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 metric dimension and dominating set are the concept of graph theory that can be developed in terms of the concept and its application in graph operations. One of some concepts in graph theory that combine these two concepts is resolving dominating number. In this paper, the definition of resolving dominating number is presented again as the term dominant metric dimension. The aims of this paper are to find the dominant metric dimension of some special graphs and corona product graphs of the connected graphs and , for some special graphs . The dominant metric dimension of is denoted by and the dominant metric dimension of corona product graph G and H is denoted by .
Flourished economic life in the city Asturabaz was the main engine of social and political conditions in the city; In order to provide factors to help the successful cultivation of the city as well as the prosperity of the industry as famous city Asturabaz since ancient times textile industry and won wide acclaim as well as leather and wood industries and the pharmaceutical industry industry in addition to the livestock that have contributed to increased imports of the city, and this led to the prosperity of the evolution of physical movement and intellectual life.
The purpose of this research is to explain the effect of the dropping of three zeroes from Iraqi dinar on the basic role of the dinar and derivative and dynamic in transaction of Iraqi economic. the importance of this research comes from the effect of this operation on the evaluation of the exchange between the individuals of Iraqi society and the other between the Iraqi individuals and the foreign whom use the Iraqi dinar as a tool for exchange also the effect of the operation on the reserves of the Iraqi dinar the results of this research are as the following:-
1-the operation of dropping of zeroes must be associated with increase of the sharing of economic sectors wi
... Show MoreAmong the findings of the research are:
1. This type of ambiguity is old in use and was adopted by the Arab poets as a
reaction against hyperbole and as a tendency towards compression of expression that
results in an. amusing suspension through the use of irony. The Andalusian poets
tended to employ this form because it involves interaction and interrogation,
2. Furthermore, it indicates the poet’s insight, talent and skill and it is, therefore,
regarded as a form. Of verse discourse that appeals to the reader, in contrast to
hyperbole.
3. Its presence in Andalusian poetry is evident n eulogy and descriptive poetry and it
held a place of prominence as a poetic form in achieving these purposes.
4. Through i
This research is concerned with the study of (the aesthetic of constructive relations in linear composition) with what distinguished Arabic calligraphy through the style and artistic method in its construction, and the specifications it carries that enabled it to pay attention to building formations to achieve in its total linear ranges aesthetic values and relationships. Through the research, the models and the exploratory study that he obtained, the researcher was able to raise the research problem in the first chapter according to the following question: What is the aesthetic of constructive relations in linear formation?
The importance of the research in achieving the aesthetics of the formations, which is a wide field according t
The arts global digital marketing activity is one of the most prominent manifestations of the contemporary transformation in the circulation of cultural products, and that this event has become a new knowledge event that deserves to be a framework for the problem of our current research, while this phenomenon is growing and developing to compete with the traditional marketing of art through galleries, exhibitions, auctions and museums. It is still the preserve of certain civilized and knowledge environments, and from here this research comes with the aim of shedding light on the mechanisms of digitizing the contemporary art market that have been linked to the two variables of the growing idea of indirect marketing through the intermediar
... Show MoreThe progress of network and multimedia technologies has been phenomenal during the previous two decades. Unauthorized users will be able to copy, retransmit, modify reproduction, and upload the contents more easily as a result of this innovation. Malicious attackers are quite concerned about the development and widespread use of digital video. Digital watermarking technology gives solutions to the aforementioned problems. Watermarking methods can alleviate these issues by embedding a secret watermark in the original host data, allowing the genuine user or file owner to identify any manipulation. In this study, lots of papers have been analyzed and studied carefully, in the period 2011–2022. The historical basis of the subject shou
... Show Moreفي بداية الستينيات ظهرت شبكة الإنترنت لاستعمالها في أغراض غير تجارية ، ثم تطورت بشكل مذهل خلال السنوات الأخيرة، فبعد أن كانت مجرد شبكة صغيرة أصبحت الآن تضم ملايين المستخدمين حول العالم ، وتحولت من مجرد شبكة بحث أكاديمي إلى بيئة متكاملة للاستثمار والعمل والإنتاج والإعلام والحصول على المعلومات .
وفي بداية تأسيس الشبكة لم يكن ثمة اهتمام بمسائل الأمن بقدر ما كان الاهتمام ببنائها وتوسيع نش
... Show More