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
To determine the relationship between celiac disease and reproductive complication, twenty five women with clinically definite unexplained infertility aged (22-35) have been investigated and compared to fifteen apparently healthy women. All the studied groups were subjected to measurement of anti-tissue transglutaminase antibodies IgA and IgG by ELISA technique and anti-endomysial antibodies IgA and IgG by IFAT technique .There was a highly significant elevation (P< 0.01) in the concentration of anti- tTG IgA Abs compared to control group, Also, there was significant elevation (P< 0.05) in the concentration of anti- tTG IgG Abs compared to control group .The results illustrated that the prevalence of anti-EMA IgA and IgG Abs were (
... 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 MoreThis 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
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.
A 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
... Show MoreThe study includes the relationship between the ecologia and Abbaside's community in the middle ages, and the role of Baghdad capital city to increasing the sensibility of the people to the outwardly peripheral.
The study explains the efforts between the people and Abbaside's government to cure the knowledge of ecologia, to prevent the separation of diseases and pollutions of the community.
Keywords: Ecologia, Abbasid's, diseases, pollutions.
T.V photo in modern shows has emerged with special characteristics and signs that have developed in cope with the development of medium and technique. This leads to adding a variety of aesthetic dimensions which are capable of attracting audience because of its communicative elements that have an important role in increasing of T.V show Watching. As a result, the research is limited to methodological Framework as the problem. The problem of the research deals with emerging the aesthetic dimensions of T.V photo. The major question is (what are the aesthetic and communicative dimension of T.V Photo?). The research aims at finding out the aesthetic dimensions of T.V photo in modern artworks. The significance of the research on the presented
... Show MoreThe primary focus of the study factor reverse polymerization styrene polymer kinetics and distribution weight Aljaia in Blma Aldhur free reverse The study was conducted wi Mamahakah and using the Monte Carlo method