الفهرس 
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Abstract
This study was divided into three parts. The first part measured and compared the marginal adaptation of the three composites. The second part measured and compared the depth of cure of the three composites. While the third part evaluated and compared the microhardness of these composites.
I- Marginal adaptation test:-
A total of sixty human mandibular first molars were used in this study. The teeth were divided into three main groups (20 teeth each) according to the composite resins that were used. In group I Surefil(packable composite) was used as the restorative material, in group II Esthet-X-improved (nanofilled composite)was used, while in group III Glacier(hybrid composite) was used .
II- Depth of cure test:-
Tefflon cylindrical moulds 24mm diameter and 6mm height were used, Cavities of 4mm diameter were machined in the center of the moulds. The composite was then applied and pressed by a glass slab to remove the excess, the composite was cured from one end. Then the mould was inverted and was ready for penetrometer evaluation. Ten specimens were fabricated for each composite restoration of the same shade (A2).
III- Microhardness test:
A total of 30 specimens, ten specimens of each composite restorative material of the same shade (A2) were prepared in a round stainless steel mould of 6mm diameter and 3mm thickness. The composite was then applied into the mould and pressed by a glass slab to remove the excess material. Then the composite was cured from both sides (top and bottom) for 10 seconds each.
The results of the present study were:
1)Highly significant difference in marginal adaptation was found between the three composite resins used.
2)Marginal adaptation of the nanofilled composite was better than the other composite resins used.
3)After specimens storage in artificial saliva, there was a gradual improvement in the marginal adaptability of the specimens.
4)Highly significant difference in depth of cure was found between the three composite resins used.
5)Depth of cure of the packable composite was better than the other two composite resins used.
6)Highly significant difference in microhardness was found between the three composite resins used.
7)Microhardness of packable was better than other composite resins used.
8)There was a strong correlation between the microhardness and the depth of cure for the three composite materials.