Development of an objective and practical method to evaluate the morphology of edentulous alveolar ridges based on the analysis of the movement of complete dentures

本研究的目的是发展一种基于有限元分析计算的全口义齿移动量来评估无牙颌牙槽嵴的方法。无牙铸造和打蜡全口义齿（78下颌，38上颌，29两者），通过试验。我们制作了定制的有限元模型，每个模型由使用非接触式3-D数字化仪获得的表面数据的粘膜和义齿组成。对每例病例的每侧人工磨牙在双侧载荷下和下颌病例在单侧载荷下进行有限元分析。我们对义齿上三个节点的位移进行了主成分分析（PCA）。另一种方法是将牙槽嵴表面规则划分网格，网格上各点的坐标作为主成分，主成分分析表明，全口义齿的位移可以用少量的主成分来表示。后一种主成分分析表明，每个脊的形态也可以用六个或七个主成分来表达。尽管这些形态PC中的大多数与先前建议的方案相一致，但其他PC被认为不太关注，并且对评估无牙槽嵴形态因素的方案具有潜在的必要性。我们以每个“位移”PC为因变量，以“形态”PC为因变量，PC作为独立变量。然而，决定系数是如此之低，在这项研究中提取的“形态”PC被认为是不足以表达或估计义齿的位移。为了推进这项研究，PCA的部分形态，更多的样本量，集中在“离群”的情况下，和/或调查的“形态”PC的功能和预后的影响，建议。

The purpose of this study was to develop a method to evaluate edentulous alveolar ridges based on the movement of the complete dentures calculated with finite element (FE) analysis. Edentulous cast and waxed complete dentures (78 mandibular, 38 maxillary, and 29 both) that passed trials were used. We made customized FE models, each consisting of mucosa and a denture from the surface data obtained using a non-contact 3-D digitizer. The FE analysis was performed under bilateral loads on artificial molars on each side on every case and unilateral loads on mandibular cases. We performed principal component analysis (PCA) of the displacement at three nodes on the dentures. Another PCA was performed with coordinates of the points on the grid defined by regularly dividing of the surface of alveolar ridges.The former PCA showed that the displacement of complete dentures could be expressed with a few principal components (PCs). The latter PCA showed that the morphology of each ridges could also be expressed with six or seven PCs. Although most of these morphological PCs were coincided with protocols previously suggested, others were considered to have been less attentive and to have a potential necessity for protocols to evaluate morphological factors of edentulous alveolar ridges.Next, we investigated the effect of morphology of the ridges on the displacement of dentures using multiple regression analysis with each "displacement" PC as dependent variables and "morphology" PCs as independent variables. However, the coefficients of determination were so low that the "morphology" PCs extracted in this study were considered to be insufficient to express or estimate the displacement of dentures. To progress this study, PCA for partial morphology, more sample size, focusing on "outlier" cases, and/or investigation of the effect of "morphological" PCs on function and prognosis were suggested.