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Article
Impact Strength of Maxillary Complete Dentures Fabricated From Different Heat Cured Acrylic Resin Denture Base Materials

Author: Mohammed A. Abdulla
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2012 Volume: 12 Issue: 19 Pages: 24-31
Publisher: Mosul University جامعة الموصل

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Abstract

AIMS: Evaluation of the impact strength of maxillary complete dentures fabricated from new type high impact heat-cured acrylic denture base material and comparison with other types of acrylic resin denture base materials. MATERIALS AND METHODS: Three types of materials were used in this study, high impact heat-cured acrylic resin; cross-linked acrylic resin (no cadmium); and conventional heat-cured acrylic resin. Twenty four maxillary complete dentures were fabricated to be tested and divided into three groups. Group 1, Group 2, and Group3 for high impact acrylic resin, cross-linked acrylic resin, and conventional heat- cured resin, respectively. Before testing, all specimens were stored in distilled water at 37ºC for 2 months. The impact strengths (J) of the dentures were measured with a falling-weight impact test. The impact strengths of both groups were compared by a repeated measures analysis of variance (ANOVA) and Duncan's Multiple Analysis Range Test to determine the signifi-cant difference among the tested groups at (p<0.001) level of significance. RESULTS: There is a sig-nificant difference of the mean values of impact strengths for high impact acrylic resin, cross linked acrylic resin and conventional acrylic resin denture base materials at crack initiation and complete frac-ture. The impact strength between crack initiation and complete fracture within each group was signifi-cantly different (p<0.001) for all the groups, and more energy was needed for complete fracture than that for crack initiation for the high impact strength acrylic resin. CONCLUSIONS: Maxillary com-plete dentures made from high impact acrylic resin denture base material have significantly higher im-pact strength than that of maxillary complete denture made from cross-linked and conventional acrylic resin denture base materials. Maxillary complete dentures made from cross-linked acrylic resin denture base material have significantly higher impact strength than that made from conventional acrylic resin denture base materials.


Article
The effect of incorporating carbon nanotubes on impact, transverse strength, hardness, and roughness to high impact denture base material

Author: Wsamaa S. Mahmood
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 1 Pages: 96-99
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: One of the most common complications of dentures is its ability to fracture, so the aim of this study wasto reinforce the high impact denture base with carbon nanotubes in different concentrations to improve themechanical and physical properties of the denture base.Materials and methods: Three concentrations of carbon nanotubes was used 0.5%, 1%, 1.5% in a pilot study to seethe best values regarding transverse strength, impact, hardness and roughness test, 1 wt% was the bestconcentration, so new samples for control group and 1wt% carbon nanotubes and the previous tests were of courserepeated.Results: There was a significant increase in impact strength and transverse strength when we add carbon nanotubesin 1wt%, compared to control group where as hardness decrease when adding carbon nanotubes.Conclusion: the addition of carbon nanotubes improves the physical and mechanical properties


Article
Evaluation of shear bond strength of artificial teeth to heat cure acrylic and high impact heat cure acrylic using autoclave processing method

