DEVELOPMENT OF METHOD FOR DETERMINING MANDIBULAR POSITION IN EDENTULOUS PATIENTS WITH DIFFICULTIES.

在评估正确的垂直颌骨关系的各种方法中，舒适区域(CZ)和最舒适位置(MCP)是值得注意的，因为它利用了受试者固有的本体感觉。目前尚不清楚该方法所确定的垂直尺寸从生理学角度是否可接受。为了评价无牙颌患者的MCP，我们记录了10名无牙颌患者的MCP，并通过头影测量分析与正常牙科患者的牙尖间隙位置(ICP)进行了比较。结果发现，MCP位于较低的下颌位置，这是因为随着下颌骨向前向上旋转，下颌骨围绕着髁突中心，面部高度明显降低。因此，有人认为，修复牙列的MCP的咬合垂直尺寸(OVD)小于原始的ICP。此外，我们从生理或功能的角度对CZ和MCP进行了评估，包括咬合力和肌电记录。分析合口肌的垂直尺寸与咬合力或肌电活动的关系是评价口腔颌面功能最重要、最基本的技术之一。与健康牙列受试者的颅内压相比，MCP不存在于任何特定的点上，而是在咬合力随垂直尺寸的增加而显著变化的范围内。这些结果表明，从功能角度来看，无牙颌受试者的MCP与有义齿受试者的颅内压是一致的。健康的牙科受试者的状况被认为是一个普遍的标准。因此，MCP在生理上是可以接受的。MCP的OVD可以建立在牙齿缺失后较低的垂直维度上，并处于与健康受试者的颅内压相似的功能位置。

Of the various methods in the assessment of correct vertical jaw relations, the comfortable zone (CZ) and the most comfortable position (MCP) are noteworthy because it utilizes proprioceptive sensations inherent to the subject. It is unknown whether or not the vertical dimension determined by this method is acceptable from a physiological point of view.For evaluation of the MCP in edentulous subjects, the MCP was recorded in ten edentulous subjects and compared with the intercuspal position (ICP) of normal dentulous people by cephalometric analysis. It was found that the MCP was at a lower mandibular position than the ICP because the facial height was markedly reduced with a front-upward rotation of the mandible centering around the condyles. Thus, it has been suggested that the occlusal vertical dimension (OVD) of the MCP in the restored dentition is less than that of the original ICP.Furthermore we evaluated the CZ and MCP from a physiological or functional point of view using bite force and EMG recording measurements. Analysis of the relationship between vertical dimension and bite force or EMG activities of jaw-closing muscles is one of the most important and basic evaluation techniques of stomatognathic function. The MCP does not exist at any specific point, but in the range where the bite force markedly changed with an increase in vertical dimension, compared to the ICP of healthy dentulous subjects. These results suggested that the MCP of edentulous subjects corresponded with the ICP of dentulous subjects from a functional point of view. The condition of healthy dentulous subjects is considered a universal standard. Therefore, the MCP is physiologically acceptable.The OVD of the MCP may be established at a lower vertical dimension after teeth loss, and positioned in a similar functional position as the ICP of healthy subjects.