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Article
Evaluation of macrohardness of recast-ed Cobalt–chromium alloy

Author: Ahmed A Al–Ali
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2007 Volume: 7 Issue: 9 Pages: 111-117
Publisher: Mosul University جامعة الموصل

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Aims: To study the effect of recasting on the macrohardness of cobalt chromium (Co–Cr)alloy, and to evaluate the effect of finishing and polishing on it. Materials and methods: Two brand of Co–Cr alloys were used, divided into three groups, the specimens of the first group were casted from new materials, the second were casted from previously casted material without the addition of any new material (100% recast), the third were casted by combination 50% new material and 50% used material. Half of the specimens just finished and the other half were finished and polished , hardness for all of them were measured. Results: Showed that recasting, both 100% and 50%, significantly increase the macrohardness of Co–Cr alloys and no significant effect of finishing and polishing on it. Conclusion: Recasting may affect properties of Co–Cr alloy and new material should be used rather than recasted material.


Article
An evaluation of the effects of different polishing materials and glazing techniques on the fracture toughness of dental porcelain

Authors: Ma’an R. Zakaria معن رشيد زكريا --- Saeed K. Shahwan سعيد شهوان
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2012 Volume: 24 Issue: 4 Pages: 29-33
Publisher: Baghdad University جامعة بغداد

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Background: As there is an increase in the importance of measuring the fracture toughness of dental porcelain,different methods and materials were supposed. The aim of this study was to compare the fracture toughness offeldspathic porcelain with different polishing materials and glazing techniques.Materials and methods: Forty-nine metal-ceramic discs (width =10 mm, height =5 mm) were fabricated andrandomly divided into seven groups (n = 7); group one was left intact and considered as a control group, othergroups’ surfaces were treated with autoglaze only, applied glaze only, polished with ceramic rubber wheel only,polished with Dentaurum universal polishing paste only, polished with paste then autoglazed, and polished withpaste followed by applied glaze respectively. Porcelain fracture toughness (KIc) for each specimen was measuredby a Micro-Vickers Hardness Tester then the mean KIc for each group was determined. The data were analyzed byusing analysis of variance (ANOVA) followed by Least Significant Difference (LSD).Results: Mean porcelain fracture toughness of all groups were 1.320, 0.665, 1.469, 1.319, 1.480, 1.108, 1.548 MN/m-3/2respectively. Very high significant differences were found between the groups (P<0.001). The highest mean of KIcvalue was recorded in group VII which represented the toughest group while the lowest mean value wasrepresented by group II.Conclusions: Surface treatment of feldspathic porcelain restorations with polishing paste and applied glaze showedhighly significant increase in fracture toughness. Polishing unglazed porcelain using ceramic rubber wheel andDentaurum universal polishing paste showed no significant differences compared with specimens treated withapplied glaze only.


Article
Optimal Design of Cylinderical Ectrode Using Neural Network Modeling for Electrochemical Finishing

Author: Nadhim M. Faleh
Journal: Iraqi Journal of Chemical and Petroleum Engineering المجلة العراقية للهندسة الكيمياوية وهندسة النفط ISSN: 19974884/E26180707 Year: 2013 Volume: 14 Issue: 3 Pages: 33-47
Publisher: Baghdad University جامعة بغداد

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Abstract

The finishing operation of the electrochemical finishing technology (ECF) for tube of steel was investigated In this study. Experimental procedures included qualitative and quantitative analyses for surface roughness and material removal. Qualitative analyses utilized finishing optimization of a specific specimen in various design and operating conditions; value of gap from 0.2 to 10mm, flow rate of electrolytes from 5 to 15liter/min, finishing time from 1 to 4min and the applied voltage from 6 to 12v, to find out the value of surface roughness and material removal at each electrochemical state. From the measured material removal for each process state was used to verify the relationship with finishing time of work piece. Electrochemical finishing proves an effective method to reduce the surface roughness (Ra) from 1.6µm to 0.1µm in 4 min. Finally, the observed relationships were used to predicate the diameter of blank, tool diameter and flow rate by neural network modeling ANN which has inputs defined by the finished hole diameter, surface roughness, and finishing time. Three of hidden layers and their neurons were found by an integration procedure. The design charts observed from this study utilize the designers in predication of diameter for blank and design of electrode.