Author: Mustafa M.J
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 71-77
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Debonding and fracture of artificial teeth from denture bases are common clinical problem, bondingof artificial teeth to heat cure acrylic and high impact heat cure acrylic denture base materials with autoclaveprocessing method is not well known. The aim of this study was to evaluate the effect of autoclave processingmethod on shear bond of artificial teeth to heat cure denture base material and high impact heat cure denturebase material.Materials and methods: Heat polymerized (Vertex) and high impact acrylic (Vertex) acrylic resins were used. Teethwere processed to each of the denture base materials after the application of different surface treatments. Thesample (which consist of artificial tooth attached to the denture base at 45 degree) are consist of (80) artificial teethfrom the same model of central incisor, they were prepared , treated and bonded to the conventional heat curedand high impact acrylic denture base material then processed.Control group (Group A 40 samples) in which acrylic resins PMMA cured by conventional water- bath processingtechnique (74°C for 1.5 hours then boil for 30 minutes),the group was subdivided to 20 samples heat cure acrylic and20 samples high impact acrylic.Experimentalgroups (Group B 40 samples) in which acrylic resins was cured by autoclave at 121°C, 210KPa. For30min.the group subdivided to 20 samples heat cure acrylic and 20 samples high impact acrylic.For each subgroup, the 20 samples were subdivided according to surface treatment into:1-Five acrylic teeth without any surface treatment (control).2- Five acrylic teeth with diatoric preparation (retention grooves).3- Five acrylic teeth conditioned with thinner.4- Five acrylic teeth with retention grooves and thinner.Results: Statistical analysis revealed that chemical and mechanical treatment of acrylic teeth improved the shearbond with heat cure and high impact acrylicalsoautoclave processing improvedthe shear bond with acrylic teeth inhigh impact acrylic.Conclusion: Autoclave polymerization is suggested as alternative method for processing denture base resins.Autoclave polymerization can be easily performed in laboratory conditions. In High Impact Acrylic, there were highlysignificant differences of autoclave processing technique compared with water bath regarding the shear bondstrength with acrylic teeth

الخلفیة:خلع وكسر الأسنان الاصطناعیة من قواعد أسنان ھي من مشاكل الطقم الشائعة، الترابط بین الأسنان الاصطناعیة وقاعدة الطقم بطریقة تسخین الاكریلیكمع طریقة معالجة الأوتوكلاف لیست معروفة جیدا، وكان الھدف من ھذه الدراسة تقییم تأثیر طریقة معالجة الأوتوكلاف على ارتباط الاسنان الاصطناعیة معقاعدة طقم الاسنان .المواد و الاسالیب:تم استعمال الاكریلك الحراري والاكرلك المقاوم للصدمات كمادة لقاعدة الطقم وتم لصق الاسنان لكل نوع من انواع الاكرلك بعد المعالجةالسطحیة تتكون العینات من ثمانین عینة نفس النوع والطراز من السن القاطع الامامي العلوي تم تحضیر الاسنان ومعالجتھا لكل نوع من انواع قاعدة الطقم,المجموعة الرئیسیة تتكون من اربعین عینة مرتبطة بالاكرلك الحراري مطبوخة بطریقة البلمرة المائیة ومقسمة الى عشرین عینة مطبوخة بطریقة البلمرةالمائیة ( 74 ) درجة سلیزیة لمدة( 1.5 ) ساعة وبعد ذلك غلیان لمدة 30 دقیقة ھذه المجموعة مقسمة الى 20 عینة اكرلك حراري و 20 عینة مقاوم للصدمات.المجموعة المختبریة تتكون من اربعین عینة مرتبطة بالاكرلك الحراري ومبلمرة بطریقة الاوتوكلیف وبنفس التقسیمات بالمجموعة الاولى .قسمت العینات تبعاً لطریقة المعاملة السطحیة على :-1 خمسة عینات بدون معاملة سطحیة .-2 خمسة عینات معاملة میكانیكیة بطریقة الاخادید السطحیة .-3 خمسة عینات معاملة كیمیائیة بمادة الثنر .-4 خمسة عینات معاملة میكانیكیاً وكیمیائیاً .الاستنتاج:مع محدودیة البحث یستنتج بأن طریقة الاوتوكلیف للبلمرة من الممكن اعتبارھا الطریقة البدیلة بطریقة البلمرة المائیة او الطبخ المائي وفي الاكرلكالمقاوم للصدمات لوحظ وجود زیادة واضحة احصائیاً لطریقة الاوتوكلیف مقارنتاً بطریقة البلمرة بالطبخ المائي في ما یخصالارتباط القصي السطحي مع الاسنانالصناعیة .


