1. Department of Dental Hygiene, Jeonju Kijeon College, Jeonju 54989, Republic of Korea
2. Department of Preventive Dentistry & Public Oral Health, BK21 FOUR Project, Yonsei University College of Dentistry, Seoul 03722, Republic of Korea
3. Department of Dental Hygiene, Dongnam Health University, Suwon 16328, Republic of Korea