Article
Effect of different polishing systems on the surface roughness of full-contour zirconia

Authors: Hussein Muhammed Wajih حسين محمد وجيه --- Adel F. Ibraheem عادل فرحان ابراهيم
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 39-45
Publisher: Baghdad University جامعة بغداد

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Background: Adjustment of any premature occlusal contact of any zirconia restoration requires its polishing orglazing in order to restore the smoothness of the restoration. The objective of this in vitro study was to evaluate theeffects of different polishing systems and glazing on the surface roughness of full-contour zirconia.Material and methods: Forty disks (diameter: 8 mm, thickness: 6.4 mm) were prepared from pre-sintered fullcontouredzirconia block; they were colored and sintered in a high-temperature furnace at 1500˚C for 8 hours. Thespecimens were then leveled and finished using grinding and polishing machine and adjusted using diamond disk.The specimens were then randomly divided into four groups (n=10), group I involves samples that were polished using(karat diamond polishing set, Vita zahnfabrik, Germany), group II involves samples that were polished with (zirconiapolishing kit, SMEdent, Shanghai, China), group III involves samples that were polished with (OptraFine® diamondpolishing system, Ivoclar Vivadent, Germany), while group IV involves samples that were glazed using glazingmedium (VITA Akzent Glaze AKZ 25, Vita zahnfabrik, Germany). Surface roughness values (Ra) (in μm) of all thespecimens were recorded at each stage of surface treatment of zirconia disks (leveling and finishing, adjustment ofthe samples and polishing / glazing) using surface roughness tester. Statistical analysis was carried out using one-wayANOVA and LSD tests.Results: The results showed that the glazing group recorded the lowest surface roughness mean value, followed by(OptraFine® polishing system), then (zirconia polishing kit) and finally (karat polishing set) which showed the highestmean of surface roughness. For all groups, there was a statistically very high significant difference of (Ra) valuebefore and after adjustment of the samples. Moreover, there was a statistically very high significant difference in (Ra)value when comparing the adjusted samples with the polished and glazed ones. Karat polishing set group showed astatistically highly significant difference with zirconia polishing kit group (P<0.01). Both, karat polishing set and zirconiapolishing kit groups showed a statistically very highly significant difference (P<0.001) with (OptraFine® polishingsystem) and glazing groups. On the other hand, no statistically significant difference was found between glazing and(OptraFine® polishing system) groups (P>0.05).Conclusions: Adjusting full-contour zirconia with diamond bur or disk resulted in a significant increase in (Ra) thatnecessitates its polishing or glazing to restore the surface smoothness. Furthermore, both glazing and OptraFine®polishing system provided the best surface smoothness, so glazing can be substituted with chairside polishing usingOptraFine® polishing system.

