Adelaide Dental School, The University of Adelaide, Adelaide, South Australia, Australia.
Adelaide Dental School, The University of Adelaide, Adelaide, South Australia, Australia.
Am J Orthod Dentofacial Orthop. 2024 Dec;166(6):583-594. doi: 10.1016/j.ajodo.2024.07.021. Epub 2024 Oct 4.
The objective of this study was to assess the relative contribution of genes to shape variation in the permanent dental arches in individuals of Western European descent.
The dental casts from 64 monozygotic and 38 dizygotic twins, housed in the Adelaide Dental School's twin record collection, Australia, were assessed. The subjects were of Western European descent, with a mean age of 19.4 ± 5.4 years. Dental casts were scanned using a 3-dimensional scanner (3Shape E4, 3Shape, Copenhagen, Denmark), and landmarks were placed on incisal edges and cusp tips of canines, premolars, and molars. Procrustes superimposition and principal components analysis were applied to examine shape variation. Two-block partial least-squares analysis was used to assess shape covariation between arches. Structural equation modeling was utilized to decompose observed shape variation into genetic and environmental components using the normal assumptions of the twin model.
The first 3 principal components (PCs) of the maxillary and mandibular arch were meaningful, accounting for 53% and 50% of the variation in shape space, respectively. The PCs represented shape variability as follows: PC1 - arch depth-width ratio, PC2 - arch taper, canine position (and first premolar rotation for the mandibular arch), and PC3 - incisor displacement and rotation. Genetic modeling indicated that a model incorporating additive genetic and unique environmental factors optimally explained the observed variation for all meaningful PCs. Within shape space, most of the variation in maxillary and mandibular arches exhibited moderate to high heritability (h = 0.61-0.74). Maxillary and mandibular dental arches had strong and significant shape covariation, with high heritability in their reciprocal influences on shape (h = 0.72-0.74; r coefficient = 0.87; P <0.05).
In this cohort, dental arch shape variation was predominantly influenced by genetic factors. High covariation and heritability were observed between the maxillary and mandibular dental arches. This information may help inform decisions around orthodontic intervention.
本研究旨在评估基因对西欧血统个体恒牙弓形态变异的相对贡献。
评估了澳大利亚阿德莱德牙科学院双胞胎记录收藏中 64 对同卵双胞胎和 38 对异卵双胞胎的牙模。这些研究对象为西欧血统，平均年龄为 19.4±5.4 岁。使用 3D 扫描仪（3Shape E4，3Shape，哥本哈根，丹麦）扫描牙模，在尖牙、前磨牙和磨牙的切缘和牙尖上放置标志点。采用 Procrustes 叠加和主成分分析来研究形态变异。采用两区块偏最小二乘法分析来评估牙弓间的形态协同变化。采用结构方程模型，利用双胞胎模型的正态假设，将观察到的形态变异分解为遗传和环境成分。
上颌和下颌弓的前 3 个主成分（PC）有意义，分别占形态空间变异的 53%和 50%。这些 PC 代表了形态变异性如下：PC1-牙弓深度-宽度比，PC2-牙弓锥度，尖牙位置（下颌弓的第一前磨牙旋转），PC3-切牙位移和旋转。遗传模型表明，纳入加性遗传和独特环境因素的模型可最佳地解释所有有意义 PC 的观察到的变异。在形态空间中，上颌和下颌牙弓的大部分变异表现出中等到高度的遗传力（h=0.61-0.74）。上颌和下颌牙弓之间存在强烈且显著的形态协同变化，其相互影响的形态具有高度遗传力（h=0.72-0.74；r 系数=0.87；P<0.05）。
在本队列中，牙弓形态变异主要受遗传因素影响。上颌和下颌牙弓之间观察到高度的协同变化和遗传力。这些信息可能有助于为正畸干预提供决策依据。
