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 current study aims to investigate the effect of strategic knowledge management practices on an excellent performance at the Institution of Industrial Development and Research- the Ministry of Iraqi Industry (IDRMII). The present research is designed according to the descriptive method. To achieve the mentioned research objective, the researchers used the questionnaire as the main data collection tool. The research sample was 150 managers who are working at the top and middle management levels. To analyses the data gathered and reaching the results, several statistical techniques were used within AMOS.V25, SPSS.V21Software, This study reached a set of results, the most important of which is the existence of a positive correlat
... Show More?Natural Occurrence of aflatoxin Bi and B2 was investigated monthly in paddy rice stored for duration of six months. Aflatoxin B| was detected at the beginning of storage. The concentration of aflatoxin Bi in paddy and polished rice was found to be (0.3 and ()) ppb respectively while aflatoxin B2 W'as not detected in both paddy and polished rice afler six months of storage, concentration of aflatoxin Bi ‘ ’ ' reached 3 ppb in paddy rice and 0.9 ppb in polished rice, while the study proved that the concentration of aflatoxin in paddy rice was higher than polished rice as a result of processing which reduce the toxin
The induced photodegradation of methyl cellulose (MC) films in air was investigated in the absence and presence of aromatic carbonyl compounds(photosenssitizers): 1,4-naphthaquinone (NQ) and benzophenone (BPH) by accelerated weathering tester. The addition of (0.01 wt %) of low molecular weight aromatic carbonyl compounds to cellulose derivatives films(25µm in thickness) enhanced the photodegradation of the polymer films.The photodegradation rate was measured by the increase in carbonyl absorbance. Decreases in solution viscosity and reduction of molecular weight were also observed in the irradiated samples. Changes in the number-average chain scission, the degree of deterioration and in the quantum yield of chain scission values are als
... Show MoreThis study was carried out to evaluate parasitological and immunological of the effect of chitosan and chitosannanoparticles loaded with spiramycin on toxoplasmosis infected mice. After injection intra peritoneal with 103viable tachyzoites for acute infection, treatments given for seven days. Peritoneal fluid examination revealed a significant decrease in the number of Toxoplasmagondiitachyzoites in all treated infected mice compared with infected non-treated. The combined therapy gave better results than single. The best effect was observed in group of mice treated with spiramycin combined with chitosan nanoparticles. Also immunoglobulin Ig Manti body and gamma Interferon (INFγ), Tumor Necrosis Factor alpha (TNF-α) cytokines responses ag
... Show MorePseudoephedrine (PSE) or (Sudafed) is one of the sympathomimetic group of drugs (ephedrine, PSE and amphetamines) which effects cardiovascular system, respiratory system, and gastrointestinal tract. However, only little researches had supported its effect on solid abdominal organs. This study aims to investigate the effects of different doses of Sudafed in the liver and kidney of albino mice. The current study included 18 albino mice grouped into 2 groups: control (3 mice), and acute group (15 mice). The acute group was further subdivided into 5 subgroups, each subgroup of 3mice wasgiven a lonely intaperitonial injection of 0.3ml of the following conc. (500mg/kg, 250mg/kg, 125mg/kg, 62.52mg/kg, and 31.24mg/kg) for 24hrs. After the m
... Show MoreThis study was conducted in the Tissue Culture laboratory of the Horticultural Department of the Faculty of Agriculture at Karbala University to investigate the effects of a light source (Florescent, LED) and adenine sulfate (Ads) a 0, 40, 80, and 120 mg l-1 on the multiplication and rooting of
Polycystic ovary syndrome (PCOS) is the most endocrine problem in women of regenerative age. PCOS women typically belong to an age and sex group which is at higher risk for severe coronavirus disease (COVID-19). COVID-19 targets cells through angiotensin-converting enzyme 2 (ACE2) receptor presents on cells in veins, lungs, heart, digestion tracts, and kidneys. Renin-Angiotensin System (RAS) over activity has likewise been described in metabolic disorders; type 2 diabetes mellitus (T2DM), and conditions shared by women with polycystic ovary condition. The point of this study is to know the job of renin and ACE2 in PCOS and coronavirus and its relationship with hormones and other metabolic parameters related. The study groups consist of 1
... Show MoreThe aim of this research is to find the impact of the efficiency of Management information systems (MIS) on the effectiveness of governmental organizations performance.
To achieve the objective of the research, the analytical descriptive method was adopted. A questionnaire was designed consisting of (35) paragraphs, and the sample consisted of (200) individual. The research attemped to answer the following question: To achieve the objective of the research, the analytical descriptive method was adopted. A questionnaire was designed consisting of (35) paragraphs, and the sample consisted of (200) individual. The research tried to answer the following question: What is the actual utilization of modern admi
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