Background/purpose: The aim of the study was to evaluate the resin–dentin interface with a qualitative scanning electron microscopy (SEM) analysis in endodontically treated teeth restored with selected luting adhesive resins and glass-fiber posts. Materials and methods: Twelve periodontically and orthodontically involved premolars were extracted and used in this study. The crowns of the teeth were sectioned at the cementoenamel junction using a low-speed diamond saw. After post space preparation, the roots were randomly assigned to four groups and restored with different adhesive systems: group 1 used RelyX ARC + Single Bond; group 2 used Panavia F 2.0; group 3 used Clearfil SA Cement; and group 4 used RelyX Unicem (all n = 3). All groups were restored with the same type of glass-fiber post. One day after post cementation, the roots were transversally sectioned in three slices at different levels (apical, middle, and coronal). SEM photographs were taken from four standardized areas of each root section to observe the bonding interface formation, the quality of the hybrid layer, and the density of the resin tags using a four-step (0 to 3) scale method. Results: The mean scores of resin tags found at the 1-, 4.5-, and 8-mm levels were statistically analyzed with the Kruskall–Wallis test to test for significance between and within groups at P < 0.05. Statistical analysis showed that the different adhesive cements affected the resin tag morphology and density of the experimental groups (P = 0.048). Differences among regions (1-, 4.5-, and 8-mm levels) were analyzed in each group and were shown to be statistically significant (Friedman test, P = 0.039). Conclusion: Coronal regions in the root canals showed the best resin tag formation regardless of the different adhesive systems used, and the RelyX ARC group with an etch-and-rinse mechanism exhibited the best resin tag formation of all root canal regions among all groups in the current study.