The Analysis of Condylar Movements Under the Masticatory Loading

人们普遍认为，咀嚼时髁突负荷过重是颅下颌关节紊乱病的主要病因。本研究的目的是系统地分析由咀嚼肌、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”，它可以同时非常准确地测量髁突运动，下颌运动和咀嚼肌肌电。除上述测量外，还用PERIOTEST测量了正常人牙周组织的动态功能。在咀嚼早期，肌电活动在髁突位置较牙尖交错位置靠前时达到高峰.咀嚼后期，髁突位于关节窝最深处时肌电活动达到峰值.结果表明：（1）牙周膜的弹性模量随食物质地的变化而变化，咀嚼过程随食物质地的变化而变化;（2）牙周膜的弹性模量随食物质地的变化而变化，咀嚼过程随食物质地的变化而变化;（3）牙周膜的弹性模量随食物质地的变化而变化，咀嚼过程随食物质地的变化而变化。本研究将以颅下颌关节紊乱病患者为研究对象，探讨颞下颌关节负荷过重与颅下颌关节紊乱病症状的关系。

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.