The Analysis of Condylar Movements Under the Masticatory Loading

人们普遍认为咀嚼过程中髁突的负荷过重是导致颅下颌关节紊乱的主要原因。但由于其位置和细节尚不清楚，不能直接识别髁突运动。本研究旨在系统分析由咀嚼肌、颞下颌关节和牙周组织三个因素组成的功能性咬合系统，阐明髁突位置与咀嚼过程的关系。为此，我们开发了一种新的测量系统“Selspot系统”，可以非常准确地同时测量髁突运动、下颌运动和咀嚼肌的肌电图。除了这些测量外，还使用PERIOTEST测量牙周组织的动态功能。正常受试者的测量结果如下：1。在咀嚼早期，肌电活动在髁突位置较尖间位置更靠前时达到高峰。在咀嚼后期，肌电活动在髁突位于关节窝最深点时达到高峰。咀嚼过程根据食物的质地而改变。根据测量头与牙齿的接触时间计算出牙周测试值，显示了牙周的倾倒效应。牙周测试值与临床牙周活动程度有密切关系。在此之后，我们将对颅下颌骨患者进行研究，明确颞下颌关节负荷过重与颅下颌骨疾病症状的关系。

It has been generally accepted that the overloading on the condyle during the mastication plays the main role as the etiologic factor of the craniomandibular disorders. But the condylar movement cannot be identified directly because of its location and the details are not clear.The purpose of this investigation is to analyze the functional occlusion system systematically which is composed of three factors, that isothe masticatory muscle,TMJ, and the periodontium and to clarify the relationship between condylar position and the masticatory process. For this purpose, we have developed a new measuring system " Selspot system" which can measure the condylar movement, the mandibular movement, and EMGs of masticatory muscles simultaneously very accurately. In addition to these measurements,the dynamic function of the periodontium was measured with the PERIOTEST.The results of the measurements of normal subjects are as follows :1. At the early stage of the mastication, EMG activity showed its peak when the condyle located more anteriorly than intercuspal position.2. At the late stage of the mastication, EMG activity showed its peak when the condyle located at the deepest point in the articular fossa.3. The masticatory process was changed according to the texture of the food.4.The Periotest value has proved to be calculated from the contact time between the measuring head and the tooth , and it showed the dumping effect of the periodontium.5.There was a close relationship between the the clinical degree of tooth mobility and the Periotest value.After this, we will study the craniomandibular patients and will make clear the relationship between the overloading on TMJs and the symptoms of craniomandibular disorders.