目的: 建立下颌骨及乳牙缺失数字化丝圈间隙保持器的三维有限元模型，以探讨下颌第二乳磨牙缺失患者佩戴丝圈间隙保持器时的应力、变形及剪切力情况。方法: 通过对患儿进行锥形束CT(cone beam computed tomography，CBCT)扫描，使用Mimics 21.0软件建立下颌第二乳磨牙缺失的数字模型。利用儿童丝圈间隙保持器设计软件构建冠部固位与丝圈结构一体化的全冠及带环丝圈间隙保持器的数字模型，并分别采用钴铬合金、聚醚醚酮(polyether ether ketone，PEEK)及钛合金三种材料进行构建。在ANSYS Work Beach 2023 R2软件中，对模型46和84的咬合面施加垂直和沿牙体长轴倾斜45°的70 N载荷，以及丝圈上表面10 N载荷，模拟患儿佩戴丝圈间隙保持器时的正中咬合与侧方咬合，分析丝圈间隙保持器及基牙的受力情况。结果: 在不同的加载条件下，带环丝圈间隙保持器的最大主应力明显低于全冠丝圈间隙保持器。应力云图显示，最大主应力峰值出现在丝圈末端与冠部结构连接处，表明这一部位更容易发生断裂；使用PEEK材料制作的带环丝圈间隙保持器内部组织面的最大剪切应力最小；46和84牙齿的等效应力(Von Mises应力)最小，分别为23.18 MPa和36.35 MPa，且最大等效应力分别位于46牙齿近中、84牙齿远中靠近牙根部与丝圈间隙保持器接触的区域。结论: 在第二乳磨牙缺失的情况下，佩戴数字化带环丝圈间隙保持器能够有效分散应力，且PEEK材料的带环丝圈间隙保持器在一定程度上降低了基牙的受力，其在临床应用中显示出一定的优越性。

Objective: To establish a three-dimensional finite element model of a digital wire loop space maintainer for the mandible and primary tooth loss, in order to investigate the stress, deformation, and shear force experienced by patients with the loss of the second primary molar when wearing the wire loop space maintainer. Methods: Cone beam computed tomography (CBCT) scans were performed on the patients to create a digital model of the mandible with the absence of the second primary molar using Mimics 21.0 software. A digital model integrating the crown's retention and the wire loop structure of the full crown and ring wire loop space maintainer was constructed using pediatric space maintainer design software, utilizing three different materials: cobalt-chromium alloy, polyether ether ketone (PEEK), and titanium alloy. In ANSYS Work Beach 2023 R2 software, vertical loads of 70 N, tilted 45° along the long axis of the tooth loads of 70 N, and a 10 N load on the surface of the wire loop were applied to the occlusal surfaces of models 46 and 84, simulating centric and lateral occlusions during chewing with the wire loop space maintainer in place. The stress states of the wire loop space maintainer and supporting teeth were analyzed. Results: Under various loading conditions, the maximum principal stress of the ring wire loop space maintainer was significantly lower than that of the full crown. Stress contour maps indicated that the peak of the maximum principal stress occurred at the junction of the wire loop and crown structure, indicating that this area was more susceptible to fracture. The ring wire loop space maintainer made from PEEK material exhibited the lowest maximum shear stress on the internal organizational surfaces, with equivalent stresses of 23.18 MPa and 36.35 MPa for models 46 and 84, respectively. Stress contour maps demonstrated that the maximum stress on tooth 46 was located at its mesial, while the maximum stress on tooth 84 was situated near the root area on its distal, in contact with the wire loop space maintainer. Conclusion: In cases of second primary molar loss, wearing the digital ring wire loop space maintainer can effectively distribute stress, and the ring wire loop space maintainer made from PEEK material reduces the stress experienced by supporting teeth to some extent, demonstrating its superiority in clinical application.