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
This study aimed to clarify the legal provisions concerning the senses and their role in financial transactions, in the light of the definition of all the vocabulary presented by this study (senses - the definition of senses apparent: they are hearing - sight - smell - taste - touch) in the first section. The study deals with the second topic of the reference and writing denominator phrase and includes two requirements, the first requirement: the establishment of the denominator of the phrase, which has two branches: Section I: signal Akhras. Section II: Signal of the Spokesman.
The second requirement is that writing takes the place of the phrase in financial transactions. The owners argue that the sale of the blind is correct a
Introduction: Biliary atresia (BA) is a disease characterized by a biliary obstruction of unknown origin. Viral agents have been proposed in the aetiology of BA such as cytomegalovirus (CMV). This virus also considered as a one of agents that can infect the liver and cause hepatitis. The aim of this study was to determine the role of CMV in children with both chronic hepatitis (negative for hepatitis B and C) and have biliary atresia in the same time.Material and Methods: A retrospective study done on 13 liver tissue paraffin blocks of children with chronic hepatitis (negative for hepatitis B and C) and biliary atresia (extra and intra). The diagnosis was based on the presence of HCMV protein (pp65) by using immunohistochemistry.Res
... Show MoreElectromechanical actuators are used in a wide variety of aerospace applications such as missiles, aircrafts and spy-fly etc. In this work a linear and nonlinear fin actuator mathematical model has been developed and its response is investigated by developing an algorithm for the system using MATLAB. The algorithm used to the linear model is the state space algorithm while the algorithm used to the nonlinear model is the discrete algorithm. The huge moment constant is varied from (-3000 to 3000) and the damping ratio is varied from (0.4 to 0.8).
The comparison between linear and nonlinear fin actuator response results shows that for linear model, the maximum overshoot is about 10%,
... Show MoreIn the name of Allah, the Beneficent, the Merciful.
Praise be to Allah, Lord of the Worlds and peace and blessings on the honest and trustworthy (Muhammad) and his family and his divine good companions.
The Islamic clothing is one of the requirements of the common and original innateness to humans; the innateness that is created by God to all people, Allah says, (So set thou thy face steadily and truly to the Faith: [establish] Allah's handiwork according to the pattern on which He has made mankind: no change [let there be] in the work [wrought] by Allah: that is the standard Religion: but most among mankind understand not) (1). Islam as a natural religion has ordered the Muslims to wear decently, Allah says, ( O Children of Adam!
The laws of the three religions tend to extend the rules and foundations of coexistence, and this is achieved in achieving the values and principles that these laws have nourished in all societies.
Our research deals with a major problem that has broken out in our societies, namely (disturbing the balance of values and behavioral standard between people), and perhaps one of the greatest causes of the problem is to move away from the correct divine discourse and sound approach, as well as corruption of common sense and the violation of its rules and found principles in the hearts of people.
Phraseological or phraseological turn - unchanged in structure and composition, integral in meaning and lexically indivisible phrase or sentence, performing the function of a separate dictionary unit - lexemes. Idioms are found in any language of the world. But such a number of winged phrases, as in Russian, is nowhere else. Idioms play a role in displaying the national-cultural characteristics of any language. They very clearly and accurately reflect the characteristics of the perception of the world, the characteristic features of the material and spiritual life of native speakers, his mentality.
The most honorable of science was what was related to the book of God, the Almighty, the Constitution of this nation and the way of its guidance and method of advancement there is no life except for him and safety only by its application and it is no secret to the competent studies of the importance of the subjective studies in the Koranic studies to address issues of great importance enlighten the path of the nation and revive From here comes the importance of the topic covered by the research, which is "Intent in the Holy Quran meanings and semantics", and this topic features features that made it worthy of writing, including the importance of clarifying theories of Qur'anic character of a systematic nature, such as the theory of inten
... Show MoreAdopting a policy of attracting investments in all countries, whether developing or developed prevailed, especially after the global crisis, and this trend is imposed by considerations of political and development (urban, economic, and social) can be formulated as a rational policy to solve many problems related to patterns of urban growth, economic, social, and including the problem of housing. As the reality of the housing sector in Iraq will require the allocation of substantial resources to promote it by the research problem is the lack of financial resources and the inability of investments to meet the various requirements including the requirements of economic sectors, particularly in the field of housing, infrastructure an
... Show MoreA Spectroscopic study has been focused in this article to study one of the main types of active galaxies which are quasars, and to be more precise this research focuses on studying the correlation between the main engine of Quasi-Stellar Objects (QSO), the central black hole mass (SMBH) and other physical properties (e.g. the star formation rate (SFR)). Twelve objects have been randomly selected for “The Half Million Quasars (HMQ) Catalogue” published in 2015 and the data collected from Salon Digital Sky survey (SDSS) Dr. 16. The redshift range of these galaxies were between (0.05 – 0.17). The results show a clear linear proportionality between the SMBH and the SFR, as well as direct proportional between the luminosit
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