الفهرس 
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Abstract
0 - No dye penetration. 1 - Dye penetration into half extension of occlusal wall 2 - Dye penetration more than half of occlusal wall. 3 - Dye penetration into the pulpal wall.
Scoring system used for gingival wall: 0 - No dye penetration. 1 - Dye penetration into half extension of the cervical wall. 2 - Dye penetration into more than half or complete extension of the cervical wall. 3 - Dye penetration into the cervical and axial walls towards the pulp.
B. Microhardness test
A custom made Teflon disk-shaped mold (4mm thickness x 6 mm diameter) was used to prepare thirty composite specimens using the three tested composite materials and divided into 3 groups, each group 10 specimens, according to the composite used.
group B1 : Ten specimens were prepared using Ormocer-based bulk-fill RBC (Admira fusion x-tra).
group B2 : Ten specimens were prepared using nanohybrid bulk-fill RBC (Tetric N Ceram).
group B3 : Ten specimens were prepared using universal nanohybrid RBC (Filtek Z350 XT) which served as a control group.
Each specimen was subjected to hardness testing using Vickers microhardness tester with 50 gm load at 15 sec. Three indentations were made on the top and 3 indentations on the bottom surface no closer than 1mm to the adjacent indentations or the margin of the specimen and the average of the indentations was calculated to determine the hardness value.
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The results regarding the microleakage test showed that, there was significant difference between the three tested groups. Tetric N-ceram bulk fill showed the highest leakage scores. This increased microleakage scores were significant compared with Filtek Z350 XT and Admira Fusion x-tra. Additionally, no significant difference in microleakage score was evident on comparing Admira Fusion x-tra and Filtek Z350 XT groups.
On comparing the microleakage scores at the occlusal with cervical walls for each of the three tested, it was found that the gingival wall in groups A1 and A3 showed significantly higher scores than occlusal one, whereas in group A2 there was no significant difference.
The results of microhardness teste revealed that there was statistically significant difference between the three groups in top and bottom Vickers Hardness Number(VHN). Moreover, when comparing the VHN of top and bottom surfaces for each material, the difference was found significant.