Aim: The purpose of this study was to analyze the effect of different post-space preparation and irrigation protocol on bond strength of resin cement to root canal dentin.
Methods: Teeth were endodontically treated. After post-space preparation every sample was assigned to one of three groups. In each group different preparation and irrigation protocol was performed as follows: 0.9% saline solution (Group A), 37% phosphoric acid etch which was activated with an ultrasonic tip then rinsed with 10 mL of 0.9% saline solution (Group B), and manipulated with abrasive diamond tapered stone with round end then rinsed with 10 mL of 0.9% saline solution for 10 seconds (Group C). Two parts (coronal and apical) of each sample were analyzed by push out test. Push out bond strength measurements were recorded. 
Results: For coronal part, group C showed the highest significant values followed by Group B followed by Group A. For apical part, group B showed the highest significant values followed by Group A followed by the Group C. For the total; Group B and C showed highest value compared to group A with insignificant difference between B and C. For comparison between Coronal and Apical; Apical section showed a significant lower value compared to Coronal section for all tested groups at p≤0.05. 
Conclusions: Phosphoric acid etch activated with an ultrasonic tip then rinsed with saline solution appeared to be the best mode of preparation and irrigation when self-etch bonding is used since the adhesion interface is made by a thick smear layer.