1Department of Conservative Dentistry, Division of Endodontology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo, Japan
2Department of Pharmacology, Showa University School of Dentistry, 2-1-1 Kitasenzoku, Ohta-ku, Tokyo, Japan
3Division of Endodontics, Department of Conservative Dentistry, Ohu University School of Dentistry, 31-1 Misumido, Tomita-machi, Koriyama, Fukushima, Japan