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
Superconducting compound Bi2Sr2-xYxCa2Cu3O10+δ were Synthesized by method of solid state reaction, at 1033 K for 160 hours temperature of the sintering at normal atmospheric pressure where substitutions Yttrium oxide with Strontium. When Y2O3 concentration (0.0, 0.1, 0.2, 0.3, 0.4 and 0.5). All specimens of Bi2Sr2Ca2Cu3O10+δ superconducting compounds were examined. The resistivity of electrical was checked by the four point probe technique, It was found th
Аннотация
В данном исследовании рассматривается символичность (( Джикора )) в лирике иракского поэта ас-Саййаба и перевода лирики o деревне и городе с арабского на русский. Русский читатель пока не имеет возможности познакомиться с стихотворениями Бадра Шакера.
Abstract
The paper aims at making the Russian reader acquainted with the Iraqi Poet Badr Shakir as-Sayyab, and showing the effect of the village an
... Show MoreThis study is about the role of the Internet in spreading rumors, especially through social networking sites "Facebook" model as the effectiveness of social networks lies in the speed of transmission of events; these two characteristics are important to the public, making the Internet a strong contender for television and its relationship with the public. That's why we find that the Internet today has become a fertile environment for the growth and spread of rumors. The more limited the platforms and places of publication, the greater the responsibility in the search for the original source in spreading this or that rumor, as the Internet is considered an easy means in the production, spreading and re-spreading of
... Show MoreThe transfer of chemical pollutants from bottled water into water due to heat, sunlight and poor storage is one of the most serious threats to human health around the world, the objective of this study was to estimate the pH value and the transport of heavy metals from plastic bottles to water, for this purpose, 30 bottles of water for 10 local brands were collected and divided into three groups, the first was left at room temperature 25°C, The second was placed in a heat oven at 25°C and the third in another oven at 50°C for two weeks. The results showed significant differences at (P<0.05) between water samples, pH value and concentrations of heavy metals (Sb, Pb, Ni, Cu, Cr, Cd and Fe) we
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The purpose of the subject of Total quality management is an important management style in organizations including hospitals through the achievement of this method of success in the administration to include this approach describes the provision of health services and make adjustment and suggestions that help to improve the quality of health care on an ongoing basis . Hence the idea of the study to shed light on the reality of the application of principles of Total quality management and to highlight the quality of health services provided in al-kindi hospital / Baghdad health department rusafa and the staff at the hospital were included to find out the appl
... Show MoreResults showed that the optimum conditions for production of inulunase from isolate Kluyveromyces marxianus AY2 by submerged culture could be achieved by using inulin as carbon source at a concentration of 2% with mixture of yeast extract and ammonium sulphate in a ratio of 1:1 in a concentration of 1% at initial pH 5.5 after incubation for 42 hours at 30ºC.
The Financial authority is considered as one of the most of benefited parts from financial statements which depends on it in process of accounting in taxes as basis to determine The Tax Base , but no confidence from financial authority part in objectivity of income financial information in them for many of limited companies led to no dependence on them to specify taxation contain & dependence on yearly regulations that issued them. To enhance the confidence of financial authority to these lists must meet its requirements, because the menus Fulfill the requirements of the financial authority increases the confidence in these statements and therefore reliable in determining the tax base. So this research aims to speci
... Show MoreThe problem of rapid population growth is one of the main problems effecting countries of the world the reason for this the growth in different environment areas of life commercial, industrial, social, food and educational. Therefore, this study was conducted on the amount of potable water consumed using two models of the two satellite and aerial images of the Kadhimiya District-block 427 and Al-Shu,laa district-block 450 in Baghdad city for available years in the Secretariat of Baghdad (2005, 2011,2013,2015). Through the characteristics of geographic information systems, which revealed the spatial patterns of urban creep by determining the role and buildings to be created, which appear in the picture for the
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