Article
Effect of Recycling on Rheological and Mechanical Properties of High Impact Polystyrene
تأثير عمليات إعادة التصنيع على خواص الانسياب و الخواص الميكانيكية لمادة البولي ستايرين المقاوم للصدم

Author: Sawsan D. A. Shubbar سوسن ضياء احمد شبر
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2010 Volume: 2 Issue: 2 Pages: 103-114
Publisher: University of Kufa جامعة الكوفة

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Abstract

High impact polystyrene (HIPS) was subjected to repeated thermal and shear stresses by different methods, using a high pressure capillary Rheometer, a laboratory extruder and a Brabender plasticorder. The results showed that the recycling of HIPS caused a decrease in the shear stresses and consequently in the viscosity at constant shear rate. The high pressure capillary Rheometer gave a greater decrease than with the Brabender plasticorder. Tensile strength values were progressively decreased with the laboratory extruder, but increased in the case of Brabender mixer; the elongation was decreased in both cases. This work was then applied in a local plant to compare experimental and actual results.

تم تعريض مادة البولي ستايرين المقاوم للصدم إلى اجهادات حرارية و قوى قص بعدة وسائط و طرق تشمل استخدام جهاز الريوميتر الشعري ذو الضغط العالي و جهاز البثق ألمختبري و جهاز خلط المعاجين البوليمريه. حيث أوضحت النتائج أن إعادة التصنيع لمادة البولي ستايرين المقاوم للصدم عن طريق إعادة صهرها و تشكيلها تسبب انخفاضا في اجهادات القص و بالتالي هناك انخفاض في اللزوجة أيضا بثبوت معدلات القص. كما لوحظ أن معدل الانخفاض في اللزوجة عند استعمال جهاز الريوميتر الشعري أعلى من مثيله عند استعمال جهاز البثق ألمختبري ؛ أما في حالة استعمال جهاز خلط المعاجين البوليمريه فقد زادت متانة الشد ولوحظ حصول تناقص في قيمة الاستطالة عند إعادة صهرها و تشكيلها بكلا الجهازين الأخيرين. من ثم تم تطبيق هذا العمل المختبري في احد المعامل المحلية لغرض مقارنة النتائج المستحصله.


Article
Effect of different palatal vault shapes and woven glass fiber reinforcement on dimensional stability of high impact acrylic denture base [Part I]

Authors: Shnay M. Atiyah --- Thekra I. Hamad ذكرى اسماعيل حمد
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2014 Volume: 26 Issue: 4 Pages: 90-94
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Change in palatal vault shape and Reinforcement of high impact acrylic denture base resin may inturn affect the dimensional accuracy of acrylic resin and affecting the fitness of the denture.This study evaluatedtostudy the effect of fiber reinforcement for high-impact acrylic resin denture base with different palatal vault shapeson adaptation or gap space between the denture base and the stone cast and compare with non-fiberreinforcement and effect of palatal vault shapes on adaptation of non-reinforced and fiber reinforced high impactdenture base acrylic resinMaterial and method: Three different palatal vault shapes were prepared on standard casts using CNC (computernumerical control) machine. 60 samples of heat polymerized high impact acrylic resin maxillary denture base werefabricated onto each definitive cast according to manufacturer instruction. Samples divided into three mainexperimental groups represented the three different palatal vault shapes (20 samples for each main group); 1strounded 2nd U-shaped and the 3rd groups V-shaped. Each main group divided into two subgroups (10 samples foreach subgroup) representing non fiber reinforced high impact acrylic group as a control and the fiber reinforcedhigh impact acrylic. The measurements of gap-space changes of denture bases done at two stages, 1st 24 hourafter polymerization and 2nd measurement done after one month storage in distilled water at room temperature.Results and conclusion: Dimensional changes of high impact acrylic denture base not affected by glass fiberreinforcement p-value for all reference pointes ≥ 0.05, while topographical change in maxillary vault shapes effectson the gap-space in non-fiber reinforced high impact acrylic denture base p-value < 0.05 in point one, four, andseven.