إن تعدیل أي إطباق مبكر سواء لتركیبات السیرامیك أو الزركون, یتطلب تلمیعھا أو إعادة تزجیجھا من أجل استعادة النعومة المطلوبة. إن الھدف من ھذه الدراسة المختبریة ھو لتقییمآثار نظم التلمیع المختلفة و التزجیج على خشونة سطح الزركون المعدل.تم تحضیر أربعین عینة من الزركون، تم تلوینھا و طبخھا في فرن ذو درجة حرارة عالیة ( 1500 درجة مئویة لمدة 8 ساعات).بعد ذلك تم تسویة اسطح العینات و صقلھا بواسطة جھازالصقل, و بعدھا تم تعدیل أسطح العینات بواسطة قرصماسي. تم تقسیم العینات بعدھا عشوائیا إلى أربع مجموعات كل مجموعة تحوي عشرة عینات.المجموعة الاولى تم تلمیع أسطحفي المجموعة الثانیة تم تلمیع أسطح العینات بواسطة (طقم التلمیع الخاص بالزركون), المجموعة الثالثة تم تلمیع أسطح عیناتھا ,(Karat العینات فیھا بواسطة (طقم التلمیع الماسيالمجموعة الرابعة تم تزجیج العینات فیھا بمادة تزجیج مناسبة. تم تسجیل قیم خشونة الأسطح (بالمیكرو متر) لجمیع العینات في المراحل ,(Optrafine® بواسطة (طقم التلمیع الماسيANOVA الثلاثة (التسویة والصقل، تعدیل سطح العینات ,تلمیع العینات/ تزجیجھا) بإستخدام جھاز قیاس خشونة السطح (البروفیلومیتر). وقد أجري التحلیل الإحصائي بتطبیق اختبار.LSD احادي الاتجاه و إختبارثم مجموعة (طقم التلمیع الخاصبالزركون), وأخیرا مجموعة (طقم ،(Optrafine® أظھرت مجموعة التزجیج أقل متوسط خشونة لأسطح العینات، تلیھا مجموعة (طقم التلمیع الماسيوالتي أظھرت أعلى متوسط خشونة. للمجموعات الأربع، كان ھناك فروق ذات دلالة إحصائیة عالیة جدا بین متوسط الخشونة قبل تعدیل العینات و متوسط (Karat التلمیع الماسيالخشونة بعد تعدیلھا. أیضا كان ھناك فروق ذات دلالة إحصائیة عالیة جدا في متوسط الخشونة بعد تعدیل العینات و متوسط الخشونة بعد تلمیع- تزجیج العینات. أظھرت مجموعة (طقمو (طقم التلمیع الخاص (Karat وأظھر كل من (طقم التلمیع الماسي .(P < فرق معنوي عالي إحصائیا مع مجموعة (طقم التلمیع الخاص بالزركون) ( 0.01 (Karat التلمیع الماسيبینما لم یظھر ھناك اي فرق معنوي ذات دلالة إحصائیة .(P < و (التزجیج) ( 0.001 (Optrafine® بالزركون) فرق ذات دلالة إحصائیة عالیة جدا مع مجموعتي (طقم التلمیع الماسي.(P= و (التزجیج) ( 0.774 (Optrafine® بین مجموعتي (طقم التلمیع الماسيو كإستنتاج, فإن فان نتائج البحث اشارت الى أن تعدیل سطح الزركون بواسطة قرص او مثقب ماسي أدى إلى زیادة كبیرة في متوسط الخشونة, مما یوجب ضرورة تلمیع سطحو (التزجیج) أفضل نعومة لسطح الزركون مع عدم وجود اي فرق احصائي بین (Optrafine® الزركون أو تزجیجھ لإستعادة نعومة السطح. قدم كل من (طقم التلمیع الماسيمعوضا عن الحاجة لتزجیج تركیب الزركون مع الحصول على (Optrafine® المجموعتین, و بالتالي , من الممكن ان یكون تلمیع سطح تركیب الزركون بواسطة (طقم التلمیع الماسينعومة سطح مشابھة.


Article
An evaluation of the effects of different finishing / polishing techniques on smoothness of composites

