[1] Department of Oral and Maxillofacial Surgery, York District Hospital, North Yorkshire
[2] Department of Gastroenterology, General Hospital, Birmingham
[3] Department of Oral and Maxillofacial Surgery, General Hospital, Birmingham
[4] Department of Microbiology, General Hospital, Birmingham
[5] Department of Oral and Maxillofacial Surgery, York District Hospital, York Y03 7HE, Wigginton Road