Background: Dimensional changes of acrylic denture bases after polymerization results in need for further adjustments or even ends with technical failure of the finished dentures. The purpose of this study was to estimate the linear dimensional changes for different palatal depths when using multiple investment materials and polymerization techniques. Materials and methods: Ninety upper complete denture bases were constructed for this study. They were divided into two main groups according to the polymerization methods: conventional water bath and experimental autoclave (short and long cycles). Each main group was further subdivided into three subgroups according to the palatal depth (shallow, medium and deep). Furthermore, for each palatal depth; complete denture bases were invested either with dental stone or laboratory silicone. For each upper complete denture, measurements of linear dimensional changes were done by fixation of metallic screws on the tissue surface of the denture base. The distances were measured by using travelling microscope with an accuracy of 0.001 %. The data were statistically analyzed using three way analysis of variance (ANOVA) for three variables, which were (palatal depth, investments and polymerization techniques), LSD test and student T test for comparisons between groups. Results: There were significant improvements in the dimensional accuracy of denture bases cured with autoclave compared with water bath. Also, silicone investments were a successful alternative to stone, study data shows that short autoclave processing with silicone reduces the magnitude of the linear dimensional changes. On the other hand, long autoclave processing and stone investments were better than silicone in reducing dimensional changes. Conclusion: The findings of this study indicates that the use of autoclave processing in acrylic curing is a promising alternative to the conventional water bath and leads to better dimensional stability for the finished dentures in all oral configurations and palatal depths. Also, Silicone is more preferable than stone, although it's not as strong investing materials when compared with stone.
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Ultrasonic absorption, velocity, viscosity, adiabatic compressibility, relaxation time and relaxation amplitude measurements are reported on different concentrations of poly(acrylic acid) solutions in common solvent water using pulsed ultrasonic apparatus technique operating at 26 kHz and 30 ºC. Results show an increase of velocity, viscosity, and absorption coefficient ،relaxation time and relaxation amplitude values with the increasing concentrations of the poly(acrylic acid) solutions, which might be the result of structural fluctuations of polymer molecules such as the segmental motions of the polymer chains. In contrast the compressibility decreases with the increasing concentration of this polymer. This study suggests there i
... Show Moreالزكاة فريضة من فرائض الإسلام وعبادة من العبادات التي اقرها الشرع الإسلامي هذه الفريضة المالية التعبدية بالإضافة الى دورها المعنوي الذي يهدف الى إرساء قواعد العدالة الاجتماعية والقضاء على مشكلة الفقر في المجتمع الاسلامي وكما ينص عليها الدين الإسلامي فان لها ابعادها ووظائفها الكثيرة التي تخدم اليات العمل الاقتصادي في مجتمع يعمل وفق نظام اقتصادي أسلامي .
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Adopting a policy of attracting investments in all countries, whether developing or developed prevailed, especially after the global crisis, and this trend is imposed by considerations of political and development (urban, economic, and social) can be formulated as a rational policy to solve many problems related to patterns of urban growth, economic, social, and including the problem of housing. As the reality of the housing sector in Iraq will require the allocation of substantial resources to promote it by the research problem is the lack of financial resources and the inability of investments to meet the various requirements including the requirements of economic sectors, particularly in the field of housing, infrastructure an
... Show MoreOscillation criteria are obtained for all solutions of the first-order linear delay differential equations with positive and negative coefficients where we established some sufficient conditions so that every solution of (1.1) oscillate. This paper generalized the results in [11]. Some examples are considered to illustrate our main results.
A total of 247 Mallard ( Anas platyrhynchos platyrhynchos L.) from Baghdad and Kut were examined for the Cestodes Diorchis stefanskii Sobolevicanthes gracilis; Hymenolepis mastigopraditae and the Nematode Amidostomum acutum in the first time in Iraq . Among these , 151 birds were found infected by these helminthes It has been found small nodules on the external surface of the intestine , Ulceration of mucosa inflammatory infiltrate , Oedemats changes and hyperplasia in the section of infected intestine were noticed.
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Abstract
The use of modern scientific methods and techniques, is considered important topics to solve many of the problems which face some sector, including industrial, service and health. The researcher always intends to use modern methods characterized by accuracy, clarity and speed to reach the optimal solution and be easy at the same time in terms of understanding and application.
the research presented this comparison between the two methods of solution for linear fractional programming models which are linear transformation for Charnas & Cooper , and denominator function restriction method through applied on the oil heaters and gas cookers plant , where the show after reac
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