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 Rivest–Shamir–Adleman (RSA) and the Diffie-Hellman (DH) key exchange are famous methods for encryption. These methods depended on selecting the primes p and q in order to be secure enough . This paper shows that the named methods used the primes which are found by some arithmetical function .In the other sense, no need to think about getting primes p and q and how they are secure enough, since the arithmetical function enable to build the primes in such complicated way to be secure. Moreover, this article gives new construction of the RSA algorithm and DH key exchange using the
primes p,qfrom areal number x.
The current research contains four chapters. The first topic included the methodological framework that included the problem of research and the need for it, and then the importance of the research, and then the aim of the research, its limits and the definition of terms linguistically, conventionally and procedurally. The second chapter (the theoretical framework) contained two topics, the topic The first is titled: The Outward Vision in Child Theater Performances, while the second topic was titled: Presentation Technology in Child Theater, Chapter Four (Research Procedures), which organized the research community and analyzed its sample, and the fourth chapter contained research results, conclusions and recommendations. The prop
... Show MoreThe construction industry plays a crucial role in the countries' economy, especially in the developed country. This point encourages the concerned institution to use new techniques and integrate many techniques and methods to maximize the benefits. The main objective of this research is to evaluate the use of risk management, value management, and building information modeling in the Iraqi construction industry. The evaluation process aims at two objectives. The direct objective was to evaluate the knowledge in risk management (RM), value management (VM), and building information modeling (BIM). The indirect objective was to support the participants with information related to the main items mentioned. The questionnaire
... Show MoreAbstract
This study highlights the importance of Iraq in the analysis of foreign trade and economic growth for the period (1980 - 2013) is an attempt to determine the equilibrium relationship long term and short term between these two variables were used ARDL model to explain the economic relationship between the two variables.
To achieve the objectives of the research has been the standard model estimate after testing the stability of exports X data series, and imports M, and GDP current prices, and exchange rate EXR, and verify the existence of a joint integration relationship between these variables.
In order to achieve the objectives of the research it
... Show MoreObjective: The aim of this study is to determine the means and the difficulties faced by students of
nursing maternal and child health nursing / College of Nursing / University of Baghdad in obtaining scientific
information in practical training.
Methodology: A purposive sample of (100) Nursing college student - Maternal and Child Health Nursing
Department were selected. Data were collected through the use of the questionnaire form during the
period from the November 2010 to April 2011. Descriptive statistical procedures were used to analyze the
data.
Results: The results showed that the highest percentage of members of the study sample aged between
(20-21 years), females are the most inhabitants of the city of Ba
The purpose of this study is to show the constants and variables geography in Russian
policy in light of variables geostrategic witnessed by the world, especially after the collapse
of the Soviet Union and the disintegration to fifteen Republic became the Russian Federation
and the heir to the Soviet Union, Geography particularly important because the impact of its
data in policy making less change ofothers, and explain the political choices cannot achieve
security through its relationship constants geographical (natural or human) paint forms of
economic activity and determine the points they national security. issue is the geographical
this or that country is determined by its policy also specifies the way in which
ABSTRACT
The research aims to study the effect of the commodity dumping phenomenon that Iraq suffered after 2003 on the consumption pattern of individuals, towards the acquisition of non-essential goods (luxury). To achieve our goal we relied on the questionnaire as a main tool for obtaining information related to the research, and it was distributed on a random sample of consumers in the city of Baghdad with 250 questionnaires. The answers of the research sample were analyzed using the statistical program (SPSS). The percentage weights and the factorial analysis method were used also to arrange the variables that affected on changing consumption patterns. The research reached a set of conclusions:
... Show MoreThe audit profession today gets an increasing interest by the financial , economic and legal contemporary societies , because of the importance of the technical & neutral auditor’s opinion to the financial reports beneficiaries in order to enable them making their investment decisions , but some of them whom suffered damage or loss when they made that decisions according to the mentioned financial statements which consolidated with auditor’s report , exposed the function to a responsibility and credibility crisis in addition to missing the trust especially at the latest years. They always ask why or what is the reason that cause the auditor didn’t giving us any warning signs about the economic mater for that companies.
Challenges facing the transition of traditional cities to smart: Studying the challenges faced by the transition of a traditional area such as Al-Kadhimiya city center to the smart style
The author addresses the issue of the linguoculturological component in the process of teaching Russian to Arabic students, focuses on the peculiarities of the national character of students. The author also refers to the long-standing ties of Russian and Arab cultures, thus emphasizing the relevance of this aspect for the current state and situation of the Russian language in Arab countries.
Автор статьи обращается к вопросу лингвокультурологической составляющей в процессе преподавания русского языка арабским студентам, останавливается на особенностях национального хара
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