1. Department of Public Health Science, Dankook University Graduate School, Cheonan-si 31116, Chungcheongnam-do, Republic of Korea
2. Department of Dental Hygiene, Jeonju Kijeon College, Jeonjucheonseo-ro, Jeonju-si 54989, Jeollabuk-do, Republic of Korea
3. Department of Dental Hygiene, College of Health Science, Dankook University, Cheonan-si 31116, Chungcheongnam-do, Republic of Korea