1. If the infection fails to clear following a conventional root treatment and redoing retreatment looks very challenging because of complicated root anatomy or previous procedural difficulties, then a surgical approach may be justified.
  2. If there is a well-fitting and intact crown/bridge retained by a post & core, then the surgical approach may be justified to resolve this problem so as to avoid the difficulty and expense of having to replace the crowns/bridges.
  3. In a certain number of cases there may be a peri-apical cyst associated with the tooth. These cases first need to be treated with conventional root treatment and then followed by a surgical approach to remove the peri-apical cyst.