Classification of edentulous mandibular alveolar ridges based on the finite element analysis on the dynamic behavior of the complete dentures.

这项研究的目的有两个：开发了一种新的方法，尽可能自动地从牙槽嵴和蜡制义齿的数字化三维形状制作有限元模型，利用三维激光扫描仪LPX-1测量了一个主模和一个蜡模义齿的三维形态，并对义齿的三维形态进行了分析，250（罗兰DG有限公司）。用C++语言开发的有限元模型生成软件可以实现有限元模型的准自动生成。与临床上测量义齿活动度的方法相比，本方法具有足够的再现性，因此，我们用16个标准铸件和相应的蜡制义齿制作了有限元模型，并分析了单侧载荷下义齿活动度。我们进行了主成分分析（PCA）与位移的三个代表节点。主成分分析表明，前后平移、水平旋转和磨牙区下沉3个主成分可以解释义齿三维位移的84%左右，主成分聚类分析显示至少有6个独立的聚类。然而，由于大多数集群由一对夫妇的情况下，更多的情况下，被认为是必要的，以制定新的分类系统的无牙下颌骨嵴。

The purpose of this study was twofold : development of a new method to make finite element model from digitized 3-dimensional shape of the alveolar ridge and a wax denture automatically as much as possible, and classification of the mandibular alveolar ridge based on the dynamic behavior of the denture calculated by finite element method.We measured three-dimensional shape of a master cast and a wax denture with 3D laser scanner LPX-250 (Roland DG Co.Ltd.). It was posssible to make FE model quasi-automatically with a software we developed in C++ programming language. The FE models was considered to have sufficient reproducibility with the denture mobility under loads comparing with another clinical method to measure denture mobility.With this method, we made FE models from 16 master casts and corresponding wax dentures, and analyzed denture mobilities under unilateral loads. We performed principal component analysis (PCA) with displacement of three representative nodes. The PCA showed that about 84 % of the three-dimensional displacement of dentures can be explained with three principal components-antero-posterior translation, rotation in horizontal plane, and amount of sinking at the molar region.The cluster analysis with principal component scores showed that there was at least 6 independent clusters. However, since most of the clusters consisted of a couple of cases, more cases were considered to be necessary to develop new classification system of edentulous mandibular ridge.