Functional magnetic resonance imaging of brain activity during chewing and occlusion by natural teeth and occlusal splints.

Brain imaging based on functional magnetic resonance (fMRI) is a useful tool for examination of neuronal networks and cerebral structures subserving visiospatial function. The purpose of this study was to compare the brain activity during chewing and occlusal function in centric occlusion on natural teeth or on occlusal splints. Four tasks were performed by 13 healthy, fully dentate subjects (21-32 years old, 6 female and 7 male): occlusal tap-tap movements in centric occlusion by natural teeth, after application of a maxillary occlusal splint and chewing movements on left and right sided rubberdam strips. In order to reveal which areas of the brain were more strongly activated, conjunction analyses between the different tasks were performed for each subject and for the average values of brain signal activity of all subjects. Whilst several known foci of activity were subtracted, differences of significant activity rested in areas of the sensorimotor cortex. Mainly ipsitaterality of hemispheres concerned the left and right sided chewing, whereas the conjunction between tap-tap movements on natural teeth and splint occlusion indicated only one weak, but significant activation foci. The study confirms fMRT as one of the most useful developing methods to clear up neuro-cortical effectiveness of occlusion and occlusal therapy.