1. Department of Preventive Dentistry, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.
2. Department of Oral & Maxillofacial Radiology, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.
3. Department of Preventive Dentistry, School of Dentistry, Chonnam National University, Gwangiu, Republic of Korea.
4. Institute of Korea Basic Science, Kyungpook National University, Daegu, Republic of Korea.
5. Brain Korea 21 Project for Medical Science, School of Dentistry, Kyungpook National University, Daegu, Republic of Korea.