University of Oulu

Nakayama M, Kondo O, Pesonen P, Alvesalo L, Lähdesmäki R (2018) Influence of long and short arms of X chromosome on maxillary molar crown morphology. PLoS ONE 13(11): e0207070.

Influence of long and short arms of X chromosome on maxillary molar crown morphology

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Author: Nakayama, Mitsuko1,2,3; Kondo, Osamu4; Pesonen, Paula5;
Organizations: 1Oral Development and Orthodontics, Research Unit of Oral Health Sciences, Medical Faculty, University of Oulu
2Medical Research Center Oulu, Oulu University Hospital
3Department of Anatomy I, Nihon University, School of Dentistry at Matsudo
4Department of Biological Science, Graduate School of Science, University of Tokyo
5Northern Finland Birth Cohorts, Faculty of Medicine, University of Oulu
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 2.4 MB)
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Language: English
Published: Public Library of Science, 2018
Publish Date: 2019-01-30


Although genes on the human X chromosome reportedly influence tooth crown morphology, little is known about X chromosome activation or inactivation systems relevant to morphological variations. We assessed the relationships between tooth crown size and crown morphological traits in females with Turner syndrome, the variants of which include complete absence of one X chromosome, lack of the short arm (Xp), or duplication of the long arms (Xq), and then estimated the functions of Xp and Xq in the process of unilateral X chromosome inactivation during tooth crown development. The mesiodistal and buccolingual diameters in the maxillary first (M1) and second (M2) permanent molars were compared among X chromosome karyotypes by multiple regression analyses, and their relationships with the development of Carabelli’s cusp and the distolingual cusp were analyzed using logistic regression analysis.

The crown sizes increased in the order of the 46,X,i(Xq) karyotype, 45,X and 45,X/46,XX karyotypes, and control group. A lower frequency of Carabelli’s cusp and higher frequency of a reduced distolingual cusp in M1 were characteristics of Turner syndrome. The overall M1 and M2 crown sizes differed among the X chromosome karyotypes, whereas a smaller crown size was associated with a reduced distolingual cusp but not with Carabelli’s cusp. Considering the differences in chromosome arrangement among females with Turner syndrome and the process of unilateral X chromosome inactivation, the observed results can be considered in terms of quantity or number of promoters/inhibitors during tooth crown development.

The X chromosome karyotypes have a strong influence on the overall crown sizes of the M1 and M2 molars because those karyotypes with variable numbers of active gene regions directly influence tooth germ development in an early stage of human odontogenesis. The later forming cusps, such as the distolingual cusp and Carabelli’s cusp, may be affected by this developmental prerequisite.

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Series: PLoS one
ISSN: 1932-6203
ISSN-E: 1932-6203
ISSN-L: 1932-6203
Volume: 13
Issue: 11
Article number: e0207070
DOI: 10.1371/journal.pone.0207070
Type of Publication: A1 Journal article – refereed
Field of Science: 313 Dentistry
3111 Biomedicine
Funding: The KVANTTI research project was supported by grants from the Emil Aaltonen Foundation (; no specific grant number), the University of Turku Foundation (; no specific grant number), and the Academy of Finland (; no specific grant number) to Professor Lassi Alvesalo. This research was supported by Oulu University Hospital and funded by a research award from Scandinavia-Japan Sasakawa Foundation (; no specific grant number).
Copyright information: © 2018 Nakayama et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.