外翼肌水平作用力與顳顎關節邊界條件對於下顎形變的影響－有限元素分析

Effect of the Horizontal Forces of Lateral Petrygoid Muscles and Boundary Conditions of Temporomandibular Joint on Mandibular Deformation-Finite Element Analysis

辜雅勤(Ya-Chin Ku) ； 材哲堂(Che-Tong Lin) ； 黃豪銘(Haw-Ming Huang) ； 張維仁(Wei-Jen Chang)

《中華民國家庭牙醫學雜誌》 5卷3期 (2010/12) Pp. 14-18

https://doi.org/10.6566/JFD/2010.5(3).14

摘要

下顎在作開口運動時，會產生一形變現象，並導致下顎骨寬度的減少。學者認為，下顎骨的形變現象與肌肉的作用有密切相關，但較少文獻探討顳顎關節的限制程度與下顎形變的關聯。本實驗利用有限元素分析法，建立出一擁有自然齒列的下顎有限元素模型。在相同的下顎骨模型上，進行開口運動的模擬，並分別改變外翼肌水平分力大小與顳顎關節在水平方向之可移動度，計算並觀察兩變因對於下顎形變量的影響。結果發現，當邊界條件設定為0.4mm至0.6mm時，下顎寬度的變化在第二大臼齒區為0.189mm至0.28mm，符合臨床實驗之觀察。且外翼肌的水平作用力越大，顳顎關節的水平可移動度越大，下顎內縮現象也越大。因此下顎的形變量和外翼肌的水平作用力及取顳顎關節限制的程度都有相關。此實驗結果顯示，顳顎關節不僅作為下顎運動之導引，更是影響下顎向中心聚縮現象的重要因素。因此當進行下顎形變現象及下顎運動的探討時，除了肌肉作用力大小的考量外，也應將顳顎關節的因素考慮在內。

關鍵字

下顎形變 ； 顳顎關節 ； 外翼肌 ； 張口運動

並列摘要

Clinical findings indicated that geometrical shape of a mandible deformed during mouth opening. This deformation results in a reduction in the width of the mandibular arch. Several scholars reported that this phenomenon is strongly related to the activation of masticatory muscles. However, the effects of the movement limitation by temporomandibular joint (TMJ) on the mandibular deformation is still unclear. The aim of this study is to evaluate the boundary effects of TMJ on the madibular deformation during mouth is undergoing an opening motion. In methodology, a mandible finite element (FE) mod el with intact denture was developed. Mandibular deformations were calculated with various degrees of TMJ restriction and pterygoid muscle forces. Our results demonstrated that the mandible width between the two second molar changed from 0.19mm to 0.29mm when the movement capability of the mandible at TMJ was set to 0.4mm and 0.6mm, respectively. This result is consistent with previous clinical reports. In addition, we found that both horizontal component of the muscles forces and movement capability of mandible at TMJ have positive effect on the mandibular deformation. These findings showed that mandibular deformation is not only related to the muscle force, bit also affected by the limitation of TMJ. Accordingly, we suggest that the restrictions of the TMJ should be considered when the related clinical practice was carried out.

並列關鍵字

mandibular deformation ； temporomandibular joint ； lateral petrygoid muscle ； mouth opening