الفهرس 
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Abstract
The current study aimed to evaluate the influence of smear layer removal on internal apical bacterial leakage of root canals obturated utilizing three different obturation techniques.The obturation techniques were single cone,lateral compaction and warm vertical compaction.One hundred and forty freshly extracted human maxillary anterior teeth were decapitated in order to standardize the root length to 15 mm.Protaper rotary files were used to prepare the root canals up to finishing file NO.5(F5), in acrown-down technique.After completion of the cleaning and shaping procedure,the samples were randomly classified into two equal groups according to whether the smear layer was removed or not.Root canals of group A were rinsed with 5 ml of 2.25% NaOCL only,so that the smear layer was left intact,whereas root canals of group B were irrigated with 1 ml of 17% EDTA solution for 1 min,followed by 5 ml of 2,25% NaOCL to remove the smear layer
The external surfaces of the roots,except the apical 2mm were coated with three successive layers of nail polish,and the apical foramina were sealed with sticky wax.Each root canal was then inoculated with 10 u1 of enterococcus faecalis suspension,which had its optical density adjusted to approximately 3 x 10 CFU/ml, by comparing its turbidity to 1 McFarland standard.Thereafter,the coronal orifices were sealed with wax,and the root segments were enclosed in sterile eppendorf tubes of 1.5 ml size and incubated at 37 C for one week.each group of roots was then randomly subdivided into three equal experimental subgroups according to the obturation technique.Root canals of subgroups 1 were obturated with the single cone technique,root canals of the second subgroup were obturated using the lateral compaction technique,while the vertical compaction technique was utilized in subgroup 3
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