1. Department of Dental Hygiene, Kangwon National University College of Health Science, Samcheok, Korea.
2. Department of Health Policy and Management, Korea University College of Health Sciences, Seoul, Korea.
3. BK21 PLUS Program in Embodiment: Health-Society Interaction, Department of Public Health Sciences, Korea University Graduate School, Seoul, Korea.
4. Department of Periodontology, Seoul National University School of Dentistry, Seoul, Korea.