Cause of apical periodontitis is/are:

Apical periodontitis (AP) may occur in a vital or nonvital tooth. Causes of AP in a vital tooth: Abnormal occlusal contacts High points in restoration Wedging of foreign object between the teeth Traumatic blow to teeth (Eg: Concussion). Causes of AP in a nonvital tooth: Sequelae of pulpal diseases   Iatrogenic Apical extrusion of debris through apical foramen during RCT. Pushing irrigants or medicaments or obturating material through apical foramen.