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Article
The effect of duration of finishing and polishing on the surface roughness of two composite resins
تأثير مدة التشطيب والتلميع على خشونة السطح لراتينتين مركبتين

Authors: Intesar S. Toma --- Media A. Saeed --- Razawa K. Saeed
Journal: Zanco Journal of Medical Sciences مجلة زانكو للعلوم الطبية ISSN: 19955588/19955596 Year: 2013 Volume: 17 Issue: 2 Pages: 405-410
Publisher: Hawler Medical Univeristy جامعة هولير الطبية

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Abstract

Background and objective: The purpose of this study was to evaluate the effect of duration of finishing and polishing procedures on the surface roughness of two different types of composite resins.Methods: Forty samples of 6 mm in diameter and 2 mm in depth were prepared, 2 types of composite resins were used (nanocomposite and hybrid composite resin). Twenty samples of each type of material were prepared and divided into two main groups and then each main group subdivided randomly into two subgroups of 10 samples for each subgroup (one). Ten samples of each material were submitted to finishing by using a finishing kit. The available finishing kits used in this study containing discs, cups and points that were used with a slow-speed hand piece in a dry field and with a light intermittent pressure for about 15 seconds. While the other 10 samples of each material were finished for about 30 second; then the analysis of the surface roughness was carried out, three readings were made on each surface using a stylus tip and the extension of each reading was 2 mm stroke.Results: There was non significant difference between the groups that were finished and polished for 15 second and the other groups that were finished and polished for 30 second for the two different types of composite resin.Conclusion: Increasing duration of finishing and polishing has no effect on the surface roughness of The two different types of composite resin.


Article
MICROMECHANICAL MODELING OF SHORT –FIBER REINFORCED POLYMERIC
النمذجة الميكانيكية الدقيقة لمركب مسلح بألواح البوليمر

Author: Kareem N. Hussien كريم نجم حسين
Journal: Muthanna Journal of Engineering and Technology(MJET) مجلة المثنى للهندسة والتكنولوجيا ISSN: 25720317 25720325 Year: 2013 Volume: 2 Issue: 2 Pages: 73-82
Publisher: Al-Muthanna University جامعة المثنى

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This paper presents a method considering the effect of fiber geometry and volume fraction for predicting the tensile strength, shear stress and Von Mises stress. The finite element scheme for the micromechanical modeling of the behavior of fiber reinforced polymeric composites under external load is developed. The model is used to estimate the stress distribution throughout the composite domain and to identify the location where maximum stresses occur. The ratio between fiber modulus and matrix modulus must be high enough to improve the mechanical properties and to reduce the premature interfacial failure. The prediction of the stress distribution by using a simulation tool could be helpful for more understanding the real reasons behind failure of polymer composites.

يقدم هذا البحث طريقة لحساب تأثير أبعاد الألياف ونسبتها الحجمية للتنبؤ بقيم مقاومة الشد, أجهاد القص وأجهاد فون ميسيس. اعتمد هذا البحث على تطوير طريقة العناصر المحدودة لنمذجة التصرف المايكروميكانيكي للبوليمر المقوى بالألياف تحت تأثير الحمل الخارجي. أستخدم النموذح العددي لتقدير توزيع الأجهاد على مدى المادة المركبة بغرض تحديد أماكن الأجهاد الاقصى. تعتبر النسبة العالية بين معامل الليف الى البوليمر أساسا لتحسين الخواص الميكانيكية ولمنع الأنهيار المبكر . أن التنبؤ بتوزيع الأجهاد باستخدام نماذج المحاكاة الدقيقة يساهم في زيادة الفهم لأسباب الأنهيار للمواد البوليمرية المركبة.


