A large bucco-distal bone defect was revealed at tooth 25 after raising the flap. The area was cleaned of all granulation tissue and carefully inspected with an operation microscope to detect possible vertical fractures or other defects in the root. No signs of such defects were found.

The fistulas closed after the operation but reappeared again some weeks later. A new operation was performed three months after the first operation, and the area was thoroughly cleaned again.

---