Lithuanian University of Health Sciences, Medical Academy, Clinic of Orthodontics, Lukšos- Daumanto str. 6, LT-50106, Lithuania.
Institute of Biology Systems and Genetics, Veterinary Academy, Lithuanian University of Health Sciences, Eiveniu st. 4, Kaunas, LT-47181, Lithuania.
Arch Oral Biol. 2019 Feb;98:220-225. doi: 10.1016/j.archoralbio.2018.11.026. Epub 2018 Nov 26.
To assess the genetic and environmental influences on the variability of human third molar (M3) root mineralization stages via a twin study.
The study sample consisted of 162 same-sex twins (66 dizygotic and 96 monozygotic, mean age: 17.9 years) with normal growth and development. Panoramic radiographs were evaluated to assess root mineralization stages of the upper and lower third molars, using the method of Demirijian et al. (1973). Zygosity was established using 15 specific DNA markers.
Females developed their third molar roots earlier in life than males. Monozygotic twins (MZ) demonstrated higher intra-pair correlations for M3 root development stages than did DZ twins. An ACE model with additive genes, as well as common and specific environmental factors, provided the best explanation of variation in M3 root development. The mineralization of M3 roots showed highly additive genetic determination, varying from 60 to 63%, whereas a common environment contributed from 25 to 27%, and a specific environment only accounted 14% of the total variation, at most.
A considerable proportion of the total variability of the third molar root mineralization rate can be attributed to additive genetic effects, while common and specific environmental effects have a smaller, yet significant, impact.
通过双胞胎研究评估人类第三磨牙（M3）牙根矿化阶段变异性的遗传和环境影响。
研究样本包括 162 对同性别双胞胎（66 对异卵双胞胎和 96 对同卵双胞胎，平均年龄：17.9 岁），生长发育正常。使用 Demirijian 等人（1973 年）的方法，通过全景 X 光片评估评估上下第三磨牙的牙根矿化阶段。使用 15 个特定的 DNA 标记确定同卵性。
女性比男性更早地发育第三磨牙牙根。同卵双胞胎（MZ）的 M3 牙根发育阶段的个体内相关性高于异卵双胞胎（DZ）。具有加性基因以及共同和特定环境因素的 ACE 模型为 M3 牙根发育变化提供了最佳解释。M3 牙根的矿化具有高度的加性遗传决定，从 60%到 63%不等，而共同环境的贡献从 25%到 27%不等，特定环境的贡献最多仅占总变异的 14%。
第三磨牙牙根矿化速度的总可变性相当一部分归因于加性遗传效应，而共同和特定环境效应的影响虽然较小，但却具有重要意义。
