Aim: To verify whether patients with temporomandibular disorders
(TMD) present masticatory muscle hyperactivity with the mandible in the
rest position. Method: Forty-six women were selected (18-33
years-old, mean age = 22.7 ± 3.52 years), 31 with TMD
(experimental group) and 15 without TMD (control group).
Electromyography (EMG) was performed in two situations: 1) with the
mandible in the rest position and 2) in maximal dental clenching. RMS
(root mean square) was used for EMG signal analysis. Data were analyzed
statistically by the Mann Whitney U-test. Result: The experimental
groups presented increased EMG activity of the muscles evaluated with
the mandible in the rest position compared to the control. In maximal
dental clenching, no differences were observed between the groups.
Analyzing the percentage of EMG activity at rest, the control group
presented EMG activity around 1 to 6% of maximal dental clenching and
the experimental group, around 1 to 12% of the same activity.
Conclusion: The experimental group presented an increase in EMG
activity at rest in the studied muscles, mainly in the anterior portion
of the temporal muscle, bilaterally. However, this increase should not
be called muscular hyperactivity, but should rather be considered as an
important sign of TMD