Author: Dr. Zahraa Nazar Al-Wahab, B.D.S., M.Sc.* د. زهراء نزار
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2009 Volume: 6 Issue: 2 Pages: 104-109
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Rough, poorly polished resin – based composite surfaces contribute to staining, plaque accumulation, gingival irritation and recurrent caries. Proper finishing and polishing enhance both the esthetics and longevity of restored tooth. To evaluate the effect of different finishing / polishing techniques on the surface roughness of minifilled hybrid Filtek Z250 and very fine particles hybrid Latitude composite resins. Two types of composite resin were used, Filtek Z250 and Latitude. 32- disc shaped specimens for each type of composite were made (with diameter of 10 mm and 2mm thick) and total is 64 –specimens. All the specimens were cured under Mylar – matrix strip and divided into four groups: control had no surface treatment, finished with fine and extra fine diamond burs, finished with 12 – fluted and 30 – fluted carbide finishing burs, treated with diamond burs plus coarse, medium, fine and extra fine Sof – lex discs. Surface roughness of the specimens was evaluated using profilometer, and the data were analyzed by 2 – way ANOVA test and LSD test. There was statistically significant difference in the average surface roughness values among Mylar – strip, diamond bur, carbide bur, diamond bur plus Sof – Lex discs. For both materials, there was no significant difference between them. Surface roughness of composite resin is directly influenced by finishing / polishing technique used. For both types of composite resin tested in this study, there was no significant difference between them. The Mylar strip provided a smoother surface than the other groups. It was followed bydiamond bur plus Sof – Lex disc, carbide bur and, the diamond bur produced the highest surface roughness values.


Article
ASSESSMENT OF THE RUTBA FORMATION SILICA SAND AS ABRASIVE FOR GRINDING AND POLISHING GALENA: A CONTRIBUTION IN ORE MICROSCOPY
تقييم رمل السليكا لتكوين الرطية كمادة صاقلة لتنعيم وصقل الغالينا: مساهمة في دراسة مجهرية الخامات

Authors: Rana A. Ali رنا عباس علي --- Salih M. Awadh صالح محمد عوض
Journal: Iraqi Bulletin of Geology and Mining مجلة الجيولوجيا والتعدين العراقية ISSN: 18114539 Year: 2017 Volume: 13 Issue: 1 Pages: 99-106
Publisher: Ministry of Industry and Minerals وزارة الصناعة والمعادن

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Abstract

This study aims to assess the Iraqi silica sand collected from Rutba Formation as an abrasive for grinding and polishing galena surface for mineralogical study under the reflected light microscope. Grinding is performed using four-grain sizes of silica sand (68, 46, 30, and 18 µm) which are equivalent to 260, 325, 600, and 1200 mesh respectively. Polishing and buffing stages are done using two-grain size of diamond paste (7 and 2.5 µm). The reflectance (R%) values are inversely proportional to the grain size (the lower particle size, the higher the reflectivity), while the surface roughness (Ra) is directly proportional to the grain size. The reflectance is increased from 0, 5.4, 12.2, 16.4, 23.5, 28.3, to 32.3% and roughness is decreased from 57.2, 47.8, 35, 22.5, 8.4, 6.9, to 3.3 µm with grinding and polishing abrasives of grain sizes of 68, 46, 30, 18, 7, and 2.5 µm. The ideal reflectance of the polished surface of galena at 546 nm (air) is 43.1%, and 41.9% at 589 nm in air. The highest reflectance of 32.3% at 546 nm in air achieved by this study is adequate to diagnose galena and its texture intergrowth under the polarized reflected light microscope.

تهدف هذه الدراسة الى تقييم رمل السليكا من تكوين الرطبة كمادة صاقلة لتنعيم وصقل وتلميع سطح معدن الغالينا لأغراض الدراسة المعدنية تحت المجهر العاكس للضوء. تم اجراء عملية التنعيم باستخدام اربع احجام حبيبية من رمل السليكا (68 و 46 و30 و 18 مايكرون) والتي تكافيء 260 و 325 و 600 و 1200 مش على التوالي، فيما اجريت مراحل الصقل والتلميع باستخدام حجمين حبيبيين من معجون الماس (7 و 2.5 مايكرون). تناسبت قيم الانعكاسية عكسيا مع الحجم الحبيبي (حيث تزداد قيم الانعكاسية كلما قل الحجم الحبيبي للمادة الصاقلة)، فيما تناسبت خشونة السطح طرديا مع الحجم الحبيبي. إزدادت قيم الأنعكاسية من 0، 4.5، 12.2 ، 16.4، 23.5 ،28.3، الى 32.3% وتناقصت قيم الخشنونة من 57.2، 47.8، 35، 22.5، 8.4، 6.9، الى 3.3 مايكرون مع مواد التنعيم والصقل ذات الاحجام الحبيبية 68 و 46 و30 و 18 و7 و 2.5 مايكرون. تبلغ الإنعكاسية المثالية لسطح معدن الغالينا المصقول عند 546 نانوميتر (في الهواء) 43.1%، وعند 589 نانوميتر في الهواء 41.9%. إن أعلى قيمة للأنعكاسية تم التوصل اليها من خلال هذه الدراسة عند 546 نانوميتر في الهواء هي%32.3 والتي بدت كافية لتشخيص معدن الغالينا وأنسجة نموه المتداخل تحت المجهر العاكس للضوء.


