To standardize the EMG potentials of the four muscles analyzed with occlusal contacts, two strips of Parafilm M® (American National Can TM, Chicago, USA) folded into five parts (10 mm in thickness) will be positioned bilaterally over the mandibular first and second molars of each subject. The electrodes will transfer data to a portable device with a real-time display. The system will process and compare the data with a set of predefined models for the evaluation of muscle activity during specific tasks.52 The EMG signal will be amplified and digitized (gain of 150 x, peak-to-peak input of 28 ± 14 mV, resolution of 12 b, sampling frequency of 2230 Hz A/D and theoretical resolution of 16 IV) using a differential amplifier with a rejection rate of 105 dB in the range of 0 to 60 Hz, input impedance of 10 GX and low-pass analog filter with a band width of 0 to 580 HZ as well as a digital filter with a band width of 30 to 400 Hz. The signals will be recorded for subsequent analysis.