الفهرس 
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Abstract
The aim of this study was to compare the bond strength of two adhesive
systems to the canal wall and the fracture resistance of roots obturated by
those systems.
One hundred human, single-rooted, central incisors were cut at CEJ and
mechanically prepared using Revo s system, and then divided into 5
equal groups. Group I: obturated with Activ GP system single cone
technique. Group II:obturated with Real Seal system. Group III:obturated
with Activ GP multiple cones. Group IV: obturated with Gutta percha and
Activ GP sealer with cold lateral compaction technique. Group V: obturated
with Gutta percha and AH plus sealer.
Fifty roots was mounted in acrylic resin cylinder and cut horizontally to
form one 2 mm thick coronal slice and one 2mm thick middle slice .push
out test was done by materials testing machine (Model LRX-plus; Lloyd
Instruments Ltd., Fareham, UK).The mode of failure was examined using
steromicroscope x 40 maginfication.The data of load at which failure occur
was recorded and statistically analyzed using Kurskal-Wallis test to
compare between the five groups. Mann-whitney U test was used for pairwire
comparisons between the groups. Wilcoxon signed-rank test was used
to compare between the two root segments within each group.
The remaining fifty human teeth were selected mounted vertically on acrylic
cylinder leaving 9 mm exposed over acrlylic resin .Specimen was mounted
in the lower fixed compartment of a Materials Testing Machine (Model LRXPlus,
Lloyd Instruments, Fareham, UK). The force at which fracture occur
was recorded and statistically analyzed using Kruskal-Wallis and Mann-
Whitney U tests.
The result regarding push out test in coronal third showed that group V
(GP/ AH Plus ) showed the statistically significant the highest mean while .
Group II ( Real Seal SE system )showed statistically significant lower
mean . There was no statistically significant difference between Group I
(Activ GP system Single cone), Group IV( Activ GP sealer / GP cones) and
Group III (Activ GP multiple cones) ; all showed the statistically significant
lowest mean push-out bond strength values. The result in middle third
showed that no statistically significant difference between the five groups
.The predominant mode of failure of all groups was mixed failure.
The results regarding fracture resistance showed that no statistically
significant difference between Group I (Activ GP Single cone), Group IV
(Activ GP sealer + GP ),Group III Activ GP (multiple cones) and Group II (
Real Seal SE) ; all showed the statistically significant highest mean . Group
V ( AH Plus/GP) showed the statistically significant lowest mean fracture
resistance.
Conclusion:
According to the condition of current study I can concluded that:
1- Single cone technique showed defiance bond strength in comparison
to multiple cone technique however it performed efficiently in
increasing the fracture resistance in comparison to multiple cone
technique.
2- There is no relation between bond strength and increase the fracture
resistance of endodnotically treated tooth.
3- Use of Activ GP point together with Activ GP sealer has no effect on
the bond strength.
4- Resin based sealer is better than glass ionomer sealer in bond
strength in coronal third.
Recommendation:
1- Further investigation is recommended to test the pushout bond
strength in apical one third of the canal.
2- Further investigation is need concern the adaptation of obturation
material to dentine wall using SEM