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Article
The Measurement of Surface Hardness of Mineral Trioxide Aggregate Material (MTA) using Two Techniques of Condensation.

Author: Maha A. Al.Murad
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2008 Volume: 8 Issue: 2 Pages: 266-269
Publisher: Mosul University جامعة الموصل

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Abstract

Aims: This in vitro study was conducted to exam the effect of condensation technique on surface hardness of MTA. Materials and Methods: In this study, 20 acrylic blocks were used. In each block a cubic shape cavity 4 mm in width and 4 mm in depth was prepared. The first group which involve ten samples were filled with MTA using hand condensation method. The other ten samples were filled with MTA using hand method followed by ultrasonic activation for one second after each increment.All sample after setting were prepare for Vickers Hardness Test. The first group subjected to a loadstarted from 0.5 Kg and show fatigue at 1 kg using the Vickers Hardness Machine. The second groupsubjected to a load started from 0.5 Kg and increased the load until showed fatigue of the material at 3 Kg using the Vickers Hardness Machine. All the samples were examined using stereo microscope themagnification power about 200x to perform hardness number. Results: Samples condensed with hand method followed by ultrasonic condensation showed more surface hardness than samples condensed with hand method only. There was highly significant difference between samples. Conclusions: Because OF use MTA as pulp capping is import to use Ultrasonic condensation for placement of MTA.

Keywords

Surface hardness --- condensation --- MTA


Article
The Surface Hardness Measurement of Stone and Improved Die Stone After the Addition of a Mixture of Chemical Additives with Different Proportion

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Abstract

Background: Incorporation of chemical additives has long been a technique used to improve properties of the gypsum products. The purpose of this work was to study the effects of adding a combination of gum Arabic and calcium hydroxide to a type III dental stone and type IV improved die stone with different proportion. The effect on water/powder ratio, and surface hardness was determined.Material and method: Both material stone and die stone were blended with two proportion of additives so that each material was mixed twice but with different proportion of gum Arabic (0.1% and 0.2%) and calcium hydroxide (0.5 % and 0.3%). Data for hardness were subjected to two-way analysis of variance.Results: The results revealed that the chemical additives were reduced the water requirements of gypsum products so that the reduction of water lead to increase the density of mixture that sets harder. For type III dental stone the additives significantly improved the surface hardness, while for type IV improved die stone the surface hardness was not enhanced except it was designed to be mixed at low water/powder ratio, and in some instances a reduction in hardness was observed, especially at the most reduced water / powder ratio (0.18)


Article
The effect of mouth rinses on surface micro hardness of two esthetic restorative materials

Authors: Sabiha M.Kanan --- Amaal k.Mohammed
Journal: nursing national Iraqi specility المجلة العراقية الوطنية للعلوم التمريضية ISSN: 18122388 Year: 2012 Volume: 25 Issue: 1 Pages: 101-108
Publisher: Baghdad University جامعة بغداد

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Abstract

Objective: To evaluate the effect of mouth rinses (Biofresh and ZAK) on the surface micro hardness of two light cure restorative material (Tetric ceram ivoclar-vivadent) and (3M Z 250) dental composite.Methodology: The microhardness values of (sixty) composite specimens were measured at the top surfaces after 24 hours of immersion in different solutions (Biofresh, Zak mouth wash and distilled water as control). Comparison done using descriptive statistics (mean, SD, SEM, minimum and maximum values) and inferential statistics (ANOVA and LSD) test.Results: The biofresh mouth rinse which has high alcohol containing has less effect on microhardness of tetric ceram than the zak &distiled water , while the effect of Zak mouth rinse on microhhybrid composit (3M Z250) is less than biofresh &distiled water, also there was highly significant difference between subgroup of tetric ceram and the same for (3M Z250) composite & the effect of the mouth rinse on hardness was material dependent it may be attributed to the differences in chemical composition and filler type of each material. Since it was found that alcohol is not the only factor that has the softening effect on the restorative material, other ingredient in a mouth rinse. may have softening effect on polymer matrix.Recommendations: We recommend for a comparison of color stability for restorative material under the effect of mouth rinsing.

