Oral Cancer Research Institute, Yonsei University College of Dentistry, Seoul, 120-752, South Korea. kky1004@yuhs.ac|Oral Cancer Research Institute, Yonsei University College of Dentistry, Seoul, 120-752, South Korea. kky1004@yuhs.ac|Oral Cancer Research Institute, Yonsei University College of Dentistry, Seoul, 120-752, South Korea. kky1004@yuhs.ac|Oral Cancer Research Institute, Yonsei University College of Dentistry, Seoul, 120-752, South Korea. kky1004@yuhs.ac|Oral Cancer Research Institute, Yonsei University College of Dentistry, Seoul, 120-752, South Korea. kky1004@yuhs.ac