ABSRTACT Background: Soft liner material is become important in dental prosthetic treatment. They are applied to the surface of the dentures to achieve more equal force distribution , reduce localized pressure and improve denture retention by engaging undercut . So the aim of the study is to evaluate the effect of different surface treatment by air-abrasion AL2O3 and laser treatment with CO2 laser on improving the shear bond strength of the denture liner to acrylic denture base material . Materials and methods: the 30 specimens of heat cured acrylic denture base material (high Impact acrylic )and heat cured soft liner (Vertex ,Nether Lands )were prepared for this study .They were designed and divided according to type of the surface treatment 10 specimens for each group and as follows :Group I without any treatment (control group ), Group II was treated with air-abrasion (AL2O3). While group III was treated with CO2 laser which has continuous pulses with wave length(10.6) micro-meter for (15) seconds . Results: The results revealed that lowest mean values in shear bond strength the specimens treated with AL2O3 (0.498 N/mm2)and control group (0.569 N/mm2)and the highest mean values for the specimens treated with CO2 laser (0.648 N/mm2) . Conclusion: within the limitation of this study ,CO2 laser surface treatment of the heat cure acrylic denture resin with soft liner material resulted in highly significantly increased in shear bond strength values than control and AL2O3 .
Adversity and psychosocial stress are involved in aging through the following pathways. psychological stress enhances the nerve system to secrete endocrine mediators (hormones). Mitochondrial respiration mediates energy production stimulated by binding to these hormones to their receptors. Energy produced by mitochondria accelerates metabolism and, in its turn, leads to increases in reactive oxygen species (ROS) of free radicals. Cellular stress and accumulation of damage can result from an excess of ROS. Accumulation of damage comprises damages in telomeric and nontelomeric DNA, in addition to mitochondrial DNA. Mitochondrial DNA damage plays an important role in increasing the pathway of p53/p21. The expression of the PGC-1α gene is inhi
... Show MoreObjective: To evaluate the antibacterial effect of mastic gum against the most common aerobic oral bacteria and
emphasized on oral streptococci.
Methodology: In this study 10 persons (males and females of 18-60 years old) were randomly assigned to chew
mastic gum (1.5 gm for 45 minutes). Mouth washes were collected before and after gum chewing .The two mouth
washes were diluted (10-1 – 10-6) and cultivated aerobically for 24 hours at 37C0 on BHI agar for total bacterial
count and on MSF agar for counting the oral streptococci.
Results: The results showed that the total bacterial count for staphylococci, Neisseria and oral streptococci on BHI
agar and MSF agar for oral streptococci after mastic chewing were highly r
The present study deals with the experimental investigation of buried concrete pipes. Concrete pipes are buried in loose and dense conditions of gravelly sand soil and subjected to different surface loadings to study the effects of the backfill compaction on the pipe. The experimental investigation was accomplished using full-scale precast unreinforced concrete pipes with 300 mm internal diameter tested in a laboratory soil box test facility set up for this study. Two loading platforms are used namely, uniform loading platform and patch loading platform. The wheel load was simulated through patch loading platform which have dimensions of 254 mm *508 mm, which is used by AASHTO to model the wheel load of a HS20 truck. The pipe-soil system
... Show MoreUnderstanding how wing geometry and internal structural configuration influence vibration behavior is essential for ensuring the aeroelastic stability and structural integrity of modern aircraft. This study presents a comprehensive numerical investigation of the modal and deflection characteristics of aircraft wings with different geometries (symmetric tapered planform and swept-back) and spar configurations (box and I-section) using the finite element method (FEM) in ANSYS Mechanical APDL R.15. Six NACA airfoil profiles (0024, 2411, 2416, 2424, 4412, and 4421) with angle of attack 9° under 50 m/s speed and 1,100 kg pay load were analyzed under identical aerodynamic and material conditions using linear elasti
... Show MoreThe analysis of the classic principal components are sensitive to the outliers where they are calculated from the characteristic values and characteristic vectors of correlation matrix or variance Non-Robust, which yields an incorrect results in the case of these data contains the outliers values. In order to treat this problem, we resort to use the robust methods where there are many robust methods Will be touched to some of them.
The robust measurement estimators include the measurement of direct robust estimators for characteristic values by using characteristic vectors without relying on robust estimators for the variance and covariance matrices. Also the analysis of the princ
... Show MoreThe toxicity effect of some heavy metals (Lead, Cadmium, Copper, and Zinc) on the growth of alga Scenedesmus dimorphus which belongs to the Division of Chlorophyta was studied and depended on the total cell number . The growth rate and doubling time were also calculated accordingly in present of absent of the the heavy metals . There were differences in toxic effects of the metals (p<0.05) . The growth was decreased gradually with alga when exposured to Lead at 15,20 and 25 mg/l in comparison with the control , mean while 30 mg/l caused an acute decrease in growth . Treating the alga with 0.05,0.1,0.5 mg/l concentration of Cadmium the number of cells decreased while at 1 mg/l the effect was more pronounced . As for Copper the conc
... Show MoreTransparent thin films of CdO:Ce has been deposited on to glass and silicon substrates by spray pyrolysis technique for various concentrations of cerium (2, 4, and 6 Vol.%). CdO:Ce films were characterized using different techniques such as X-ray diffraction (XRD), atomic force microscopy(AFM) and optical properties. XRD analysis show that CdO films exhibit cubic crystal structure with (1 1 1) preferred orientation and the intensity of the peak increases with increasing's of Ce contain when deposited films on glass substrate, while for silicon substrate, the intensity of peaks decreases, the results reveal that the grain size of the prepared thin film is approximately (73.75-109.88) nm various with increased of cerium content. With a sur
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