Department of Oral Pathology, Radiology, and Medicine, University of Iowa, College of Dentistry, Iowa City, Iowa, USA.
Division of Oral and Maxillofacial Radiology, Oral Diagnostic Sciences Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia.
Orthod Craniofac Res. 2023 Dec;26 Suppl 1:48-54. doi: 10.1111/ocr.12694. Epub 2023 Aug 1.
During embryogenesis of mandible, the initial ossification centre begins at the bifurcation of the inferior alveolar (IA) and the mental nerves. Additionally, in congenital anomalies like craniofacial microsomia (CFM), the IA canal is completely absent on the microsomic side. These observations led us to hypothesise that there may be a morphological integration between these structures - the IA nerve and the mandibular shapes. Therefore, the primary objective of this study was to test for morphological integration between these structures and the secondary objective was to determine if there were shape variations in these structures among skeletal Classes I, II and III subjects.
The sample size of the study is 80 full-head cone-beam computed tomography (CBCT) scans (age 16-56 years).
We retrieved CBCT scans from our archived database using specific inclusion/exclusion criteria. In the de-identified CBCT scans, traditional coordinate landmarks and sliding semi-landmarks were placed on the mandible and the IA canal (proxy for IA nerve). Using geometric morphometric analyses, we tested integration between the IA canal and the mandibular shapes. We used Procrustes ANOVA to test for overall shape variations among the three skeletal classes (Classes I, II and III).
The IA canal and posterior/inferior border of mandible showed strong integration (r-PLS = .845, P = .001). Similar strong integration was also observed between the IA canal and the overall shape of the mandible (r-PLS = .866, P = .001). Additionally, there was a statistically significant variation in overall shape between skeletal Class I and Class II (P = .008) and Class II and Class III (P = .001).
The strong integration between two structures suggests that the IA nerve may play a role in establishing mandibular shape early in development. We posit this may be important in driving mandibular defects seen in CFM, which warrants further investigation.
在颌骨胚胎发育过程中，最初的骨化中心始于下颌下（IA）和舌下神经的分叉处。此外，在颅面小颌畸形（CFM）等先天性畸形中，小颌侧的 IA 管完全缺失。这些观察结果使我们假设这些结构之间可能存在形态整合 - IA 神经和下颌形状。因此，本研究的主要目的是测试这些结构之间的形态整合，次要目的是确定在骨骼 I 类、II 类和 III 类受试者中这些结构是否存在形状变化。
本研究的样本量为 80 例全头颅锥形束 CT（CBCT）扫描（年龄 16-56 岁）。
我们使用特定的纳入/排除标准从存档数据库中检索 CBCT 扫描。在去识别的 CBCT 扫描中，在颏下和 IA 管（IA 神经的代表）上放置了传统坐标标志点和滑动半标志点。使用几何形态测量分析，我们测试了 IA 管与下颌形状之间的整合。我们使用 Procrustes ANOVA 测试了三个骨骼类（I 类、II 类和 III 类）之间的整体形状变化。
IA 管和下颌后/下边界显示出强烈的整合（r-PLS =.845，P =.001）。IA 管和下颌整体形状之间也观察到类似的强烈整合（r-PLS =.866，P =.001）。此外，在骨骼 I 类和 II 类（P =.008）以及 II 类和 III 类（P =.001）之间，整体形状存在统计学上的显著差异。
两种结构之间的强烈整合表明 IA 神经可能在发育早期对下颌形状的建立起作用。我们假设这可能对 CFM 中所见的下颌缺陷很重要，这需要进一步研究。
