## 2 Materials and Methods
### Outcome Measures  
The TMD pain was the primary outcome measure, assessed by the VAS, using a 10-cm ruler with the left and right sides corresponding to no pain (0) and unbearable pain (10), respectively. As a secondary outcome, the activity of the masseter and anterior temporalis muscles was assessed by sEMG through a wireless medical device that was able to detect the electrical activity of masticatory muscles, reporting occlusal parameters representing the distribution of loadings on the dental arches [37; 38]. Thus, we performed a complete sEMG analysis of the patient occlusion. The sEMG was performed with four surface electrodes with clip connection (41.5 \(\times\) 24.8 \(\times\) 14 mm mother electrode--O 16 \(\times\) 12 mm satellite electrode, FREE1000 BTS Bioengineering, Milano, Italy) using bipolar surface electrodes (diameter, 0.8 cm; interelectrode distance, 2 cm; disposable, surface Ag/AgCl Ambu, Neuroline, Ballerup, Denmark) with 16 bit resolution, 1 kHz acquisition frequency, and a IEEE 802.15.4 wireless data transmission (probes--USB receiver) [27; 39; 40; 41; 42; 43]. As shown in Figure 1, we have elaborated the following indices [32; 44; 45; 46]:  
1. POC (Percentage of Overlapping Coefficient), a symmetry index computed between the right and left temporalis (POC AT), and the right and left masseter muscles (POC MM). In details, the POC calculates the symmetry of activation between the right and left temporalis, and between the right and left masseter. The POC measure, expressed as percent, is the difference between the normalized (MVC) sEMG signal of the muscle considered. A normality range between 83% and 100% indicates a good symmetry. 2. BAR: Occlusal centre of gravity (anterior/posterior), obtained by calculating the ratio between the activities of the pair of temporalis muscles and the pair of masseter muscles. When the temporalis muscles are predominant with respect to the masseeters, the occlusal centre of gravity is anterior; conversely, when there is a predominance of the masseter muscles, the occlusal centre of gravity is placed in the posterior sectors of the mouth. 3. TORS: Mandibular Torsion Index. It measures the horizontal mandibular torsion during occlusion. It is obtained by comparing the torque of the crossed muscle pairs:comparison between the torque of the right temporalis and the left masseter and between left temporalis and the right masseter. * ASIM: Asymmetry index. It compares the activity of the right muscles (right AT and right MM) with the activity of the left muscles (left AT and left MM). A positive value indicates greater activation of the right side, conversely a negative value indicates greater activation of the left side. The normal condition varies between \(-10\) and \(10\). * IMP: Impact of total standardized muscle activity. The under the curve area of right and left AT and MM over time (5 s MVC). Reference value are between 85 and 115%. Outcome measures were assessed at the following time-points: T0: Baseline; T1: at the end of the treatment; T2: 12 weeks after the end of the treatment. Figure 1: Functional sEMG Indices. Blue lines: representation of the polarity of asymmetry. Green lines: overlap plans. Yellow lines: representation of muscle activity. POC TA and MM: Percentage overlapping coefficient (anterior temporalis muscles or masseter muscles), measuring of the predominance of the right or left anterior temporalis in the anterior teeth contacts and masseter muscle in the posterior occlusal contact. BAR: Barycenter as percentage overlapping coefficient between posterior and anterior teeth contact. A measure of the predominance of the posterior or anterior teeth contacts. TORS: Torsion index is obtained by comparing the torque of the crossed muscle pairs. IMP: Impact index as the work performed by the muscle during its contractile activity. The work is represented geometrically by the area subtended to the curve of electrical activity of the muscles examined over time. ASIM: Asymmetry index.