الفهرس 
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Abstract
The aim of this study was to evaluate the effect of four final irrigants. (Distilled water, Chlorohexidine, Chlorohexidine + Ethanol and Ascorbic acid) on the push out bond strength of AH Plus sealer.
A total of fourty human single-rooted teeth were used in this study. Teeth were decronated, cleaned and shaped using crown down technique. Samples were divided into four groups (n=10) according to the final irrigation protocols: Group 1 Distilled water (control group), Group 2: 2% Chlorohexidine, Group 3: 2% Chlorohexidine + 99% Ethanol, Group 4: 10% Ascorbic acid , and each group was divided into two subgroups (n=5) according to presence or absence of solution activation.
Teeth were obturated using AH Plus sealer by the lateral condensation technique. The shear bond strength was evaluated using the push out test by the universal testing machine, while the failure mode was analyzed using digital microscope for all tested samples.
Results of the bond strength showed that group 4 (ascorbic acid) statistically recorded the highest bond strength followed by group 2( Chx) and followed by group 1 (D.water). The lowest bond strength was recorded with group 3 (Chx + ethanol) P≤0.05.
Agitation subgroups showed higher push out bond strength than the non-agitation subgroups in all groups but this is statistically non-significant p>0.05.
As regard canal regions: The coronal part showed the highest bond strength followed by the middle and the least were recorded in the apical part, in all groups and differences were statistically significant P≤0.05.
The failure mode analysis revealed a predominance of mixed failure in all groups only group 1 which showed adhesive failures.
Within the limitation of this study, it can be concluded that:
1. Bond strength of resin sealers to radicular dentin is adversely affected by NaOCl irrigation.
2. Ascorbic acid & CHX are able to improve the bond strength of resin sealers to coronal dentin.
3. The use of ethanol to Chx adversely affected the bond strength of resin sealers to coronal dentin