Lähdesmäki Raija, Alvesalo Lassi
Department of Oral Development and Orthodontics, University of Oulu and Oulu University Hospital, Finland.
Eur J Orthod. 2006 Aug;28(4):339-44. doi: 10.1093/ejo/cji121. Epub 2006 May 5.
Studies on individuals with sex chromosome anomalies have provided proof of a direct differential promoting effect of the X and Y chromosome genes on tooth crown growth. 45,X/46,XX females are one subgroup of Turner patients who have both normal XX and one X sex chromosome cell lines. Their permanent tooth crown size is reduced, which is mainly due to thin enamel. 45,X females likewise show reduced crown size and enamel thickness, and their root size is reduced. By contrast, the lengths of the roots in 47,XYY males or males with an extra Y chromosome and 46,XY females or females with a male sex chromosome constitution are increased. The aim of the present study was to investigate permanent tooth root lengths in 45,X/46,XX females to obtain additional information on their dental growth. The study group consisted of 15 45,X/46,XX females, mean age 23.4 years; 10 female relatives, mean age 24.5 years; and 47 population control females, mean age 29.8 years, from the Kvantti research project. Root length measurements were made from panoramic radiographs on both sides of the jaw using a sliding digital calliper. The results showed that permanent tooth root lengths in 45,X/46,XX females were, in most cases, significantly shorter than those of the population controls or relatives. It is apparent that a reduced tooth crown size in 45,X/46,XX females is followed by reduced root growth. This begins 3 years after birth and continues to at least 14 years of age. It is suggested that the reduction in crown and root growth in 45,X/4,XX females is due to a deficiency in the amount of dental growth-promoting genes on the sex chromosomes.
对性染色体异常个体的研究已证明X和Y染色体基因对牙冠生长具有直接的差异促进作用。45,X/46,XX女性是特纳综合征患者的一个亚组，她们同时拥有正常的XX和一个X性染色体细胞系。她们的恒牙冠尺寸减小，这主要是由于牙釉质薄。45,X女性同样表现出牙冠尺寸和牙釉质厚度减小，且牙根尺寸也减小。相比之下，47,XYY男性或具有额外Y染色体的男性以及46,XY女性或具有男性性染色体组成的女性的牙根长度增加。本研究的目的是调查45,X/46,XX女性的恒牙牙根长度，以获取有关其牙齿生长的更多信息。研究组由来自Kvantti研究项目的15名45,X/46,XX女性（平均年龄23.4岁）、10名女性亲属（平均年龄24.5岁）和47名群体对照女性（平均年龄29.8岁）组成。使用滑动数字卡尺从颌骨两侧的全景X光片上测量牙根长度。结果显示，在大多数情况下，45,X/46,XX女性的恒牙牙根长度明显短于群体对照或亲属。显然，45,X/46,XX女性牙冠尺寸减小后，牙根生长也会随之减少。这种情况在出生后3年开始，至少持续到14岁。有人认为，45,X/4,XX女性牙冠和牙根生长减少是由于性染色体上促进牙齿生长的基因数量不足所致。
