There are many case reports about cysts within the bones of the jaws associated with impacted third molars. When osmotic pressure is introduced into a cyst, the cyst expands and displaces the third molar. If continuity of cyst wall is lost, cystic expansion cannot occur, and the cyst cannot displace the third molar. This study analyzed four cases of pathologic migration of the third molar in ruptured cystic lesions that had formed bone tunnels and intraoral fistulas to identify the causes and factors contributing to this migration. Authors hypothesized that closure of fistulas repeated generation of pressure, it may temporarily increase the osmotic pressure within a cyst that has lost its continuity, causing displacement of the third molar. A cyst that has lost its continuity due to fistula formation within the oral cavity can cause ectopic displacement of the adjacent impacted teeth.