1. Department of Oral and Maxillofacial Surgery II, School of Dentistry, Aichi-Gakuin University, Nagoya, Japan
2. Preventive Dentistry, Niigata University, School of Dentistry, Niigata, Japan
3. Oral Medicine and Pathology, Guy's, King's, and St Thomas' Dental Institute, WHO Collaborating Centre for Oral Cancer and Precancer, King's College, London, UK
4. Bureau of International Cooperation, International Medical Center of Japan, Tokyo, Japan
5. Oral and Maxillofacial Surgery, Osaka Prefectural Hospital, Osaka, Japan