Title: 3057 - Unilateral Jaw Muscle Pain Does Not Modify Contralateral Muscle Activity


Isbel Sandoval (Presenter)
The University of Sydney

Polyana Moura Ferreira, The University of Sydney
Terry Whittle, The University of Sydney
Gregory Murray, Westmead Center for Oral Health


Objectives: Pain in jaw muscles can affect the performance of the stomatognathic system, compromising specific functions such as talking or chewing. Therefore, the aim of this study was to determine if the electromyographic (EMG) activity of the left masseter and anterior temporalis muscles during isometric biting tasks in asymptomatic humans, is altered by experimental pain in the right masseter.

Methods: Bipolar surface electrodes recorded the EMG activity from the left masseter and anterior temporalis muscles, while isometric biting tasks (increasing closing force at fast and slow rates, and holding forces at two different levels) were performed on an intraoral force transducer in 18 participants during a painful block caused by the infusion of hypertonic saline solution (5% NaCl) into the right masseter muscle and during control blocks with isotonic saline solution (0.9% NaCl) and a baseline without saline infusion. Pain intensity was maintained between 40-60/100 on a 100 mm visual analogue scale (VAS). Statistical analysis was performed with ANOVA to determine variance in the achieved force rates and force levels and root mean square (RMS) for the effects of pain on the jaw muscle EMG activity (Statistical significance p<0.05).

Results: The VAS scores were significantly (p<0.001) higher during hypertonic than isotonic saline infusion blocks. There were no significant differences in the force rates (N/s), force levels (N) or RMS EMG activity of the left masseter and anterior temporalis muscles across the different blocks.

Conclusions: The findings suggest that experimentally induced jaw muscle pain in the right masseter does not modify left masseter and temporalis muscle EMG activity.

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE