Nakayama Mitsuko, Lähdesmäki Raija, Niinimaa Ahti, Alvesalo Lassi
Oral Development and Orthodontics, Oral Health Research Unit, Medical Faculty, University of Oulu, Finland.
Medical Research Center, University hospital of Oulu, Finland.
Am J Hum Biol. 2015 Jul-Aug;27(4):486-93. doi: 10.1002/ajhb.22674. Epub 2015 Apr 18.
The purpose of this study was to observe the expression of Carabelli's trait in maxillary first (M1) and second (M2) permanent molars in relation to tooth crown size and cusp number and to consider the role of the shortage of sex chromosome material in these features during tooth crown development.
The data were derived from dental casts belonging to the KVANTTI Research Project on sex chromosome abnormalities headed by Professor Lassi Alvesalo in Finland. The subjects comprised 86 45,X females, 51 first-degree female relatives, and 150 population control females. Carabelli's trait was divided into three grades and cusp number was classified into two classes in Dahlberg's P12 and P9. The tooth crown diameters were measured with a sliding digital caliper.
M1 in the 45,X females expressed a lower frequency of Carabelli's trait (19.8%) than in the female relatives (37.2%, P < 0.05). There was also a higher frequency of the three-cusp pattern (11.1%) than in the female relatives (2.4%, P = 0.055) or the control females (1.3%, P < 0.001). The expression of Carabelli's trait in M2 was of the same magnitude in the 45,X females and normal controls and was related to tooth crown size, whereas its expression in M1 of the 45,X females was associated with the cusp number rather than the tooth crown size.
The shortage of one X chromosome in females has an influence on the morphology of the lingual cingulum region of the maxillary first permanent molar during tooth crown development.
本研究旨在观察上颌第一恒磨牙（M1）和第二恒磨牙（M2）中卡氏特征的表达与牙冠大小和尖牙数量的关系，并探讨牙冠发育过程中性染色体物质短缺在这些特征中的作用。
数据来源于芬兰拉西·阿尔韦萨洛教授领导的关于性染色体异常的KVANTTI研究项目的牙模。研究对象包括86名45,X女性、51名一级女性亲属和150名正常对照女性。在达尔伯格的P12和P9中，卡氏特征分为三个等级，尖牙数量分为两类。用滑动数字卡尺测量牙冠直径。
45,X女性的M1中卡氏特征的表达频率（19.8%）低于女性亲属（37.2%，P<0.05）。三尖模式的频率（11.1%）也高于女性亲属（2.4%，P=0.055）或对照女性（1.3%，P<0.001）。45,X女性的M2中卡氏特征的表达与正常对照女性的表达程度相同，且与牙冠大小有关，而45,X女性的M1中卡氏特征的表达与尖牙数量有关，而非牙冠大小。
女性缺少一条X染色体对牙冠发育过程中上颌第一恒磨牙舌隆突区域的形态有影响。
