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Search Results: 1 - 10 of 1121 matches for " Masoud Parirokh "
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Artifacts in Cone-Beam Computed Tomography of a Post and Core Restoration: A Case Report
Masoud Parirokh,Karim Ardjomand,Hamed Manochehrifar
Iranian Endodontic Journal , 2012,
Abstract: : Cone-beam computed tomography (CBCT) has been accepted as a useful tool for diagnosis and treatment in endodontics. Despite a growing trend toward using CBCT in endodontic practice the CBCT images should be interpreted carefully. This case report presents a case that showed radiolucency inside and around a tooth which was free of pathologic changes under a dental operative microscope and conventional radiographs. A male patient was referred to an endodontic office for evaluation of radiolucency inside and around tooth #21 in his CBCT images. The post and crown over the tooth was removed and the tooth was observed under a dental operative microscope. Clinical examination as well as direct observation under a dental operative microscope showed no pathological lesions inside and around the tooth. The misdiagnosis was based on an artifact on CBCT. Despite the advantages of CBCT images as a great radiographic aid in endodontic practice, in the presence of metallic structures such as post and core the images should be interpreted with caution.
Twenty Years of Research on Mineral Trioxide Aggregate: A Scientometric Report
Saeed Asgary,Hamid Reza Motazedian,Masoud Parirokh,Mohammad Jafar Eghbal
Iranian Endodontic Journal , 2013,
Abstract: Introduction: Mineral trioxide aggregate (MTA) has been suggested for root-end filling, vital pulp therapy, apical plug, perforations repair, and root canal filling. Since the introduction of MTA in 1993, many studies about this material have been published. The aim of this survey was to illustrate statistical information about published articles in PubMed-index journals vis-à-vis the various aspects of this biomaterial. Material and Methods: A PubMed search was performed to retrieve the relative articles from 1993 to August 2012. The data of each article including publication year, journal name, number of authors, first author name, affiliations and study design were recorded. Citation of each article till 2009 was obtained from Scopus and Google scholar databases. Data were analyzed to determine the related scientometric indicators. Results: In total, 1027 articles were found in PubMed-indexed journals which show considerable increase from 2 papers in 1993 to 139 in 2011. While ~62% of articles had no level of evidence, only ~5% could be classified as having the highest level of evidence (LOE1); however, the majority of LOE1 articles originated from Iran (~1%: n=10). Journal of Endodontics, as the top rank journal, published 31.7% of MTA related articles. The majority of articles were four-authored (19.6%). Most of the articles originated from USA (21.9%), Brazil (18.5%) and Iran (8.76%). The average number of citation for the top ten articles from Scopus was 231. Conclusion: This data demonstrates that during the past two decades, research on this novel endodontic biomaterial had a rapid positive trend especially during the last 5 years. Further high-level evidence articles for the various clinical applications of MTA would result in superior clinical decision making and stronger scientific-based endodontic practice.
A Comparative In Vivo Study of Tissue Reactions to Four Suturing Materials
Shahla Kakoei,Fahimeh Baghaei,Shahriar Dabiri,Masoud Parirokh
Iranian Endodontic Journal , 2010,
Abstract: INTRODUCTION: The purpose of this study was to compare the histopathologic reaction of four suturing materials: silk, polyvinylidene fluoride (PVDF), polyglycolic acid, and catgut in the oral mucosa of albino rabbits. MATERIALS AND METHODS: The twenty-one male mature albino rabbits which were used in this study were randomly divided into three groups of seven each. Silk, PVDF, polyglycolic acid and catgut suture materials were tested in the oral mucosa of these animals. The animals were sacrificed 2, 4, and 7 days after suturing. Two pathologists evaluated the samples by determining the presence and level of inflammation, granulation tissue, and fibrosis formation. Data were statistically analyzed by Kruskal Wallis and Mann-Whitney U tests. RESULTS: Histological features of the samples showed that PVDF and plain catgut suture materials produced more fibrous tissue (favorable response) on the fourth day in comparison with silk suture (P=0.02). Also, in the 7-day samples PVDF sutures produced the mildest inflammation when compared with the silk sutures (P=0.015). CONCLUSION: According to the results of this study, it can be convey that PVDF suture materials created mild tissue reactions and can be a reasonable candidate for suturing oral tissues.
