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
Context has a significant impact on the interpretation of Qur'anic and literary texts, especially in ancient Arabic poetry since that language is no longer considered as a contemporary understandable language. Hence this research is entitled: (the impact of context on the morphological semantics in the Diwan of Abi Al-Aswad Al-Dau’ali) and the morphological meanings indicated by the morphological formula which lack the combination of other contextual clues. The researcher depended on the analytical approach to show the impact of pairing occurring between the contextual elements on determining the morphological meaning.
The most important findings reached at:
1- Context has a great impact in dispelling the possibilities arising fr
This dissertation explores the role of Iraqi E-press in crystallizing the orientations or directions of the public towards the local political issues like (demonstrations, parliamentarian elections, provincial elections, the public budget and its consequences, Iraq’s relations with neighboring countries, Iraqi HOR and its sessions, and the relation of the federal government with KRG). The dissertation’s main problem revolves around a central inquiry: what is the role of the Iraqi E-press in crystalizing the direction of the Iraqi public towards the local political issues?
The dissertation included a number of assumptions; the first assumes the relation of demographic variants (gender, age, social status, education, working status
The phenomenon of terrorism is one of the most serious challenges facing the world at present. So this concept has occupied a great deal of interest of researchers and scholars in the relevant disciplines. There is no doubt that the study of the concept of terrorism requires a study of its various aspects. However, this study will be limited to knowing the role of television channels in providing the public with information about terrorist events, the extent to which young people rely on these channels to shape their attitudes towards terrorism issues. This study also seeks the relationship between satellite television channels and terrorism based on the relevant media li
... Show MoreThis research presents the results of the tests of the physical, chemical and biological treatments performed on the industrial effluent of Al-Rashid Factory for vegetable oils during January to July, 2010. Some environmental parameters such as temperature, electrical conductivity(ec), Biological oxygen demand(bod), chemical oxygen demand(cod), total suspended solids(tss), dissolved oxygen(o2) and total dissolved solids(tdc) have been investigated. The study shows that the industrial effluent contains a percent of organic pollution and in different values, and that it is responsible for the (bod), which records (5.15-67)ppm, while the (cod) ranges between (25-170.5)ppm, the (ec) values range between (
... Show MorePsychological aspects are a major influence and motivation factor in many cinematic and television works such as television series. There are many films that dealt with psychological issues through the personality affected by psychological projections and complexes that lead towards abnormal behavior and actions in most cases, so the researchers chose the title and the research problem was raised through the following question: What is the mechanism that fulfills a psychological role in the narrative film? The objectives of the research were to reveal the mechanism used to instill psychological contents in the feature film? As for the limits of the research, it was an intentional sample, and the researchers adopted the descriptive anal
... Show MoreThis study was designed to evaluate the effects of cellulose membranes produced by Acetobacter xylinum bacteria, after enrichment of the growth media with Alzahdy palm dates syrup to enhance cellulose production for reducing the contamination of locally-produced white cheese with pathogenic bacteria. Cellulose was vitally activated by incubation with both probiotics Lactobacillus acidophilus and Lactobacillus plantarum and the effectiveness of the produced cellulose membranes was measured by studying six characteristics: elongation, tensile strength, membrane rupture, permeability to oxygen, permeability to water vapor, and thickness (mm). The produced membranes showed remarkable functionality and characteristi
... Show MoreThe current research aims to identify the level of effective leadership practices dimensions (clear vision and specific goals, good planning and effective influence, and monitoring well as evaluation) among the senior leaders in the Office of the Iraqi Interior Ministry., The researchers adopted the descriptive analytical approach to collect data through the questionnaire as a main tool, developed by relying on international standards after making adjustments to its items consisting of (25) items that included the research variable, the questionnaire was distributed to all the research community (comprehensive inventory) by 120 forms from emplo
... Show MoreThe presence of deposition in the river decreases the river flow capability's efficiency due to the absence of maintenance along the river. In This research, a new formula to evaluate the sediment capacity in the upstream part of Al-Gharraf River will be developed. The current study reach lies in Wasit province with a distance equal to 58 km. The selected reach of the river was divided into thirteen stations. At each station, the suspended load and the bedload were collected from the river during a sampling period extended from February 2019 till July 2019. The samples were examined in the laboratory with a different set of sample tests. The formula was developed using data of ten stations, and the other three s
... Show MoreThe research aims to introduce international valuation standards and to identify the relationship between international valuation standards and international accounting and financial reporting standards in enhancing the quality of financial reporting (appropriate accounting information) through the use of statistical models for the purpose of measuring the property of appropriateness of accounting information through the use of statistical models for the purpose of proving the hypothesis that The research referred to it, and accordingly, the Francis and Kothari models were used to measure the appropriateness of accounting information (the quality of the information). The conclusions reached by the two researchers is that the sett
... Show MoreOne of the major environmental problems is the pollution of water and soilsby toxic
heavy metals.The aim of current study was estimatation the ability of Eclipta alba
plant for the removal of (Pb) from the polluted water by phytoremedation technique
and study the effect of a number of parameters(Pb concentration, contact time and
pHvalues). The plant showed higher removal efficiency (99.2%) after 7 days of
treatment at 50ppm.The best removal efficiency of Pb 98.95% at 100ppm was
occurred at pH7. The root ability to accumulate Pb was more than the shoot ability,
after 7 days treatment of water and pH=7, they were 2852.5 mg/kg, 2497.5 mg/kg
and 502.5 mg/kg in roots, stems and leaves respectively. These results showe