Background: With the increased in the demands of adult orthodontics, the challenge of direct bonding to non-enamel surface (zirconium) had been increased. The present study was carried out to compare the shear bond strength of three different brackets (stainless steel, sapphire and composite) bonded to zirconium surface and study the mode of bond failure. Materials and methods: The sample was comprised of 30 models (8mm *6mm*1.5mm) of full contour zirconium veneers. They were divided into three groups according to the brackets type; all samples were treated first by sandblast with aluminum oxide particle 50 µm then coated by z-prime plus primer. A central incisor bracket of each group was bonded to the prepared zirconium surface with lig

Background: The potential use of zinc oxide and other metal oxide nanoparticles in biomedical are gaining interest in the scientific and medical communities, largely due to the physical and chemical properties of these nanomaterials. The present work revealed the effect of zinc oxide nanoparticles (ZnONPs) on the total salivary peroxidase enzyme activity of human saliva in comparison to de-ionized water. Materials and methods: Forty eight unstimulated saliva samples were collected from dental students/University of Baghdad 18-22 years. Then measure the total salivary peroxidase activity first without any addition to human saliva as a control, second with dilution the saliva with de-ionized water, and third with zinc oxide nanoparticles in c

An acidic environment causes surface changes of resin composites. Filler particlesize and filler distribution also have a direct effect on these surface changes. This invitro study evaluated the influence of Pepsi Cola drink on the surface roughness ofComposan LCM and Composan Ceram over time. Sixteen disc shaped specimens(10mm diameter, 2mm thickness) of each resin composite were fabricated, therebyforming two groups (n= 8). Surface roughness (Ra) was analyzed after 24 hrs beforeexposure to beverage. The specimens were submitted to a five minutes immersion inPepsi Cola three times daily interrupted by immersion in deionized distilled water (37C˚). Surface roughness measurements were done at 10, 30, and 60 days intervals. Datawere

An experimental and numerical study has been carried out to investigate the heat transfer by natural convection in a three dimensional annulus enclosure filled with porous media (silica sand) between two inclined concentric cylinders with (and without) annular fins attached to the inner cylinder under steady state condition; The experiments were carried out for a range of modified Rayleigh number (0.2 ≤Ra*≤ 11) and extended to Ra* =500 for numerical study, annulus inclination angle of (δ = 0˚, 30˚, 60˚ and 90˚). The numerical study was to write the governing equation under an assumptions used Darcy law and Boussinesq’s approximation and then solved numerically using finite difference approximation. It was found that the averag

،يريغت وأ ةلكشم وأ ةثداح ةجيتن ،ةعمالجا وأ درفلا هذختي فقوم هرهوج في ماعلا يأرلا دعي ةيوبرت تماكارتو ،ةيرثك تانوكم لىع هسسأ في موقي وهف اذل ،ةشاعلما ةايلحا تاقايس في لصيح فيو ،عمتمج يلأ يعماتجلاا لعفلا ةيصوصخ تاقايس بسحب يرسي ايرطف نوكي ام اهنم ،ةيفاقثو يعولا ةلاح تيبثت ديرت تاهج نم ةلعتفمو ةعنطصم تايطعمب اهيريست وأ اهذحش متي ىرخأ نايحأ ليكشت ةيلمع تنترقا ذل ،ةثدالحا كلت مهف ةأطو ليلقت وأ يريغت وأ فرح وأ ي

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