Background: The demand for esthetic orthodontic appliances is increasing; so the esthetic orthodontic archwires were introduced. Among them, Teflon and Epoxy coated stainless steel archwires. The amount of force available from the archwire depends on the structural properties and susceptibility to corrosion. All metallic alloys are changed during immersion in artificial saliva, chlorhexidine mouthwash andtoothpaste, but their behaviors differ from one type to another. They corrode at different rates, which lead to decrease the amount of force applied to the teeth. This in vitro study was designed to evaluate the corrosion pits in stainless steel archwires coated with Teflon and with Epoxy in dry and after immersion in artificial saliva, chlorhexidine(0.2%( (Parodontax) and toothpaste media (Sensodyne) for (1, 7 and 28) days intervals. Moreover, this study is intended to compare the corrosion pits for each type of archwires at these different media among all intervals. Materials and Methods: In this study, two hundred forty pieces of orthodontic wires of Teflon (Hubit) coated Stainless steel (120 pieces) and epoxy (Orthotechnology) coated Stainless steel (120 pieces), rectangular in cross section, size (0.019 x 0.025) inch and 15mm in length divided into four groups according to immersion media: (dry environment group, artificial saliva group, chlorhexidine group and toothpaste group). The atomic force microscope was used to measure the corrosion pits for all samples at dry and wet conditions and after different immersion periods. Results: Statistical analysis showed that there was a highly significant increase in the corrosion pits of Teflon coated stainless steel archwires (P ≤ 0.05) in wet environment at 28 days immersion period.The highest corrosion pits were found in the toothpaste medium for the two archwire types at 28 days immersion period. Conclusion: We can conclude that Epoxy coatedstainless steel archwires are indicated to be used above Teflon coated stainless steel archwires in terms of corrosion resistance. IfTeflon coated stainless steel archwires should to be used, they should be change in shorter periods than Epoxy coated stainless steel archwires type Key words: Esthetic coated archwire, corrosion, Teflon, Epoxy, wet environment, AFM.
Public relations are amongst the social sciences that rely on scientific methods in achieving new knowledge or resolving existing problems by means of its scientific researches that are often applied and require a classification in terms of their results’ analysis. It also requires subtle statistical processes whether in constructing their material or in analyzing and interpreting their results.
This research seeks to identify the relation between public relations and statistics, and the significance a researcher or practitioner in the domain of public relations should assign to statistics being one of the important criteria in identifying the accuracy and object
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This research is based on an analyzing the relation between premiums and compensations of life insurance, for individual and the group insurance, and a reality of the
... Show MoreThe self-evident truth existing in today's business environment is the continuity of change and its continuity and turmoil, also its increase over time as it is more abundant, abundant, wide and complex than ever before, and it is the dominant feature in the business environment, as different organizations and operating units can find themselves shifting from the top to the bottom. And then it requires its departments to strive to adapt to these rapid and turbulent shifts and changes by bringing about a series of organizational and adaptive changes that are not limited to one organizational aspect only but rather include all organizational components. Accordingly, this research came to determine the readiness of public organizations to chan
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The purpose of this research is to investigate the relationship between organizational ethnography and resonant leadership in the University of Kufa, importance of research includes rare of studies that investigated the relationship between organizational ethnography and resonant leadership. Moreover, it comes as an attempt to reduce or bridge the knowledge gap between the variables of the research. As well as try to put the right foundations and appropriate for industry leaders of various Iraqi organizations aimed at profit or service. Based on the random sampling, 450 questionnaires were distributed to employees at the University of Kufa. Only 392 questionnaires were returned. Out of which 104 questionnaires we
... Show MoreThe Purpose of this study is mainly to improve the competitive position of products economic units using technique target cost and method reverse engineering and through the application of technique and style on one of the public sector companies (general company for vegetable oils) which are important in the detection of prices accepted in the market for items similar products and processing the problem of high cost which attract managerial and technical leadership to the weakness that need to be improved through the introduction of new innovative solutions which make appropriate change to satisfy the needs of consumers in a cheaper way to affect the decisions of private customer to buy , especially of purchase private economic units to
... Show MorePolyacrylamide Solutions of different concentrations (0.2, 0.4, 0.6, 0.8, 1.0 %) of Ag nanoparticles and ZnO nanoparticles were prepared, the viscosities and surface tension were measured for all solutions, where measurements indicated an increase in these properties with increased concentration, where the relative viscosity of polyacrylamide/zinc nanoparticles increased from 1.275 to 2.243, and the relative viscosity of polyacrylamide/silver nanoparticles increased from 1.178 to 1.934. Viscosity is significant parameters during electrospinning process. While the surface tension of the polyacrylamide/zinc nanoparticles has changed from 0.0343 Nm-1 to .0.0.0 Nm-1 and changed from .0.000Nm-1 to.0.0.0 Nm-1. Also the constants KH and KK were
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