1. Department of Prosthodontics, Oral Science Research Center, Yonsei University College of Dentistry, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea
2. Department of Prosthodontics, Gangnam Severance Dental Hospital, Eonju-ro 612, Gangnam-gu, Seoul 135-720, Republic of Korea
3. Department and Research Institute of Dental Biomaterials and Bioengineering, Yonsei University College of Dentistry, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Republic of Korea
4. Department of Dental Biomaterials, Institute of Biomaterials-Implant, Wonkwang University School of Dentistry, 460 Iksandae-ro, Iksan 570-749, Republic of Korea