Department of Orthodontic Science, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Department of Oral and Maxillofacial Surgery/Orthodontics, Yokohama City University Medical Center, 4-57, Urafune-cho, Minami-ward, Yokohama, 232-0024, Kanagawa, Japan.
Sci Rep. 2024 Oct 6;14(1):23241. doi: 10.1038/s41598-024-74014-2.
Masticatory muscle forces influence craniofacial morphology development. The antegonial notch (Notch) is a bony concavity on the inferior border of the mandible. Considering the Notch is located anteriorly to the insertion of the masseter muscle and varies among individuals, we hypothesised that these muscles influence the formation of the Notch. Therefore, this study aimed to investigate the correlation between mandible morphology and Notch formation. Sixty Japanese patients who visited the Department of Orthodontics at our university hospital were retrospectively evaluated. Morphological and morphometric analyses of the Notch and related craniofacial parameters were conducted using lateral cephalograms taken at the patients' initial visits. Standard values for the Notch area and depth were determined, and the morphology of the Notch and mandible was analysed using Spearman's rank correlation coefficient (p < 0.05). The mean Notch area and depth was 78.71 ± 36.54 mm and 3.11 ± 1.09 mm, respectively. The Notch area was significantly correlated with ramus inclination (p = 0.044, r = 0.261) and with the Y-axis (p = 0.039, r = 0.267). This study indicated that both the masticatory muscles and mandibular growth could contribute to the Notch formation.
咀嚼肌力量影响颅面形态发育。下颌支前缘的下颌切迹（Notch）是下颌骨下缘的一个骨性凹陷。由于 Notch 位于咬肌止点的前方，并且在个体之间存在差异，我们假设这些肌肉会影响 Notch 的形成。因此，本研究旨在探讨下颌形态与 Notch 形成之间的相关性。
我们回顾性评估了 60 名曾在我们大学医院正畸科就诊的日本患者。使用患者初诊时拍摄的侧位头颅侧位片，对 Notch 及相关颅面参数进行形态学和形态计量学分析。确定了 Notch 面积和深度的标准值，并使用 Spearman 秩相关系数（p < 0.05）分析 Notch 和下颌的形态。
Notch 面积和深度的平均值分别为 78.71 ± 36.54mm 和 3.11 ± 1.09mm。Notch 面积与下颌升支倾斜度（p = 0.044，r = 0.261）和 Y 轴（p = 0.039，r = 0.267）显著相关。
本研究表明咀嚼肌和下颌生长都可能有助于 Notch 的形成。
