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 relationship between infertility and Helicobacter pylori infection was investigated; samples from thirty-five infertile patients (aged 20-49 years) were collected from Kamal Al-Samaraei hospital , Baghdad, Iraq during the period from the first of February until April 2018. These patients were compared with 10 apparently fertile individuals who served as a control. The study was carried out to detect the DNA of H.pylori in both serum and seminal fluid of male infertile patients and for the control group by Real-Time Polymerase Chain Reaction (RT-PCR) technique. The results revealed that there was a significant difference (P<0.01) in the detection of DNA of H.pylori between pa
... Show MoreThe lithostratigraphic and biostratigraphic studies of the Shiranish Formation in the Diana area, Erbil, Northern Iraq, were conducted to distinguish the main lithostratigraphic units, depositional environment and the formation age. The Shiranish Formation in the study area can be divided into three rock units. The lower and upper units consist of marly limestone, marl and limestone deposited in the outer shelf environment, while the middle unit is dominated by laminated calcareous shale and marl deposited in the upper bathyal environment. Calcareous nannofossils showed the presence of about 20 species/genera in the studied Shiranish Formation. Three biozones are identified; Misceomarginatus pleniporus biozone;
... Show MoreHuman cytomegalovirus (CMV) infection is associated with higher risk of cardiovascular diseases in immunocompromised organ transplant patients; it has been linked with the elevated arterial blood pressure. This study aimed to find a relationship between CMV antibody titers and blood pressure elevation by using the enzyme-linked immunosorbent assay (ELISA) to measure CMV IgG levels in the serum of 60 patients with high blood pressure, in comparison to 30 healthy persons with normal blood pressure as a control. All patients and control were 25-50 years old. The results showed that CMV antibody titers were higher in those who undergo blood pressure elevation. This finding supports the hypothesis that; the common CMV infection may leads to i
... Show MoreGround penetrating radar (GPR) is one of the geophysical methods that utilize electromagnetic waves in the detection of subjects below the surface to record relative position and shape of archaeological features in 2D and 3D. GPR method was applied in detecting buried archaeological structure in study area in a location within the University of Baghdad. GPR with 3D interpretation managed to locate buried objects at the depth of (1m) . GPR Survey has been carried (12) vertical lines and (5) horizontal lines using frequency antenna (500) MHZ .
The role of teacher of kindergarten plays an important role in the educational institution for kindergarten role in the educational institution for kindergarten and the failure of its role in the development of the mental processes of children kindergarten means failing in this institution .and hence the importance and effectiveness of the role of the student applied section kindergarten application period it is there fore necessary to be aware of the importance of learning. in preschool and good professional setting and enjoy a significant level of psychological and social systems and mental qualities and study is the urgent need to find generations hare systematic thinker's mind so stay away from memorization and trad
... Show MoreWith the growing number of patient’s being diagnosed with Parkinson’s disease and Multiple Sclerosis each year it is becoming ever more important to find the cause for these neurological disorders. The present study attempts to shed light on one of the factors that may play a role as a causative agent in these neurological diseases by finding a correlation between the Herpes simplex virus type 1 and 2 in patients with Parkinson’s disease and multiple sclerosis by detecting the virus in these patients using immunological techniques. Sixty patients with neurological diseases (40 patients with Multiple sclerosis and 20 patients with Parkinson’s disease) who’s ages ranged from (17-76) years have been investigated. Samples wer
... Show MoreThe research aims to verifying the tax exemptions granted in accordance with the Iraqi tax legislations, showing their suitability for basic tax rules, and identifying their role to reduce the tax evasion phenomenon and the negative effects resulting therefrom, which arerepresented by a decrease in the proceeds of tax revenue and therefore leadings to a reduction of public revenues of the state. Also, the research tries to identify the ways to reduce cases of tax evasion due to their reflection positively on the public budgetof the state. The data of the research was collected through two models of questionnaires distributed to a sample of taxpayers from some professions and a sample of the tax administration staff. The research has reac
... Show MoreThe research seeks to know the social loafing of kindergarten teachers and their relation to personality traits. In order to achieve the research objectives, the researcher constructed the social loafing scale, which she applied to kindergarten teachers. The scale consists of (22) paragraphs. It has good credibility and stability. The coefficient of stability (85.0) was the retest method and (81.0) Alpha Cronbach equation. In addition, the researcher has adopted (Raymond Cattel) personality traits scale, which has been adapted to the Arab environment (Abdel Rahman and Abu Abada,1998), The scale consists of (39) paragraphs, and enjoys the apparent honesty. The measure of social loafing and the measure of personality traits was applied to
... Show MoreZora Neale Hurston's (1891-1960) is an outstanding African American
novelist, playwright, autobiographer and essayists. Her work is considered as an
important part of the African American and Harlem Literature.**** It represents a
milestone and a keystone in the African-American literary canon because it breaks
from the style of the previous works and makes a beginning of a new style. Hurston
shifts from the black works that stick to racial themes and sheds the light on new
aspects and themes in blacks' life especially on feminist themes. Her exceptional fame
culminates in her novel Their Eyes Were Watching God (1937). 1
Their Eyes Were Watching God examines with a great deal of artistry
the struggle of a black
The paper aims to build a model that supports organizational sustainability by analyzing the correlations and revealing the impact between the two main variables (entrepreneurial leadership) with its dimensions of proactive outlook, risk, and creativity (Van Zyl & Mathur-Helm, 2007), and (organizational sustainability) with its economic, environmental, and societal dimensions (Hansmann et al., 2012). As well as identifying the level of awareness and informing managers in the General Company for the Automotive and Equipment Industry, of the theoretical implications and performance, and its vital importance to society and the surrounding ecological environment, and drawing attention to that and improving performance, and indicatin
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