الهدف: تقييم مدى تاثير غسول الفم المعقم الحاوي على مادة الكحول على صلابة نوعين من حشوات الاسنان الضوئية.المنهجية: في بحثنا هذا تم مقارنة نوعين من غسول الفم وتاثيرها عاى درجة صلابة نوعين من الحشوات الضوئية (هيبرد تترك سيرام ومايكرو هيبرد كومبوزت) تم عمل ستين نموذج وتم غمرها في محلول غسول الفم (بايو فرش و زاك و ماء مقطر) لمدة اربعة وعشرين ساعة وبعدها تم قياس الصلابة في جهاز الانسترون وسجلت النتائج وقورنت احصائيا.النتائج: ظهر بان تاثير البايو فرش والذي يحوي على نسبة عالية من الكحول على صلابة التترك السيرام اقل من تاثير الزاك والماء المقطر بينما تاثيرالزاك على صلابة المايكروهيبرد كومبوزت (3M Z250) اقل من البايو فرش والماء القطر وان هناك فرق معنوي عالي بين المجاميع وذلك يعود لمكونات المادة او الى المادة الحافظة وان الكحول ليس العامل الوحيد في غسول الفم الذي يؤثر على صلابة الحشوات.التوصيات: عمل مقارنة لايجاد تاثير غسول الفم على ثبات اللون للحشوات الضوئية


Article
Effect of silver nitrate on some mechanical properties of heat polymerizing acrylic resins

Authors: Assiss. Prof. Dr. Sabiha Mahdi د. صبيحة مهدي --- Dr. Firas Abd K. Abstract Aim: د. فراس عبد كاطع
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2017 Volume: 14 Issue: 1 Pages: 110-117
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Aim: The aimed study was to evaluate the influence of silver nitrate on surfacehardness and tensile strength of acrylic resins.Materials and methods: A total of 60 specimens were made from heat polymerizingresins. Two mechanical tests were utilized (surface hardness and tensile strength)and 4 experimental groups according to the concentration of silver nitrate used.The specimens without the use of silver nitrate were considered as control. Fortensile strength, all specimens were subjected to force till fracture. For surfacehardness, the specimens were tested via a durometer hardness tester. Allspecimens data were analyzed via ANOVA and Tukey tests.Results: The addition of silver nitrate to acrylic resins reduced significantly thetensile strength. Statistically, highly significant differences were found among allgroups (P≤0.001). Also, the difference between control and experimental groupswas highly significant (P≤0.001). For surface hardness, the silver nitrate improvedthe surface hardness of acrylics. Highly significant differences were statisticallyobserved between control and 900 ppm group (P≤0.001); and among all groups(P≤0.001)with exception that no significant differences between control and150ppm; and between 150ppm and 900ppm groups(P>0.05).Conclusion: The addition of silver nitrate to acrylics reduced significantly the tensilestrength and improved slightly the surface hardness.


Article
The effect of 30% at-home bleaching on surface hardness of esthetic restorative materials

Author: Dr. Amaal kadhim ALSaadi, B.D.S.,M.Sc. د. امال كاظم
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2010 Volume: 7 Issue: 2 Pages: 166-173
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

Abstractin vitro study to evaluate the effect of an at-home bleaching product on thesurface hardness of three composite restorative materials.The aim of this study was to evaluate the effect of at-home bleaching on thesurface hardness of the tooth colored restorative materials.Thirty specimens were prepared; 10 specimens of each material 5 specimenscontrol of each group. All specimens were stored in distilled water at roomtemperature for 24 hrs before testing. A universal testing machine (Micromet microhardness testers) was used for testing brinell surface hardness for the three groups&for every tested material. Three tested materials was assessed by ANOVA& furtherexploration between all possible paired combination of tested material was assessedby bonferroni adjusted t-test p value less than 0.05 was considered statisticallysignificant .The statistical analysis showed that at home bleaching technique have statisticallysignificant effect of the micro hardness of composite resin.At-home bleaching agents have a softening effect on some toothcolored restorative material, and the patient must be aware before using them


Article
The Effect of the Poly Vinyl Chloride (PVC) Addition on Surface Hardness and Impact Strength Properties of Heat-Cured Acrylic Resin Denture Base Material
تأثیر إضافة بولي فنیل كلورید على خواص الصلادة وقوة التصادم لمادة طقم الاسنان المبلمرة ح ا رریا

Author: Ehsan Ali Abed احسان علي عبد
Journal: Journal of university of Anbar for Pure science مجلة جامعة الانبار للعلوم الصرفة ISSN: ISSN: 19918941 Year: 2010 Volume: 4 Issue: 3 Pages: 50-53
Publisher: University of Anbar جامعة الانبار

