## 2 Materials and Methods  
Twenty-two Dental students attending Vita-Salute San Raffaele University in Milan (11 F, 11 M, average age 25 \(\pm\) 2.88) voluntarily underwent a recording of the masticatory cycle. The participants had complete and healthy denti with at least 28 teeth, showed no limitations in mouth opening, did not experience any pain or disorders in the temporomandibular joint, and reported no chewing impairment. These subjects did not suffer from temporomandibular disorders (TMD) according to DC/TMD criteria [18]. This study was approved by the ethics committee of IRCCS San Raffaele Hospital (Milan, Italy) with the document \"parere09/int/2023\". During this experimental clinical study, small savory biscuits (Gullon, Ctra. Burgos, Km 1.5, 34800 Aguilar de Campoo, Palencia, Spain) were used as test food. This food test allowed the recording of condylar paths and electromyographic activity for 15 s.  
Each volunteer underwent digital scanning of their dental arches using IOS iTERO (c) 2023 Align Technology, Inc.; San Jose, CA, USA) (Figure 1). The obtained dental scan data were exported and imported into the TWIM(tm) software (Modjaw(r), Tech in motion(tm), Villeurbanne, France) for the analysis of mandibular movements with Modjaw devices (Figure 2). This device is based on 3D stereophotogrammetry technology: the optical sensors are placed on the jaw and head of the patient to capture data. Modjaw(r) captures movements of the hinge axis of the patient during functional jaw movements and transfers them, along with the personal reference plane of the patient, to the TWIM(tm) software (version 3.5). The devices are also integrated with an HD camera for high precision and high frequencies for real-time 4D visualization, a touch screen PC, and a rotative arm and stable cart with a locking system [5]. The delay time of the Modjaw(r) system is minimal, typically within 10 ms, which ensures near-instantaneous capture of mandibular kinematics. This low latency is crucial for real-time 4D visualization and accurate dynamic movement tracking during functional activities such as chewing, talking, and swallowing. According to recent studies by [PERSON] et al., the repeatability of recordings was good to excellent in healthy subjects. The Modjaw(r) device also offers a high level of reliability in recording mandibular kinematics with excellent precision [4; 5]. For mandibular kinematics recording, the volunteer assumed an upright position on the dental chair, with their back straight and head raised, not resting on the backrest (Figure 3). Figure 1: (**a**) iTERO intraoral scanner device; (**b**) Dental scan frontal view iTERO iOS. Figure 2: Jaw-tracking device Modjaw®. After the Modjaw(r) device calibration, the markers (Fork and Tiara) were then positioned on the volunteer's jaw and head (Figure 3). Calibration of the Modjaw(r) system is a fundamental step to ensure the accuracy of measurements of mandibular kinematics and occlusal dynamics. The Modjaw(r) system requires the definition of an \"individual reference plane\" for the patient as a reference for jaw movements. This is done through the acquisition of anatomical reference points related to the position of the head using the optical markers on the tiara and the \"interincisal point,\" the most anterior point between the lower incisors, using the optical markers on the wand. During calibration, it is also essential to identify the \"hinge axis\" of the jaw by marking both the condylar lateral poles of the patient. All volunteers were instructed to perform movements before registration and the experimenter monitored upon the correct execution of procedures. Before the masticatory test, the volunteer was also instructed to place a biscuit on the tip of their tongue and to start every test with their teeth initially closed. Upon receiving a vocal command from the experimenter, the volunteer commenced chewing unilaterally for a duration of 15 s. In this study, the volunteers were asked to begin with right-sided unilateral chewing.