Institute of Dentistry, University of Oulu, Finland.
Acta Odontol Scand. 2010 Jul;68(4):223-7. doi: 10.3109/00016357.2010.490954.
Previous studies have demonstrated differential effects of the X and Y chromosomes on dental development. The expression of sexual dimorphism in terms of tooth size, shape, number and developmental timing has been explained especially by Y chromosome influence. The Y chromosome promotes enamel, crown and root dentin development. The X chromosome has an effect on enamel deposition. The aim of this research is to study the influence of the extra X chromosome on the development of permanent tooth root length.
The study subjects (all of whom were from the Kvantti Dental Research Project) were seven 47,XXX females, five female relatives and 51 and 52 population control men and women, respectively. Measurements were made from panoramic radiographs on available permanent teeth by a digital calliper according to established procedures.
The results showed that the maxillary root lengths of the 47,XXX females were of the same magnitude as those in normal women, but the mandibular root lengths were longer in 47,XXX females than in normal men or women.
Increased enamel thickness in the teeth of 47,XXX females is apparently caused by the active enamel gene in all X chromosomes having no increased influence on crown dentin formation. These results in 47,XXX females indicate an increase in root dentin development, at least in the mandible, which together with the data on crown formation reflects a continuous long-lasting effect of the X chromosome on dental development.
先前的研究表明 X 和 Y 染色体对牙齿发育有不同的影响。牙齿大小、形状、数量和发育时间的性别二态性表达，特别是通过 Y 染色体的影响得到了解释。Y 染色体促进牙釉质、牙冠和牙根牙本质的发育。X 染色体对牙釉质沉积有影响。本研究旨在研究额外的 X 染色体对恒牙牙根长度发育的影响。
研究对象（均来自 Kvantti 牙科研究项目）为 7 名 47,XXX 女性、5 名女性亲属以及 51 名和 52 名分别来自人群对照的男性和女性。通过数字卡尺根据既定程序从全景放射片中测量现有恒牙的根长。
结果表明，47,XXX 女性的上颌根长与正常女性相同，但下颌根长比正常男性或女性长。
47,XXX 女性牙齿的牙釉质厚度增加显然是由于所有 X 染色体上活跃的釉质基因对牙冠牙本质形成没有增加的影响。这些 47,XXX 女性的结果表明牙根牙本质发育增加，至少在下颌，这与牙冠形成的数据一起反映了 X 染色体对牙齿发育的持续持久影响。
