1. Tokyo Medical and Dental University, Department of Restorative Sciences, Cariology and Operative Dentistry, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
2. University of Washington School of Dentistry, 1959 NE Pacific Street, Seattle, Washington 98195, United StatescTokyo Medical and Dental University, International Exchange Center, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
3. National Center for Geriatrics and Gerontology, National Hospital for Geriatric Medicine, Department of Advanced Medicine, Division of Oral and Dental Surgery, 36-3, Gengo, Morioka, Obu, Aichi 474-8511, Japan