The Relationship Between Vertical Dimension And Bite Force, Electromyography In Edentulus People

ObjectiveThe purpose of this study was to investigate the relationship between vertical dimension and bite force,electromyography(EMG) in elderly edentulus people,and to provide some information for determining the occlusal vertical dimension in clinical application.Materials and methods10 edentulus sbujects who went to stomatology hospital zhe jiang university college of medcine,in healthy condition and without obvious diseases in oral and maxillofacial system,were choosen. The normal occlusal vertical dimension was determined by conventional method, and acrylic resin temporary base was maken. Based on the normal occlusal vertical dimension, other 12 vertical dimensions were settled at 0.5 mm steps by increase or decrease the number of sheet metal positioned over the temporary base.In the study, bite force was measured using an occlusometer at 13 different vertical dimensions,while electromyography from bilateral masseter and anterior temporal muscles were recorded by multichannel physiologic collection device.Maximal bite force.normonized muscle activity and muscle activity/ bite force were employed for the statistical analysis. Result1. Bite force increased with the increase of occlusal vertical dimension, significance appears when the change of vertical dimension exceed 1.5mm from normal occlusal vertical dimension.2. As the increse of occlusal vertical dimension, normonized masseter muscle activity increasd, significance appears when the changeof vertical dimension exceed 1.0mm from normal vertical dimension.But the change of normonized anterior temporal muscles activity wan't significant until the vertical dimension exceed 3.0mm from normal one.3. Masseter muscle activity/bite force and anterior temporal muscles activity/bite force increased with the increase of occlusal vertical dimension. Significance appears when the change of vertical dimension exceed 1.0mm from normal one in masseter muscle activity/bite force while it appears when decrement exceed 2.0mm or increment exceed lmm in anterior temporal muscles activity/bite force.Conclusion1.Bite force increased with the increase of occlusal vertical dimension.The normal occlusal vertical dimension wasn't the place where bite force was maximal.2.Without regarding to the influnce of bite force, masseter muscle activity decreased with the increase of occlusal vertical dimension,but the change of anterior temporal muscle activity wasn't so apparent compared to masseter muscle activity.3.Regard to the influnce of bite force,the activity of masseter muscle and anterior temporal muscle decreased with the increase of occlusal vertical dimension.4. There maybe a stable area nearby the normal occlusal vertical dimension.Inside the stable area,the change of bite force, masseter muscle and anterior temporal muscle activity were not significant.