الفهرس 
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Abstract
The radiation used in the treatment of tumors that occur in the mouth area has many side effects such as mucositis, skin fungus, and dryness of the mouth due to lack of saliva, difficulty in swallowing, eating and speech, resulting in a spread of tooth decay. In dental science we use the glass ionomer restoration because it has great effectiveness by the antimicrobial properties.
The aim of this study was to determine the effect of various radiation doses and the time difference of radiation exposure to the antibacterial effect of two types of glass ionomer restoration by different types against strains of mutant streptococci, in addition to the effect of different radiation doses in different radiation time on the release of the fluoride ion from the glass ionomer restoration by different types.
A total of 150 samples were used in this study as follows: 100 samples to evaluate the anti-bacterial effect and 50 samples to evaluate the release of fluoride ion from glass ionomer restoration. These samples were classified according to the materials used in two categories; A) Conventional glass ionomer restoration. B) Resin modified glass ionomer restoration.
Each sample of restorations was subjected to two different doses of therapeutic radiotherapy (40 Gy, 60 Gy) at a different time (after 24 hours, after 7 days) of preparation, and samples were not exposed to radiation (control group).
The groups of antibacterial activity test were divided from group (1) to group (10). The groups (1-5) for Fuji II, the groups (6-10) for Fuji IX. Also, the groups of fluoride release test were divided from group (I) to group (X). The groups (I-V) for Fuji II, the groups (VI-X) for Fuji IX.
Agar diffusion test was used to estimate the anti-bacterial properties of glass ionomer restoration against strains of mutant streptococci. When the fluoride release was evaluated, each specimen in this test was immersed in 20ml deionized water. The fluoride ions releases (µg/cm2) from each specimen were measured twice, at the 1st day and the 7th day from exposure to radiation. After 24 hours the specimens are removed and the deionized water was used to measure fluoride ion release in 24 hours after radiation. The specimens that are taken were transferred to tubes filled with 20 ml of deionized water. The water was changed every day until the seventh day. Then, the fluoride ions release was measures in 7th day after radiation from the last 20ml renewed deionized water that was used at the 7th day.
The data from all tests was collected, tabulated and analyzed statistically. Three Way Analysis of variance (ANOVA) for all variables under study was used to study the effect of radiation dose, radiation time and material used their interaction with each other on each of the tests performed. One-way ANOVA followed by Tukey post hoc test was used to compare between two non-related samples. The significance level was set at P ≤ 0.05. Statistical analysis was performed with IBM® SPSS® Statistics Version 20 for Windows.
Under the limitations of this study, these conclusions could be suggested:
1) Antibacterial test in this study was unreliable for the two types of the tested GICs.
2) Fluoride release from the tested GICs following ionizing radiation was material type and radiation dose dependent.
3) Both the times of restorative procedures as well as the radiation were a decision factors regarding to the fluoride release of tested GICs.
And, the following recommendations could be suggested:-
A. Further studies are needed to evaluate the effect of ionizing irradiation in terms of mechanical properties of the two types of the tested GICs.
B. Other Antibacterial tests are needed for antibacterial evaluation of GICs rather than the agar diffusion test.