Evidence of Neuroplasticity in Cortical Control of Masseter Muscles Following Increases in Vertical Bite Dimension

Objectives: Transcranial magnetic stimulation (TMS) has been used to assess characteristics of the corticomotor control of jaw muscles. The aim of this study was to investigate the cortical motor control of masseter muscle before and after prothodontic rehabilitation involving an increase in of vertical bite dimension.
Methods: Seven patients with a reduced vertical bite dimension were enrolled in the study, and were rehabilitated with conventional removable dentures. The motor evoked potentials (MEPs) in the masseter muscles and the first dorsal interosseos muscles (FDI, control) were recorded by TMS in the two sessions: 1. Pre-treatment (baseline); 2. One month post-treatment (1m after fabrication and installation of provisinal dentures). The vertical bite dimension was increased by 4 ± 0.58 mm (Mean ± SD) . The change in the cortical motor control was assessed by the following indicators: Stimulus-Response curves for the MEPs and motor cortex mapping.
Results: The result showed that there were significant increases in MEPs Stimulus-Response curves and are of motor cortex mapping masseter muscles (P<0.01), while no significant difference was observed in the FDI (P>0.05).
Conclusions: The results indicate that prosthodontic rehabilitation of the occlusion invoving an increase in vertical bite dimension can induce neuroplastic changes in the corticomotor control of the masseter muscles.