرانية تعد من الدراسات المتعلقة في اللغة العربية لانها تتعلق بدراسة جانب من جوانب اعجاز القرأن الكريم لذلك قمت بدراسة جانب من جوانب اعجاز القران الا وهي لفظة اكل