1. Department of Periodontology, Seoul National University School of Dentistry, Seoul, Korea.
2. Department of Biomedical Radiation Sciences, Seoul National University Graduate School of Convergence Science and Technology, Seoul, Korea.
3. Department of Dental Hygiene, Kangwon National University, Samcheok, Korea.
4. Dental Research Institute, Seoul National University School of Dentistry, Seoul, Korea.
5. Department of Oral and Maxillofacial Radiology, Seoul National University School of Dentistry, Seoul, Korea.