Prof. Francesco Grande
DDS, MS, PhD
• Graduated cum Laude in Dentistry at the University of Bologna, he completed a second-level Master’s degree in Oral Surgery and Implantology. He obtained a PhD in Digital Prosthodontics at the Polytechnic University of Turin.
• He served as Adjunct Professor in Dental Materials at the University of Ferrara, where he continues to maintain active scientific and teaching collaborations.
• He is an Editorial Board Member of Digital Dentistry Journal and BMC Oral Health, a member of the Italian Board of the Digital Dentistry Society (DDS), an active member of SIDOC, and an Honorary Member of IDEA.
• Author of more than 40 articles in the last 5 years published in indexed international peer-reviewed journals, his clinical and research activity is mainly focused on fixed prosthodontics, implant, oral surgery and digital workflows.
In the evolution of prosthodontics, the digital revolution has progressively expanded the boundaries of clinical diagnostics and treatment planning [1]. From the analog articulator to the 4D virtual patient [2], dentistry has shifted from static records to dynamic, data-driven workflows. The introduction of jaw tracking systems (JTSs) has made it possible to record mandibular movements and transfer them into the virtual environment, allowing the clinician to reproduce the functional logic of conventional articulators [3] within a digital workflow [4]. By aligning intraoral scans and mandibular motion data, the clinician can now create a 4D patient in which both esthetic and functional information coexist [2]. What once required complex mechanical devices can now be simulated virtually with optical tracking systems such as Zebris, which accurately capture the real envelope of mandibular function [5].
When using a jaw tracking system
When using a jaw tracking system
The idea behind JTS is to bring the logic of conventional articulators into the digital environment and match the mandibular movements together [6]. The steps for assembling a virtual articulator (VA) are similar to those of a conventional articulator; they are only digitally translated (fig. 1) [2,6].
In fact, the creation of a 4D virtual patient begins with the acquisition of static data – facial scan, hinge axis position, Camper and Frankfurt planes, bipupillar line, and the three-dimensional position of the maxilla [7]. These records create the 3D virtual patient which can be useful to make an esthetic planning and a functional occlusal planning (static occlusion) [8]. When these data are integrated with mandibular dynamics – such as protrusive, right and left lateral, and masticatory mandibular movements – a 4D virtual patient is generated, allowing the dental technician to perform functional and dynamic technical modeling (fig. 2-5) [2].
In this way, the dental technician can skip from a type III virtual semiadjustable articulator into a type IV fully adjustable articulator [9]. Devices like Zebris use sensors to record these motions in real time, translating them into digital files that can be integrated into the CAD environment. This integration allows clinicians to visualize condylar positions, occlusal plane inclination, and hinge axis movement directly on the screen. It also enables the adjustment of occlusal vertical dimension (OVD) along the hinge axis without altering cast relationships—an approach long theorized by McCollum [10] and now simply achievable through modern digital tools. For instance, Zebris records mandibular opening movements to detect the phase of pure rotation and determine the hinge axis position, similarly to how kinematic facebows operated [11].
So, in everyday practice, JTSs are particularly useful especially for three tasks: to individually set a virtual/analog articulator, to design functionalized interim or definitive prostheses and to fabricate occlusal devices with balanced occlusion [6,12]. An individualized setting of the VA on a CAD software is only possible if the JTS provides data on the Bennett angle, immediate side shift, condylar angle, and occlusal plane inclination [13]. This information are valuable even when working in maximal intercuspal position (MIP), as it has been demonstrated that the guidance of prostheses designed with a VA is influenced by the position of the occlusal plane [13]. These data can also be transferred to a conventional analog articulator. However, to perform this step correctly, specific plates and pins must be used to accurately position the maxillary cast in relation to the hinge axis of the semi-adjustable articulator. The Zebris system allows the maxillary cast to be mounted on several analog semi-adjustable articulators, including Artex, Panadent, SAM, Protar, and Stratos. This procedure is mandatory when the clinician requests cut-back restorations, such as metal-ceramics [14], or even when working with monolithic restorations, to verify that the sintering of zirconia – which is always subject to a certain degree of anisotropic shrinkage [15] – has not altered the previously established occlusion.
JTSs allow clinicians to define anterior and lateral guidance with good accuracy, minimizing occlusal interferences, deflective occlusal contacts and reducing the need for intraoral adjustments (fig. 5). Studies by Lepidi, Kois and Feng demonstrated that using dynamic occlusal data improves anterior guidance recovery and occlusal predictability in digital prosthesis design [2,12,13]. From a clinical perspective, this means shorter delivery times, less adjustment at insertion, and especially the preservation of ceramic integrity (fig. 6).
Chairside occlusal adjustments of zirconia, for example, can reduce its flexural strength by up to 59% and this can be even higher as yttria content increase (multilayered zirconia) [16]. Clinical adjustments can also alter zirconia optical properties such as translucency and color [17]. All those risks can be avoided or reduced by integrating accurate functional data from systems such as Zebris within the digital workflow.
In prosthodontics, when there is a need to increase the OVD and establish a new maxillomandibular relationship (utility position) [18], JTSs can greatly assist clinicians and technicians in achieving this with ease. After registering the 3D position of maxillary arch in relation to hinge axis (as with the digital facebow), the free opening/closure movement of the patient allows to define the actual arc of closure and to measure the “hinge axis range” – when the mandible is in pure rotation. The Zebris system not only allows the localization of the hinge axis and the different maxillomandibular relationships along the closing arc, but also enables the clinician to fix a predetermined mandibular position along this axis and export the digital models of the maxilla and mandible – together with their relative spatial relationship – to CAD systems such as Exocad. This new mandibular position then can be used by the dental technician to make the wax-up based on the mandibular movements of the patient (fig. 7).
