1. Yasushi Chiba, DDS, graduate student, Nihon University Graduate School of Dentistry, Department of Operative Dentistry, Tokyo, Japan
2. Kanako Yamaguchi, DDS, graduate student, Nihon University Graduate School of Dentistry, Department of Operative Dentistry, Tokyo, Japan
3. *Masashi Miyazaki, DDS, PhD, assistant professor, Nihon University School of Dentistry, Department of Operative Dentistry, Tokyo, Japan
4. Keishi Tsubota, DDS, PhD, instructor, Nihon University School of Dentistry, Department of Operative Dentistry, Tokyo, Japan
5. Toshiki Takamizawa, DDS, PhD, instructor, Nihon University School of Dentistry, Department of Operative Dentistry, Tokyo, Japan
6. B Keith Moore, PhD, professor, director of Graduate Dental Materials, Indiana University School of Dentistry, Department of Restorative Dentistry, Division of Dental Materials, Indianapolis, IN, USA