الفهرس 
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Abstract
A total of 270 specimens of three esthetic restorative materials were used in this study. The specimens were divided into three main groups, ninety each, according to the material used (resin-modified glass-ionomer, conventional glass-ionomer and polyacid-modified composite resin). Each of the previously mentioned three main groups was subdivided into six equal subgroups, fifteen each, according to their immersion media used (pH4-pH9).
The materials were tested in aqueous solution adjusted to different pHs to determine the degree of solubility, water sorption and fluoride release. The specimens were weighted using an electronic sensitive balance before and after immersion then the weight difference was calculated, after each prescribed immersion period, each solution into which the specimens was immersed, was subjected to testing the amount of fluoride release using Ion chromatography.
The results showed, the highest fluoride released was from resin-modified galss-ionomer (Photac-Fil) followed by conventional glass-ionomer (Ketac-Fil) and compomer (F2000). In addition, the highest weight gain value was recorded for Photac-Fil, while the lowest weight gain value was recorded for F2000.
Under the conditions of this study, several conclusions could be detected:
1. All materials tested in the study demonstrated the ability to release fluoride.
2. The pH of the environment affected the fluoride released.
3. Regardless of the test period, the resin-modified glass-ionomer (Photac-Fil) released more fluoride compared to other glass-ionomer formulations.
4. Resin-modified glass-ionomer exhibited a greet amount of water sorption in comparison to conventional-glass and compomer.
5. Further studies concerning the long-term clinical behavior of those materials are suggested.