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Article
Marginal Discrepancy and Fracture Resistance of CAD/CAM Ceramill Sintron Metal Copings with Different Porcelain Materials

Authors: Ammar A. Al-Sa'ady --- Mustafa N. Abdulghani --- Eanas I. Jellil
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2017 Volume: 29 Issue: 2 Pages: 7-12
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: This study was performed to compare the marginal fit changes and facture resistance of metal ceramiccrowns constructed from Ceramill Sintron metal coping veneered with three different porcelain veneering materials(Vita Master Koromikos VMK, Willi Geller Creation CC and GC initial MC), also to evaluate the influence ofthermocycling on load at fracture.Materials and Methods: Master brass die was scanned ,then metal coping was designed and milled from CeramillSintron blank to get 60 metal copings, then divided randomly into three groups(20 sample), then veneered withporcelain: VITA, Creation or GC. The marginal gaps were measured before and after porcelain veneering thenmarginal fit changes was calculated. Fracture resistance test was done by Instron®, the master die was duplicatedto sixty analogs then each analog was fixed into acrylic base. After that each crown was cemented onto thecorresponding die analog. Ten samples of each group were subjected to compressive loading to fracture and otherten subjected to thermocycling followed by compressive loading to fracture.Result and Conclusion: The result of marginal fit changes showed that GC group had the lowest marginal gap followby VITA and Creation. While VITA group showed the highest fracture resistance follows by GC then Creation.Thermocycling process did not significantly reduce the load at fracture for all groups


Article
PREPARATION & CHARACTERIZATION OF STEP-WISE AL-AL2O3 FUNCTIONALLY GRADED MATERIALS

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Abstract

In this work, simple ceramic-metal functionally graded materials with three different layers has been prepared and tested. Ceramic and metal materials were represented by alumina and aluminum respectively. Powder technology practices were used extensively in preparing each of four set of FGMs samples. All samples have the same chemical composition. Two variables were studied, compacting load and sintering temperature. All samples were imparting graded hardness reading across the thickness. The values of hardness readings are increased according to the hardest constituent’s increment (i.e. Alumina) at constant sintering temperature and compacting load. Compaction load increment as well as sintering temperature imparts another reasons for improvement in hardness properties. Microscopic observations show an interesting features of the layers microstructure where composed from an aluminum and alumina particles and show good adhesive between alumina particles and Aluminum while Aluminum surrounded alumina particles from all studies due to good mixing practice during preparation stage.

تم في هذا العمل تحضير واختبار مواد المتدرجه بالخواص مكونه من ثلاث طبقات من سيراميك – معدن. السيراميك والمعدن متمثل بالالومينا والالمنيوم على التوالي. طريقه تكنولوجيا المساحيق استخدمت خصيصاً في تحضير اربع مجاميع من عينات المواد المتدرجه بالخواص، كل العينات تمتلك نفس التركيب الكيمياوي. وتم دراسه متغيرين ، حمل الكبس و درجه حراره التلبيد. ازدادت قراءات قيم الصلاده وفقا لزياده المكون الاصلد (الالومينا) عند ثبوت درجه حراره تلبيد و حمل الكبس. تلعب زياده حمل الكبس ودرجه حراره التلبيد كسبب اخر في تحسين خواص الصلاده. اظهرت الملاحظات التركيبيه خواص مميزه للطبقات والمتكونه من الالمنيوم ودقائق الالومينا واظهرت التصاقا جيدا بين دقائق الالومينا ومعدن الالمنيوم بينما احاط الالمنيوم دقائق الالومينا في جميع الحالات نتيجة للخلط الجيد اثناء عملية التحضير.

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