Background: One common undesirable side effect of orthodontic treatment with fixed appliances is the development of incipient caries lesions around brackets, particularly in patients with poor oral hygiene. Different methods have been used to prevent demineralization; the recent effort to improve the resistance against the demineralization is by the application of lasers. Materials and method: Thirty human premolars extracted for orthodontic purposes were used to test the effect of two energy level of ER-YAG laser on enamel resistance to demineralization. The brackets were bonded on the teeth and all the labial surface excluding 2 mm area gingival to the brackets were painted with acid resistance varnish. Three groups were generated. The first group was the control group (A), with no treatment was performed. In group II (B)and groups III (C); teeth were irradiated by ER-YAG laser of 200, 60 mj energy respectively. All the teeth were individually subjected to acid challenge cycle for 30 days. After debonding longitudinal sections were taken and examined under stereomicroscope. The enamel demineralization evaluation was done by taking the average of three depths at the centre of the artificial lesion. Also the enamel surface was classified by an experienced investigator according to acid etch pattern. Comparisons of the average depth values of the groups were performed with ANOVA and LSD tests. The statistical significance level was set at p ≤ 0.05. Results: The results revealed that average lesion depth was significantly deeper at the control group than the laser groups, and its significantly deeper in group (B) 200 mj than in group (C) 60 mj, enamel surfaces showed deeper pits and craters than in control group. Conclusions: the decrease in artificial caries lesion depth associated with use of the two laser energy level support the ER-YAG laser as a tool to increase enamel resistance to demineralization and white spot lesion prevention. Key words: Demineralization, ER-YAG, laser.
The proposal of this study is demonstrating a simple vapor sensor for chloroform (CHCI3) utilitizing air gap region of the Mach-Zehnder interferometer (MZI) by using a single mode optical fiber coupler (3 dB) structure. In the last few decades, flammable liquids such as chloroform have been highly used. This chemical liquid has some degrees of carcinogenic effects in humans in addition to acute and chronic exposure results like blurred vision and nausea. The two arms of MZI contain a free space gap utilized to serve the sensing mechanism by adding chemical liquid volumes (0.2, 0.4, 0.6, 0.8, and 1) ml and to set the phase difference with air-gap distance 0.5 mm. The small variation in the effective refractive index of ch
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This research aims to give a splitting structure of the projective line over the finite field of order twenty-seven that can be found depending on the factors of the line order. Also, the line was partitioned by orbits using the companion matrix. Finally, we showed the number of projectively inequivalent -arcs on the conic through the standard frame of the plane PG(1,27)
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The aim of the research is to identify the educational and psychological effects of the positive and negative aspects of using social networking websites. The researcher administered a number of questions to (250) users of different types of social networking websites. He analyzed his research results and obtained a number of results. The research has reached a number of recommendations and suggestion: Regulating the use of social media. Monitoring the parents of the sites used by children in a way that they do not feel they are observers. It is necessary to devote an hour daily to show the importance of real social life for children other than using social media. It is necessary to show the importance of choosing friends who hav
... Show MoreThe cross section evaluation for (α,n) reaction was calculated according to the available International Atomic Energy Agency (IAEA) and other experimental published data . These cross section are the most recent data , while the well known international libraries like ENDF , JENDL , JEFF , etc. We considered an energy range from threshold to 25 MeV in interval (1 MeV). The average weighted cross sections for all available experimental and theoretical(JENDL) data and for all the considered isotopes was calculated . The cross section of the element is then calculated according to the cross sections of the isotopes of that element taking into account their abundance . A mathematical representative equation for eac
... Show MoreThe objective of this study was to assess the impact of the COVID-19 pandemic on healthcare providers (HCPs) at personal and professional levels.
This was a cross-sectional descriptive study. It was conducted using an electronic format survey through Qualtrics Survey Software in English. The target participants were HCPs working in any healthcare setting across Iraq. The survey was distributed via two professional Facebook groups between 7 April and 7 May 2020. The survey items were adopted with modifications from three previous studies of Severe Acute Respiratory Syndrome (SARS) and Avia
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In this study, bauxite and modified bauxite /polymer, which were prepared as an adsorbent surfaces to adsorption of the tetracycline from aqueous solutions. A series of adsorption experiments were conducted to determine the equilibrium time and temperature effect on the adsorption process. The results showed that adsorption was agreed with the Freundlich equation model for the surface of the bauxite. As for the modified bauxite surface, the results were consistent with the Langmuir equation model. The values of the basic thermodynamic functions of the adsorption process were calculated, so the process of adsorption was founded spontaneous and endothermi
Abstract
The research aims to determine the impact of the strategy performance evaluation and of the Standards (leadership, people, knowledge, processes, financial) in the achievement of organizational effectiveness in accordance with the dimensions (planning and setting goals, Exploitation of the Environment, achieve the goals, the ability to adapt, information management and communications) and the relationship between them, the problem of the research in the growing interest in the process of performance evaluation for organizations, the erroneous belief that the performance evaluation activity is useful, and the fact that performance evaluation process is one of the main tasks of the work of the Office of the Inspecto
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The objective of this study was to assess the impact of the COVID-19 pandemic on healthcare providers (HCPs) at personal and professional levels.
This was a cross-sectional descriptive study. It was conducted using an electronic format survey through Qualtrics Survey Software in English. The target participants were HCPs working in any healthcare setting across Iraq. The survey was distributed via two professional Facebook groups between 7 April and 7 May 2020. The survey items were adopted with modifications from three previous studies of Severe Acute Respiratory Syndrome (SARS) and Avia
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