Effects of temporomandibular joint sensory deprivation on cerebral activity during clenching

ObjectiveThe objective of this study was to investigate the effect of sensory deprivation of the temporomandibular joint on cerebral activity during clenching.Materials and methodsThe subjects comprised 4 healthy volunteers without temporomandibular joint disorder. First, functional magnetic resonance images (fMRI) were obtained during clenching without anesthesia using a 1.5-T clinical scanner. Next, Lidocaine (2 ml) was injected into the left superior temporomandibular joint cavity for sensory deprivation, and images during clenching were obtained. Additionally, sensory deprivation of the right temporomandibular joint was performed and images were obtained in the same manner. Statistical parametric mapping software was used for image processing and statistical analysis of the fMRI data.ResultsAnalysis results on clenching without local anesthesia revealed cerebral activation in bilateral sensory, motor, and premotor areas, the sensory association and prefrontal cortex, limbic system, and left parietal association cortex. Bilateral parietal association cortices were activated on sensory deprivation of the bilateral temporomandibular joint. There was no activation of the bilateral limbic system with sensory deprivation of the left or bilateral temporomandibular joint during clenching.ConclusionThese results suggest that sensory input from the temporomandibular joint cavity during clenching is closely related to the activated state of the brain.