Article
The effect of two finishing and polishing systems on the surface roughness of two composite resins
تأثير نظامي التشطيب والتلميع على خشونة السطح لريتين من الراتنجات المركبة

Authors: Razawa K. Saeed --- Intesar S. Toma --- Media A. Saeed
Journal: Zanco Journal of Medical Sciences مجلة زانكو للعلوم الطبية ISSN: 19955588/19955596 Year: 2013 Volume: 17 Issue: 3 Pages: 484-489
Publisher: Hawler Medical Univeristy جامعة هولير الطبية

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Abstract

Background and objective: The purpose of this study was to evaluate the effect of two finishing and polishing systems on the surface roughness of two different types of composite resins.Methods: Fourty samples of 6 mm in diameter and 2 mm in depth were prepared, 2 types of composite resins were used (nanocomposite and hybrid composite resin). Twenty samples of each type of material were prepared and divided into two main groups and then each main group subdivided randomly into two subgroups of 10 samples each. Ten samples of each material were submitted to finishing by finishing disc. While the other 10 samples of each material were submitted to finishing by finishing bur. Both finishing systems were used with a slow-speed hand piece in a dry field and with a light intermittent pressure for about 15 seconds for each disc and bur. After storage of the samples for 48 hours; the analysis of the surface roughness was carried out, three readings were made on each surface using a stylus tip, and the extension of each reading was 2 mm stroke.Results: There was non significant difference between the groups except there was a significant difference between the two finishing systems when used with hybrid composite.Conclusion: Finishing discs gave best results on nano composite and hybrid composite when compared with finishing diamond bur, with highly significant effect on nano composite.


Article
Radiopacity of modified microhybrid composite resin: (An in vitro study)

Authors: Sazan Sh. Saleem سازان سليم --- Salem A. Al-Samarai سالم السامرائي --- Dara H. Saeed دارا سعيد
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2013 Volume: 25 Issue: special issue 1 Pages: 18-22
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The aim of this study was to measure the radiopacity (RO) of modified microhybrid composite resins byadding 2 types of nanofillers (Zinc Oxide and Calcium Carbonate) in two concentrations 3% and 5% and comparingthem to unmodified microhybrid composite resins and to nanofilled composite resin.Materials and Methods: Two types of composite resin were used (Microhybrid composite MH Quadrent anterior shineand Nanofilled composite resin Filtek Z350 XT), for each tested group five disk-shaped specimens (1-mm-thick and 15mm diameter) were fabricated. The material samples were radiographed together with the aluminum step wedge.The density of the specimens was determined with a transmission densitometer and was expressed in term ofequivalent thickness of aluminum. Data analyzed by one-way ANOVA.Results: The radiopacity (RO) values of the tested group ranged between (0.9293- 2.6242 Eq. Al thickness) and therewere significant differences among them. Nanofilled composite resin Filtek Z350 XT showed the highest value of ROwhile unmodified Microhybrid composite MH Quadrent anterior shine showed the lowest value of RO.Conclusion: The addition of 3% of both the ZnO and CaCO3 nanofillers fillers to microhybrid composite significantlyincreased the RO, while the addition of 5% of CaCO3 and ZnO nanofillers to microhybrid composite showed nonsignificantincrease in the RO of the composite.


Article
Monitoring and Instantaneous Evaluation of Composite Resin Linear Shrinkage with Computerized Topography

Author: Amer A Sultan
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 1 Pages: 102-107
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To measure the linear shrinkage of composite resin by digital image analysis, to evaluate the effect of light curing type on composite resin linear shrinkage, to evaluate the effect of light curing intensity on linear shrinkage of composite resin and to evaluate the linear shrinkage of composite resin after 24 hours. Materials and method: images of composite samples were obtained before curing. The samples were cured with four types of light curing units, halogen light curing unit 420 mW/cm2, LED light curing unit 420 mW/cm2, halogen light curing 300 mW/cm2 and LED light curing unit 300 mW/cm2. the curing time was 40 seconds. After curing, the cured composite surface was exposed to the microscope allowing the attached camera to capture an image. The samples were then stored in 37 degree centigrade incubator for 24 hours and another image for each sample, was obtained. The images were analyzed via specially prepared image analysis program and the linear shrinkage was measured.Results: Regarding the type of LCUs, statistical analysis showed that composite samples cured with QTH LCUs exhibit significantly higher linear shrinkage values than those cured with LED LCUs. While regarding the intensity of the curing light, it was shown that LCUs with higher curing light in-tensities produce a significant higher values of linear shrinkage. Conclusion: The type and the intensity of the light curing unit play a major role in the end result linear shrinkage of the cured composite resin. Image analysis system is an excellent method to determine linear shrinkage.


