1. Department of Oral Medicine, School of Dentistry; Kyung Hee University; Seoul Korea
2. Department of Oral and Maxillofacial Pathology; MRC, School of Dentistry, Kyung Hee University; 1 Heogi-dong Dongdaemun-gu Seoul 130-701 Republic of Korea
3. Department of Dentistry, Graduate School; Kyung Hee University; Seoul Korea