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
Of non-Muslim minorities In the Muslim community
The world of Contemplations is a controversial concept among scholars, writers, thinkers and the public. The theory of the dialogue of souls indicates that souls communicate and think with each other despite the distances. Islamic studies have researched this concept, and this research paper aims to explain the concept of the world of Contemplations and what is the dialogue between God Almighty and the souls that God brought forth from the back of Adam and took from them the covenant and pledge to unify Him, and its effects on human life in this world. The researcher found that scholars and writers differ in proving the existence of the world of Contemplations despite the existence of examples of it in verses of the Holy Quran, and that the
... Show MoreAn analytical form of the ground state charge density distributions
for the low mass fp shell nuclei ( 40 A 56 ) is derived from a
simple method based on the use of the single particle wave functions
of the harmonic oscillator potential and the occupation numbers of
the states, which are determined from the comparison between theory
and experiment.
For investigating the inelastic longitudinal electron scattering form
factors, an expression for the transition charge density is studied
where the deformation in nuclear collective modes is taken into
consideration besides the shell model space transition density. The
core polarization transition density is evaluated by adopting the
shape of Tassie mod
Magic is an attempt to affect people or events either by cheating and charlatanry means or by expecting devil powers in order to bring advantage or to avoid a harm or to bring harm to others or to for see the future and divition .
Magic is either real by the devil like writing majic works to prevent the marriage of someone and to depart the husband and his wife , causing someone to be distressed the physical and nervous diseases and stopping the stories and the project; majic can be artificial by being intellect and legerdemain and different types of triks and to cancel the magic by using magic or by protecting the self by using Talismans as well as presenting or offering sacrificers to the masters and th
... Show MoreEminent figures in Quranic studies in the fourth century of the Hegira, in his
copacity as the founder of the essentials of the indicative approach in interpretation
which is based on the consideration of research principles in interpretation science.
Al-Qushayri participated in clarifying the promotions of this approach in his
works which represent this approach. The mast distinguished of these works is
Tafseer Lataef Al-Isharat. The researcher examined the characteristics of this
approach and its effect on the interpretative movement in Al-Qushayri age an come to
employ them as a practical example for the indicative approach in studying the
interpretation mebods in Islamic sciences.
Objectives: To evaluate the families’ attitudes toward environment pollution, and determine the relationship
between families’ attitudes towards environment pollution and their demographic characteristics of age,
education, type of family, and socioeconomic status.
Methodology: A descriptive design is carried throughout the present study to evaluate families’ attitudes toward
environment pollution for the period of October 5th2013 to May 7th2014. A non-probability "purposive" sample of
(110) families’ is selected. The sample is comprised of two groups; (75) urban families’ and (35) rural ones. An
evaluation tool is designed and constructed for the purpose of the study. It is consisted of (4) main parts;
dem
Receipt date:10/8/2019 acceptance date:18/12/2019 Publication date:31/12/2021
This work is licensed under a Creative Commons Attribution 4.0 International License.
This research is concerned with the concept of identity in general "Overall definition" and is not exposed to the classifications of identity or concepts that deal with their types and classifications, only the concept in terms of the initial picture as well as the views of thinkers on the proof of
... Show MoreThis article discusses the most beloved and creative dialect of the Arabs - the Iraqi dialect, despite its complexity, but it has a lot of beautiful foreign vocabulary. We followed a descriptive and historical approach, also tracked phonetic changes in this dialect, and then gave phonological explanations for these phenomena, trying to connect most of the phenomena with their historical roots in the standard Arabic "al-Fussha" and in ancient Arabic dialects. Most modern linguists have realized the need to study these dialects, since many of the modern dialect characteristics are only extensions of some ancient Arabic dialects, and do not refer them to the classical language. The study of modern Arabic dialects may be faced with a nu
... Show MoreThe aim of the research is to clarify the role of service quality through its dimensions represented by (tangibility, reliability, safety, response, empathy) in tax compliance with taxpayers, i.e. performance of the duties and obligations of the taxpayer through its dimensions (registration, accounting, payment of the amount of tax), and to know For this role, a sample was taken from the taxpayers of the branches of the General Authority for Taxes spread in the governorate of Baghdad and its affiliated districts, which amount to (15) tax branches, as (215) questionnaires were distributed to know the impressions and reactions of the taxpayers regarding the level of service quality through the aforementioned dimensions. Using the statistic
... Show MoreMedia theories and studies have provided many diligences on the concept of social media and the circle of influence, including the theory of social marketing which deals with how to promote ideas espoused by the elite in a society to become a recognized social value. The emergence of social networks provided a revolutionary breakthrough, taking the media to unprecedented horizons; and giving its users great opportunities to influence and move across borders without restrictions and censorship, except in a relatively limited manner.
So, the emergence of social media has created channels of live broadcasting from its audience in a method of development that changes the essence of the known communication theories; a
... Show More