An apicoectomy is done only after a tooth has had at least one root canal procedure and retreatment has not been successful or is not possible.
Apicoectomy, is occasionally needed when inflammation or infection persists at the apex of the root after a root canal procedure. In this microsurgical procedure, the endodontist will lift the gum away from the bone in the area of the tooth and remove any inflamed or infected tissue.
To complete the apicoectomy, the endodontist will clean and seal the end of the tooth’s canal. A small filling may be placed to seal the end of the root canal. An x-ray will be taken to make sure the filing is properly placed. Once this is done the endodontist will reposition the gum tissue and stiches will be placed to help the tissue heal. Subsequent post op appointments may be required to monitor healing of the bone.
Source: American Association of Endodontists