The aim was to evaluate the effects of different irrigation protocols on the bonding ability of fiber posts on root canal dentin through push-out test and the dentin tubule penetration of luting cement by confocal laser scanning microscope (CLSM). Forty-eight single-rooted premolars were divided into six groups (n=8) based on post space irrigation protocols: Saline 0.85%; Etidronate 18% (HEBP); EDTA 17%; NaOCl 5.25%+EDTA 17%; NaOCl 2.5%/HEBP 9% combination; SmearOFF. Two specimens per group were assessed with CLSM. The push-out test and the failure analysis were performed. Whilst EDTA had the highest bond strength at the coronal and middle thirds, it was not statistically significant compared to saline, HEBP, and NaOCl/HEBP at the middle third (p>0.05). Cement/dentin adhesive failures were predominant (41.9%) and the intratubular fluorescence intensity was significant among the groups (p<0.05). EDTA resulted in highest bond strength values and dentinal penetration.