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Article
The Influence of Co-Cr Thickness on The Color Parameters of Metalo-Ceramic System

Author: Abdullah J. Mohammed
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2016 Volume: 16 Issue: 32 Pages: 41-48
Publisher: Mosul University جامعة الموصل

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Abstract

ABSTRACT Aims: The thickness of Co-Cr metal beneath the ceramic in the metalo-ceramic system can affect the color parameters. This study investigated the effect of different thicknesses of Co-Cr plate on the color parameters. Materials and method: Thirty square Co-Cr samples were made (10x10)mm length, width, respectively with varying thickness (0.3, 0.5, 1)mm, two shades (A1, A3.5) of ceramic build on the metal squares five of each thickness, and they were tested by colorimeter to measure the color parameters. Results: Mean L*value of 0.3mm metal thickness of both shades have shown a significant increase on expense of other thicknesses at (P>0.05). Conclusions: L* values were increased with the decrease in the metal thickness to a value near the opaque layer thickness, and decreased with the increase of metal thickness up to five folds of opaque layer thickness, metal thickness had no effect on the means of a*b* values.


Article
The Effect of Thickness on The Color Parameters of The Vinyl Addition Maxillofacial Elastomer

Authors: Abdullah J. Mohammed --- Radhwan H. Hasan
Journal: Medical Journal of Babylon مجلة بابل الطبية ISSN: 1812156X 23126760 Year: 2014 Volume: 11 Issue: 3 Pages: 699-704
Publisher: Babylon University جامعة بابل

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Abstract

Aim of the study : The study investigated the effect of material thickness on color parameters of maxillofacial silicon . Materials and methods :sixty samples made of silicone rubber. Samples ( 20 * 10 * 3) mm length , width , thickness, and (20 * 10 * 1.5) mm length, width, and thickness were divided into three groups, white, yellow and pink ( 10 samples a thickness of 3 mm and 10 samples thickness of 1.5 mm in each group) . And then the samples were tested for recording color parameters .Results : There was a significant difference for the three color values at different thicknesses, where the value of * L and a * in the three groups decreased as thickness increased while the b * value rose up with the thickness . Conclusions: The increase in the thickness of the maxillofacial silicon associated with a decrease in the value of L * , a * and a rise in the value of b *.

أهداف الدراسةِ: تَحرّتْ الدراسةُ تأثيرَ سمك مادة مطاط السليكون الوجه الفكي والمستعملة في تعويض اجزاء الوجه والفكين المفقودة على مقاييسِ لونَ المادة لما له من تاثيرعلى جمالية الجزء المصنع واندماجه مع بقية اجزاءالوجه. المواد وطرائق العمل: ستون عينة صنعت مِنْ مطاطِ السيليكونِ الوجه فكي. 30 عينة تحمل الابعاد (20*10*3) مليمتر طول ، عرض، وسُمك،و 30 عينة اخرى بالابعاد(20*10*1.5) مليمتر طول ، عرض، وسُمك قسمتَ إلى ثلاث مجموعاتِ أبيضَ ، أصفرَ ووردي (10عينات بسمك 3ملم و10 عينات بسمك 1.5ملم في كُلّ مجموعة من الالوان الثلاثة). وبعد ذلك إختبرَت العينات لتَسجيل مقاييس اللونَ. النَتائِج: كان هناك اختلاف معنوي لقيم اللون الثلاثة عند اختلاف السمك حيث ارتفعت قيمة *Lوa* في المجموعاتِ الثلاث بانخفاض السمك بينما ارتفعت قيمة b*بارتفاع السمك. الاستنتاجات: الزيادة في سمك مادة مطاط السيليكون الوجه الفكي تترافق مع نقصان في قيمة L* وa* وارتفاع في قيمة b*.


Article
The Effect of Laser Welding on the Ten-sile Strength and Radiographic Analysis of Co-Cr Repaired Joints

Authors: Abdullah J Mohammed --- Nazar Gh Jameel --- Nadira A Hatim
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2012 Volume: 12 Issue: 23 Pages: 1-13
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: To evaluate the effect of laser welding and arc welding on the ultimate tensile strength, radio-graphic appearance of the joints, and microscopic porosities in the fractographs. Four joining methods have been used, laser welding, and arc welding using three types of electrodes (iron, stainless steel, and brass). Effect of surface roughness on the aforementioned properties was evaluated. Materials and Methods: Three specimens as-cast control group, seventy two specimens were treated by polishing, laser, and sandblasting, and joined with the four joining methods. Joints examined by radiograph and porosities were measured by Dimax software program, their ultimate tensile strength, and strain was tested, and the microscopic porosities in the fractographs were measured using AutoCAD software program. Three cobalt chromium bars from the third group were joined to three stainless steel bars from the fourth group of the same diameter to test the ultimate tensile strength, and strain of the dissi-milar alloys. Results: Laser welded and brass soldered joints had significantly lower ultimate tensile strength and strain when compared to the control group, while the iron, and stainless steel soldered joints had insignificant differences in the ultimate tensile strength and strain when compared to the control group. Results shown that the iron and stainless steel soldered samples fractured in the heat affected zone while the brass soldered and laser welded samples fractured in the weld zone. The iron and stainless steel soldered joints had superior mechanical properties when compared with the control group. Laser welding of dissimilar alloys had the lowest mechanical properties among all techniques. Conclusions: revealed that laser welding was the most precise technique used in the current study. Weld fractures shown less tensile strength average and more brittle behavior. Radiographic properties had no influence on the mechanical properties of the joints.


Article
Biocompatibility of Soldering Materials Used for Repair of Cobalt Chromium Joints

Authors: Nadira A Hatim --- Nazar Gh Jameel --- Abdullah J Mohammed
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2013 Volume: 13 Issue: 25 Pages: 7-13
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: The aim of this study is to evaluate the biological activities of three soldering materials used for joining Co-Cr joints (iron, stainless steel, and brass) on the tissue of the Rabbit. Materials and Meth-ods: Nine specimens of each iron, stainless steel, and brass where made as cylinders (3mm x 2.5mm). The middle part was made of the brazing materials and the upper and lower parts were made of Co-Cr. These specimens where implanted in the subcutaneous tissue of the rabbit, after two weeks the animals where sacrificed and biopsies where made and examined under microscope by three oral pathologists. Results: Stainless steel implants were the most biocompatible material among the three materials used as brazing materials. Stainless steel sites had insignificant differences with the control sites. Significant difference was found between the iron implanted sites and the control group. This result found by two viewers (A, and M), while the third viewer (Z) found no significant difference between the control group, and the iron implanted sites. Significant difference was found between the brass implanted sites and the control group, this result was found by the three viewers (A, M, and Z). Conclusions: The stainless steel had the most favorable tissue response among the three soldering materials, iron is in the second rank, and brass showed unfavorable tissue response due to release of Cu.

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