ORIGINAL ARTICLE Comparison of mesiodistal tooth crown diameters and arch dimensions between modern Mongolians and Japanese Yuh Hasegawa • Bazar Amarsaikhan • Netrporn Chinvipas • Shin-Ichi Tsukada • Kazuto Terada • Satoshi Uzuka • Wataru Miyashita • Satoshi Iguchi • Kazuhito Arai • Ikuo Kageyama • Sen Nakahara Received: 29 June 2012 / Accepted: 14 July 2013 / Published online: 12 September 2013 Ó The Society of The Nippon Dental University 2013 Abstract The purposes of this study were to establish normative data for mesiodistal tooth crown diameters and arch dimensions in Mongolian adults and to compare them with those of Japanese adults. The study materials com- prised dental casts of 100 modern Mongolian and 100 Japanese subjects (50 males, 50 females for each) with Angle Class I normal occlusion. The mean ages were 20 years 8 months for the Mongolian subjects and 20 years 0 months for the Japanese subjects. On the dental casts, the mesiodistal tooth crown diameters (excluding wisdom teeth) and dental arch dimensions were measured. The following arch dimensions were measured: inter-canine lingual, inter-premolar lingual, inter-molar lingual, inter- molar central, coronal arch length, basal arch length, and basal arch width. In the Mongolian samples, significant sex differences were noted, and most of the items were sig- nificantly larger in males than in females. Significant dif- ferences between the Mongolian and Japanese samples were mainly noted in the premolar and molar regions, rather than in the anterior region, and were significantly smaller in the Mongolian samples. In the Mongolian samples, the molar section widths and basal arch width and length were significantly larger in males and females compared with the Japanese samples. These results suggest that the tooth crown size and arch dimensions in the Mongolian samples differed from those in the Japanese samples, and that establishment of the clinical norm for Mongolian adults might be helpful in formulating treat- ment plans for Mongolian patients, given that these parameters are the basic tools for diagnosis. Keywords Mesiodistal tooth crown diameters Á Dental arch dimensions Á Basal arch dimensions Á Dental casts Á Mongolian Y. Hasegawa (&) Á N. Chinvipas Á K. Terada Department of Orthodontics, The Nippon Dental University School of Life Dentistry at Niigata, 1-8 Hamaura-chou, Chuo-ku, Niigata 951-8580, Japan e-mail: haseyu@ngt.ndu.ac.jp B. Amarsaikhan Health Sciences University of Mongolia, Ulaanbaatar, Mongolia S.-I. Tsukada School of Education, Meisei University, Tokyo, Japan S. Uzuka Á W. Miyashita Orthodontic Dentistry, The Nippon Dental University Tokyo Hospital, Tokyo, Japan S. Iguchi Division of Dentistry, Tokyo Metropolitan Children’s Medical Center, Fuchu, Japan K. Arai Department of Orthodontics, The Nippon Dental University School of Life Dentistry at Tokyo, Tokyo, Japan I. Kageyama Department of Anatomy I, The Nippon Dental University School of Life Dentistry at Niigata, Niigata, Japan S. Nakahara The Nippon Dental University School of Life Dentistry at Tokyo, Tokyo, Japan 123 Odontology (2014) 102:167–175 DOI 10.1007/s10266-013-0130-5