下颌骨颏部骨折合并双侧髁突囊内骨折创伤机制的三维有限元分析
[Three-dimensional finite element analysis of traumatic mechanism of mandibular symphyseal fracture combined with bilateral intracapsular condylar fractures].
作者信息
Zhou W, An J G, Rong Q G, Zhang Y
机构信息
Department of Oral and Maxillofacial Surgery, Peking University School and Hospital of Stomatology & National Center of Stomatology & National Clinical Research Center for Oral Diseases & National Engineering Laboratory for Digital and Material Technology of Stomatology, Beijing 100081, China.
Department of Mechanics and Engineering Science, College of Engineering, Peking University, Beijing 100871, China.
出版信息
Beijing Da Xue Xue Bao Yi Xue Ban. 2021 Oct 18;53(5):983-989. doi: 10.19723/j.issn.1671-167X.2021.05.029.
OBJECTIVE
To analyze the biomechanical mechanism of mandibular symphyseal fracture combined with bilateral intracapsular condylar fractures using finite element analysis (FEA).
METHODS
Maxillofacial CT scans and temporomandibular joint (TMJ) MRI were performed on a young male with normal mandible, no wisdom teeth and no history of TMJ diseases. The three-dimensional finite element model of mandible was established by Mimics and ANSYS based on the CT and MRI data. The stress distributions of mandible with different angles of traumatic loads applied on the symphyseal region were analyzed. Besides, two models with or without disc, two working conditions in occlusal or non-occlusal status were established, respectively, and the differences of stress distribution between them were compared.
RESULTS
A three-dimensional finite element model of mandible including TMJ was established successfully with the geometry and mechanical properties to reproduce a normal mandibular structure. Following a blow to the mandibular symphysis with different angles, stress concentration areas were mainly located at condyle, anterior border of ramus and symphyseal region under all conditions. The maximum equivalent stress always appeared on condylar articular surface. As the angle between the external force and the horizontal plane gradually increased from 0° to 60°, the stress on the mandible gradually concentrated to symphysis and bilateral condyle. However, when the angle between the external force and the horizontal plane exceeded 60°, the stress tended to disperse to other parts of the mandible. Compared with the condition without simulating the disc, the stress distribution of articular surface and condylar neck decreased significantly when the disc was present. Compared with non-occlusal status, the stress on the mandible in occlusal status mainly distributed on the occlusal surface, and no stress concentration was found in other parts of the mandible.
CONCLUSION
When the direction of external force is 60° from the horizontal plane, the stress distribution mainly concentrates on symphyseal region and bilateral condylar surface, which explains the occurrence of symphyseal fracture and intracapsular condylar fracture. The stress distribution of condyle (including articular surface and condylar neck) decreases significantly in the presence of arti-cular disc and in stable occlusal status when mandibular symphysis is under traumatic force.
目的
采用有限元分析（FEA）探讨下颌骨正中联合骨折合并双侧髁突囊内骨折的生物力学机制。
方法
对一名下颌骨正常、无智齿且无颞下颌关节疾病史的年轻男性进行颌面CT扫描及颞下颌关节（TMJ）MRI检查。基于CT和MRI数据，利用Mimics和ANSYS软件建立下颌骨三维有限元模型。分析在正中联合区域施加不同角度创伤载荷时下颌骨的应力分布情况。此外，分别建立有或无关节盘的两种模型，以及咬合或非咬合状态的两种工况，比较它们之间应力分布的差异。
结果
成功建立了包含颞下颌关节的下颌骨三维有限元模型，其几何形状和力学性能能够再现正常下颌骨结构。在下颌骨正中联合处以不同角度受到撞击后，在所有工况下应力集中区域主要位于髁突、下颌支前缘和正中联合区域。最大等效应力始终出现在髁突关节面上。随着外力与水平面夹角从0°逐渐增加到60°，下颌骨上的应力逐渐集中于正中联合处和双侧髁突。然而，当外力与水平面夹角超过60°时，应力倾向于分散到下颌骨的其他部位。与未模拟关节盘的工况相比，存在关节盘时关节面和髁突颈部的应力分布显著降低。与非咬合状态相比，咬合状态下下颌骨的应力主要分布在咬合面上，下颌骨其他部位未发现应力集中。
结论
当外力方向与水平面呈60°时，应力分布主要集中在正中联合区域和双侧髁突表面，这解释了正中联合骨折和髁突囊内骨折的发生机制。当下颌骨正中联合受到创伤力时，在存在关节盘且咬合稳定的状态下，髁突（包括关节面和髁突颈部）的应力分布显著降低。
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