1. Department of Oral and Maxillofacial Radiology, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
2. Department of Oral and Maxillofacial Radiology, Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Hiroshima 734-8553, Japan
3. Department of Oral and Maxillofacial Surgery, Saiseikai Senri Hospital, 1 Chome-1-6 Tsukumodai, Suita, Osaka 565-0862, Japan
4. Department of Preventive Dentistry, Faculty of Dentistry, Khon Kaen University, Amphur Muang, Khon Kaen 40002, Thailand