Abstract
BackgroundThe cognitive effects of wearing a denture are not well understood. This study was conducted to clarify the effects of denture use on prefrontal and chewing muscle activities, occlusal state, and subjective chewing ability in partially edentulous elderly individuals.MethodsA total of 16 partially edentulous patients were enrolled. Chewing-related prefrontal cortex and jaw muscle activities were simultaneously examined using a functional near-infrared spectroscopy (fNIRS) device and electromyography, under the conditions of unwearing, and wearing a denture. Occlusal state and masticatory score were also determined under both conditions. Using multiple linear regression analysis, associations between prefrontal and chewing activities with wearing were examined using change rates.ResultsChewing rhythmicity was maintained under both conditions. As compared with unwearing, the wearing condition was associated with improved prefrontal cortex and chewing muscle activities, occlusal state in regard to force and area, and masticatory score. Also, prefrontal activities were positively associated with burst duration and peak amplitude in masseter (Mm) and temporal muscle activities, as well as masticatory scores. In contrast, prefrontal activities were negatively associated with occlusal force.ConclusionWearing a denture induced a positive association between burst duration and peak amplitude in Mm and temporal muscle activities and prefrontal activity, which may indicate a parallel consolidation of prefrontal cortex and rhythmical chewing activities, as well as masticatory scores. On the other hand, denture use induced a negative association of occlusal force with prefrontal activities, which might suggest that prefrontal compensative associations for the physiocognitive acquisition depended on biomechanical efficacy gained by wearing a denture.
Highlights
Epidemiologic studies have suggested associations between cognitive ability and oral conditions, such as number of teeth (Luo et al, 2015; Li et al, 2017; Oh et al, 2018) and dental occlusion (Ono et al, 2010; Franco et al, 2012; Takeuchi et al, 2015)
The present study found that wearing a denture induces a positive association of burst duration and peak amplitude of jaw muscle activities and masticatory score with prefrontal activities in frontopolar area (FPA)/orbitofrontal cortex (OFC)
Our results in this study suggested that wearing a denture induced negative associations of the biomechanical factors in occlusal force with prefrontal activities in FPA
Summary
Epidemiologic studies have suggested associations between cognitive ability and oral conditions, such as number of teeth (Luo et al, 2015; Li et al, 2017; Oh et al, 2018) and dental occlusion (Ono et al, 2010; Franco et al, 2012; Takeuchi et al, 2015). Oral reconstruction by means of wearing a denture may induce cortical activation in prefrontal, sensorimotor, and sensory association cortices during chewing performance (Kimoto et al, 2011; Kamiya et al, 2016) and might contribute to antiaging cognitive activation in the prefrontal cortex of elderly edentulous patients (Banu et al, 2016). A well-fitting denture may help to maintain cognitive ability and prevent its decline otherwise caused by tooth loss in elderly edentulous patients. In individuals with tooth loss who do not wear a denture, cognitive decline might be accelerated with age. This study was conducted to clarify the effects of denture use on prefrontal and chewing muscle activities, occlusal state, and subjective chewing ability in partially edentulous elderly individuals
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