Nonlinear Multiple Model Predictive Control of Solution Polymerization of Methyl Methacrylate  [PDF]
Masoud Abbaszadeh
Intelligent Control and Automation (ICA) , 2011, DOI: 10.4236/ica.2011.23027
Abstract: A sequential linearized model based predictive controller is designed using the DMC algorithm to control the temperature of a batch MMA polymerization process. Using the mechanistic model of the polymerization, a parametric transfer function is derived to relate the reactor temperature to the power of the heaters. Then, a multiple model predictive control approach is taken in to track a desired temperature trajectory.The coefficients of the multiple transfer functions are calculated along the selected temperature trajectory by sequential linearization and the model is validated experimentally. The controller performance is studied on a small scale batch reactor.
Comparison of Acidic and Polymeric Agents in Synthesis of TiO2 Nanoparticles via a Modified Sol-Gel Method  [PDF]
Masoud Karimipour
World Journal of Nano Science and Engineering (WJNSE) , 2013, DOI: 10.4236/wjnse.2013.33012
TiO2 nano particles were synthesized in Rutile and Anatase phases by sol-gel method using two kind of complex agents, acidic (Citric Acid) and organic complex agent (acetyl acetone) at 400°C, 500°C, 650°C sintering temperatures. The structural analysis by XRD diffraction confirmed phase formation of titanium oxide. Particles sizes were determined by using Scherrer formula. TEM was employed to confirm nano particles formation. The size of nano particles as well as Phase formation can be controlled by the type of complex agent and sintering temperature. Acetyl Acetone causes a more crystalline structure and more uniformity of size distribution in 400°C sintering temperatures. Moreover, it results in obtaining single phase TiO2 nanoparticles at 400°C and 650°C sintering temperature. On the other hand, at high sintering temperature, the particles obtained from polymeric agent tend to agglomerate larger in size than the acidic product.
Effect of Using Stone Cutting Slurry Waste (Al-Khamkha) on the Compaction Characteristics of Jerash Cohesive Soil  [PDF]
Talal Masoud
Open Journal of Civil Engineering (OJCE) , 2015, DOI: 10.4236/ojce.2015.52021
Abstract: The aim of this research is to study the effect of using (Al-KHAMKHA) is stone cutting slurry waste local name in JORDAN on the unit weight and moisture content of Jerash cohesive soil Al-Khamkha which is the local name of the stone cutting slurry waste which is produced during the cutting operation, This water carries large amounts of stone powder, which leads to complex nature of environmental problem so these waste material needs to be utilized meaningfully in economic way. The degree of compaction of a soil is measured in terms of its dry unit weight Al-Khamkha mixed with Jerash cohesive soil at different amount ranges from 0%, 5%, 10%, 15%, up to 50% and compaction characteristics of Jerash cohesive soil without and with different amount of Al-Khamkha was studied. This investigation show that as the amount of Al-Khamkha increase from 0% to 15%, the dry unit weight of Jerash cohesive soil increase from 14.4 KN/m3 at 0% of Al-Khamkha to 16.5 KN/m3 at 15% and after that .any increase of Al-Khamkha decrease the dry unit weight. On the other hand, the optimum water content of the Jerash cohesive soil was increases with increasing the percentage of Al-Khamkha on the cohesive soil.
