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很多。通过对广岛大学口腔科学生的问卷调查，发现有许多潜在的无自觉症状的患者。换句话说，这种疾病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有效和有用的牙科治疗对策。目前关于矫治器长期安装所引起的不良反应的研究较少。因此，我们在实验条件下研究了戴用口腔矫治器后下颌向前运动量与下颌肌活动变化的关系。在最大、最小、20%和40%MVC的实验性咬合状态下，活动指数的变化结果表明，下颌向前运动量约为最大前伸偏移距离的2/3是可以接受的，并重点关注了口腔矫治器垂直厚度的大小。我们检查了他们在晚上睡眠时的肌肉活动。每个受试者制作两种类型的矫治器，垂直尺寸为3（S3）和6 mm（S6）。最小夹板厚度确定为3 mm，以防止在使用和调整过程中器械表面穿孔，考虑到舒适度，临床上应用的最大厚度为6 mm。采用便携式肌电记录仪评价两种垂直厚度的口腔矫治器对夜间肌电活动（肌电积分值）的影响。通过对夜间肌肉活动的分析，提出了考虑到矫治器安装周期较长，口腔矫治器应尽可能薄。

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.