Background: The high reactivity of hydrogen peroxide used in bleaching agents have raised important questions on their potential adverse effects on physical properties of restorative materials. The purpose of this in vitro study was to evaluate the effect of in-office bleaching agents on the microhardness of a new Silorane-based restorative material in comparison to methacrylate-based restorative material. Materials and method: Forty specimens of Filtek™ P90 (3M ESPE,USA) and Filtek™ Supreme XT (3M ESPE, USA) of (8mm diameter and 3m height) were prepared. All specimens were polished with Sof-Lex disks (3M ESPE, USA). All samples were rinsed and stored in incubator 37˚C for 24 hours in DDW. Ten sample of each material were subjected to 37.5% hydrogen peroxide gel (Pola office +, SDI)for 8 minutes while exposed to light curing device, this step was repeated three times for 3 weeks. While the other ten samples for each material was served as control. All specimens were subjected to microhardness test using digital microhardness tester to determine the VHN (Vickers Hardness Number) Results : The Filtek™ P90 exhibited higher microhardness value than Filtek™ Supreme XT. After hydrogen peroxide treatment, both types of composites exhibited low microhardness values but still Filtek™ P90 is harder than Filtek™ Supreme XT. Conclusion : In-office hydrogen peroxide bleaching agent resulted in reduction in microhardness values for both composite materials. Silorane- based composite is more affected by the bleaching agent than methacrylate-based composite.
Background: Separation and deboning of artificial teeth from denture bases present a major clinical and labortory problem which affect both the patient and the dentist. The optimal bond strength of artificial teeth with denture base reinforced with nanofillers and flexible denture bases and the effect of thermo cycling should be evaluated. This study was conducted to evaluate and compare the shear bond strength of artificial teeth (acrylic and porcelain) with denture bases reinforced by 5% Zirconium oxide nanofillers and flexible bases under the effect of different surface treatments and thermo cycling and comparing the results with conventional water bath cured denture bases. Material and methods: Two types of artificial teeth; acrylic and
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The study aimed to identify the impact of the use of systemic approach in the collection of geographical material and cognitive motivation when fifth grade students of literary, experimental design researcher adopted a partial seizures, and telemetric to two unequal one experimental and the other officer.
The sample consisted of fifth grade literary students from secondary (inherent) for Boys in Baghdad (the Republic of Iraq. (By Mjootain, and the number of students of each group (30 students). And has rewarded the two groups, in the variables (chronological age, average scores half-year, degree IQ),
Promising researcher himself requirements of research to determine the scientific material and teaching plans and the formulation of
In this paper, an experimental study was conducted to enhance the thermal performance of a double-pass solar air heater (SAH) using phase change material (PCM) for thermal storage at climatic conditions of Baghdad city - Iraq. The double-pass solar air heater integrated with thermal storage system was manufactured and tested to ensure that the air heating reserved after the absence of the sun. The rectangular cavity filled with paraffin wax was used as a latent heat storage and incorporated into the lower channel of solar air heater. Experiments were carried out to evaluate the charging and discharging characteristics of two similar designed solar air collectors with and without using phase change material at a constant
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An Indirect simple sensitive and applicable spectrofluorometric method has been developed for the determination of Cefotaxime Sodium (CEF), ciprofloxacin Hydrochloride (CIP) and Famotidine (FAM) using reaction system bromate-bromide and acriflavine (AF) as fluorescent dye. The method is based on the oxidation of drugs with known excess bromate-bromide mixture in acidic medium and subsequent determination of unreacted oxidant by quenching fluorescence of AF. Fluorescence intensity of residual AF was measured at 528 nm after excitation at 402 nm. The fluorescence-concentration plots were rectilinear over the ranges 0.1-3.0, 0.05-2.6 and 0.1-3.8 µg ml-1 with lower detection limits of 0.013, 0.018 and 0.021 µg ml-1 an
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