Investigation of the Stability of Oxadiasole and Their Analogs Using Quantum Mechanics Computation  [PDF]
Masoud Karimi
Computational Chemistry (CC) , 2016, DOI: 10.4236/cc.2016.41002
Abstract: This study aimed at investigating factors affecting the stability as well as structural properties of different Oxadiasole and Thiadiasole isomers based on theoretical level B3LYP/6-311+G**, Nuclear Magnetic Resonance (NMR), and Nucleus-independent Chemical Shift (NICS). Qualitative relationships between relative stabilities of 1,2,3-Oxadiazole, 1,2,4-Oxadiazole, 1,2,5-Oxadiazole and 1,3,4-Oxadiazole were obtained. Aromatic stabilization energy (ASE), aromatic ring current (NICS), HUMO-LUMO gaps, electro-negativity (X), hardness (η), softness (S), electro-philicity (ω) and structural parameters were also calculated in the same theoretical level. The results show that 1,3,4-Oxadiazole is more stable than 1,2,3-Oxadiazole, 1,2,4-Oxadiazole and 1,2,5-Oxadiazole. Unlike the trends observed in Oxadiazoles, 1,2,5-Thiadiazole isomer is more stable than other corresponding Isomers.
Evaluation of Reasons of Permanent Teeth Extraction in Iranian People (2009)
Kakoei S.,Fatemian M.,Eskandari Zadeh A.,Parirokh M.
Journal of Dentistry , 2012,
Abstract: Statement of Problem: Everyday, many people lose their teeth because of various reasons. Knowing the reasons of tooth extraction would help officials to make decisions for helping patients saving their teeth.Purpose: The aim of this study was to investigate the reasons of teeth extraction in dental clinics and some private offices in the city of Kerman in November 2009- February 2010.Materials and Method: In this cross-sectional study, the reasons of teeth extraction in 2076 teeth from 1500 patients selected by simple sampling from Kerman dental clinics were evaluated. Personal data such as gender, age, educational level, occupation, and family size as well as the main reason of tooth extraction (decay, periodontal diseases, prosthesis, tooth impaction, orthodontic reasons, and patient’s request) and the type of tooth were collected by a checklist. Data were analyzed in SPSS, version 11.5 using χ2 test.Results: The two main reasons of tooth extraction were dental caries (43.6%) and patient request (30.6%), respectively. Overall, the first and third molars of the lower jaw were the most commonly extracted teeth. There was a significant relationship between gender and tooth extraction because of caries and orthodontic reasons ( p <0.0001). Meanwhile, the patients’ age had a significant relationship with most teeth extraction reasons ( p <0.0001). Except for patient’s request, educational level had a significant impact on other teeth extraction reasons ( p <0.0001). Conclusion: According to the results of this study, the most common reasons of tooth extraction were dental caries and patient request despite their restorability. Preventive programs and routine dental examination are recommended.
Light Scattering Study of Mixture of Polyethylene Glycol with C12E5 Microemulsion  [PDF]
Soheil Sharifi, Masoud Amirkhani
Soft Nanoscience Letters (SNL) , 2011, DOI: 10.4236/snl.2011.13014
Abstract: The mixture of C12E5 microemulsion with PEG have been studied by small-angle X-ray scattering and dynamic light scattering in order to determine structure and dynamic of the system. Light scattering experiment shown an exponential relaxation for pure C12E5 microemulsion that with increasing of PEG concentration in the C12E5 microemulsion, relaxation becomes non-exponential, which demonstrates that increase of cooperativity. The study structure of the system with SAXS experiment, shown with increasing of PEG concentration, the size of the droplet doesn’t change but interaction between droplets increases that have agreement with light scattering data’s.
Bessel Function and Damped Simple Harmonic Motion  [PDF]
Masoud Asadi-Zeydabadi
Journal of Applied Mathematics and Physics (JAMP) , 2014, DOI: 10.4236/jamp.2014.24004

A glance at Bessel functions shows they behave similar to the damped sinusoidal function. In this paper two physical examples (pendulum and spring-mass system with linearly increasing length and mass respectively) have been used as evidence for this observation. It is shown in this paper how Bessel functions can be approximated by the damped sinusoidal function. The numerical method that is introduced works very well in adiabatic condition (slow change) or in small time (independent variable) intervals. The results are also compared with the Lagrange polynomial.

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