Preferred Language
Articles
/
nRcsno0BVTCNdQwCxBbn
The effect of composite bonding spot size and location on the performance of poly-ether-ether-ketone (PEEK) retainer wires
...Show More Authors

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

Scopus Crossref
Publication Date
Mon Jun 01 2015
Journal Name
Int. J. Adv. Appl. Math. Andmech.
The effect of external source of disease on the epidemic model
...Show More Authors

Publication Date
Sun Mar 30 2008
Journal Name
Iraqi Journal Of Chemical And Petroleum Engineering
Effect of Promoters on the Catalytic Activity of the Iosmerization Catalyst
...Show More Authors

The crystalline zeolite, namely faujasite type Y with SiO2/Al2O3 mole ratio of 5 was used as raw material for preparation of isomerization catalysts. A 0.5 wt % Pt/HY-zeolite catalyst was prepared by impregnation of the decationized HY-zeolite with chloroplatinic acid. The dectionized HY-zeolite was treated with HCl, HNO3 and HI promoters using different normalities and with different concentrations of Sn, Ni and Ti promoters by impregnation method to obtain acidic and metallic promoters' catalysts, respectively. A 0.5 wt% of Pt was added to above catalysts using impregnation method. Isomerization of n-hexane was carried out at different prepared catalysts. The isomerization temperature varied from 250–325° C over weight hourly space

... Show More
View Publication Preview PDF
Publication Date
Sat Oct 03 2026
Journal Name
Baghdad Science Journal
Study the effect of position on the time of astronomical twilight
...Show More Authors

Twilight is that light appear on the horizon before sunrise and after sunset, Astronomically it is known that sunrise and sunset are effected by high above sea level, but the effect of high above sea level on the time of astronomical twilight still not decided and controversy among astronomers, in This research we studies the effect of high above sea level on the time of astronomical twilight, through adding the equation correct high above sea level to equation computation of twilight and then calculate of changing in the time of twilight for different highest (0-10000) meters above sea level , and the ratio of increase for time with high between (15.45-20.5) minutes. It was found that there was an increase in the time of the twilight along

... Show More
View Publication
Publication Date
Wed Dec 14 2022
Journal Name
Nasaq Journal
The Effect of Co-text on the Comprehensibility of World Englishes
...Show More Authors

MR Younus, Nasaq Journal, 2022

View Publication
Publication Date
Thu Jan 04 2018
Journal Name
International Journal Of Science And Research (ijsr)
Effect of Doping on Properties of the Hall Effect and Electrical Conductivity for AgInTe2 Thin Films
...Show More Authors

The effect of different doping ratio (0.3, 0.5, and 0.7) with thickness in the range 300nmand annealed at different temp.(Ta=RT, 473, 573, 673) K on the electrical conductivity and hall effect measurements of AgInTe2thin film have and been investigated AgAlxIn(1-x) Te2 (AAIT) at RT, using thermal evaporation technique all the films were prepared on glass substrates from the alloy of the compound. Electrical conductivity (σ), the activation energies (Ea1, Ea2), Hall mobility and the carrier concentration are investigated as a function of doping. All films consist of two types of transport mechanisms for free carriers. The activation energy (Ea) decreased whereas electrical conductivity increases with increased doping. Results of Hall Effect

... Show More
Preview PDF
Publication Date
Sat Dec 28 2024
Journal Name
Journal Of Physical Education
The Effect of Competitive Exercises Using Physical Performance Tracking Technology (GPS Playertek Plus and Polar H9) on Developing Speed in Iraqi Premier League Football Players
...Show More Authors

Football is one of the most important team sports, practiced by men and women, young and old, across various age groups. The physical development in this sport can be attributed to athletic training and modern technology, which have contributed significantly to advancing the sports field in general. Outstanding performance in football requires precise and quick physical abilities, closely tied to the competitive nature of the game. Speed is fundamental in football, making the use of technologies such as GPS tracking devices and heart rate monitors essential in both training and matches. This study aims to develop the speed of Al-Talaba SC players in Baghdad using a scientifically-based approach to improve their performance. The impo

... Show More
View Publication
Crossref
Publication Date
Thu Jun 01 2023
Journal Name
Baghdad Science Journal
Design and study the effect of inner bore diameter on the magnetic and optical properties of the unipolar lens
...Show More Authors

    Many designs have been suggested for unipolar magnetic lenses based on changing the width of the inner bore and fixing the other geometrical parameters of the lens to improve the performance of unipolar magnetic lenses. The investigation of a study of each design included the calculation of its axial magnetic field the magnetization of the lens in addition to the magnetic flux density using the Finite Element Method (FEM) the Magnetic Electron Lenses Operation (MELOP) program version 1 at three different values of current density (6,4,2 A/mm2). As a result, the clearest values and behaviors were obtained at current density (2 A/mm2). it was found that the best magnetizing properties, the high

... Show More
View Publication Preview PDF
Scopus (1)
Scopus Crossref
Publication Date
Wed Jan 01 2020
Journal Name
Technologies And Materials For Renewable Energy, Environment And Sustainability: Tmrees20
Studying the effect of the annealing on Ag2Se thin film
...Show More Authors

View Publication
Scopus (11)
Crossref (7)
Scopus Clarivate Crossref
Publication Date
Wed Jul 03 2019
Journal Name
Scientific Reports
A Novel Etchant System for Orthodontic Bracket Bonding
...Show More Authors
Abstract<p>Orthodontic treatment is widely used to correct irregular teeth and/or jaw discrepancies to improve oral function and facial aesthetics. However, it is frequently associated with enamel damage that include chipping, demineralisation, and white spot formation. So far, current bonding systems that can maintain shear bond strengths (SBS) suitable for clinical performance are unable to limit enamel demineralisation, adhesive remnants and damage caused on removal of brackets after treatment. This study reports a novel “safe enamel etch” clinically viable procedure that was accomplished via application of novel etchant pastes developed with β-tricalcium phosphate and monocalcium phosphate monohydrate </p> ... Show More
View Publication
Scopus (39)
Crossref (34)
Scopus Crossref
Publication Date
Wed Dec 01 2021
Journal Name
Journal Of Physics: Conference Series
The effect of left ventricle ischemia severity on cardiac performance appeared on ejection fraction using radioactive TC <sup>99m</sup> MIBI in comparison with echocardiography
...Show More Authors
Abstract<p>Ischemic heart disease is a major causes of heart failure. Heart failure patients have predominantly left ventricular dysfunction (systolic or diastolic dysfunction, or both). Acute heart failure is most commonly caused by reduced myocardial contractility, and increased LV stiffness. We performed echocardiography and gated SPECT with Tc<sup>99m</sup> MIBI within 263 patients and 166 normal individuals. Left ventricular end systolic volume (LVESV), left ventricular end diastolic volume (LVEDV), and left ventricular ejection fraction (LVEF) were measured. For all degrees of ischemia, there was a significant difference between ejection fraction values measured by SPECT and echo</p> ... Show More
View Publication
Scopus Crossref