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Abstract

Abstract:The most common materials used for fabrication of denture base are poly methylmethacrylate (PMMA) and methyl methacrylate (MMA). Preparation of heat cured, ultered ormodified, denture base acrylic resin was carried out by preparing of poly (methyl methacrylate)Polymer, - PMMA- (75%) and poly vinyl chloride -PVC - (25%), and the liquid part composed ofmethyl methacrylate -MMA- monomer. All the specimens were cured by using short curing cycle (90min. at 74ºC followed by 30 min. at 100º C). Some mechanical properties of the prepared materialwere evaluated in comparison with the control denture base acrylic resin. The polymer was prepared bygraft copolymerization method. The total 40 specimens, 20 specimens for each experimental or controlmaterial were tested.The results showed that the experimental polymer has hardness and impactstrength higher than that of control polymer

تهدف هذه الد ا رسة إلى إضافة مادة بولیمر فنیل كلورید الى مادة بولیمر مثیل میثااكریلات التي تعتبر أكثر المواد شیوعا فيعمل طقوم الأسنان البلمرة ح ا رریاً ود ا رسة بعض الخواص المیكانیكیة مثل الصلادة وقوة التصادم بالمقارنة مع مادة بولیمر مثیلمیثااكریلات( المادة القیاسیة). في هذه الد ا رسه تم تحضیر بولیمر مثیل میثااكریلات ( ٧٥ % ) وبولیمر فنیل كلورید ( ٢٥ %) وتمخلطهما مع سائل مثیل میثااكریلات باستخدام طریقة البلمرة المشتركة المطعمة. تم تحضیر ٤٠ عینه بمعدل ٢٠ عینه لكل اختبار منكل ماده.أظهر النتائج ان الصلادة وقوة التصادم لعینات المادة التجریبیة أكبر منه في عینات المادة القیاسیة وكان هذا الاختلاف غیرمعنوي إحصائیا. وهذا یعود لوجود مادة البولیمر فنیل كلورید الذي أعطى المادة التجریبیة أكثر تماسكا من المادة القیاسیة


Article
Surface microhardness and depth of cure of composite resin cured with LED and Halogen units

Author: Dr. Firas Saddam Oglah B.D.S., M.Sc. د. فراس صدام
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2011 Volume: 8 Issue: 1 Pages: 13-18
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

The aim of this study was to evaluate the surface hardness and depth of cure ofresin composites cured with a quartz tungsten halogen (QTH) lamp or a light emittingdiodes (LED) unit.Swiss Tec (colten/whaledent AG, Switzerland) resin composite was placed in1, 2,3, and 4 mm depth and 8 mm width metallic molds and cured using the QTH light orthe LED unit for 40s.A total of 40 samples were made that divided into two groups according to thetype of curing light with 20 samples each. Each group was subdivided into 4 groupsaccording to the height of the mold with 5 samples each. Microhardnessmeasurements were performed using a calibrated Vickers indenter (100 g load and30s dwell time). Measurement of depth of cure was carried out by means of hardnessratio (bottom/top × 100).Results were analyzed by paired student's t-tests (P < 0.05). Results showed thatLED exhibited higher microhardness values than QTH unit and the difference wasstatistically significant (P = 0.03) at the top surface and highly significant (P = 0.001)at the bottom surface.Further more the results revealed that LED produced samples with hardness ratio(depth of cure) higher than QTH unit and the difference was highly significant (P =0.004) at 3 mm depth. Both curing lights inadequately cure samples at 4 mm depth.Conclusions: Curing effectiveness of resin composite is better with LED thanQTH unit especially when the composite thickness exceed 2 mm.


Article
Comparisons the microhardness of different cured acrylic denture base systems after subjected to chemical cleaning solutions

Author: Dr. Hawraa Khalid Aziz, B.D.S, M.Sc.* د. حوراء خالد عزيز
Journal: MUSTANSIRIA DENTAL JOURNAL مجلة المستنصرية لطب الاسنان ISSN: 18138500 Year: 2013 Volume: 10 Issue: 1 Pages: 77-87
Publisher: Al-Mustansyriah University الجامعة المستنصرية

