1. Department of Dentistry Oral and Maxillofacial Surgery, Ogaki Municipal Hospital, 4-86 Minaminokawa, Ogaki, Gifu 503-8502, Japan
2. Department of Oral and Maxillofacial Surgery and Stomatology, Okazaki City Hospital, 3-1 Goshoai, Koryuji-cho, Okazaki, Aichi 444-8553, Japan
3. Department of Oral Medicine, King’s College London Dental Institute, WHO Collaborating Centre for Oral cancer/Precancer, Bessemer Road, London SE5 9RS, UK
4. Department of Oral and Maxillofacial Surgery, Yokkaichi Municipal Hospital, Yokkaichi, Mie 510-8567, Japan