The recommended length of the apical seal to be maintained after the placement of a post-core following root canal treatment is 5 mm.

- The apical seal is critical to prevent microleakage and bacterial contamination, which can compromise the success of root canal treatment.
- Maintaining an adequate apical seal length ensures the sealed portion of the root canal filling remains intact, preserving the hermetic seal at the apex.
- Studies and endodontic principles suggest that leaving at least 5 mm of gutta-percha apically provides an effective seal against periapical contamination.
- Leaving less than 5 mm may increase the risk of apical leakage and failure.
- While technically feasible to leave longer lengths of gutta-percha, such as 7 or 10 mm, 5 mm is considered the minimum and standard length necessary to balance structural support for the post and maintain apical seal integrity.

This guideline helps practitioners ensure long-term endodontic success when restoring endodontically treated teeth with post-core systems.