This study was performed to investigate the effect of intraoral snoring device on the electromyographic(EMG) activity of several masticatory muscles. For the study, 40 dental students were selected. They had no visible signs and symptoms except mild joint sound. Two types of intraoral appliance were fabricated : anterior positioning splint(APS), commonly used for patients with tempormandibular disorders, and snoring appliance(SA), mandibular advancement type device. The mean distance of mandibular advancement of each appliance was 3mm and 5mm, respectively.
The BioEMGR Bioreserch Inc., USA) was used to measure of the EMG activity of three pairs of muscles, which were anterior temporalis(TA), superficial masseter(MM), and anterior digastricus(DA), with regard to change of mandibular positions.
Three sessions of measurement were carried out. First session was baseline measurement, to record the EMG activity before insertion of intraoral device. The mandibular positions observed were rest position, protrusive position, protrusive-clenching position, and clenching position. Second session was the measurement of the EMG activity related to APS, which was performed two times, namely, with APS and without APS. Third session was also measured two times, with SA and without SA.
The data were processed with SPSS windowsR program for the maximum and the mean value of EMG activity in each recording.
The maximum EMG activities with adaptation of SA were higher than those with APS or with natural occlusion in general, but the EMG activity in protrusive-clenching position were higher with APS.
The correlation of the mean EMG activity between each session in the same mandibular position showed two patterns. That was, without appliance, correlation among three sessions were highly significant in general, but with appliance, there were no consistent pattern of correlaion.
In summary, adaptation of intraoral snoring device increased masticatory muscle activity, especially in the mandibular rest and the protrusive position. This results also suggest, however, that the muscle activity might be lowered if baseline activity is lowered with many pro-treatment modalities for mandibular relaxation.
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