Background: Thermocycling simulates the temperature dynamics in the oral environment. This in vitro study done to measure and compare the effect of thermocycling on the shear bond strength of stainless steel and sapphire brackets bonded to human enamel teeth using light cured orthodontic adhesive and debonded at various time, and to measure adhesive remnant index after debonding. Materials and Methods: one-hundred-twenty extracted upper first premolars for orthodontic reason were used in this study; depending on weather thermocycled or not, the sample was divided into two main groups, then within each group 30 teeth were used for stainless-steel brackets (Bionic®) and for sapphire brackets (Pure®). Both groups were subdivided into three groups (n = 10) according to the debond times: I: debond after 24 hour, II: debond after 7 days and III: debond after 30 days. Within 24 hr, half of the sample was thermocycled manually for 500 complete cycles between 5/55°C and the remaining sample was stored in distilled water at room temperature and water was changed daily until debond time for each group was performed. The adhesive remnant index was tested under 20X magnification lens using stereomicroscope. Results and Conclusions: Both bracket types demonstrated high shear bond strength values before thermocycling (P?0.05), whereas after 500 thermocycles, there were significant changes in shear bond strength resulted in marked reduction in the stainless steel brackets than in the sapphire brackets (P?0.05). Shear bond strength values increased with time for both stainless steel and sapphire brackets with and without thermocycling (P?0.05). The tendency of bond failure was increased at the bracket/adhesive interface rather than enamel/bracket interface in the stainless steel brackets whereas at the enamel/bracket interface rather than bracket/adhesive interface in the sapphire brackets.
This play is written in 1932 by Lynn Riggs who is half Cherokee. The play is set in Claremore Mound, Oklahoma almost a century after the Trail of Tears. Riggs presents mixed- blood, young Cherokees to portray a post-colonial state of spiritual loss and disruption of traditional community ties. The new generation lives in darkness, and the title of the play tells about the dramatist's view that night comes to his Cherokee Nation. The Indian ghost is one of the play’s characters. It is an Indian ghost of a warrior. It comes to remind Cherokees of their heritage and traditions. The ghost sees the new generation as nothing as ghosts because they are neither good for themselves nor for their nation. This paper is important as it discu
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Summary:
We are aware that we cannot reach a correct level of understanding of the Arabic language without using the Quran as our main source in our research. Since the word of the Quran that put an end to all words which kneeled before it all the phrases that lead to the showcasing of the Arabic language in its best self.
Arab scientist realized this truth and gave all their attention to the singular and created from it an important subject for their research in the origins of the language and the science behind. Thus, since they dealt with the structure and studied the significance of the context through the use of vocabulary. Therefore, researching Islamic words or the “surat” mentioned in the Qur’an was necessar
The most important topics that constitute the aesthetic and substantive aspect of the theatrical performance represented by the spatial environment of the presentation and the proposed virtual place that contains the technical and artistic elements of the presentation and highlights the strength of influence on it. In light of the above, the researchers divided the topic into four chapters.
The first chapter contained (the methodological framework), which included the research problem with regard to the directing treatments between the directors in establishing or creating theatrical venue, the importance of the research and the aim of the research, and the limits of the research to conclude the chapter by defining the terms.
... Show MoreNew developments imposed different patterns of interactions between major international powers and Iran during 2018, ranging to varying degrees between cooperation and tension, the most important of which is the new measures taken by the United States to withdraw from the nuclear agreement and impose new US sanctions on Iran, which in turn insisted on not responding to pressure to which they are exposed to make changes in their policies and to negotiate again about the main contentious files, especially the nuclear program and ballistic missiles, and the roles they play for crisis countries, especially supporting some armed organizations in Syria, Lebanon, Iraq and Yemen. These differences have put the international forces before difficult
... Show MoreEvery cultural achievement is a creative text, and every text is a group of signs. The Winged Bull sculpture is a sort of text that is not confined to some signs; indeed, its cultural signs go far beyond as they are open-ended, everlasting and it lends itself to various horizons of interpretation. The recipient has to combine the signs of this sculpture, which belong to different patterns, in the pursuit for perfection so that he can decode its media message.
I have tackled this sculpture by adopting a semiotic approach. The semiotic approach is a modern critical approach which is as wide as culture and as rich as knowledge. It has been linked to modernism, which in turn has been linked to modern critical approaches, because it can
At the time when many important political events and evolutions took place, the cinema has been pretty active, and witnessed the historical events before and after the two world wars and the cold war. During the first half of the 20th century, the cinema had great interest from the major countries and their politicians, as well as the commercial turnout of large companies to invest in that field for the profits. In the beginning of the 20th century, the major powers like the Soviet Union, the United States, Germany, Italy, England, and France started to compete in the development of their film industry and the investment of the new medium and the transformation of some famous works of fiction into films that perpetuate their cultur
... Show MoreNations witnessed since its existence a state of wills conflict as a result of the intersection and intertwining of interests, through which it sought to achieve its goals and objectives, and this has often led to direct military conflicts and countless wars, and witnessed the entry into global wars in which humanity lost millions of lives and losses .Despite the great changes in the international arena, especially in recent decades, the conflict of wills has not ceased, although some of its features and forms have changed, and it has become more complicated after the withdrawal of this conflict to international organizations and bodies, including the Security Council. It is mandated under the Charter of the United Nations to wor
... Show MoreThe current study aims to
1) identify the prevalent Enneagram personality types and the academic self among the sixth-grade students of the distinguished secondary schools; 2) the differences of relationship between the Enneagram personality types and the academic self-concept based on gender; 3) identify the correlation between the Enneagram personality types and the academic self-concept; and 4) identify the contribution of each type of personality types to the academic self-concept. To this end, two instrument were used to collect the data: Riso-Hudson’s scale,1995 was administered to measure enneagram types which had translated to the Arabic language by ( al-yassery,2004), the other instrument was
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