الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
The purpose of the present study was to evaluate the apical leakage of RealSeal SE root canal sealer by utilizing two different preparation techniques, step-back technique and crown-down technique, with different obturation techniques ( thermoplasticized gutta-percha, soft core, vertical condensation and lateral condensation ). Evaluation of microleakage was accomplished using dye penetration test and clearance method then measured by stereomicroscope . Eighty single rooted teeth were used in the present study , The selected teeth were radiographed from two projections, bucco-lingual and mesio-distal to ensure that the single straight root canal with no calcification, pulp stones or internal resorption . Decapitation of the crowns were done at the cemento-enamel junction using a diamond disc and the crowns were discarded . The lengths of the roots were measured just as the file tip appeared at the apical foramen . Teeth were then stored in labeled vials containing 0.09% normal saline solution . The Eighty samples included in this study were randomly divided into two main groups .
Group I : forty samples was prepared by step-back technique .
Group II : forty samples was prepared by Crown-down technique .
Each group was further subdivided into four subgroups ( A, B, C and D ) according to the obturation technique .
Groups 1A : Ten teeth were prepared by step-back technique then obturated by injectable thermoplasticized gutta-percha
groups 1 B : Ten teeth were prepared by step-back technique then obturated by Soft – Core obturation System with ( Real seal ) root canal sealer .
Groups 1 C: Ten teeth were prepared by step-back technique then obturated by vertical condensation gutta percha with (Real seal) roat canal sealer .
Group 1D : Ten teeth were prepared by step-back technique then obturated by lateral condensation gutta percha with ( Real Seal ) Root canal sealer .
Group 2A : Ten Teeth were prepared by crown – down technique then , obturated by injectable thermoplasticized gutta percha with ( Real Seal ) Root canal sealer .
Group 2 B : Ten Teeth were prepared by Crown-down technique then obturated by Soft – Core obturation with ( Real Seal ) root canal sealer .
Group 2 C : Ten Teeth were prepared by Crown-down technique then obturated by vertical condensation gutta percha with ( Real Seal ) root canal sealer .
Group 2 D : Ten Teeth were prepared by Crown-down technique then obturated by lateral condensation gutta percha with ( Real Seal ) root canal sealer .
N.B : ( Real Seal ) root canal sealer will be with the obturation technique in all groups . We used the clearance method to evaluate the dye penetration through the apical seal of the obturation system . The samples were merged in india
ink for 3days,then The roots were merged in nitric acid 3% for dehydration of the roots, then the roots were merged in a mixture of methyl salicylate& alcohol having 1:1 concentration that was change every 24 hours until complete transparency of the root was achieved, so the obturation material together with the dye inside the canal could be visualized and evaluated . The roots were examined under stereomicroscope with magnification*10mp for linear evaluation of the leakage present, then the image was analyzed using computer software program. The results found that there is no significant difference between the two main groups (group 1 : step back technique)&(group 2: crown down technique) but there was a statistically significant difference amoung the four different obturation systems. Especially the injectable thermoplasticized gutta percha showed statistically significantly higher mean dye penteration than soft core obturation, also there was no interaction between the techniques of preparation and the obturation system.