1. Division of Endodontology, Kyushu University Hospital, Kyushu University, Fukuoka, Japan
2. Division of General Dentistry, Kyushu University Hospital, Kyushu University, Fukuoka, Japan
3. Department of Periodontology and Endodontology, Graduate School of Dental Medicine, Hokkaido University, Sapporo, Japan
4. Department of Endodontology and Operative Dentistry, Faculty of Dental Science, Kyushu University, Fukuoka, Japan