Article
Evaluation of the Surface Roughness for Three Different Types of Composite Resin Materials Using (Sof–Lex) Finishing and Polishing Systems: A Comparative Study

Author: Sabah A Ismail
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 2 Pages: 221-227
Publisher: Mosul University جامعة الموصل

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Abstract

Aim: To evaluate the surface roughness of three different types of light activated composite resin using (Sof-Lex) – polishing system, a profilometer study. Materials and Methods: A total of 30 resin com-posite disks were prepared from three different types of composite resin include 3 – groups. Group I: 10 specimens were prepared from light activated nano hybride (Tetric n – Ceram, Ivoclar – Vivadent – Liechtenstein). Group II: 10 specimens were prepared from light activated microhybride composite resin (Arabesk – Voco, Germany). Group III: 10 specimens were prepared from light activated poly-glas composite resin (Solitaire – 2, Heraeus, Kulzer, Germany). The resin blocks finished and polished using (Sof – Lex) polishing system. The specimens were analyzed for surface roughness using “Pro-filometer”. Results: Tetric n – Ceram composite resin showed the lowest roughness average (0.112 μm) followed by Arabesk composite (0.150 μm), Solitaire – 2 composite resin showed the highest roughness average (0.341 μm). Conclusions: Tetric n– Ceram (nano-hybride) was the best polished composite resin, showed the least roughness average.


Article
Effects of Different Types of Fillers on Dry Wear Characteristics of Carbon-Epoxy Composite
تأثير الحشوات السيراميكية على خواص البلى للمواد المتراكبة للايبوكسي- كاربون

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Experimental investigations had been done in this research to demonstrate the effect of carbon fiber and Ceramic fillers contents on the tribological behaviour of (15% volume fraction) carbon-epoxy composite system under varying volume fraction, load, time and sliding distance. The wear resistance were investigated according to ASTM G99-05standard using pin on disc machine to present the composite tribological behaviour. The influence of three ceramic fillers, granite, perlite and calcium carbonate (CaCO3), on the wear of the carbon fabric reinforced epoxy composites under dry sliding conditions has been investigated. The effect of variants in volume fraction, applied load, time and sliding distance on the wear behaviour of polymer composites is studied by measuring the weight changes . In the experiments with wear test pin having flat face in contact with hardening rotating steel disc, sliding speed, time and loads in the range of 200 RPM, 300–900s and 40–60 N respectively was used. It is observed that the wear resistance increase with the increasing of reinforcement material volume fraction while, the wear rate increases with increasing of applied load, time and sliding distance. The results showed that the filler of granite perlite and CaCO3 as filler materials in carbon epoxy composites will increase the wear resistance of the composite greatly than carbon fiber fillers epoxy composite only and granite filled CE Composite exhibited the maximum wear resistance.

