Background: Poly-ether-ether-ketone(PEEK) has been introduced to many dental fields. Recently it was tested as a retainer wire‎ following orthodontic treatment. This study aimed to investigate the effect of changing the bonding spot size and location on the performance of PEEK retainer wires. Methods: A biomechanical study involving four three-dimensional finite element models was performed. The basic model was with a 0.8 mm cylindrical cross-section PEEK wire, bonded at the center of the lingual surface of the mandibular incisors with 4 mm in diameter composite spots. Two other models were designed with 3 mm and 5 mm composite sizes. The last model was created with the composite bonding spot of the canine away from the center of the crown, closer to the lateral incisor. The linear displacement of the teeth, strains of the periodontal ligament, and stresses in PEEK wire and composite were evaluated. The data was numerically produced with color coded display by the software. Selected values were tabulated and compared among models. Results: The amount of linear displacement and strain was very low. Stresses in the wire and composite were affected by the size and position of the composite bonding spot. The safe limits were identified at 235 MPa for PEEK and 100 MPa for composite. The basic model had a von Mises stress in the PEEK wire of 122.09 MPa, and a maximum principal stress in the composite of 99.779 MPa. Both stresses were within the safe limits, which means a lower risk of failure in PEEK and composite. All other models had stresses that exceeded the safe limit of the composite. The 3 mm composite model was the only one that developed stresses in the wire more than the safe limits of PEEK. Conclusions: Within the limitations of this study, bonding PEEK wires with 4 mm bonding spots to the clinical crown center provided the best mechanical performance of the wires and spots; otherwise, the mechanical properties of the wire and composite would be affected and, therefore, might affect the retention process. Keywords: Retention, PEEK, Finite element analysis
The research aims to study the extent of the influence of the dimensions of sensory marketing on the perceptual mental image of customers, knowing the type of relationships that link the dimensions of sensory marketing with each other, no one from the researcher mentioned (as far as the researcher knows) the link between sensory marketing and mental image, from this point of view the main goal is determined, the effect of sensory marketing on the mental image taken from customers, as the research was conducted on a number of first-class restaurants represented (Chef City, Chili House, Mado, Fried Chicken Saj Alreef) and the research community was represented by the customers of the aforementioned restaurants, a
... Show MoreChina is moving towards building the largest economic power in the world, so what does this mean economically and politically for Europe, America, the Middle East and the Arab world? This project is called the expansionist Chinese Marshall Plan which is a revival of the old Silk Road in a new way. It represents the aspirations of the Chinese people and their president, Xi Jinping, to build a transport route from Asia to Europe and a railway plan to transport goods. The purpose of this is to develop the economic growth model, expand into new markets, promote the Chinese currency, and expand economic and political influence in the areas covered by the Chinese initiative. Equal opportunities in distributing investments to these countries, a
... Show MoreBackground: One of the most predominant periodontal diseases is the plaque induced gingivitis. For the past 20 years, super-oxidized solutions have be..
The Strait of Malacca is one of the waterways of strategic, political, and economic importance. This strait has an increasing importance to its neighboring countries. The Strait of Malacca is very important for China, especially in the field of energy supply security, as the vast ma jority of energy supplies come to China through this strait. China seeks to ensure its security, especially in light of the cooperation of countries that look forward to this strait as well as the United States, and what the United States may cause to China, as many of them are at war with China over the China Sea, not to mention the countries that overlook it. The importance of the research emerges from the basic idea that the strategic importance of the Strait
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The aim of the research is to demonstrate the impact of the salary localization service in enhancing banking competitive advantage. In order to achieve this goal, salary localization was chosen as an independent variable and its impact was studied on the dependent variable, which is the competitive advantage. The research problem lies in the fluctuation of the salary localization service from one bank to another and the impact of this on the competitive advantage. The study sample included five private Iraqi banks, namely (the National Bank of Iraq, the International Development Bank, Assyria International Bank, Al Khaleej Commercial Ban
... Show MoreThe research dealt with the effect of the tax examiner's efficiency in detecting tax evasion, as the research problem dealt with tax evasion, especially in Iraq, for many reasons and factors, including those related to tax administration represented in administrative corruption and the complexity of procedures in the tax accounting process and failure to achieve justice in the tax treatment, including the taxpayer himself, as he tries to evade for reasons Related to the level of tax awareness, loss of confidence in the tax administration, and reasons related to the state's inability to manage the services file well and its ability to achieve the set goals, This reflected negatively on the emergence of some of the consequences of
... Show MoreOyster mushroom (Pleurotus ostreatus (Jacq. ex Fr.) P. Kumm.) is involved in the destruction of dead wood which is the main place of settlement of several living organisms. After humification, dead wood also becomes an important component of forest soils.
The purpose of the research is to study temperature and moisture conditions of extensive cultivation of oyster mushrooms on various wood substrates. To accomplish this goal, the following tasks were set: to determine the amount of effective stress temperatures and moisture content of substrates and their influence on the appearance of fruiting bodies of the oyster mushroom; to study the features of the extensive culti
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