1. a Research student, Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Science, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
2. Corresponding author: Dr Aya Kurusu, Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Science, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima Bunkyo-ku, Tokyo, 113-8549, Japan (aya_1122_rsw@yahoo.co.jp)
3. b Assistant Professor, Orthodontic Science, Department of Orofacial Development and Function, Division of Oral Health Science, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan
4. c Professor Emeritus, Tokyo Medical and Dental University, Tokyo, Japan