Influence of placement position and designing of removable partial denture on oral sensation

为探讨不同形状的可摘义齿对口腔感觉的影响，确定舒适位置和主要连接体的设计，将4种不同截面形状和不同放置位置的实验性腭带分别放置于6名健康受试者的口腔中，用问卷调查法检测舌触觉。结果表明，刃状边缘横截面形状和主连接体咬合面对称形状的钛板，其舌侧触觉不适感较轻，对10名健康受试者应用不同厚度的钛板，实验金属板厚度越薄，结果表明，咀嚼片的咀嚼反应比厚金属片和树脂片更敏感，并建立了两种评价咀嚼能力的新方法，适用于部分无牙颌患者的义齿修复。一种是通过计算米饼咀嚼冲程数来分析食团形成能力的方法。另一组通过测定磨牙咀嚼时咀嚼液中谷氨酰胺氨基酸的含量来分析唾液中鲜味的含量，无牙颌患者口腔粘膜的压痛阈（PPT）值戴义齿组比不戴义齿组低40%，豚鼠实验用生理学方法探讨了无牙颌患者调节咬合垂直距离的神经机制。三叉神经中脑核参与了咬合垂直距离的调节。增加或减少咬合垂直距离可改变闭颌肌的长度，从而改变肌梭的敏感性，提示口腔感觉与口腔功能密切相关，设计可摘局部义齿时，除考虑固位力和功能负荷分配外，还应考虑口腔感觉。

This study aimed to investigate the effects of different shapes of removable dentures on oral sensation, and to identify comfortable position and designing of major connectors.Four different cross sectional form and different placement position of experimental palatal straps were delivered to 6 healthy subjects and examined as for lingual tactile sensation with questionnaire. The results were that with the knife-edged marginal shape of cross sectional form and the symmetrical form at the occlusal view of major connector exihibited less uncomfortable lingual tactile sensation.When applying different thickness plates to 10 healthy dentulous subjects, with the thinner experimental metal plates, it showed more sensitive gustatory response than with the thicker metal or resin plates.Two types of new method to evaluate the ability of mastication were developed and were applied to the partial edentulous patients with dentures. One was the method to analyze bolus formation ability by counting the number of rice cracker chewing strokes. Another was to analyze the amount of umami in saliva solution by measuring the glutamine amino acid in mastication of tangle at the molar teeth.As to the pressure pain threshold(PPT) of edentulous oral mucosa, denture-wearing patients exhibited 40% lower value of PPT than non-denture-wearing patients.In guinea pig experiment the neuronal mechanism of adjusting occlusal vertical dimension was investigated by physiological method. And the trigeminal mesencephalic nucleus were proved to be involved in the regulation of the occlusal vertical dimension. Raising or reducing occlusal vertical dimension alters the length of jaw-closing muscles, resulting in changing the sensitivity of the muscle spindles.It was suggested that oral sensation and oral function are closely related with each other and consideration of oral sensation is necessary for the designing of removavle partial denture as much as retentive force and distribution of functional load.