Study on relationships between use of dentures and cerebral function in the elderly by means of positron CT

本研究采用正电子发射断层扫描（PET）技术，观察了咀嚼口香糖时咀嚼肌和脑的活动情况。结果发现，咬肌、颞肌、翼内肌、翼外肌和舌肌的活动可以同时测量和量化。根据Friston等人的研究，还使用SPM 96分析了咀嚼口香糖期间大脑的PET图像，以阐明大脑活动的特征。在任意咀嚼过程中，初级感觉运动区、运动前区和小脑的双侧激活程度较高，而在右侧咀嚼过程中，这些活动在左右两侧存在差异。任意咀嚼和右侧咀嚼时的脑电活动差异有统计学意义。右侧初级感觉运动区的活动在任意咀嚼时显著高于右侧咀嚼。右侧咀嚼时的脑活动与任意咀嚼时的脑活动相比，左侧丘脑和中脑，右侧壳核和小脑显示出显着较高的活动。因此，这似乎是不同的咀嚼方式的大脑活动，这表明，使用活动义齿也影响大脑活动。另一方面，力传感器的开发，以测量义齿固位，这是一个评价因素之一，可摘义齿。将该传感器应用于10名受试者的实验腭板固位力的测量，结果表明该传感器是有效的。平均固位力和标准差分别为0.71 - 1.00 N和0.16 - 0.61。虽然固位力显示受试者之间的差异很大，但测量的重现性是可以接受的。

Positron Emission Tomography (PET) with 18F-fluoro-D-deoxy glucose (FDG) was performed in healthy volunteers in order to investigate activities of the brain and the skeletal muscles in relation to masticatory function during gum chewing. As a result, it was found that activities of the masseter, temporal, medial pterygoid, lateral pterygoid, and tongue muscles could be simultaneously measured and quantified. PET images of the brain during gum chewing were also analyzed using SPM96 according to Friston et al. To clarify the characteristics of the brain activities. The primary sensorimotor areas, the premotor areas and the cerebellum were highly and bilaterally activated during arbitrary chewing while those activities were different in the left and right sides of the brain during the right side chewing. There were statistically significant differences in the brain activities during arbitrary chewing and the right side chewing. The activity of the right primary sensorimotor areas showed significantly higher during arbitrary chewing compared to the right side chewing. When the brain activities during the right side chewing was compared to those during arbitrary chewing, the left thalamus and mid brain, and the right putamen and cerebellum showed significantly higher activities. Thus it was appear that the brain activities differed depending on the chewing manner and this suggests that use of removable dentures also affect the brain activities.On the other hand, a force transducer was developed to measure denture retention that was one of the evaluating factors for removable dentures. The transducer was proved to be useful when it was applied to the measurement of retention force for an experimental palatal plate in 10 subjects. The average retention force and the standard deviation ranged 0.71 to 1.00 N and 0.16 to 0.61, respectively. Whereas the retention forces showed wide variations between subjects, reproducibility of the measurement was acceptable.