في هذا البحث تمت دراسة تأثير الياف الكاربون والحشوات السيراميكية على الخواص الترايبولوجية لراتنجات الايبوكسي المقواة بالياف الكاربون عمليا وعند كسر حجمي 15%. تم دراسة مقاومة البليان وفقا للمواصفةASTM G99-05 باستعمال جهاز المسمار مع القرص الدوار وعند احمال 40–60 N ومسافات انزلاقm 942-1507.2 وازمان مختلفة 300–900s وبعد اجراءالاختبارات لوحظ بان مقاومة البليان تزداد مع زيادة الكسر الحجمي لمواد التدعيم بينما معدل البلى بصورة عامة يزداد بزيادة الحمل المسلط والزمن ومسافة الانزلاق، ويكون معدل البليان للعينات الغير مدعمة اعلى بكثير من العينات المدعمة بالياف الكاربون فقط والعينات المدعمة بنسبة 15% الياف كاربون مع الحشوات السيراميكية المختلفة وان مقاومة البليان للعينات المحتوية على حشوات سيراميكية تكون اعلى من العينات المدعمة بالياف كاربونية فقط وان مقاومة البليان لمجموعة العينات المقواة بالياف كاربون مع كرانيت بلغت اعلى قيمة لها تليها ألعينات المدعمة بالبرلايت ثم عينات كاربونات الكالسيوم. نستنتج من ذالك اضافة الحشوات السيراميكية مع الياف الكاربون يحسن بشكل كبير من مقاومة البليان.


Article
Fire retardancy characteristics of polymeric composite materials
صفات تثبيط اللهب للمواد المركبة البوليميرية

Authors: Naser A.Alwash نصر عبد الأمير علوش --- Ali J.Salaman علي جاهل سلمان --- Mustafa A. Rijab مصطفى أحمد رجب** --- Ali I .Al-Mosawi علي إبراهيم الموسوي
Journal: Baghdad Science Journal مجلة بغداد للعلوم ISSN: 20788665 24117986 Year: 2013 Volume: 10 Issue: 3عدد خاص بموتمر الكيمياء Pages: 828-831
Publisher: Baghdad University جامعة بغداد

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Abstract

Fire retardancy characteristics of polymeric composite material reinforced by fibers using coating by a fire retardant layer represent antimony tetroxide was studied. A coating layer (4mm) thickness from antimony tetroxide was used as a surface layer to react and prevent spread of flame on surface of epoxy resin reinforced by carbon – Kevlar fibers and exposed this coating layer to direct flame generated from oxyacetylene flame with different exposure distances (10,15,20mm) and study how it can protect the substrate . The experimental results showed that a great increment in thermal resistance and flame retardancy after coating by antimony tetroxide as well as rising flame resistance increased exposure distances to flame. .

الخلاصة :صفات تثبيط اللهب لمادة مركبة بوليمرية مقواة بالألياف بإستخدام الطلاء بطبقة مثبط لهب متمثلة برابع أوكسيد الأنتيمون قد تم دراستها . تم إستخدام طبقة طلاء بسمك (4mm) من رابع أوكسيد الأنتيمون كطبقة طلاء سطحية لمقاومة ومنع إنتشار اللهب على سطح راتنج الإيبوكسي المقوى بألياف الكربون - كيفلار ، وتعريض هذه الطبقة للهب مباشر الناتج متولد من شعلة أوكسي أستيلينية مع مسافات تعرض مختلفة (mm10،15،20) ودراسة كيف تستطيع حماية الطبقة التحية. أظهرت النتائج العملية زيادة كبيرة في المقاومة الحرارية وتثبيط اللهب بعد طلاء برابع أوكسيد الأنتيمون وكذلك إرتفاع مقاومة اللهب مع زيادة مسافات التعرض .


Article
Studying the Effect of Aluminum Powder Addition on Dielectric Behavior of Polyester Composite Materials
دراسة تأثير اضافة مسحوق الالمنيوم على سلوك العزل الكهربائي للبولي استر

Authors: Nirvana A. Abd Alameer --- Shayma. H. Mohammad
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2013 Volume: 31 Issue: 7 Part (A) Engineering Pages: 1388-1394
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

The effect of both weight fraction of aluminium and frequency on dielectric properties of Al- powder reinforced polyester composite materials were investigated. We study the dielectric behaviour of composite materials reinforced with (0, 5, 15, 30 &45) weight fraction of Al and frequency ranges (50-106) Hz at room temperature. The results show the dielectric constant and dielectric losses factor were increased with increasing in weight fraction of aluminium due to high conductivity of aluminium. The decrease in the dielectric constant and dielectric losses with higher frequencies can be explained by the fact that as the frequency increases, the interfacial dipoles have less time to orient themselves in the direction of the alternating field.

