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 effectiveness inhibitory to extract alcohol for the leaf and flower to plant sage Salvia pratensis each of Staphylococcus aureus, streptococcus epidermidis, Salmonella typhi, Pseudomonas aeroginosa, Escherichia coli, Aspergillus niger and Candida albicans whom had any inhibition to aqueous extracts of the parts itself species bacterial and fungal. The study also demonstrated that the extract of plant containing compounds chemical such as tannins, Alkaloids, Flavonoieds, and saponins, which owns effectiveness of medical. The MIC, MBC and inhibition zones for crud extract were determinated for microbial agents.
Targeted this study underlined the importance of the adoption of international accounting standards and their impact on the process of tax for settlements to achieve taxation justice the application on a sample of foreign banks investing in the local environment in order to achieve many of the objectives:
- Definition of the concept of justice for settlements taxation.
- To identify the impact of adopting international accounting standards in achieving the justice for settlements taxation.
- To determine the impact of the adoption of international accounting standards in attracting foreign investment.
They are summed up the problem of the study in the light of the nature of the problem and que
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The integer simulation and development finite impulse response (FIR) filters taking into account the possibilities of their realization on digital integer platforms are considered. The problem statement and solution of multifunctional synthesis of digital FIR filters such a problem on the basis of the numerical methods of integer nonlinear mathematical programming are given. As an several examples, the problem solution of synthesis FIR-filters with short coefficient word length has been given. The analysis of their characteristics is resulted. The paper discusses issues of modeling and synthesis of digital FIR filters with provision for the possibilities of their implementation on digital platforms with integer computation arithme
... Show MoreThe present study is a linguistic study of comment clauses in the American Series „Friends‟ .Comment clauses refer to those clauses which comment on the content of the main clause or the attitude of the speaker towards the way of speaking .The problem of this study is to answer the following questions ; what types of comment clauses can be used in the face- to –face conversations , for what functions these comment clauses could be used , and how these comment clauses are used by the participants of these conversations . This study is a qualitative one . The study aims to investigate the types of comment clauses used in the American Series “Friends‟. The study also aims to investigate the pragmatic functions of these comment clause
... Show MoreGypseous soil is considered as a problematic soil for embankment construction, however, implementation of emulsified asphalt as a stabilization agent could be a proper solution for enhancing its properties as a subgrade soil. In this work, the sustainability of asphalt stabilized soil has been assessed in terms of its resistance to cyclic (freezing-thawing) and (heating-cooling) processes. Specimens have been prepared at optimum fluid content (moisture and emulsion) and tested under direct shear stresses while subjected to 30 cycles of (freezing-thawing) and (heating-cooling). Both of dry and soaked testing conditions have been implemented. Data have been observed after each 10 cycles, and compared with that of reference mix. It was conclud
... Show MoreInclination Of The Lumbosacral Angle In Normal Individuals: An Mri Study,GJRA - Global Journal For Research Analysis(GJRA) GJRA is a double reviewed monthly print journal that accepts research works. 36572+ Manuscript submission, 9855+ Research Paper Published, 100+ Articles from over 100 Countries
Abstract:
In its theoretical farm, the research adobet the subject of human resource management strategies and the cognitive skills. It comes as result of the rapid development which considers it human resource. as main axis in organization , the research in includes ,connective analysis , between human resource management strategies and cognitive skills which is considers one of the new concept that should be studied widly so that the organization can be able recognize it as concept and type and its importance for people in the organization.The study method was descriptive and analytics , it identified collation of hypothesis which were by statist too
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