Department of Orthodontics, Guangdong Engineering Research Center of Oral Restoration and Reconstruction, Guangzhou Key Laboratory of Basic and Applied Research of Oral Regenerative Medicine, Affiliated Stomatology Hospital of Guangzhou Medical University, Guangzhou, 510182, Guangdong, People's Republic of China.
BMC Oral Health. 2024 Aug 30;24(1):1016. doi: 10.1186/s12903-024-04788-4.
TMJ morphology/position and trabecular structure are influenced by various factors. The role of the interincisal angle, an indicator of the anterior occlusal relationship, on TMJ remains unclear. This study aims to investigate the morphology, trabecular bone structure, and position of the condyle, as well as the glenoid fossa's morphology in skeletal class II populations with different interincisal angles.
A total of 150 adult patients with normodivergent facial types and skeletal class II malocclusions were selected and divided into three groups based on their interincisal angles: normal, small, and large angle groups. The indexes of TMJ were measured using cone-beam computed tomography (CBCT) data and analyzed using Dolphin Imaging, Mimics, and ImageJ.
The small angle group had the smallest anteroposterior diameter (APD), while the large angle group had a greater mediolateral diameter (MLD). The large angle group exhibited significantly the largest maximum axial area, bone surface area, and bone volume (P < 0.05). Small and large angle groups exhibited greater bone trabeculae (Tb. N) and thinner trabecular thickness (Tb. Th). Compared to the normal angle group, the small angle group exhibited a larger horizontal condylar angle and smaller bilateral condylar angles on the axial plane, while the large angle group showed the opposite trend. Small and large angle groups showed a reduced vertical condyle angle on the coronal plane, with the largest reduction observed in the large angle group (P < 0.05). Small and large angle groups had higher heights of the glenoid fossa (GFH). The large angle group exhibited the greatest GFH and width of the glenoid fossa (GFW) (P < 0.05).
The large angle group had elongated oval and large condyles, and deeper glenoid fossae, while a flattened-oval and smaller condyle, and wider and shallower glenoid fossae were observed in the small angle group. Small and large interincisal angle affects the structure of condylar trabeculae, resulting in thinner Tb. Th and greater Th. N. In the condylar position, small and large angle groups exhibit condylar rotation in the axial and coronal planes. Therefore, the interincisal angle affects the morphology, position, and trabecular structure of the TMJ. This implies that we must pay attention to the impact of the interincisal angle on TMJ, and it is crucial to restore the normal interincisal angle during orthodontic treatment.
TMJ 的形态/位置和小梁结构受多种因素影响。切牙间角作为前牙咬合关系的指标，对 TMJ 的影响尚不清楚。本研究旨在探讨不同切牙间角的骨骼 II 类人群中 TMJ 的形态、小梁骨结构和髁突位置以及关节窝形态。
选择 150 名具有正常生长型和骨骼 II 类错畸形的成年患者，根据切牙间角分为三组：正常角组、小角组和大角组。使用锥形束 CT（CBCT）数据测量 TMJ 指标，并使用 Dolphin Imaging、Mimics 和 ImageJ 进行分析。
小角组的前后径（APD）最小，而大角组的横径（MLD）最大。大角组的最大轴向面积、骨表面积和骨体积最大（P<0.05）。小角组和大角组的骨小梁（Tb. N）较多，小梁厚度（Tb. Th）较薄。与正常角组相比，小角组在轴位上的水平髁突角较大，双侧髁突角较小，而大角组则相反。小角组和大角组在冠状面上的垂直髁突角减小，其中大角组减小最大（P<0.05）。小角组和大角组的关节窝高度（GFH）较高。大角组的关节窝高度和宽度（GFW）最大（P<0.05）。
大角组的髁突呈长椭圆形且较大，关节窝较深，而小角组的髁突呈扁椭圆形且较小，关节窝较宽且较浅。小角组和大角组的切牙间角影响髁突小梁结构，导致 Tb. Th 变薄和 Th. N 增加。在髁突位置方面，小角组和大角组在轴位和冠状位上均有髁突旋转。因此，切牙间角影响 TMJ 的形态、位置和小梁结构。这意味着我们必须注意切牙间角对 TMJ 的影响，在正畸治疗中恢复正常切牙间角至关重要。
