1. Department of Oral and Maxillofacial Radiology, Aichi-Gakuin University School of Dentistry, Nagoya, Japan
2. Department of Endodontics, Aichi-Gakuin University School of Dentistry, Nagoya, Japan
3. Department of Oral Radiology, Asahi University School of Dentistry, Mizuho, Japan
4. Department of Electrical, Electronic and Computer Faculty of Engineering, Gifu University, Gifu, Japan