## 2 Materials and Methods
Data on unilateral chewing on both the right and left side were recorded, along with right and left laterotrusion to measure the Bennet angle, and protrusion-retrusion to measure condylar slopes angle. These were recorded and analyzed. Figure 4 shows an example of a right masticatory cycle recorded by [PERSON](r), the software represents the traces of the right and left condyle recorded from the points located on the right and left condyle and the tracing of mandibular movements recorded from the interincisal point during the 15 s of recording. Figure 4: _Cont_. Figure 3: (**a**) Lateral view of a volunteer student wearing tiara and fork; (**b**) Volunte performing chewing movements. Similarly, the volunteer again positioned the biscuit on the tip of their tongue. Upon receiving the voice command, they commenced unilateral chewing on the left side for 15 s.  
Figure 5 shows similar recorded data during masticatory cycle on the left side. Electromyography was recorded using TMJoint sEMG device (c 2023 BTS Bioengineering, Garbagnate Milanese, MI, Italy) with the software Dental Contact Analyzer (Version 4.0.43.2). After the examination with [PERSON](r), the experimenter removed the markers and prepared the volunteer's skin by cleaning it with ethanol on the masseter and anterior temporal muscles to enhance electrode adhesion and reduce impedance (Figure 6a,b). Before the start of the examination, in order to place the electrodes, the volunteer was asked to clench their teeth while the experimenter palpated the position of the masseter and temporalis muscles with their finger (Figure 6c-f) and placed the TMJoint(r) sensors accordingly on the muscle bellies parallel to the muscle fiber (Figure 6d-f). Following the instructions in the manufacturer's user guide, the first pre-operative test was registered and consisted of recording a maximum voluntary contraction (MVC) of the teeth by interposing 10 mm cotton rolls for 5 s on the mandibular second premolar to standardize the sEMG potential (Figure 7). Figure 4: (**a**) Chewing recording with Modjaw® Right Trial; (**b**) Right masticatory cycle from an interincisival point of view frontal plane; (**c**) Right condyle path on the axial plane during unilateral chewing on the right side; (**d**) Left condyle path on the sagittal plane during unilateral chewing on the right side. Figure 5: (**a**) Chewing recording with Modjaw® Left Trial; (**b**) Left masticatory cycle from an interincisival point of view; (**c**) Right condyle path on the sagittal plane during unilateral chewing on the left side; (**d**) Left condyle path on the sagittal plane during unilateral chewing on the left side. Afterwards, the masticatory test was performed, during which the volunteer was instructed to place a bicsuit on the tip of their tongue, as during the jaw-tracking recording, and to start every test with their teeth initially closed. Upon receiving a vocal command from the experimenter, the volunteer performed chewing unilaterally for a duration of 15 s. Also, during sEMG test the volunteer was asked to begin with right-sided unilateral chewing. Similarly, for the left side, the volunteer again positioned the biscuit on the tip of their tongue. Upon receiving the voice command, they commenced unilateral chewing on the left side for 15 s.  
The following Parameters were extracted from the Dental contact Analyzer(r) software data:  
* SMI: The symmetry muscular index (SMI, %) is a measure that evaluates the balance and coordination of muscle activation during chewing. It quantifies the symmetry between the right and left sides of the masticatory muscles. The SMI is expressed as a percentage, with 100% representing perfect symmetry. Values lower than 100% indicate asymmetry, with one side exhibiting greater muscle activity than the other. This index is valuable for assessing muscular imbalances and functional issues in the masticatory system, as well as monitoring the effectiveness of treatment interventions aimed at improving chewing function and restoring muscle balance.