The purpose of this study is to investigate the heritability of total rotation, matrix rotation, and intramatrix rotation of the mandible in Korean monozygotic (MZ) twins, dizygotic (DZ) twins, and their siblings. The samples consisted of 75 pairs of Korean twins (39.7 + 9.26 years; MZ group, 36 pairs; DZ group, 13 pairs; sibling group, 26 pairs). Lateral cephalograms were taken, and 13 variables related to internal and external mandible rotation were measured. Three types of occlusal planes (bisected occlusal plane, functional occlusal plane, and the MM bisector occlusal plane) were used to evaluate genetic influence on the occlusal plane. Heritability (h2) was calculated by using the intraclass correlation coefficient (ICC) and Falconer’s method. With regard to mandibular rotation, the MZ twin group showed significantly higher ICC values compared to the DZ twin and sibling groups. The ICC mean values for 13 cephalometric measurements were 0.85 (MZ), 0.62 (DZ), and 0.52 (siblings) respectively. The heritability of the total rotation (0.48) and matrix rotation (0.5) between the MZ and DZ groups was higher than that of the intramatrix rotation (− 0.14). All of the three types of occlusal plane showed high heritability, and among the three types, the functional occlusal plane showed the highest heritability (h2 = 0.76). Based on these findings that showed a strong genetic effect on total rotation and matrix rotation, maintaining these rotations should be carefully considered in the orthodontic treatment plan, while the lower border of the mandible may be responsive to various treatments. Occlusal plane change, especially with regard to the functional occlusal plane, may not be stable due to strong genetic influences.

中文翻译：

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孪生研究—下颌骨和三个不同咬合平面中基质旋转与基质内旋转的遗传比较

本研究的目的是调查韩国单卵（MZ）双胞胎，双卵（DZ）双胞胎及其兄弟姐妹中下颌骨的总旋转，基质旋转和下颌骨旋转的遗传力。样本由75对韩国双胞胎组成（39.7 + 9.26岁； MZ组为36对； DZ组为13对；兄弟姐妹组为26对）。拍摄侧位脑波图，并测量13个与内部和外部下颌骨旋转相关的变量。三种类型的牙合面（一等分牙合面，功能性牙合面和MM二等分牙合面）用于评估遗传对牙合面的影响。遗传力（h2）使用类内相关系数（ICC）和Falconer方法计算。关于下颌旋转 与DZ双胞胎和兄弟姐妹组相比，MZ双胞胎组的ICC值明显更高。13次头颅测量的ICC平均值分别为0.85（MZ），0.62（DZ）和0.52（兄弟姐妹）。MZ和DZ组之间的总旋转（0.48）和矩阵旋转（0.5）的遗传力高于矩阵内旋转（-0.14）。三种类型的咬合面均显示出较高的遗传力，而在三种类型中，功能性咬合面均显示出最高的遗传力（h2 = 0.76）。基于这些显示出对总旋转和基质旋转有强烈遗传效应的发现，在正畸治疗计划中应仔细考虑保持这些旋转，而下颌骨的下边界可能对各种治疗有反应。面平面改变