Background: Separation and deboning of artificial teeth from denture bases present a major clinical and labortory problem which affect both the patient and the dentist. The optimal bond strength of artificial teeth with denture base reinforced with nanofillers and flexible denture bases and the effect of thermo cycling should be evaluated. This study was conducted to evaluate and compare the shear bond strength of artificial teeth (acrylic and porcelain) with denture bases reinforced by 5% Zirconium oxide nanofillers and flexible bases under the effect of different surface treatments and thermo cycling and comparing the results with conventional water bath cured denture bases. Material and methods: Two types of artificial teeth; acrylic and porcelain were used and prepared for this study. Five specimens of each tooth type were processed to each denture base materials after the application of different surface treatments; these teeth were bonded to heat polymerized, nano composite resin and flexible denture bases. Specimens were thermo cycled and tested for bond strength until fracture with an Instron universal testing machine. Data were analyzed with analysis of variance and student T-test. Photomicrographic examinations were used to identify adhesive and cohesive failures within debonded specimens. Results: The mean force required to fracture the specimens were obviously larger for nanocomposite specimens compared with the heat cured and flexible specimens. The most common failure was cohesive within the tooth or the denture base. With each base material, the artificial teeth which were treated with thinner exhibited highest shear bond strength. Thermocycling had deleterious effect on the flexible denture base specimens. In general, nanocomposite and heat cured groups failed cohesively within the artificial tooth. While the valplastic groups failed adhesively at the tooth denture base interface. Conclusions: Within the limitations of this study, the type of denture base materials and surface treatments of the tooth selected for use may influence the shear bond strength of the tooth to the base. Selection of more compatible combinations of base and artificial teeth may reduce the number of prosthesis fractures and resultant repairs. Key words: acrylic teeth, porcelain teeth, Nano composite denture base, thermo cycling, flexible denture, thinner,
Old Iraq includes the first experiences in establishing the first residential settlements in the Mesopotamian, and model villages designed and the pulp units in it and their natural matter, that made it perennial, and construction continues until now with it. These experiences were the basis for the emergence of the Iraqi civilization and thus the world and the beginning of writing, trade and the religions of the divine since before history, and then the Sumerian, Babylonian and Assyrian civilizations, and their villages that formed the Fertile Crescent.
There is a lack of knowledge and disregard for the distant and near history of Iraq in the field of rural housing, despite Iraq's leadership in this field, with the aim of the re
... Show MoreThe Moslem women between west and Islam ,This study deals with Muslim women
from the west Pont of view in the oriental studies or the western media and how it was
exposed to ill-treatment or evil-eyed by the west due to misunderstanding or it was done on
purpose that they didn’t comprehend how the women deals with Islam ,so this western view
assured that Islam had disparaged the women's position and hindered her freedom, aiming at
stabbing Islam and dislocate the Islamic tissue which is formed from man and women.
This study has established with evidences the distance of this western view from reality
Islam in fact raised and lifted women's position while the western women was living on
the margin of life, robbed
Androgenetic alopecia (AGA) or baldness is a common form of hair loss, affecting men more than women .The exact causes and pathogenesis of baldness are not well understood. A search for new drug is still needed. This study aims to evaluate the role of gonadotropins hormones in hair loss in males and its possibility to be used as treatment target. A total of 78 volunteers 43 with baldness and 35 healthy men were participated in this study. Their age ranged between (20-49) years, the studied groups were divided into two categories: firstly according to age (group1: 20-29 year), (group2: 30-39 year),and (group3: 40-49 year).Secondly according to baldness degree. LH and FSH were measured by using Enzyme Linked Immunosorbent Assay (ELISA) kits.
... Show MoreDirectional control valves are designed to control direction of flow, while actuators maintain required speeds and precise positions. Magnetorheological (MR) fluid is a controllable fluid. Utilizing the MR fluid properties, direct interface between magnetic fields and fluid power is possible, without the need for mechanical moving parts like spools. This study proposes a design of a four-way three-position MR directional control valve, presents a method of building, and explains the working principle of the valve. An analysis of the design and finite elements using finite element method of magnetism (FEMM) software was performed on each valve. The magnetic circuit of the MR valve was analyzed and the performance was simulated. The
... Show MoreAbstract
Praise be to God, Lord of the Worlds, and prayers and peace be upon the most honorable of creation, Muhammad, whom God sent as a mercy to the worlds, and his infallible, pure, and pure family, and his faithful companions
I did not find anyone who studied stylistic structures except for one study, which is (The Literature of Imam Al-Jawad (peace be upon him), a stylistic study by the student Mina Reda Kazem, a master’s thesis), and it did not address the Hadi and the military men (peace be upon them) as the text of those texts. Coherently complementing each other.
I decided to stand by this heritage as a single text in a uniform period of time approximately from the year 195-260 AH, some
... Show MoreThis paper aims to give an overview of acculturation in the literature by means of its explicit definitions, main characteristics, and categorical process. It also foreshadows the significance of acquiring novice culture with particular connection to second language acquisition. Schumann and John Berry underscored acculturation each with its own model of acculturation. In the case of this review, you will realize that Schumann's two main aspects are firmly rooted in berry's model of acculturation as an exclusive description in relation to second language acquisition. Steven Krashen outlined acquiring language from the intellectual and linguistic view of learning, whereas Micheal Long demanded for communication in social perspective. It has
... Show MoreAbstract In this work we introduce the concept of approximately regular ring as generalizations of regular ring, and the sense of a Z- approximately regular module as generalizations of Z- regular module. We give many result about this concept.
Speech is associated with all early term grammar - somewhat - talking about the beginnings of the emergence of grammar, its foundation, and the truth is that this period has remained obscure, what came of them was a novels dealt with a facilitator beginnings as, and this means that what was of grammatical terms in the period of the first generation of grammarians do not constitute in itself, but the initial harbingers of serious way as in the science, and the real beginning of the term grammar mature as orally were at Hebron and Sibawayh evident in the book, then the efforts of the grammarians available until after the term of grammar arrived to what it is .
In this area is (actor) a grammatical terminology, which won at the ancient s
This paper is devoted to the discussion the relationships of connectedness between some types of graphs (resp. digraph) and Gm-closure spaces by using graph closure operators.