Are the bite force and electromyographic activity altered in muscle TMD patients with abfraction lesions?

OBJECTIVE

To verify if the maximal molar bite force (BF) and the electromyographic activity (EMG) are altered in TMD patients with abfraction lesions (AL) when compared to those without AL.

METHODS

The sample was composed of 45 patients (18-60 years old), 30 diagnosed with TMD (RDC/TMD) (15 with AL and 15 without AL) and 15 controls. The BF and the EMG of the masticatory muscles (maximal voluntary contraction (MVC) and chewing gum) were measured.

RESULTS

TMD patients showed decreased BF (p < 0.001), without differences between patients with and without AL. The electromyographic activity during MVC was similar among all groups (p > 0.05), although there was a greater trend of muscular balance for the control group (percentage overlapping coefficient and electromyographic indexes). The TMD group without AL showed a lower number of cycles and masticatory frequency.

DISCUSSION: TMD patients with and without AL exhibited similar results in the analysis of the BF and EMG, without differences.