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Abstract

In selecting chemical cleaning solutions for dental prostheses, compatibilitybetween them and the type of denture base materials must be considered to avoidadverse effects on the hardness of the acrylic resin in different curing systems. Thisstudy aimed to compare the effect of different disinfectant and denture cleanser on thesurface hardness of the light and heat cured acrylic resin materials. Eighty specimensare made from two different denture base materials. Forty specimens are made oflight cured acrylic and forty specimens are made of heat cured acrylic resin. Eachmaterial is subdivided into four subgroups according to the type of the disinfectant(0.12% chlorhexidine digluconate, 0.5% sodium hypochlorite), the denture cleansers(Corega) and compared to the distilled water as control group. The surface hardnesstest is measured for each specimen to show the effect of each chemical cleaningsolution on the light and heat cured denture base hardness. The results of the presentstudy showed non significant differences in the surface hardness comparing betweenthe two curing systems light and heat cured acrylic resin. Also there are nonsignificant differences in the surface hardness when different disinfectant and denturecleansers have been used in comparison to the distilled water. It was concluded fromthis study that the hardness of acrylic materials is not affected by immersion in anytype of disinfectant and denture cleanser as well as it is found that there is no differentin the hardness of the light cured when compared to the heat cured acrylic denturebase.


Article
Improvement of Surface Hardness By Ball Milling Technique for Carbon Steel (CK 45).

Author: Abdul Wahab Ahmed Daud
Journal: Al-Qadisiyah Journal for Engineering Sciences مجلة القادسية للعلوم الهندسية ISSN: 19984456 Year: 2014 Volume: 7 Issue: 3 Pages: 265-272
Publisher: Al-Qadisiyah University جامعة القادسية

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Abstract

This research is devoted to study the effect of ball milling technique to improve the surface hardness of carbon steel (CK 45) die guides. This process depends on a rotating cylinder with number of certain size steel balls. Experimental works are carried out on guides rods with (15 mm) diameter, and (35 mm) length processed on laboratory ball mill. The factors those studied in this process are rotating speed, and time. The surface hardness is recorded before and after the processing. The results show that the best surface hardness is (86.11 Hv) obtained with ball size (5 mm) diameter rotate with (30 rpm) for (90 min.) processing time.

في هذا البحث استخدمت تقنية طاحونة الكرات المتدحرجة لتحسين الصلادة السطحية لعمود دليل قالب التشكيل من الصلب الكاربوني (CK45). تعتمد هذه العملية على دوران اسطوانه وهي محملة بعدد من الكرات بحجم محدد مصنعة من الصلب. تم إجراء التجارب العملية على أعمدة بقطر (15 mm) وطول (35 mm) . وقد تم دراسة العوامل المؤثرة منها سرعة الدوران والزمن. وقد تم قياس وتسجيل قيم الصلادة السطحية قبل العملية وبعدها. وقد أظهرت النتائج بأن أفضل صلادة سطحية هي (86.11 Hv) تم الحصول عليها بإستخدام حجم كرات بقطر مقداره (5 mm) وسرعة دوران للصندوق مقدارها (30 rpm) خلال زمن مقداره (90 min.)..


Article
Effects of aluminum oxide addition on the surface roughness and hardness of acrylic resin denture base

Author: Makarem Abdul-Rassol Jaber مكرم عبد الرسول جبار
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2015 Volume: 3 Issue: 1 Pages: 32-38
Publisher: Tikrit University جامعة تكريت

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Abstract

Problem: Acrylic dentures frequently fracture during service due to their poor strength characteristic. Several attempts have been carried out to improve strength of acrylic by addition some materials such as fibers or Aluminum oxide. The purpose of this study was to evaluate the effect of adding Aluminum oxide (AL2O3) on the surface roughness and hardness of heat cure acrylic resin denture base material.Materials and Methods: 60 specimens were made from the heat cure acrylic resin denture base after being cured in microwave oven, 30 specimens prepared for surface roughness test and these where subdivided according to concentration of AL2O3 into three subgroups as follow:Group (A): 10 specimens of acrylic resin without AL2O3 (control group)Group (B): 10 specimens of acrylic resin+2.5% by weight AL2O3Group (C): 10 specimens of acrylic resin +5% by weight AL2O330 specimens prepared for surface hardness test and these where subdivided according to concentration of AL2O3 into three subgroups as follow:Group (A): 10 specimens of acrylic resin without AL2O3 (control group)Group (B): 10 specimens of acrylic resin+2.5% by weight AL2O3Group (C): 10 specimens of acrylic resin +5% by weight AL2O3The average of the surface roughness of the samples has been determined with using the profilometer (surface roughness tester)¸ also the average of the surface hardness of the samples has been determined with using surface hardness tester (digital micro Vickers).Result: The results showed that there were no statistically significant differences in the surface roughness and hardness.Conclusion: The addition of aluminum oxide in low percentage not affected on the surface roughness and hardness of heat cure acrylic resin.

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