المقدمھ:دعم الاكلریلك عالي الصدمات المستخدم في قاعده الطقم ممكن ان یؤثر على الاستقرار البعدي للراتنج الاكلریك ویؤثر بالتالي على ثبوتیھ الطقمالھدف من الدراسھ: ھو بحث تاثیر الیاف االزجاج الداعمھ وتاثیر تغییر شكل القحف على الاستقرار البعدي للطقم العلوي المصنوع من راتنج الاكلریك عالي الصدماتالمواد والطرق المستعملھ:تم تحضیرثلاثھ اشكال من القحف للفك العلوي باستعمال جھاز النحتبالكومبیوتر الرقمي, ثم یستنسخ القالب الحجري باستعمال ماده السلیكون الخاصللحصولعلى 60 قالب صخر . 60 عینھ قاعده طقم علوي من ماده الاكلریك عالي الصدمات تحضر لكل قالب صخري حسب تعلیمات المنشاء . لقیاس التغییر بالابعاد ( 60 عینھ لكل طریقھ):ولكل مجموعھ 20 ,u- وحرف v - تقیس مسافھ الفراغ بین القالب الحجري وقاعده الطقم . ثم العینات تقسم الى ثلاث مجموعات رئیسیھ حسب شكل القحف وھي الدائري ,وشكل حرفعینھ, ثم كل مجموعھ رئیسیھ تقسم لمجموعتین فرعیتین( 10 عینات لكل مجموعھ فرعیھ): مجموعھ فرعیھالاولى تستخدم الاكریلك عالي الصدمات غیر المدعم والمجموعھ الفرعیھالثانیھ تستخدم الاكلریلك عالي الصدمات المدعم بالالیاف الزجاجیھ. كل القیاسات لمسافھ الفراغ بین القالب الحجري وقاعده الطقم تقاس لمرحلتین :المرحلھ الاولى بعد 24 ساعھ منالطبخ والمرحلھ الثانیھ للقیاس تتم بعد 30 یوم من حفظ العینات بالماء المقطر بدرجھ حراره الغرفھ.النتائج: مسافھ الفراغ بین القالب الحجري وقاعده الطقم في الاكریلك عالي الصدمات لاتتأثر بالدعم من الالیاف الزجاجیھ, وتغییر شكل القحف یؤثر على مسافھ الفراغ الموجود بینالقالب الصخري وقاعده الطخم. بالاضافھ تغییر شكل القحف یؤثرعلى مسافھ الفراغ في الراتنج الاكریلك عالي الصدمات الغیر مدعم بینما لایؤثر على الراتنج الاكریلك عالي الصدماتالمدعم بالالیاف الزجاجیھالاستنتاج: تغییرومسافھ الفراغ الموجود بین القالب الحجري وقاعده الطقم لایتاثرباستعمال الیاف الزجاج الداعم, لكن تغییر شكل القحف یؤثر في مسافھ الفراغ في الاكریلك عاليالصدمات


Article
Effect of different palatal vault shapes and woven glass fiber reinforcement on dimensional stability of high impact acrylic denture base [part II]

Authors: Shnay M. Atiyah --- Thekra I. Hamad
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 1 Pages: 92-95
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: Change in palatal vault shape and Reinforcement of high impact acrylic denture base resin may inturn affect the dimensional accuracy of acrylic resin and affecting the fitness of the denture. The aim of study is toevaluate the effect of fiber reinforcement for high-impact acrylic resin denture base with different palatal vaultshapes on linear dimensional change and effect of palatal vault shapes on linear dimensional changes of nonreinforcedand fiber reinforced high impact denture base acrylic resinMaterial and method: Three different palatal vault shapes were prepared on standard casts using CNC (computernumerical control) machine. 60 samples of heat polymerized high impact acrylic resin maxillary denture base werefabricated onto each definitive cast according to manufacturer instruction. Samples divided into three mainexperimental groups represented the three different palatal vault shapes (20 samples for each main group); 1strounded 2nd U-shaped and the 3rd groups V-shaped. Each main group divided into two subgroups (10 samples foreach subgroup) representing non fiber reinforced high impact acrylic group as a control and the fiber reinforcedhigh impact acrylic. The measurements of linear dimensional changes of denture bases done at two stages, 1st 24hour after polymerization and 2nd measurement done after one month storage in distilled water at roomtemperature.Results and conclusion: Linear dimensional changes of high impact acrylic denture base not affected by glass fiberreinforcement p-value in all reference lines ≥ 0.05, while topographical change in maxillary vault shapes effects onthe linear dimensional changes in woven glass fiber reinforced high impact acrylic denture base p-value < 0.05