Article
Evaluation the Effect of Staining Agents on the Color Stability of Composite Resins that Polished at Different Interval Times (an in Vitro Study)

Author: Shaymaa SH. Hassan
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2016 Volume: 16 Issue: 28 Pages: 30-40
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: This study investigated the effect of polishing times (immediately, 1 hour and 24 hour after light curing) and staining solutions on the color stability of two composite resins. Materials and Methods: Nanocomposite (Filtek Z350) and microhybrid composite (Valux plus) were used. Sixty discs (8mm diameter×2mm height) were made for each composite, and divided into four groups: the first group was polished immediately after light curing; second group was polished after 1 h; third group was polished after 24 h of curing; and the fourth group was the control. Color was measured with spectrophotometer. After baseline color measurements, the specimens of each group divided into three subgroups; specimens of first subgroup were immersed in coffee; specimens of second subgroup were immersed in orange juice; specimens of third subgroup were immersed in distilled water, after 7 day of immersion, the color was measured again and ΔE were calculated. Statistical analysis: Two-way ANOVA, Duncan's Multiple Range test and t-test. Results: The influence of polishing times and staining solutions on color change was significant. Polishing 24 hours after curing presented lowest ΔE value. Coffee promoted more color change than orange juice and distilled water, Filtek Z350 showed lower ΔE than Valux plus. Conclusions: Immediate polishing negatively affect the color stability of composite resins, coffee had a significant influence on discoloration of composite resins. The nanocomposite showed higher color stability than microhybrid composite.


Article
Evaluation the effect of burning investment and black sand materials on the surface roughness of acrylic resin denture base

Author: Makarem A Jaber
Journal: nursing national Iraqi specility المجلة العراقية الوطنية للعلوم التمريضية ISSN: 18122388 Year: 2012 Volume: 25 Issue: 2 Pages: 62-70
Publisher: Baghdad University جامعة بغداد

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Abstract

Objective: The aim of this study was to evaluate the effect of pumice, burning investment material and black sand on the surface roughness of heat cure acrylic resin.Methodology: Sixty specimens were prepared from pink heat cure acrylic resin, the specimens where grouped into; 20 specimens which polished with pumice and water (control group); 20 specimens which polished with investment material (after burning it) and water; and 20 specimens which polished with black sand and water. The average surface roughness of specimens after polishing procedure had been determined by profilometer (surface roughness tester).Results: Through the application of ANOVA and LSD tests, the result of this study showed that there was a highly significant difference among the three groups at (P<0.001).Recommendation: it may be concluded that the smoother surface of specimens gained by burning investment material was significantly higher than that of black sand and pumice materials. So that burning investment material can be used as a polishing material for heat cure acrylic resin denture base instead of pumice material.

