If the infection or symptoms do not respond to retreatment and the removal of the tooth is not desired, then endodontic surgery can sometimes be attempted.
An incision is made and the gum is lifted allowing access to the root tip. The area can then be treated and sealed. This does allow the existing restoration to be kept, but retreatment usually gives a better result and should be attempted first.
Illustrations reproduced with permission from the American Association of Endodontists