Background: The accuracy of fitness of any dental casting is imperative for the success of any prosthodontic treatment. From the time that dental casting was first introduced, efforts have been made to produce more accurate and better fitted castings with minimal marginal discrepancy. The aim of this in vitro study was to evaluate the effects of three different investing and burnout techniques on the vertical marginal discrepancies ofceramometalcopings invested with two types of phosphate- bonded investments. Materials and methods: Sixty wax patterns were fabricated on a standardized prepared brass die representing an upper central incisor by the aid of a custom-made split mold. Three different investing and burnout techniques were applied for an Iraqi investment and a commercial type; Group I:Ring investing with conventional burnout technique (RC);Group II: Ringless investing with conventional burnout technique (RLC);Group III: Ring investing with accelerated burnout technique (RA).Twenty wax patterns of each group were divided into two subgroups according to the type of investment material used (10 for each subgroup) represented as (B) for the BellaStar XL and (W) for the WYMvest investments. Complete castings were finished and seated on the metal die. The accuracy of fit of each coping was determined by measuring the vertical marginal discrepancies between the finish line on the metal die and the margins of each coping at four specific reference points on the labial, mesial, palatal, and distal aspects of the die by the aid of a light microscope supplied with a digital camera.The arithmetic mean of each three records was computed and regarded as the amount of the marginal discrepancy of each coping and was used as a unit for the statistical analysis. Results: Mean marginal accuracy for W(RLC)was found to be the least (13.839+4.5724 um) while the highest mean value related to B(RLC) (29.033+2.102 um). In general, ANOVA test showed significant results among the mean values of the Binvestment subgroups while LSD test showed non-significance between the (RA) and both the (RC) and (RLC) subgroups. On the other hand, significance was present between the (RLC) and (RA)of the Winvestment subgroups while non-significance was located between the (RC) and both the (RLC) and (RA) subgroups. Comparing similar subgroups of the two tested investments, the Student's t-test showed non-significance between the (RC) subgroups while high significance was located between the (RLC) and (RA) subgroups respectively.Concerning the vertical marginal discrepancy of the copings, applying the (RC) technique for both investments caused non-statistical significance between the labial, mesial, palatal, and distal aspects.The (RLC) technique caused high significance between the four aspects, while the (RA) technique caused non-significance between the labial aspect only and the others. Conclusion: The Iraqi investment generally produced less vertical marginal discrepancies (using the three different investing and burn-out techniques) than the commercial investment.In order to achieve a better marginal fit, it seems that ceramometalcopings invested with the commercial investment tested are better be cast using the conventional ring investing and burnout technique.
Acidity constants at 30co and 0.125 ionic strength have been determined for the Nitrogous bases of nucleic acid; cytocine, uarcil and thymine, and found to be 3.55 x10-19 , 1.44 x10 -19 and 7.24 x10 -20 respectively. Stability constants of these bases with Thorium and uranyl ions have been determined. Results showed that metal ions Thorium and uranyl ions behave as hard acids and the nitrogenum bases behave as Hard bases according to Pearson's definition .Hardness – softness parameters for these ligands were calculated ,stability constants of complexes with metal ions could be arranged as follows :- Cytosine > Uracil > Thymine .
