A study on occlusion and periodontium using high precision displacement detector

我们开发了四种不同类型的运动检测器来研究咬合和牙周组织的特性。这些运动探测器利用磁场，测量六个自由度的运动。第一个运动检测器由六个1800毫米的方形线圈组成。测量精度为立方磁场中心区10μm级。由于该装置具有环绕整个人体的大磁场，该系统可用于夜间磨牙时颌部运动的测量。第二个运动检测器使用磁性合金作为初级线圈的核心。由于该装置体积较小，操作方便，可用于日常牙科诊所。第三种运动检测器具有更高的精度，能够测量咬合期间轻微的牙齿运动。该装置由6个直径为1000mm的圆形线圈组成，测量精度为在磁场中心区域平移1.3 μm，旋转0.00017度。同时测量右侧上第一前磨牙和下颌运动。咬合接触对牙齿运动的影响很大，在某些情况下，牙齿运动的旋转中心在牙齿附近。最后一个运动检测器测量一个自由度的运动，但具有极高的精度，能够评估牙齿变形与咬合力。用该装置测量上犬齿和第一前磨牙颊面垂直长度。这些牙齿的颊面随着颊尖负荷的增加而缩短，而随着腭尖负荷的增加而扩大。

We developed four different types of motion detector to study occlusion and periodontal tissue properties. These motion detector utilizes magnetic field and measure movement in six degrees of freedom.The first motion detector consisted in six square coils 1800 mm on a side. The accuracy of the measurement is the level of 10μm at the central area of cubic magnetic field. Since this device possesses large magnetic field that surround whole human body, the system can be applied for the measurement of the jaw movement during nocturnal bruxsim.The second motion detector used magnetic alloy for the core of the primary coils. Since this device has relatively small size, the system can handle easily and may used in daily dental clinic.The third motion detector possess higher accuracy that enable to measure slight tooth movement during occlusion. This device consisted in six round coils 1000mm in diameter and the accuracy of the measurement is the level of 1.3 μm for translation and 0.00017 degrees for rotation at the central area of magnetic field. The simultaneous measurement of right side upper first premolar and jaw movement was performed with this device. Occlusal contacts were very influential for tooth movement and the rotation centers of the tooth movement were found near teeth in some cases.The last motion detector measures movement in one degree of freedom but possesses extremely high accuracy that enable to evaluate tooth deformation with occlusal force. Vertical length of buccal surface of upper canine and first premolar was measured with this device. Buccal surfaces of these teeth were shortened with buccal cusp loading and expanded with palatal cusp loading.