*Masamichi Kato1, Hitoshi Abekura1, Fumiko Nishio2, Koji Morita1, Hanako Umehara1, Kazuko Kagawa1, Kazuhiro Tsuga1
(1. Department of Advanced Prosthodontics, Graduate School of Biomedical and Health Sciences, Hiroshima University, 2. Department of Fixed Prosthodontics, Kagoshima University Graduate School of Medical and Dental Sciences)