Endodontic treatment procedures in some teeth are still a challenge in clinical practice. Procedural errors, such as separated instruments, perforations, overfilling, under filling, ledges, apical zipping and so on are the direct cause of endodontic failures. In the most clinical cases, in which endodontic failures are diagnosed do not affect the treatment outcome unless a concomitant microbial infection is present. The biological factors of endodontic failures are closely related to microbial infections, which include: no rubber dam placement; application of incorrect irrigants; inability to prepare the canal to working length; missed canals; poor obturation; root fracture; unsatisfied coronal restoration, size of periapical radiolucency. The purpose of this article is to discuss some reasons for the endodontic failure in contemporary clinical practice and minimally invasive treatment.
