1. 1 Department of Dental Anesthesiology, Kanagawa Dental University, Yokosuka, Japan
2. 2 Department of Dental Anesthesiology, Nagasaki University, Nagasaki, Japan
3. 3 Department of Dental Anesthesiology, Niigata University, Niigata, Japan
4. 4 Department of Dental Anesthesiology, Hokkaido University, Sapporo, Japan