Background: Thermocycling simulates the temperature dynamics in the oral environment. This in vitro study done to measure and compare the effect of thermocycling on the shear bond strength of stainless steel and sapphire brackets bonded to human enamel teeth using light cured orthodontic adhesive and debonded at various time, and to measure adhesive remnant index after debonding. Materials and Methods: one-hundred-twenty extracted upper first premolars for orthodontic reason were used in this study; depending on weather thermocycled or not, the sample was divided into two main groups, then within each group 30 teeth were used for stainless-steel brackets (Bionic®) and for sapphire brackets (Pure®). Both groups were subdivided into three groups (n = 10) according to the debond times: I: debond after 24 hour, II: debond after 7 days and III: debond after 30 days. Within 24 hr, half of the sample was thermocycled manually for 500 complete cycles between 5/55°C and the remaining sample was stored in distilled water at room temperature and water was changed daily until debond time for each group was performed. The adhesive remnant index was tested under 20X magnification lens using stereomicroscope. Results and Conclusions: Both bracket types demonstrated high shear bond strength values before thermocycling (P?0.05), whereas after 500 thermocycles, there were significant changes in shear bond strength resulted in marked reduction in the stainless steel brackets than in the sapphire brackets (P?0.05). Shear bond strength values increased with time for both stainless steel and sapphire brackets with and without thermocycling (P?0.05). The tendency of bond failure was increased at the bracket/adhesive interface rather than enamel/bracket interface in the stainless steel brackets whereas at the enamel/bracket interface rather than bracket/adhesive interface in the sapphire brackets.
Accurate description of thermodynamic, structural, and electronic properties for bulk and surfaces of ceria (CeO2) necessitates the inclusion of the Hubbard parameter (U) in the density functional theory (DFT) calculations to precisely account for the strongly correlated 4f electrons. Such treatment is a daunting task when attempting to draw a potential energy surface for CeO2-catalyzed reaction. This is due to the inconsistent change in thermo-kinetics parameters of the reaction in reference to the variation in the U values. As an illustrative example, we investigate herein the discrepancy in activation and reaction energies for steps underlying the partial and full hydrogenation of acetylene over the CeO2(111) surface. Overall, we find th
... Show MoreBackground: Low-level laser therapy (LLLT) has been extensively applied to improve wound healing due to some biostimulatory properties presented by laser arrays apparently able to accelerate the repair of soft tissue injuries. However, the role of proinflammatory interlukines not been studied yet. IL_1 ? represent one of the most important poroinflammatory interlukines that involved in wound healing. The goal of this study was to investigate the effect of 790-805nm diode laser on the expression of IL_1 ? during wound healing in mice. Materials and Methods: Standard-sized wounds (1.5cm) were carried out in the face of 96 white albino mice. Half of them underwent LLLT treatment (360 J/cm 2) at 790-805 nm delivered immediately after wound pro
... Show MoreThis research aims to identify the nutritional status of the individual's relationship to malnutrition using anthropometric measurements such as weight, height and impact on the values ??of the blood study sample included 200 male and 200 female of the inhabitants of the cities of Baghdad and Baquba reviewers Central Mahtbrat
The aim of the research is to identify the cognitive method (rigidity flexibility) of third-stage students in the collage of Physical Education and Sports Sciences at The University of Baghdad, as well as to recognize the impact of using the McCarthy model in learning some of skills in gymnastics, as well as to identify the best groups in learning skills, the experimental curriculum was used to design equal groups with pre test and post test and the research community was identified by third-stage students in academic year (2020-2021), the subject was randomly selected two divisions after which the measure of cognitive method was distributed to the sample, so the subject (32) students were distributed in four groups, and which the pre te
... Show MoreThe study deals with an analysis of the contents of the publications of the campaign (Together to defeat Corona), which was established by the United Nations Development Program in Iraq in the face of the Covid 19 virus.The research problem raises a main question:What are the implications of the campaign (Together to defeat Corona) of the United Nations Development Program (Iraq office) in addressing the Covid-19 virus in Iraq?From this main question, several sub-questions emerged, which were answered by this study in its chapters and investigations, including regarding the contents of advertisements, photos and videos for the publications of the (Together to Defeat Corona) campaign for the United Nations Iraq Office on their Facebook pageA
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The research dealt with the risks of reinsurance and its impact on the financial performance of the National Insurance Company by focusing on reinsurance in the marine insurance branch. Negative impact on the financial performance of the NICs and the Marine Insurance Branch. The research sample resulted in a main hypothesis that reflects this relationship. Lee in the analysis of financial information reports National Insurance Company of the branch of marine insurance for the period of 2010 until 2017, and the use of (retention) for measuring the re-insurance operations index, and (insurance financial surplus rate) to measure financial performance. For the purpose of obtaining the results, a number of statistical methods were used accord
... Show MoreThe study seeks to determine the levels of credit structure (independent variable) depending on its components (loans, credit disseminate, other facilities) To get the eight patterns of the structure of bank credit for the purpose of assessing the relationship between changes in levels of each style of structure credit (increase or decrease) and reflected in maximizing the value of the Bank(The adopted a measured variable depending on the approximate equation of simple Tobin's Q) to determine the style that achieves the highest value of the Bank, to take advantage of it in management, planning and control by knowing the strengths and weaknesses of the historical distribution of the facilities . the sample of the
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This study was aimed to conduct one of the vertical garden systems , selecting suitable plant species that with stand the climate conditions of Baghdad city in outer space to determine the appropriate growing medium for the (LWS), and to assess the impact of spraying with potassium silicate on the resistance of the cultivated plants to heat stresses . The study carried out at at Al-Batool Park of (Al-Kadhimiya Holy City). Two experiments were carried out, each one with a different plant species, including Wedelia trilobata and Tradescantia pallida, during the winter season of 2021 and summer season of 2022. The experiments were designed using a split block design. The experiments included two factors, the first being the growing med
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This study aimed to provide a theoretical framework for the impact of the Turkish intervention in northern Syria and the extent of its impact on the relations between the two countries.
It also sought to answer the study's main question: What is the impact of the Turkish intervention in northern Syria on Turkish-Syrian relations during the period 2011-2019 ?.
In this study, the historical method, the descriptive method, and the systems analysis method were used, with the aim of arriving at an accurate and realistic understanding of the Turkish-Syrian relations.
The study reached a set of results, the most important of which was that the Syrian-Turkish relations are based on interests, and that all alliances and
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