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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
The Effects of Different Investment Materials on Dimensional Accuracy and Surface Roughness of Thermosens Maxillary Complete Dentures

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Abstract

Background: Limited data are available on the dimensional stability and surface roughness of ThermoSens, which is a material used in denture processing. This study aimed to measure the vertical teeth changes and surface roughness of ThermoSens dentures prepared using three different investment materials.Materials and methods: For the dimensional changes test, 30 complete maxillary dentures were prepared using different investment methods: group I, dental stone; group II, silicone putty; and group III, a mixture of dental stone and plaster (ratio, 1:1; n = 10 for each group). Four screws were attached to the dentures: two were attached to the buccal surface of the canine and first molar, and the other two were attached in the flange areas of the canine and first molar in line with the previously mentioned screws. Measurements were made using a micrometer microscope in the wax stage before flasking and in the deflasking stage. The above investment techniques were also used to prepare samples for a surface roughness test (n = 10 per group). These samples were prepared according to the specifications of the American Dental Association. Data were examined using analysis of variance (ANOVA) and the least significant difference (LSD) test.Results: One-way ANOVA and LSD revealed that dimensional changes significantly differed among all groups, except that the vertical teeth changes on the left side did not differ between groups I and II for both the canine and molar regions. Surface roughness was significantly higher in group I than in group II, and in group III than in group II.Conclusion: The use of putty silicone for investing ThermoSens complete dentures reduced dimensional changes and resulted in dentures with a better fit. Surface roughness could be reduced by the addition of a putty silicone layer over the denture before the addition of the second investment layer during denture processing

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