الفهرس 
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Abstract
in an attempt to enhance properties of glass ionomer cements, resulting in better mechanical strength, increased translucency and, faster setting times. I use In this study, different ratio of chitosan was employed to prepare in vitro different disks of glass ionomer. Three concentrations of chitosan were selected and prepared in form of aqueous solution dissolved in acetic acid to be studied after mixing with polycarboxylic acid.
CGIC powder / chitosan: polycarboxylic acid liquid; 1/ (0.25:0.75) V. group 2, 1/ (0.5:0.5) V group3 and 1/ (0.75:0.25) V for group 4 then The different disks were subjected to mechamical tests such as (compressive, microshear bond strength and surface hardness) also disks subjected to physical tests as working time setting time film thickness, surface roughness ph measurement fluoride, chitosan release, antibacterial test by inhibition zone and characterized by XRD and FTIR.
X-Ray differaction XRD analysis (XRD)results in our study releaved that disks of CGIC and group 2,3 4. composed of (Aluminum Silicon (Al0.963 Si0.037) and Sodium Silicon Fluoride (Na2 Si F6). But differ in intensity. group1 high intensity where group2and 3least intensity.
Mechanical properties of conventional glass ionomer modified by chitosan were negatively affected by chitosan addition more than 25% in proportion to polycarboxylic acid liquid.
It was found that among all groups, after 24 hrs storage; the highest significant compressissive strength was recorded by group 1 while group4 show least compressissive strength in all interval in which percentage of chitosan high led to Chitosan molecules segregate and interact with one another rather than with GIC components resulting in poor mechanical performance.
Increasing chitosan amount decreased both working and setting time of conventional glass ionomer cement.group 1 showed the highest significant setting time, whereas Group2 was the least significant one CH is explicated by the protonation of the free amino groups (NH2) to NH3+ This is because CH can be considered a strong base as it possesses primary amino groups. The presence of the amino groups indicates that pH substantially alters the charged state. At low pH these amines get protonated and become positively charged.