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

用18F-氟-D-脱氧葡萄糖(FDG)对健康志愿者进行正电子发射断层扫描(PET)，研究咀嚼口香糖时大脑和骨骼肌活动与咀嚼功能的关系。结果发现，可以同时测量和量化咬肌、颞肌、翼内侧肌、翼外肌和舌肌的活动。根据Friston等人的说法，还使用SPM96分析了咀嚼口香糖时大脑的宠物图像。阐明脑活动的特点。在任意咀嚼时，大脑的初级感觉运动区、运动前区和小脑高度激活，而在右侧咀嚼时，左右两侧大脑的这些活动有所不同。在任意咀嚼和右侧咀嚼时，大脑活动有统计学意义上的差异。在任意咀嚼过程中，右侧初级感觉运动区的活动明显高于右侧咀嚼。当将右侧咀嚼时的脑活动与任意咀嚼时的脑活动进行比较时，左侧丘脑和中脑，右侧壳核和小脑的活动明显更高。因此，大脑活动因咀嚼方式的不同而不同，这表明使用可摘义齿也会影响大脑活动。另一方面，开发了一种力传感器来测量义齿固位力，这是可摘义齿的评价因素之一。将该传感器应用于10名受试者的腭板固位力测量，证明是一种实用的方法。平均固位力和标准偏差分别为0.71~1.00N和0.16~0.61。虽然固位力在不同受试者之间表现出很大的差异，但测量的重复性是可以接受的。

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.