In the event that infection or a dental cyst persists in the jaw bone following root canal treatment, an apicoectomy may be indicated. It is a surgical procedure in which 3-4 mm of the root end is sectioned from the rest of the root. The existing root filling material is removed and the root end checked for any fractures under a high power microscope. Once cracks in the root are ruled out as the cause for the persistant infection, a bioceramic filling is placed to seal the end of the root from ingress of bacteria. Sometimes a bone graft and/or resorbable membrane is placed to aid in healing.