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Article
Effects of Different Core Thickness on The Microhardness of Lithium- Disilicate Glass Ceramic

Authors: Ihab Naffea Yassen --- Nawras Adnan Mohammed
Journal: Journal of Oral and Dental Research مجلة طب الفم والاسنان ISSN: 23106417 Year: 2019 Volume: 6 Issue: 1 Pages: 51-58
Publisher: Iraqi Association for Oral Research الجمعية العراقية لبحوث طب الفم

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Abstract

Lithium disilicate is the major crystal phase, and be composed of needle-resemble crystals. These crystals are measured from 3 to 6 μm in length. In general, E.maxpress properties are very slightly uppermost crystals found in E.max-CAD because of the larger and longer crystals. Due to the materials that have different firing temperatures (820⁰C for E.max-press). The objective of this study is to estimate the effect of various thickness on the hardness of a sample prepared by lithium disilicate glassceramic material.Materials and methods Thirty disc-shaped wax patterns wereprepared with three core thickness of (0.5mm, 1mm and 1.5mm). All the specimens fabricated with 10mm in diameter and designed according to the ISO specification 6872. Vickers diamond indenter has widely utilized in this study in accordance with the micro-hardness tester device. Results The present data were analyzed statistically using SPSS (V-22). One-way ANOVA and (LSD) test show that the mean values of 0.5mm core thickness was of 800(±120), while the mean value of 1mm core thickness was of 1229 (±139), and that of 1.5mm core thickness was 1117(±221).Conclusions the results showed that the lithium disilicate glass ceramic material had more advanced surface hardness at thickness of 1mm than that of 0.5mm and 1.5mm thickness of the same materials.


Article
Evaluation the Effect of Different Thicknesses Core on the Micro-Hardness of Zirconia Ceramic Material
تقييم تأثير اختلاف السمك على صلادة السطح لمادة الزركونيا المستخدمة في صناعة الاسنان الصناعية

Authors: Nawras Adnan Mohammed نورس عدنان محمد --- Ihab Naffea Yassen ايهاب نافع ياسين
Journal: Al-Nisour Journal for Medical Sciences مجلة النسور للعلوم الطبية ISSN: 26640562 26640554 Year: 2019 Volume: 1 Issue: 2 Pages: 223-231
Publisher: Al-Nisour University College كلية النسور الجامعة

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Abstract

All-ceramics have been increasingly used in prosthetic dentistry to fabricate a wide variety of restorations ]1[ The most recently core materials are the yttrium oxide partially stabilized zirconia (Y-TZP), were found as a new material for all dental ceramic restorations Partially stabilized yttria tetragonal zirconia polycrystalline (Y-TZP) ceramics are a relatively new class of dental ceramics introduced to the market. that are made into blanks and milled to the favorite dimensions using the CAD/CAM (Computer Aided Design/Computer Aided Manufacturing) technology. Objective: To evaluate the effect of different thicknesses on the hardness of disks fabricated by the yttrium oxide partially stabilized zirconia (Y-TZP). Method: This quantitative study was conducted to assess and evaluate the surface hardness of disks in terms of fabrication thirty disc-shaped of wax pattern were prepared in three core thicknesses materials (0.5 mm, 1mm and 1.5 mm), and each all-ceramic system with a 10 mm diameter were prepared according to ISO specification 6872 Vickers diamond indenter was utilized in accordance with micro-hardness tester. Result: The hardness of tetragonal yttrium partial stabilized zirconia with different thicknesses (0.5,1 and 1.5) mm, were as follows: The mean value of 1mm thickness (2557.2967) is greater than mean value of 0.5 mm (2240.4433) in a high significant amount (H.S), and also greater than mean value of 1.5mm (2520.3600) in a significant amount. So, the partially stabilized zirconia specimens with 1mm thickness has better hardness than 1.5mm and 0.5 mm thicknesses. Conclusion: The results concluded that the tetragonal partially stabilized zirconia displays a higher surface hardness for thickness with 1mm than the specimens with 0.5 mm and 1.5mm thickness with the same materials.

الهدف : لتقييم تأثير سمك مختلفة على صلابة الأقراص المصنوعه من مادة الزركونيا الشائعه في صناعة الاسنا ن الصناعيةالطريقة: أجريت هذه الدراسة الكمية لتقييم صلابة السطح للأقراص من حيث التصنيع تم تحضير ثلاثين قرصًا على شكل شمع في ثلاث مواد بسماكة أساسية (0.5 مم ، 1 مم و 1.5 مم) ، ولكل نظام سيراميك كامل بقطر 10 ملم تم ISO بقطر 10 ملم تم تحضيرها طبقًا لمواصفات ISO 6872 تم استخدام إندينتر الماس فيكرز وفقًا لاختبار الصلابة الدقيقة. Iso 6872 طبقًا وتم تحضيرها لمواصفات تم استخدام إندينتر الماس فيكرز وفقًا لاختبار الصلابة الدقيقةالنتيجة: كانت صلابة الإيتريوم رباعي الزركونيا المستقر الجزئي بسماكة مختلفة (0.5،1 و 1.5) مم ، كما يلي:القيمة المتوسطة بسمك 1 مم (2557.2967) أكبر من القيمة المتوسطة البالغة 0.5 مم (2240.4433) بكمية كبيرة عالية (H.S) ، وأيضًا أكبر من القيمة المتوسطة 1.5 مم (2520.3600) بكمية كبيرة. لذلك فأن عينات الزركونيا المستقرة جزئياً بسمك 1 ملم لديها صلاده أفضل من سمك 1.5 مم و 0.5 مم.الخاتمة: خلصت النتائج إلى أن الزركونيا المستقرة جزئياً تظهر صلابة سطحية أعلى للسمك بسمك 1 مم عن العينات ذات السماكة 0.5 مم و 1.5 مم بنفس الموادالكلمات المفتاحية:قوة الصلاده, مادة الزركونيا الكاملة االمصممة باستخدام الحاسوب و المصنعة بواسطة ماكنة الحفر الالي,جهاز فيكر لأختبار الصلادة المايكروية.

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