Objective Using functional magnetic resonance imaging (fMRI) to detect the cerebral cortical somatotopy during maximum voluntary clenching with soft occlusal pad in healthy adults. By comparing with the cerebral cortical activation during clenching with andwithout soft occlusal padwe try to detect the central mechanism of the rule of the occlusal pad.Methods Ten healthy subjects were selected and scanned by Elscint/GE 2.0 TeslaMR system. Block designwas used and the movement pattern was maximum voluntary clenchingwith soft occlusal pad. The fMRI datawere analyzed by SPM99 software and group map analysis was done.Results The activation areas were found in bilateral or unilateral motor cortex, somatosensory cortex, prefrontal cor- tex, temporal cortex, premotor cortex, insula, frontal operculum, basal ganglia (putamen), parietal cortex and cingulate. Group map analysis showed activation in bilateral motor cortex, right somatosensory cortex, bilateral basal ganglia, and bilateral insula. The activation of left motor cortex was significantly higher than right side. Compared with cortical activation without occlusal pad, the motor and somatosensory cortex changed a lot.Conclusion The changes of the activation of motor and somatosensory cortex during clenching after wearing the soft occlusal pad might be the central mechanism of the rule of the occlusal pad.
