Effect of occlusal splint in the fatigue of masseter muscle : analysis of motor evoked potentials in masseter

Abstract

We investigated the effect of the occlusal splint on motor evoked potentials (MEPs) of fatigued masseter muscles using transcranial magnetic stimulation (IMS). We compared the root MEPs (R-MEPs) and the cortex MEPs (C-MEPs) in 10 volunteers who performed continuous voluntary contractions without the splint, with a 2.0-mm splint, and with a 10-mm splint. The amplitude of both the MEPs was significantly decreased under all conditions. The ratio between the amplitude of the C-MEPs and that of the R-MEPs was significantly decreased without the splint. There were no changes in the other conditions. These findings indicated that the occlusal splint reduced reflex inhibition of peripheral feedback to the masseter muscle motor neurons during fatigue.