1. Division of Health and Nutrition Survey, Center for Disease and Prevention, Korea Centers for Disease Control & Prevention, Chungju, Korea.
2. Department of Preventive Dentistry, School of Dentistry, Kyungpook National University, Daegu, Korea.
3. Department of Preventive and Public Health Dentistry, College of Dentistry, Gangneung-Wonju National University, Research Institute of Oral Science, Gangneung, Korea.
4. Departments of Preventive & Community Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.