Department of Stomatology, Xianyang Central Hospital, Xian yang, 712000, China.
Department of Dermatology, Nuclear Industry 215 Hospital of Shaanxi Province, Xian yang, 712000, China.
Sci Rep. 2024 Oct 21;14(1):24747. doi: 10.1038/s41598-024-76216-0.
Objective The objective of this study was to measure and analyze the joint space, condylar morphology, and thickness of the roof of the glenoid fossa (RGF) in patients with unilateral second molar scissor bite using cone beam CT (CBCT). Methods A total of 80 patients were included in this study. Forty patients with a normal posterior occlusal relationship, who attended the Department of Orthodontics at the First Hospital of Shanxi Medical University from December 2021 to August 2023, were selected as the control group. The experimental group consisted of 40 patients with unilateral second molar scissor bite during the same period. All patients underwent CBCT scanning, and the resulting images were analyzed using the NNT viewer software in multiplanar reconstruction (MPR). Axial, coronal, and sagittal adjustments were made for each patient. Results In the control group, the right and left joint spaces (PS, SS, AS), the height of the upper part of the condyle, and the depth of the glenoid fossa did not show statistically significant differences (P > 0.05). When comparing bilateral condylar morphology and joint space in the experimental group, it was found that the posterior joint space on the scissor bite side was greater than that on the normal occlusion side, while the anterior joint space on the scissor bite side was smaller than that on the normal occlusal side. Additionally, the height of the upper condyle and the depth of the glenoid fossa on the scissor bite side were greater than that on the normal occlusal side, with statistically significant differences (P < 0.05). However, there were no statistically significant differences in SS, internal and external joint diameter, as well as anterior and posterior diameters (P > 0.05). The comparison of the minimum thickness of the roof of the glenoid fossa in both the sagittal and coronal directions between the patients in the experimental group and the control group showed no statistically significant difference (P > 0.05). Furthermore, the asymmetry index of the supracondylar height in the control group was significantly smaller than that in the experimental group, displaying a statistically significant difference (P < 0.05). The differences in the asymmetry indices of the anterior and posterior diameters of the condyle, as well as the inner and outer diameters, were not statistically significant (P > 0.05). When analyzing the position of the condyle in the sagittal direction of the glenoid fossa in the patients of the control group, it was observed that the majority were in the anterior and medial positions, with only 10% and 5% being in the posterior position. However, the analysis of the condyle position in the sagittal direction of the glenoid fossa in the experimental group revealed statistically significant differences (P < 0.05), with the condyle position on the scissor bite side being more anterior. Conclusion Unilateral second molar scissor bite can result in anterior displacement of the condyle, greater height of the condyle superiorly as well as the depth of the glenoid fossa.
目的 本研究旨在使用锥形束 CT（CBCT）测量和分析单侧第二磨牙反𬌗患者的关节间隙、髁突形态和关节窝顶（RGF）的厚度。
方法 本研究共纳入 80 名患者。40 名具有正常后牙咬合关系的患者于 2021 年 12 月至 2023 年 8 月期间在山西医科大学第一医院正畸科就诊，被选入对照组。实验组由 40 名同期单侧第二磨牙反𬌗患者组成。所有患者均接受 CBCT 扫描，并使用 NNT viewer 软件在多平面重建（MPR）中进行图像分析。对每位患者进行轴向、冠状和矢状调整。
结果 在对照组中，右侧和左侧关节间隙（PS、SS、AS）、髁突上部高度和关节窝深度均无统计学差异（P＞0.05）。在实验组中比较双侧髁突形态和关节间隙时，发现反𬌗侧的后关节间隙大于正常咬合侧，而反𬌗侧的前关节间隙小于正常咬合侧。此外，反𬌗侧的髁突上部高度和关节窝深度大于正常咬合侧，差异有统计学意义（P＜0.05）。然而，SS、内外关节直径以及前后直径之间没有统计学差异（P＞0.05）。实验组和对照组患者的关节窝顶矢状和冠状方向最小厚度比较无统计学差异（P＞0.05）。此外，对照组的髁突上突高度的不对称指数明显小于实验组，差异有统计学意义（P＜0.05）。髁突前后直径和内外径的不对称指数差异无统计学意义（P＞0.05）。在分析对照组患者关节窝矢状方向上的髁突位置时，发现大多数位于前内侧位置，仅有 10%和 5%位于后位。然而，实验组关节窝矢状方向上的髁突位置分析显示存在统计学差异（P＜0.05），反𬌗侧的髁突位置更靠前。
结论 单侧第二磨牙反𬌗可导致髁突前移位、髁突上部高度增加以及关节窝深度增加。
