Investigation of the removable partial denture design based on the in vivo 3-D force analyses on the abutment tooth of the removable partial denture

本研究的目的是澄清行为的负载施加到基牙的三维力测量装置与压电传感器，我们已经开发。了解局部义齿的受力情况，对义齿设计包括基牙的选择和咬合方案的选择都有重要意义。定制的测力装置由形成金属芯的内部部件、力传感器和形成金属冠的外部部件组成。受试者是一名自然牙列的年轻男性和一名部分牙列缺失的老年女性。在充分解释本研究后获得知情同意书。实验牙为有牙颌患者的上颌左第二磨牙和部分无牙颌患者的下颌右第二前磨牙，当部分无牙颌患者戴用远中支托义齿时，基牙所受的载荷较无义齿时显著降低。当戴有内托义齿时，最大咬合力时，载荷方向的角度比不戴义齿时明显减小。另一方面，与内侧支托和与远侧支托的角度之间存在显著差异。当戴用远中支托义齿时，最大咬合力时，载荷方向的角度比戴用中支托义齿时明显增大。内侧和远端支架指向最外侧的力矢量，以及内侧支架指向最下方的力矢量。四种不同状态下的额面方向无显著性差异，有牙颌者MVC时最大值为173.3±15.3N。随着压缩力大小的增加，载荷方向发生三维变化。在咀嚼粘性食物的整个过程中记录牵引力。

The purpose of this study is to clarify the behavior of the load applied to the abutment tooth by means of the 3-dimensional force measuring device with a piezo-electric transducer that we have developed. It is important to know that load for partial denture design including the selection of the abutment tooth and occlusal scheme. The custom-made force measuring device comprised an inner part forming a metal core, a force transducer, and an outer part forming a metal crown.The subjects were a young male with natural dentition and an old female with partial edentulous dentition. Informed consent was obtained after full explanation of this study. The experimental teeth were the maxillary left second molar of dentulous subject and mandibular right second premolar of partial edentulous subject.When the partial edentulous subject wearing the denture with distal rest clenched maximally, the magnitude of the load applied to the abutment tooth decreased significantly than without the denture. When the partial edentulous subject wearing the denture with medial rest clenched maximally, the angle of the load direction was decreased significantly than without the denture. On the other hand, there was significant difference between the angles with the medial rest and with the distal rest. When the partial edentulous subject wearing the denture with distal rest clenched maximally, the angle of the load direction was increased significantly than the denture with medial rest. The force vector with the medial and distal rests directed most laterally, and that with the medial rest directed most downward. There was not significant difference among the directions of four different conditions in the frontal plane.In the dentulous subject, The maximum magnitude was 173.3±15.3N during MVC. As the magnitude of the compressive force increased, the load direction changed three dimensionally. Tractive forces were recorded throughout the chewing the sticky food.