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Article
Evaluation of the effect of surface treatments on shear bond strength between lithium disilicate ceramic and dentin

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Abstract

Purpose: To evaluate the effect of different surface treatments on shear bond strength between dentin and IPS e.max lithium disilicate glass-ceramic.Materials and Methods: Eighteen extracted third molars were embeded in epoxy resin. The tooth was sectioned vertically in mesiodistal direction using a low speed hard tissue microtome. The buccal and lingual surfaces of each section were ground flat using 600 grit Silicone carbide paper. Eighteen ceramic discs consisted of lithium disilicate glass-ceramic were prepared with a diameter of 4.7mm and height of 2.2mm. The discs were divided in two groups (n=10): (1) IPS e.max treated with hydrofluoric acid and Monobond Plus (MBP) and (2) IPS e.max treated with Monobond Etch &Prime (MBEP). The tooth was cemented with Multilink Automix and stored for 24hours at room temperature before thermocycling and subsequently loaded to failure in Universal Testing Machine. Failure mode were recorded for each specimen.Result: Bond strength analysis and t-test analysis MBEP demonstrated the higher shear bond strength (SBS). MBP and MBEP showed no statistically significant difference were found between them. One-way ANOVA and t-test was used to determine differences in bond strength within and between the groups. Cohesive failure in resin cement was predominant with higher results while adhesive and mixed with lower and equal.Conclusion: Surface treatment with Monobond Etch and Prime has a favorable effect on SBS between dentin and lithium disilicate glass-ceramic with resin cement compared with Monobond Plus.


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
Fracture strength of laminate veneers using different restorative materials and techniques (A comparative in vitro study)

Authors: Abeer Gh. Abdul Khaliq --- Inas I. Al-Rawi ايناس الراوي
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 1-8
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Esthetic correction represents one of the clinical conditions that required the use of laminate veneers inpremolars region. Aim of the study: The purpose of this study was to evaluate the fracture strength of the laminateveneers in maxillary first premolars, fabricated from either composite (direct and indirect techniques) or ceramicCAD/CAM blocks.Materials and Methods: Fifty sound human maxillary premolar teeth were used in this in vitro study. Teeth weredivided randomly into one control group and four experimental groups of ten teeth each; Group A: Restored withdirect composite veneer (Filtek Z250 XT), Group B: Restored with indirect composite veneers (Filtek Z250 XT), Group C:Restored with lithium disilicate ceramic CAD/CAM blocks (IPS e. max CAD) and Group D: Restored with resin nanoceramic CAD/CAM blocks (Lava Ultimate Restorative). Standard preparations were done using Ceramic Veneer Set(Komet). Indirect laminate veneers were cemented with the Relyx Veneer Cement (3M ESPE) and all specimenswere stored in distilled water at 37°C for 2 weeks. The load was applied on the occlusal part of the veneer at 45˚ tolong axis of the tooth using universal testing machine. Results were analyzed with one-way ANOVA and LSD tests.Specimens were examined by stereomicroscope at a magnification of 20x to evaluate the mode of failure.Results: Control group showed higher mean of fracture strength with highly significant difference in comparison tothe experimental groups (P<0.01). (Group A) showed higher mean of fracture strength with statistically significantdifference in comparison to (Group B and Group D). On the other hand the difference between (Group A andGroup C) was statistically highly significant. Statistically non-significant difference was found among the threeindirectly restored groups.Conclusions: All veneers used in this study can be considered as acceptable treatment in the premolars region forpatients with normal biting force. Direct composite veneer is the most favorable technique in term of fracturestrength, while IPS e. max CAD laminate veneers were least likely to fracture and most likely to completely debond

یمثل التصحیح التجمیلي واحدة من الحالات السریریة التي تتطلب استخدام القشور التجمیلیة في المنطقة الضواحك العلویة. الغرض من ھذه الدراسة كان لتقییم قوة كسر القشور.CAD / CAM التجمیلیة في أسنان الضواحك, مصنوعة من المواد المركبة أو من قوالب السیرامیك باستخدام ثلاثة طرق مختلفة: المباشرة, الغیر المباشرة و باستخدام تقنیة التم اختیار خمسین سنا من الضواحك العلویة لاشخاص بالغین ، تم تقسیم الأسنان بشكل عشوائي في خمس مجامیع؛ مجموعة قیاسیة و أربع مجموعات تجریبیة (عشرة أسنان لكلالمجموعة (ب): رممت ,(Filtek Z250 XT, 3M ESPE) منھم)؛ المجموعة (أ) :رممت باستخدام القشور التجمیلیة مصنوع من المادة المركبة بصورة مباشرة على الاسنانالمجموعة (ج): رممت باستخدام القشور (Filtek Z250 XT, 3M ESPE) باستخدام القشور التجمیلیة مصنوع بطریقة غیر مباشرة على قالب الحجر باستخدام المادة المركبةو المجموعة (د): رممت باستخدام قشور تجمیلیة مصنوعة من قوالب (IPS e. max CAD, Ivoclar Vivadent) التجمیلیة المصنوعة من قوالب سیرامیك اللیثیوم ثنائي السیلیكاتCEREC inLab ) CAD / CAM في المجموعتین (ج و د), تم صناعة القشور التجمیلیة باستخدام تقنیة ال .(Lava Ultimate Restorative, 3M ESPE) راتنج نانو سیرامیكتم تثبیت تعویضات .(Ceramic Veneer Set) 4.02 )..وقد تم عمل التحضیرات القیاسیة ( داخل المینا) لكل الاسنان في المجامیع التجریبیة باستخدام , milling system, Sironaلمدة اسبوعین ˚ المتصلب بالاشعة الضوئیة وخزنھا بالماء المقطر بدرجة حرارة 37 (Relyx Veneer Cement) القشور التجمیلیة الغیر مباشرة باستخدام السمنت المركب الرانتیجيLSD ) واختبار اقل فرق معنوي (ANOVA) تم تحلیل النتائج احصائیا باستخدام اختبار .(Universal testing machine) قبل اجراء فحص قوة الكسر باستخدام جھاز الاختباروقد تم فحص العینات الفاشلة تحت المجھر لتحدید نمط الفشل. في الختام استنتادا الى نتائج ھذه الدراسة, یمكن استخدام القشور التجمیلیة للاسنان الضواحك العلویة ولكن .(testاستخدامھ للمریضمع خطأ في أداء الوظیفة الاطباقیة ینبغي تقییمھبعنایة. القشور التجمیلیة المصنوعة من المركب الراتنیجي بالطریقة المباشرة ھو الأسلوب الأكثر ملاءمة من حیث قوةالكسر في الضواحك.


Article
Failures of Porcelain Laminate Veneers Using Different Techniques of Bonding, A Comparative Study

Authors: Safa Adnan Gaeed --- Prof. Ammar Atta-Allah Ali
Journal: Journal of Oral and Dental Research مجلة طب الفم والاسنان ISSN: 23106417 Year: 2017 Volume: 4 Issue: 1 Pages: 35-46
Publisher: Iraqi Association for Oral Research الجمعية العراقية لبحوث طب الفم

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