الفهرس 
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Abstract
This in vitro study was conducted to evaluate an experimental Glass Ionomer Cement(GIC) modified by nanogold, nanosilver and a mixture of both with different ratios regarding antibacterial, some mechanical and physical properties. A total of 441 specimens were prepared. Ketac Cem Radiopaque powder (GIC) was used and divided into seven groups according to the liquids used in mixing. The antibacterial effect was evaluated against Streptococcus Mutans using the agar diffusion test.
For shear bond strength test, 70 human premolars teeth were used . Roots were removed and the proximal surfaces ground exposing the dentin and mounted in self-cured acrylic resin blocks, specimens of glass ionomer cement from each group were prepared, stored in distilled water at 37o c for 24 h and shear bond strength was evaluated using a Universal Testing Machine at across head speed 0.5 mm/min.
For mechanical tests a total of 140 specimens were prepared using a split Teflon molds of 4mm diameter and 8 mm thickness for compressive strength test and 6mm diameter and 3 mm thickness for diametral tensile strength test, stored for 24 h in distilled water then subjected to compressive load using a universal testing machine.
For water sorption and solubility tests, a total of 140 specimens of 10 mm diameter and 2 mm thickness were prepared, weighed, immersed in distilled water for a week at 37oc immediately weighed then transferred to a desiccator to reach a constant weight. Water sorption and solubility were calculated by changes in weight. Corrected water sorption was calculated by adding the solubility value to water sorption value.
Setting time was done according to ISO 9917-1 standard. The obtained results were submitted to statistical analysis using One Way ANOVA and Tukey’s post-hoc test.
The results of agar diffusion test showed that GIC modified with nanogold significantly increased the antibacterial effect as compared to the control group . The addition of nanosilver, a mixture of nanogold and nanosilver with a ratio of 2:1 and 1:2 showed non-significant differences with the control group and the ratio 1:1 significantly decreased the antibacterial effect. The results of shear bond strength showed non-significant differences between all tested groups.
The results of mechanical tests showed that, modifications of GIC with nanogold, nanosilver and a mixture of both with different ratios showed higher insignificant increase in mean values of compressive and diametral tensile strength.
Water sorption percent of GIC modified with nanogold, nanosilver and a mixture of both with a ratio of 1:1showed no significant differences compared to the control group while a ratio 2:1and 1:2 showed significant decrease as compared to the control group.
Water solubility percent increased significantly in all tested groups compared to the control group. For the corrected water sorption% there was significant increase in GIC modified with nanogold and a mixture with ratio of 1:2 as compared to the control group while modified with nanosilver, a ratio of 1:1and 2:1 showed no significant differences as compared the control group. For setting time all tested groups with the accepted range of ISO standard.