Mesnard M, Ramos A, Simões J A
University of Bordeaux, I2M, CNRS, UMR 5295, France.
University of Aveiro, Department of Mechanical Engineering, Portugal.
J Craniomaxillofac Surg. 2014 Apr;42(3):194-200. doi: 10.1016/j.jcms.2013.04.010. Epub 2013 May 29.
A 3D finite element model of an in vitro implanted mandible was analysed. The load point was placed on the condyle in three positions (inside the mouth, centred and outside) to simulate different contact points between the mandible condyle and the temporal bone. The strain fields in the condyle were assessed and detailed around the surgical screws. The temporomandibular implant studied here was modelled on a commercial device that uses four screws to fix it in vivo in a very similar position. The boundary conditions of the numerical model simulated a load on the incisors with a 15 mm mouth aperture. The same contact loads were applied to the two condyles. Numerical results were successfully obtained for the three different contact points: the inside contact produced lower strains on the condyle. The first screw created a critical strain distribution in the bone, just under the screw. The study shows that centred and inside contact induces lower strain distributions. This suggests that spherical condyle geometry should be applied in order to reduce the strains in fixation. As the top screw was observed to play the most critical role, the third screw is in fact unnecessary, since the lower strain distribution suggests that it will be loosened.
对体外植入下颌骨的三维有限元模型进行了分析。加载点放置在髁突的三个位置（口腔内、中心和外侧），以模拟下颌髁突与颞骨之间的不同接触点。评估了髁突中的应变场，并在手术螺钉周围进行了详细分析。此处研究的颞下颌植入物是基于一种商业装置建模的，该装置在体内使用四颗螺钉将其固定在非常相似的位置。数值模型的边界条件模拟了在开口15毫米时施加在切牙上的载荷。对两个髁突施加相同的接触载荷。成功获得了三种不同接触点的数值结果：内侧接触在髁突上产生的应变较低。第一颗螺钉在其下方的骨中产生了临界应变分布。研究表明，中心和内侧接触会引起较低的应变分布。这表明应采用球形髁突几何形状以减少固定中的应变。由于观察到顶部螺钉起着最关键的作用，实际上第三颗螺钉是不必要的，因为较低的应变分布表明它会松动。
