The effects of oral appliance on sleep apnea syndrome and influence of oral appliance on jaw muscle activities

指出睡眠呼吸暂停综合征的潜在患者较多。对广岛大学口腔医学院学生进行的问卷调查结果表明，该病的潜在患者很多，没有主观症状。换言之，口腔矫治器的社会影响不容忽视，这是一个紧迫的课题。口腔矫治器被认为是一种有效的牙科治疗对策。关于长时间安装矫治器所产生的不良影响的研究较少。因此，我们研究了在实验条件下，佩戴口腔矫治器时下颌前向运动量与颌骨肌肉活动变化的关系。当我们考虑最大、最小、20%和40%MVC的实验咬合时，活动指数的变化结果表明，下颌前移量是可以接受的，约为最大前移距离的2/3。此外，重点研究了口腔矫治器垂直厚度的量，并检测了实际夜间睡眠中的肌肉活动。每个受试者分别制作垂直尺寸为3 mm(S3)和6 mm(S6)的两种矫治器。在使用和调整过程中，为了防止矫治器表面穿孔，最小夹板厚度确定为3 mm，临床上考虑舒适度后，最大夹板厚度确定为6 mm。用便携式肌电记录仪评价两种不同垂直厚度的口腔矫治器对夜间肌电活动(EMG值)的影响。通过对夜间睡眠时肌肉活动的分析，建议口腔矫治器应尽可能薄，考虑到矫治器的长期安装。

It is pointed out that there are many potential patients of sleep apnea syndrome. From the result of questionnaire investigation that has been done for the Hiroshima university dental school student, it was suggested that there were many potential patients of this disease without subjective symptom. In other words, social influence of this disease can't be ignored and this is the urgent subject.An oral appliance is considered effective and useful as a countermeasure of dental treatment. There ere few studies about adverse effect caused by long term installation period of appliance. So, we examined the relationship between the amount of forward mandibular movement by wearing the oral appliance and the change of jaw muscle activities under the experimental condition. When we consider the results of the change of activity indexes under the experimental clenching of maximum, minimum, 20% and 40% MVC, it was suggested that the amount of the forward mandibular movement, about 2/3 of the maximum protrusive excursion distances could be acceptable.Furthermore, a focus was put on the amount of oral appliance vertical thickness, and we examined the muscle activities during the actual night sleep. Two types of appliances with vertical dimensions of 3 (S3) and 6 mm (S6) were made for every subject. The minimum splint thickness was decided 3 mm to prevent perforation of the surface of the appliance during use and adjustment and the 6mm thickness was applied clinically as the maximum thickness after considering level of comfort. The effects of oral appliances with two different vertical thickness on nocturnal electromyographic (EMG) activities (the integrated EMG values) were evaluated using a portable EMG recorder. From the analysis of muscle activities during sleep at night, it was suggested that the oral appliances should be as thin as possible considering long term installation period of appliance.