A new device for measuring the stress of upper and lower lips Clinical application

为了研究唇部功能和双颌形态之间的关系，我们开发了一种简单的装置，可以测量唇部压力。在唇下插入一个金属板，并向外拉。受试者被要求施加力以防止钢板脱落。阻力被认为是最大嘴唇强度，并分别测量两个嘴唇。板与测力仪相连，信号输入便携式计算机。普通强度通常可由最大肌力计算（普通强度为最大强度的20-30%），且形态与强度关系密切（最大强度与截面积成正比）。由于嘴唇不被认为是孤立的或完全独立的器官，它们被认为至少对颌面复合体的前部有影响。基于这一想法，我们对24名受试者进行了一项研究，以检验双嘴唇的最大强度与颌面复合体之间的关系。硬组织在脑电图上进行评估，软组织在照片上进行评估。与上唇相比，下唇与上颌面部复合体的形态学表现出更强的相关性。在骨骼模式中，下唇与ANB的相关系数为r=-0.427， A-B平面的相关系数为r=0.460。牙型中U-1与SN的相关系数r=0.398， L-1与SN的相关系数r=0.313。软组织方面，下唇与下脸的相关系数r=0.463。两唇最大强度的相关系数r=0.418。因此，下唇最大强度高的人下颌骨有向各个方向发展的趋势。

To investigate the relation between the function of lips and morphology of both jaws, we have developed a simple device that allows measurement of lip pressure.A metal plate is inserted under the lip, and pulled outward. The subject is asked to apply force to prevent the release of the plate. The resistance force is considered as the maximum lip strength and is measured for both lips separately. The plate is connected to a force gauge, and the signal is input into a portable computer.The ordinary strength can usually be calculated from the maximum muscle strength (ordinary strength 20-30% of the maximum strength), besides there is a close relation between morphology and strength (maximum strength is proportional to the cross-sectional area). As lips are not thougth to be isolated or completely independent organs, they are believed to influence at least on the anterior part of the maxillo-facial complex. Based on this idea, we conducted a study on 24 subjects to cxamine the relation between the maximum strength of both lips, and the maxillo-facial complex. The hard tissue was evaluated on cephalograms, and the soft tissue were evaluated on photographs.The lower lip showed stronger correlation to the morphology of the maxillo-facial complex more than the upper lip did. In skeletal patterns, the coefficient correlation between the lower lip and ANB was r=-0.427, for A-B plane it was r=0.460. In dental patterns the coefficient correlation for U-1 to SN r=0.398, for L-1 to SN it was r=0.313. As to the soft tissue, the coefficient correlation between the lower lip and the lower face was r=0.463. The coefficient correlation between the maximum strength of both lips was r=0.418.It is therefore concluded that, the mandible has a tendency to develop in all direction in people with high maximum strength of the lower lip.