الهدف: الهدف من هذه الدراسة هو تقييم تأثيرمادة الأكساء المحروق) investment) والرمل الاسود على الخشونه السطحية لمادة الاكريلك الحارالمنهجية: : تم تحضير60 عينة من مادة الاكريلك الحار ثم قسمت العينات الى ثلاث مجاميع: 20 عينة(عينات قياسية) لمّعتْ بمادة ال pumice والماءِ; 20 عينة تم تلميعها باستخدام مادة الأكساء المحروق والماء و20 عينة لمعت بالرمل الاسود والماء. ان معدل الخشونة السطحية للعينات بعد عملية التلميع كانت قد حددت بواسطة جهاز فحص الخشونة بروفيلوميتر.النتائج: أظهرت النتائج بوجود فرق معنوي عالي بين المجاميع الثلاثة.التوصيات: يمكن الاستنتاج بان السطح الأنعم للعينات تم الحصول عليه بواسطة مادة الأكساء المحروق كَانَ أعلى جداً مِنْ مادتي الرمل الاسود وال pumice لذا مادة الأكساء المحروق يمكن ان تستعمل كمادة تلميع لمادة الاكريلك الحارالمستخدمة في صناعة قاعدة طقم الاسنان عوضا عن مادة ال .pumiceمفتاح الكلمات: الاكريلك الحارالمستخدمة في صناعة قاعدة طقم الاسنان, الخشونه السطحية, مادة التلميع


Article
Effect of Conventional Polishing Procedure in Water Sorption of Cold and Heat Cured Acrylic Denture Base Material

Author: Azad Mohammed Ridha Al-Muthaffer
Journal: Medical Journal of Babylon مجلة بابل الطبية ISSN: 1812156X 23126760 Year: 2016 Volume: 13 Issue: 2 Pages: 481 -488
Publisher: Babylon University جامعة بابل

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Abstract

Acrylic resin is almost universally for partial or complete denture base construction due to its favorable properties. Unfortunately some disadvantages such as water sorption have been reported which causes dimensional changes that may subject the acrylic denture base to internal stresses, so the water sorption is a physical property of importance. Forty square shaped specimens (twenty specimens for heat and cold cured acrylic material) were prepared. Ten specimens from heat cured acrylic (HP) and cold cured acrylic (CP) material were polished, and ten specimens from heat cured acrylic (Hx) and cold cured acrylic (Cx) were not polished as control group. At room temperature, all specimens were weighed; this weight value was considered the initial weight of the specimen (W0). All specimens were kept in distilled water bath for 24 hours, and then specimens were weighed(W1)then the specimens were kept out of water bath for 24 hours to dry to (W0), and all samples return back to water bath for 24 hours to weigh again (W2). This manner was repeated till (W4).There is a significant difference (p=0.018) between (CP) and (Cx) and a significant difference (p=0.047) between (HP) and (Hx) and no significant difference between cold and heat cured acrylic before (p=0.699) and after polishing (p=0.52) at (p ≤0.05).


Article
Effect of Surface Treatments on the Biaxial Flexural Strength of High Leucite Feldspathic Porcelains

Author: محمد يعقوب شريف
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2013 Volume: 2 Issue: 2 Pages: 123-128
Publisher: Tikrit University جامعة تكريت

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Abstract

The purpose of this study was to examine the effect of altering surface topography on the biaxial flexural strength (BFS) of four dental ceramics, Mirage (MI), Flexoceram (FL), Optec-HSP (OP) and IPS Empress (EM).Twelve groups of ten discs 123mm were prepared and fired according to the manufacturers' instructions. Ten specimens of each material were subjected to three surface treatments, polished, grit blasted and etched with 10% hydrofluoric acid (HF) for 2 minutes. Some specimens were gold coated for examination under Scanning Electron Microscope (SEM). BFS was determined using Lloyd M5K universal testing machine at a cross-head speed of 0.5 mm/min. A one-way ANOVA was used to evaluate the differences between groups.The results obtained showed that the only significant difference in the BFS was the 10% HF for OP and FL (One-way Anova, P<0.05). The decrease in BFS is most likely due to an increased surface flaw size, such that surface initiated crack growth dominates over the bulk internal flaw size of the ceramics.The BFS of dental porcelain used in this study may be governed either by the internal or surface flaws depending on the manner of surface preparation. Specimens etched with 10% HF became weaker for OP and FL ceramics.

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