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Experimental occlusal interference on brain activation during gum chewing

This study aimed to investigate brain functions by analysing changes in intensity of brain activation sites as well as the results of sensory evaluation related to occlusal interference. In 11 subjects, an interference crown was made for the left mandibular first molar, and subjects performed a gum-chewing task with crown overlay (200 μm of occlusal interference) and without (control). Sensation was evaluated using a Visual Analog Scale (VAS), and brain activation sites were evaluated using functional Magnetic Resonance Imaging (fMRI). Results were considered statistically significant at p<0.05. Unpleasant sensation during gum chewing was significantly greater in the interference group than the control group (p<0.01). On fMRI group analysis, the somatosensory-motor cortex, supplementary motor area, the insula, and the cerebellum were activated in both groups, thus establishing an experimental model to analyse the relationship between occlusal interference and brain function. In the interference group, activation was significantly higher in the amygdala (p<0.001), anterior cingulate cortex (p<0.001), prefrontal area (p<0.05), and hypothalamus (p<0.05). Our findings show that stimulation from occlusal interference is rapidly relayed to the brain and related to activation of emotions of discomfort.

Author(s): Takero Otsuka, Kenichi Sasaguri, Yuta Hayashi, Kentaro Yamada, Hiroyuki Muranaka, Yu Takakura, Hitoshi Usuniwa, Nagafumi Doi, Toshitsugu Kawata