Masseter and Temporal Electrical Activity: Analysis of Chewing Side Preferences

Objectives: The aim of the present study was to compare electrical activity in the anterior temporal and masseter muscles individually, according to preferred (PS) and non-preferred (NPS) chewing side during mastication and at rest. In addition, the increase in muscle electrical activity during chewing was assessed for the preferred and non-preferred side, analysing working (WS) and non-working (NWS) side separately.
Methods: A population of 28 young healthy women, between 18 and 32 years old, was included in the study. All the participants underwent Kazazoglu`s test for analyses the preference side of chewing. Bioresearch ‘Bio EMG’ (USA) software and bipolar surface electrodes (BioResearch, USA) were used for exams. The exams were conducted during mandibular rest (10 seconds) and unilateral mastication of raisins (10 seconds) on both the preferred and non-preferred chewing side. Working-side and non-working side on PS and NPS were analysed separately. The obtained data were then statistically analyzed with SPSS 20.0 using the Paired Samples Test at a significance level of 95%.
Results: The differences in the medium values of EMG between PS and NPS were not statistically significant at rest (Temporal p=0,247; Masseter p=0,469) and during chewing (Temporal WS p=0.86; Temporal NWS p=0.87; Masseter WS p=0.587; Masseter NWS p=0.202). Difference in the increase of muscle electrical activity between Masseter and Temporal occurred when they were in WS of chewing on PS and NPS (p=0.00). Increase in electrical activity were not statically different in NWS on PS (p=0.914) and NPS (p=0.294).
Conclusions: It was concluded that electrical activity at rest and during chewing is similar between sides, and that the increase in electrical activity is not significantly different when comparing the preferred and non-preferred chewing side. However, during mastication, the masseter increase electrical activity around 35% more than temporal muscle in the working side.