1. Nihon University Graduate School of Dentistry at Matsudo, Oral Function and Rehabilitation, Matsudo, Chiba 271-8587, Japan
2. Division of Oral Function and Rehabilitation, Department of Oral Health Science, Nihon University School of Dentistry at Matsudo, Matsudo, Chiba 271-8587, Japan
3. Department of Removable Prosthodontics, Tsurumi University School of Dental Medicine, Kanagawa, Japan