Analysis of denture mobility of complete dentures with numerical simulation and intraoral experiments.

本研究的目的是：1)建立和验证一套能同时测量上下全口义齿和下颌骨运动的三维测量系统；2)分析义齿运动与下颌功能过程中闭合轨迹的关系。使用一个带有四个红外电视摄像头的三维运动捕捉系统。它用红外线反射膜识别多个目标。为每个受试者准备了12个目标。其中三个被固定在眼镜的边缘上，用于校准头部的运动，三个被放置在上下义齿上，遗体被放置在连接到下颌的金属框架上。然后，根据每个靶点的位置计算义齿和下颌运动的方向和范围。通过义齿咬合平面与下颌平面法向量法向量内积的变化，分析下颌义齿与下颌运动的关系。下颌运动可分为两种类型。1例(79.9%)为正常卒中(闭合路径在咀嚼同侧：IS)，另1例(20.1%)为反向闭合(闭合路径在对侧：CS)。结果表明：该系统能测量出0.3 mm以内的义齿松动度。在IS病例中，上颌义齿倾向于向非工作侧移动，而在CS病例中，上颌义齿倾向于向工作侧移动。下部义齿倾向于向咀嚼侧移动和倾斜。无论工作侧或非工作侧，上颌义齿的活动度与下颌的移动均有相关性，且下口义齿有向工作侧移动的趋势。

The purpose of this study was 1) to assemble and verify a system to measure the three-dimensional (3-D) movement of the upper and lower complete denture and the movement of the mandible simultaneously, and 2) to analyze a relation between denture movements and the path of closure of the mandible during functions. A 3-D motion capture system with four infrared TV cameras was used. It recognizes a number of targets with infrared rays reflecting membrane. Twelve targets were prepared for each subject. Three of them were attached to a rim of eyeglasses for the calibration of head movements, three of them were placed on each upper and lower denture, and remains were on a metal frame attached to the mandible. Then, the direction and range of dentures and mandibular movements were calculated from loca of each three targets. The relation between lower dentures and the mandibular movements was analyzed with the change of the inner product of normal vectors of denture occlusal planes and mandibular planes. The mandibular movements could be c1assified into two types. One (79.9%) was the type of normal stroke (the path of closure was on ipsilateral side of mastication : IS) and the other (20.1%) was reversed (the path of closure was on contralateral side : CS). The results are followed : This system could measure the denture mobility within 0.3 mm errors. Upper dentures tended to move toward the nonworking side in a case of IS, and toward the working side in a case of CS.The lower dentures tended to move and incline toward mastication side. The mobility of upper dentures had a correlation to the mandibular movement regardless of working side or nonworking side, and lower dentures had a tendency to move toward the working side.