1. Graduate School of Science and EngineeringIwate University4‐3‐5, Ueda Morioka Iwate 020‐8551 Japan
2. Division of Operative Dentistry, Department of Restorative DentistryTohoku University Graduate School of Dentistry4‐1 Seiryo‐machi Sendai Miyagi 980‐8575 Japan