Persistent apical periodontits associated with endodontically treated teeth – A review

Apical periodontitis, a chronic inflammatory lesion of the periradicular tissue, is caused by etiological agents of endodontic origin. It is considered as a potent communication between microbiological factors and defense system of the host at the interface of periodontal ligament and infected radicular pulp. Endodontic treatment failure is often characterized by the existence of post-treatment apical periodontitis, which may be persistent, recurrent or emergent. The major etiology of persisting disease is an intraradicular infection, however in certain cases a secondary intraradicular infection due to factors like leakage from the coronal part of the tooth or an extraradicular infection may be the cause of failure.