1 Division of Oral Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama, 350-0283, Japan. idef@dent.meikai.ac.jp.
2 Division of Oral Pathology, Department of Diagnostic and Therapeutic Sciences, Meikai University School of Dentistry, 1-1 Keyakidai, Sakado, Saitama, 350-0283, Japan.
3 Department of Operative Dentistry, Cariology and Pulp Biology, Tokyo Dental College, 2-9-18 Kandamisaki-Cho, Chiyoda-ku, Tokyo, 101-0061, Japan.