Journal of Zhejiang University-SCIENCE B

, Volume 19, Issue 1, pp 38–48 | Cite as

A finite element analysis of the stress distribution to the mandible from impact forces with various orientations of third molars

  • Yun-feng Liu
  • Russell Wang
  • Dale A. Baur
  • Xian-feng Jiang



To investigate the stress distribution to the mandible, with and without impacted third molars (IM3s) at various orientations, resulting from a 2000-Newton impact force either from the anterior midline or from the body of the mandible.

Materials and methods

A 3D mandibular virtual model from a healthy dentate patient was created and the mechanical properties of the mandible were categorized to 9 levels based on the Hounsfield unit measured from computed tomography (CT) images. Von Mises stress distributions to the mandibular angle and condylar areas from static impact forces (Load I-front blow and Load II left blow) were evaluated using finite element analysis (FEA). Six groups with IM3 were included: full horizontal bony, full vertical bony, full 450 mesioangular bony, partial horizontal bony, partial vertical, and partial 450 mesioangular bony impaction, and a baseline group with no third molars.


Von Mises stresses in the condyle and angle areas were higher for partially than for fully impacted third molars under both loading conditions, with partial horizontal IM3 showing the highest fracture risk. Stresses were higher on the contralateral than on the ipsilateral side. Under Load II, the angle area had the highest stress for various orientations of IM3s. The condylar region had the highest stress when IM3s were absent.


High-impact forces are more likely to cause condylar rather than angular fracture when IM3s are missing. The risk of mandibular fracture is higher for partially than fully impacted third molars, with the angulation of impaction having little effect on facture risk.


Finite element analysis Third molar Mandible Biomechanical simulation 

有限元方法分析具有不同形态第三磨牙的下颌骨 受到冲击力时的应力分布



评估下颌骨在具有不同形态的第三磨牙或者没有 第三磨牙的情况下,当遭受到前部或侧部2000 N 冲击力时,其应力分布。


第三磨牙的存在对下颌骨的力学性能有影响,而 且不同位置形态的第三磨牙对下颌骨的力学性 能的影响存在差异。


根据一个具有完整牙列的健康下颌骨的计算机断 层扫描(CT)图像构建出其三维模型,以CT 图 像上的Hounsfield 值(HU)为基础,计算出下颌 骨的力学性能参数(包括密度和杨氏模量),共 分成9 组数据。构建出第三磨牙分别为水平向、 垂直向以及近中方向呈45 度角时的完全阻生和 部分阻生的共6 组下颌骨计算模型。并以无第三 磨牙的下颌骨为基准模型,利用有限元方法计算 在下颌前部和侧面分别受到2000 N 的静态冲击 力的情况下Von Mises 应力分布。


有限元分析结果显示,相同载荷条件下,当第三 磨牙部分阻生时的下颌骨髁突颈和角部区域的 应力值比完全阻生时要大,因此具有部分阻生第 三磨牙的下颌骨具有更高的骨折风险;当具有水 平向部分阻生的第三磨牙时,下颌骨骨折的风险 最大。对于各种计算模型,下颌骨受到侧向冲击 力时,应力最大位置均位于下颌角区;对于无第 三磨牙的下颌骨,应力最大位置位于髁突颈部区 域,此时髁突颈更容易发生骨折。


有限元分析 第三磨牙 下颌骨 生物力学仿真 

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Copyright information

© Zhejiang University and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Key Laboratory of E&M (Zhejiang University of Technology)Ministry of Education & Zhejiang ProvinceHangzhouChina
  2. 2.Department of Comprehensive CareSchool of Dental Medicine, Case Western Reserve UniversityClevelandUSA
  3. 3.Department of Oral and Maxillofacial SurgerySchool of Dental Medicine, Case Western Reserve UniversityClevelandUSA

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