1. Removable Partial Prosthodontics, Masticatory Function Rehabilitation, Division of Oral Health Sciences, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo, Tokyo 113-8549, Japan; and
2. Department of Removable Prosthodontics, School of Dentistry, Iwate Medical University, 1-3-27, Chuodori, Morioka, Iwate 020-8580, Japan