本文由人體下顎骨之斷層掃描圖，建立出三維有限元素模型，在相同受力狀態下以不同的材料性質模擬下顎骨受負荷的情況，探討材料性質的定義對分析結果的影響；施加咬力在右側臼齒與下門齒時，觀察下顎骨的應力分佈並討論肌肉力量對應力分佈的影響；以及當下巴受到外力作用時下顎骨的應力分佈。以主應力分佈探討下顎骨在咬合時之受力狀況，並討論下顎骨幾何形狀與應力集中位置的關係。

分析結果發現材料性質的定義對下顎骨的力學分析有相當的影響；而肌肉力量在咀嚼行為時，對於下顎骨有減低其應力集中之效果；另外，外力的施加缺乏肌肉力的作用，下顎骨幾何形狀變化較大之位置便出現應力提高的現象。

The objective of this paper is to set up a three-dimensional finite element model of a mandible from computer tomography image and to obtain the stress field during bite or external point force on the jaw. The magnitude of the four muscle forces via temporalis, masseter, internal pterygoid and external pterygoid muscles are computed from static force equilibrium with bite force. The cortical and cancellous bones of mandible can be simulated as an isotropic or transversely isotropic material.
The results are shown graphically by plotting the principal stress contours. The regions where the stresses concentrate are selected to show the differences when isotropic or transversely isotropic material is used. In addition, the stress concentration can be reduced when four muscle forces are properly introduced.

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