## 4 Discussion
In both groups, at T0, the greater part of the parameters demonstrated values out of the normal range, while at T2, the majority of parameters in both groups changed significantly reaching the normal range showing a general improvement of muscular function and symmetry in both groups [12; 24]. No significant differences were observed concerning \(\Delta\) (delta) variation over time between digital and traditional techniques. At T2, in both groups, the EMG exam confirmed an absence of any predominance of left/right sides in the masticatory muscle activity (the parameters POC TA, POC MM and ASIM were in the normal range), the absence of any torque in the muscular function (the parameter TORS were in the normal range), and a normal pattern of muscular work (the parameters IMP and TOT were in the normal range). Only slightly low values (\(<\)90) were registered in both groups for the BAR parameter that indicates the distribution of forces between anterior and posterior segments of dental arches, suggesting the slight predominance of posterior forces and occlusal contacts that is typical of full arch prosthetic rehabilitation. From the clinical point of view, the effect of OVD loss on masticatory efficiency demands our attention to avoid progressive damage, which may lead to create intensely destructive zones [25; 26]. Thus, restorative treatment can replace the loss of tooth structure and has been retrospectively observed to be able to obtain acceptable functional occlusal parameters (only functional complication, mostly a difficulty in speech were observed, which was solved in two weeks after rehabilitation) [27]. In the [PERSON] et al. study, 50 patients with advanced teeth wear who received prosthodonic treatment using conventional wax up method, underwent electromyographic analysis of the anterior temporal and masseter muscles [28]. Although those authors report a general improvement of masticatory function after treatment that agrees with the present study, in their study no assessment of the symmetric index between right and left muscles was provided, and no normalization was carried out by closing the mouth while cotton rolls are placed inside. Thus, their obtained results are not directly comparable with the ones from the present study. In the present study, slightly different distributions between the two groups at T1 for the IMP were observed. In particular, at T1, an excessive value for the IMP parameter was registered in the traditional group indicating an excessive muscular work, significantly higher than the digital group. This difference disappeared at T2 when in both groups the IMP parameter reached a normal value, with no significant difference between the two groups, thus it does not seem to be important for achieving the general success of prosthetic rehabilitation. At the authors' knowledge this is the first study concerned with the assessment of functional/oclusal symmetry during prosthetic rehabilitation, in particular in the mockup phase, utilizing electromyography. The present findings suggest that for ensuring the final restoration of a functional symmetry both traditional and digital methods can still be considered to be effective and applicable procedures, in terms of impact on masseter and anterior temporalis muscle activity. The advantages of the digital mockup technique can be mentioned as follows; it provides easier phonetic testing as the prosthesis is divided into two sections, and aesthetic evaluation can be achieved without difficulty. The digital mockup represents identical features as the definitive prosthesis is fabricated by the traditional technique in the form and points of contact (contacts absent in the anterior part of dental arch, and present at the posterior part) as well as the guide paths (incisive and canine, or group) can be early established.