Article
A Study the Effect of Addition of Silanized Zirconium Oxide Nanoparticles on Some Properties of High-Impact Heat-Cured Acrylic Resin

Authors: Soodad A. Al-Hiloh سوداد الحلو --- Intisar J. Ismail انتصار جميل اسماعيل
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2016 Volume: 28 Issue: 2 Pages: 19-25
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: The incorporation of rubber has not been entirely successful because it can have detrimental effectson the transverse Strength and hence the rigidity of the denture base.Materials and methods: Zirconium oxide nanoparticales were coated with a layer oftrimethoxysilylpropylmethacrylate (TMSPM) before sonication in monomer (MMA) with the percentages 3% byweight then mixed with powder using conventional procedure.(100) samples were prepared and divided into fivegroups according to the test performed ,Each group consisted of 20 specimens and these were subdivided into 2groupsGroup (A): control group (10 specimens of high impact acrylic resin without zirconium oxide) and Group(B):zirconium oxide group(10 specimens of high impact acrylic resin with 3% wt zirconium oxide).The testsconducted were impact strength, transverse strength, indentation hardness(shore D), surface roughness, watersorption and solubility. The results were statistically analyzed using Dunntt t-test.Results: Highly significant increase in impact strength and transverse strength occurred with the incorporation of 3%wt Zirconium oxide nanofiller. A highly significant increase in surface hardness, but the water sorption and solubilitywere significantly decreased with the addition of silanized (ZrO2) Nano particles compared with the control group.nosignificant statistical difference in surface roughness.Conclusions: The addition of silanized ZrO2 Nano particles to high impact heat cure acrylic resin material improves theimpact strength, transverse strength and surface hardness of high-impact heat-cure acrylic resin at the same timethis addition decreases water sorption and solubility. On the other hand there was no change in surface roughnesswith the addition of 3% wt of silanized ZrO2Nano particles


Article
The Effect of Plasma Treatment on Shear Bond Strength of High Impact Acrylic Resin Denture Base Lined with Two Types of Soft Lining Materials after Immersion in Distilled Water and Denture Cleanser

Authors: Shahad Basim Mustafa شهد باسم مصطفى --- Thekra Ismael Hamad ذكرى اسماعيل
Journal: Journal of baghdad college of dentistry مجلة كلية طب الاسنان بغداد ISSN: 16800087 Year: 2015 Volume: 27 Issue: 4 Pages: 44-51
Publisher: Baghdad University جامعة بغداد

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Abstract

Background: In dentistry, dentist takes the advantages of soft lining materials due to the viscoelastic properties. Themajor problem is the adhesion of the soft liner with the denture base material.Materials and Methods: Heat cured of high impact acrylic resin specimens prepared with dimensions 75x13x13mm forshear bond strength test, soft lining material (Refit and Mollosil) with a 3-mm thickness and used to join each twoacrylic blocks. Also four specimens with the same previous dimensions utilized for chemical and physical surfaceanalysis. The specimens grouped as control (without plasma) and experiment (with oxygen plasma) treated highimpact acrylic specimens.Results: Plasma treatment increased the shear bond strength for both Refit and Mollosil soft lining material afterimmersion in distilled water for 30 days as compared with the control group, also there was decrease in shear bondstrength for both Refit and Mollosil soft lining material of the experimental group after immersion in denture cleanserfor 30 days as compared with the control (without plasma treated) group. AFM analysis revealed that oxygenplasma treatment led to formation of (pits and protuberances) that increase the surface area and increase theshear bond between soft liners and high impact acrylic denture base.Conclusions: Oxygen plasma surface treatment was an effective method for increasing adhesion by physicaltopographic surface (due to the plasma etching process which in turn led to removal of some material from thesurface and this led to increase the bond strength).

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