Background: Crown preparation of vital teeth involve the removal of a sound tooth structure, and when enamel removed this lead to exposed dentin with an increase in the number of open dentinal tubules also the diameter of dentinal tubules will increase, furthermore lead to increase movement of fluids inside the tubules all that causes post preparation sensitivity. The aim of this study is to evaluate the effect of desensitizing by Er:Cr:YSGG laser on shear bond strength of prepared tooth and resin cement. Materials and methods: Thirty sound maxillary premolars, grouped into three groups(n=10). Group A is the control group, group B irradiated by Er:Cr:YSGG laser with (0.25 W, 20 Hz, 10%water and air), group C irradiated by Er:Cr:YSGG laser with (0.5 W, 20 Hz, 10% water and air). Results: SEM examination showed complete occlusion of opened dentinal tubules after laser irradiation of both groups that irradiated with laser. Statistical analysis showed significant increase in surface roughness in group B and C. SBS was significantly increase in group B with no significant increase in group C. Conclusion: Er:Cr:YSGG laser can occlude open dentinal tubules without and adverse effect on the retention of the restoration, on the contrary it increase bonding strength. And this increasing was significant in group B with (0.25W, 20 Hz, 10 % water and air). suggestion: so the parameters used in group B (0.25 W, 20Hz, 10 % water and air) is recommended for desensitizing prepared tooth and induce enhancement to the bonding strength of resin to tooth surface.
The paper discusses the lack of a uniform definition of politeness due to the constant tension between its universality and language specificity, and argues that some of the theoretical debate could be resolved if the distinction between politeness as a commonsense notion and politeness as a theoretical construct were clearly addressed and acknowledged in the research.
Current research strives to achieve the following aims:
- Develop a scale for dominant values of Tikrit university students.
- Measuring the dominant of Tikrit university students.
- Identifying the significant differences among dominant values of Tikrit university students according to(sex, specialty, time).
- Measuring the dominant values of each one of the six fields of the scale.
- Identifying the differences in dominant values of each field according to the sex variables.
The current research has limi
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ABSTRACT: Polypyrrole and polypyrrole / silver nanocomposites were fabricated by in-situ polymerization employing Ammonium Persulphate as an oxidizing agent. Nanocomposites were synthesized by combining polypyrrole and silver nanoparticles in various weight percentages (0.1%, 0.5%, 3%, 5% and 7% wt.). Crystallographic data were collected using X-ray diffraction. PPy particles were found to have an orthorhombic symmetry. In contrast, PPy/Ag nanocomposites were reported to have monoclinic structure. The crystallite size was determined by XRD using Scherrer equation and considered to be within 49 nm range. DC conductivity of pelletized samples was evaluated in the temperature range of 323.15k to 453.15k. The conductiv
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The derivatives formed after the successive acetylation, esterification and nitration reactions to cholic, deoxycholic, and taurocholic acids were identified to be of the following general strucure: Colt, Where RI=NO3, OH, 0=, or CH3COO. R2=H, NO3, OH, 0-=, or CH3COO. R3=H, NO3,01-1, 0=, or CH3COO. R4=OH, NH(CH2)2S03Na, NH(CH2)2S03H, or OMe. By using U.V-visible and I.R spectrophotometry . The number of hydroxyl groups was determined, purity was checked from T.L.C, Most of these derivatives will find pharmaceutical application.
Pore volume, pore diameter, and pore volume distribution of three of Iraqi natural clay deposites were measured using mercury intrusion porosimetry .The clays are white kaolin, colored kaolin, and bentonite .The results showed that the variation of the pore area of the clay deposites followed the following order :- Coloured Kaolin > White Kaolin > Bentonite While the pore volume may be arranged as in the following sequence:- White Kaolin > Coloured Kaolin >Bentonite Also , Bentonite exhibits the narrow range pore size distribution than the white and coloured kaolin.
This paper deals with the nonlinear large-angle bending dynamic analysis of curved beams which investigated by modeling wave’s transmission along curved members. The approach depends on the wave propagation in one-dimensional structural element using the method of characteristics. The method of characteristics (MOC) is found to be a suitable method for idealizing the wave propagation inside structural systems. Timoshenko’s beam theory, which includes transverse shear deformation and rotary inertia effects, is adopted in the analysis. Only geometrical non-linearity is considered in this study and the material is assumed to be linearly elastic. Different boundary conditions and loading cases are examined.
From the results obtai
... Show MoreThe current research aims to measure Generalized Anxiety Disorder among students of the University of Sulaymaniyah / College of Basic Education, and to identify the significance of differences between sex, scientific specialization and age, and for that reason, the research sample of (102) male and female students was chosen in a random manner, and the researcher used the diagnostic criteria for the generalized anxiety disorder contained He mentioned it in the Statistical and Diagnostic Manual of Psychiatry, and the paragraphs of the scale were formulated according to those standards after they verify the conditions of honesty and consistency, and the use of appropriate statistical means. The results of the research indicated that genera
... Show MoreThe precipitation of calcite induced via microorganisms (MICP) is a technique that has been developed as an innovative sustainable ground improvement method utilizing ureolytic bacteria to soil strengthening and stabilization. Locally isolated Bacillus Sonorensis from Iraqi soil samples were found to have high abilities in producing urease. This study aims to use the MICP technique in improving the undrained shear strength of soft clay soil using two native urease producing bacteria that help in the precipitation of calcite to increase the cementation between soil particles. Three concentrations of each of the locally prepared Bacillus sonorensis are used in this study for cementation reagent (0.25M, 0.5M, and 1M) during
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