Background: Surface treatment of machined dental zirconia for enhancement of the adhesion to resin cement, using Er,Cr:YSGG Laser. Materials and Methods: Total number of 42 zirconia disc specimens (9 mm diameter, and 2 mm height) was sintered according to the manufacturer instruction. They are divided into six groups, each group of seven samples. Laser groups (Experiment parameters) were depend on laser total irradiation time, pulse duration, and power. Group (A): 20 sec., 60 µs pulse duration. Group (B): 30 sec., 60 µs pulse duration. Group (C): 40 sec., 60 µs pulse duration. Group (D): 20 sec., 700 µs pulse duration. Group (E): 30 sec., 700 µs pulse duration, with different powers used (1, 1
... Show MoreIn this study, sawdust as a cheap method and abundant raw material was utilized to produce active carbon (SDAC). Physiochemical activation was utilized where potassium hydroxide used as a chemical activating agent and carbon dioxide was used as a physical activating agent. Taguchi method of experimental design was used to find the optimum conditions of SDAC production. The produced SDAC was characterized using SEM to investigate surface morphology and BET to estimate the specific surface area. SDAC was used in aqueous lead ions adsorption. Adsorption process was modeled statistically and represented by an empirical model. The highest specific surface area of SDAC was 688.3 m2/gm. Langmuir and Freundlich isotherms were used to
... Show MoreObjective: The objective of the study was to test the hypothesis, that umbilical cord blood crude serum applied topically with its high concentration of growth factors may promote an early healing for animal models with burn injury.
Methods: Fresh human umbilical cord blood UCBS was collected and screened for transmitted diseases such as hepatitis B, hepatitis C and HIV. Mice and rabbits were scalded by boiling water and chemical burning by NaOH, then treated with UCBS. In comparison with a Cetrimide treated group and a control group (without treatment). The UCBS was subjected to microbial testing to demonstrate the presence or absence of extraneous viable contaminating microorganisms.
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In this article, the solvability of some proposal types of the multi-fractional integro-partial differential system has been discussed in details by using the concept of abstract Cauchy problem and certain semigroup operators and some necessary and sufficient conditions.
The spectral characteristics and the nonlinear optical properties of the mixed donor (C-480) acceptor (Rh-6G) have been determined. The spectral characteristics are studied by recording their absorption and fluorescence spectra. The nonlinear optical properties were measured by z-scan technique, using Q-switched Nd: YAG laser with 1064 nm wavelength. The results showed that the optimum concentration of acceptor is responsible for increasing the absorption and the emission bandwidth of donor to full range and to 242 nm respectively by the energy transfer process, also the efficiency of the process was increased by increasing the donor and acceptor concentration. The obtained nonlinear properties results of the mixture C-480/ Rh-6G showed
... Show MoreThe study is done in the period between (February 20 and October 20) by using ten adult quail Coturnix coturnix (Linnaeus, 1758). The sections are preparing by paraffin method then stain in Harris haematoxylin-eosin. The histological aspects of spinal cord in quail (Coturnix coturnix) the white matter is in the outer part, while the gray matter is arranged in from of X represents its internal part, the dorsal region is called the dorsal horns while the ventral region is called the ventral horns and the central canal cavity, the spinal cord areas appeared as follows: The medial column, column of von Lenhossek, lateral column, dorsal magnocellular column and marginal paragriseal, columns are also called Hoffmann’s nuclei.
Objective(s): To determine the quality of life for adults with a chronic obstructive pulmonary disease.
Methodology: A descriptive study was carried out on (80) patients with a chronic obstructive pulmonary disease from
December 2008 through October 2009 with special inclusion criteria (adult paƟents from 18 years and above exclude
the patients who suffer complication related of disease and from psychological problems and other chronic illnesses.
The data were analyzed through the application of descriptive data analysis approach and inferential data approach.
Result: The study indicated that the determination of QoL for COPD depended on the level of effect .The grades
according to R.S are: "high" effect of disease in
This contribution evaluates the influence of Cr doping on the ground state properties of SrTiO3 Perovskite using GGA-PBE approximation. Results of the simulated model infer agreement with the previously published literature. The modification of electronic structure and optical properties due to Cr3+ doping levels in SrTiO3 has been investigated. Structural parameters infer that Cr3+ doping alters the electronic structures of SrTiO3 by shifting the conduction band through lower energies for the Sr and Ti sites. Substituting Ti site by Cr3+ results the energy gap in being eliminated revealing a new electrical case of conducting material for the system. Furthermore, it has been noticed that Cr doping either at Sr or Ti positions could effectiv
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