1. Department of Oral and Maxillofacial Pathology, School of Dentistry and Research Center for Tooth and Periodontal Regeneration (MRC), Kyung Hee University, Seoul 130-701, Republic of Korea
2. Institute of Cell and Tissue Engineering, College of Medicine, The Catholic University of Korea, Seoul 137-701, Republic of Korea
3. Department of Oral and Maxillofacial Surgery, Kyung Hee University Dental Hospital at Gang-dong, School of Dentistry, Kyung Hee University, Seoul 134-727, Republic of Korea