تم في هذا البحث دراسة تاثير الكسر الوزني والتردد على خواص العزل الكهربائي للبولي استر المدعم بكسور وزنية مختلفة من مسحوق الالمنيوم. تم دراسة سلوك العزل للمواد المتراكبة المدعمة ب (0, 5, 15, 30&45 )% من مسحوق الالمنيوم عند معدلات تردد (50 -106 )Hz عند درحة حرارة الغرفة. اظهرت النتائج ان قيم كلا من ثابت العزل وعامل الفقدان العزلي يزداد بزيادة الكسور الوزنية للالمنيوم ويعزى ذلك الى التوصيلية العالية للالمنيوم. في حين قلت قيمهم عند التردات العالية وهذا يوضح الحقيقة وهي عندما يزداد التردد,الجزيئات ثنائية الاقطاب بين السطحين تملك وقت قليل لترتب نفسها داخل الحقل الكهربائي.


Article
Marginal leakage of amalgam and modern composite materials related to restorative techniques in class II cavity (Comparative study)

Authors: Mohammad K. Sabah --- Luma M. Baban
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2013 Volume: 25 Issue: 3 Pages: 35-42
Publisher: Baghdad University جامعة بغداد

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Background: Restoration of the gingival margin of Class II cavities with composite resin continues to be problematic,especially where no enamel exists for bonding to the gingival margin. The aim of study is to evaluate the marginalleakage at enamel and cementum margin of class II MOD cavities using amalgam restoration and moderncomposite restorations Filtek™ P90, Filtek™ Z250 XT (Nano Hybrid Universal Restorative) and SDR bulk fill with differentrestoratives techniques.Materials and method: Eighty sound maxillary first premolar teeth were collected and divided into two main groups,enamel group and cementum group (40 teeth) for each group. The enamel group was prepared with standardizedClass II MOD cavity with gingival margin (1 mm above C.E.J) on both box sides. While the cementum group with thegingival margin (1 mm below C.E.J) on both sides. The enamel and cementum groups were then subdivided intoeight subgroups for each (five teeth) with 10 boxes for each group. Subgroups within the main group namedaccording to materials and techniques that were used with it as following: Amalgam subgroup (Permite, SDI), SDRsubgroup (DENTSPLY) with bulk technique, Filtek™ P90 subgroup (3M ESPE) with three incremental techniques(Oblique, Horizontal and Centripetal technique), and Filtek™ Z250XT subgroup (3M ESPE) with three incrementaltechniques (Oblique, Horizontal and Centripetal technique).After specimens were stored in distilled water at 37°C for7 days. All specimens were subjected to thermocycling at (5° to 55 °C). Microleakage was evaluated bystereomicroscope (20 X). Data were analyzed statistically by Kruskal-Wallis test and Mann-Whitney U-test.Result: All experimental groups showed leakage at cementum more than enamel groups. SDR bulk fill subgroupshowed the highest marginal leakage among all experimental groups followed by Filtek™ Z250 XT subgroup withhorizontal technique at both enamel and cementum groups. Silorane and Filtek™ Z250 XT subgroups with obliquetechnique showed the least marginal leakage followed by centripetal technique at both enamel and cementumgroups. Amalgam restoration subgroup shows lesser leakage than SDR bulk fills subgroup significantly at both enameland cementum groups. While it show higher leakage than Silorane subgroup with oblique technique significantly atenamel margin only.Conclusion: The limiting factors for marginal leakage are technique and material dependent

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