An incorrect localization of the hinge axis may lead to inaccurate occlusal contacts during mandibular closure, resulting in anterior or posterior deflective contacts depending on the recorded hinge axis position [10]. However, previous studies have shown that this discrepancy is not highly significant from a clinical standpoint as it resulted in less then 100 µm of occlusal discrepancies at molar and incisal level [19,20].
Another important application concerns the fabrication of occlusal splints or custom mouthguards. Using jaw tracking data, clinicians can simulate balanced occlusion during dynamic movements, as reported by Ntovas et al. [21]. This approach not only improves comfort but also ensures even distribution of functional loads and reduce time for occlusal device adjustments (fig. 8) as occlusal contacts resulted already balanced as in the digital environment.
However, accuracy remains dependent on both the device and the workflow. Errors can arise from improper bite paraocclusal attachment positioning, inaccurate intraoral scans, or poor spatial alignment of reference planes. For consistent results, the paraocclusal attachment must be rigid (high Shore A/D hardness) and must not interfere with occlusion during mouth opening. Checking its alignment before acquisition is essential. Zebris systems, thanks to their optical calibration and real-time feedback, help reduce these potential errors, but operator precision remains crucial. When recording mandibular dynamics, even small hinge axis deviations—of about 5 mm—may lead to occlusal discrepancies of up to 200 µm at the molar level (Weinberg, 1961). This underlines the importance of accurate reference positioning, especially in full-mouth rehabilitations or when modifying the OVD.
Conclusions
Conclusions
JTSs are reshaping digital prosthodontics by integrating function into the virtual workflow. By capturing the real motion of the mandible, they allow clinicians to customize treatments, optimize occlusal schemes, and enhance the precision of both analog and digital articulators. Devices such as Zebris bridge the gap between esthetic design and functional accuracy, providing clinicians with a powerful diagnostic and planning tool that improves predictability and reduces complications. Although still influenced by device settings, patient factors, and operator skill, the use of jaw tracking technology represents a decisive step toward the complete digitalization of prosthodontics—where the virtual patient finally moves like the real one.
References
[1] M. Revilla-León, D.E. Kois, J.M. Zeitler, W. Att, J.C. Kois, An overview of the digital occlusion technologies: Intraoral scanners, jaw tracking systems, and computerized occlusal analysis devices, J Esthet Restor Dent 35 (2023) 735–744. https://doi.org/10.1111/jerd.13044.
[2] L. Lepidi, B.C. Kim, L. Giberti, C. Suriano, J. Li, F. Grande, The 4D virtual patient: A proof of concept in digital dentistry, J Prosthet Dent (2024) S0022-3913(24)00194-X. https://doi.org/10.1016/j.prosdent.2024.02.029.
[3] L.A. Weinberg, An evaluation of the face-bow mounting, J Prosthet Dent 11 (1961) 32–42. https://doi.org/10.1016/0022-3913(61)90107-X.
[4] P. Nuytens, F. Grande, J. Li, L. Lepidi, Maxillomandibular relationship and virtual facebow integration in complete-arch intraoral implant scan: A novel clinical technique, J Prosthodont 34 (2025) 545–553. https://doi.org/10.1111/jopr.13840.
[5] L. Lepidi, F. Grande, G. Baldassarre, C. Suriano, J. Li, S. Catapano, Preliminary clinical study of the accuracy of a digital axiographic recording system for the assessment of sagittal condylar inclination, J Dent 135 (2023) 104583. https://doi.org/10.1016/j.jdent.2023.104583.
[6] G. Goldstein, C. Goodacre, Selecting a Virtual Articulator: An Analysis of the Factors Available with Mechanical Articulators and their Potential Need for Inclusion with Virtual Articulators, J Prosthodont 32 (2023) 10–17. https://doi.org/10.1111/jopr.13517.
[7] P. Nuytens, F. Grande, R. D’haese, Z. Salameh, L. Lepidi, Novel complete-arch pillar system (CAPS) to register implant position and maxillomandibular relationship in one single visit, J Dent 143 (2024) 104885. https://doi.org/10.1016/j.jdent.2024.104885.
[8] P. Nuytens, F. Grande, S. Vandeweghe, L. Lepidi, Integrating facial scanning into the complete arch pillar system to create a 3D virtual patient: A dental technique, J Prosthet Dent (2025) S0022-3913(25)00445–7. https://doi.org/10.1016/j.prosdent.2025.04.048.
[9] The Glossary of Prosthodontic Terms 2023: Tenth Edition, J Prosthet Dent 130 (2023) e1–e3. https://doi.org/10.1016/j.prosdent.2023.03.003.
[10] B.B. McCollum, The mandibular hinge axis and a method of locating it, J Prosthet Dent 10 (1960) 428–435. https://doi.org/10.1016/0022-3913(60)90005-6.
[11] G.A. Thompson, C. Nick, P. Francisco, L. Lux, J.P. Wiens, Comparison of two arbitrary cast transfer systems with a kinematic facebow for mounting a maxillary cast on a semiadjustable articulator, J Prosthet Dent 128 (2022) 597–603. https://doi.org/10.1016/j.prosdent.2020.12.023.
[12] J.C. Kois, J.M. Zeitler, M. Revilla-León, Use of an optical jaw tracking system to capture the envelope of function when designing interim and definitive prostheses: A dental technique, J Prosthet Dent (2024) S0022-3913(24)00240–3. https://doi.org/10.1016/j.prosdent.2024.03.048.
[13] Y. Feng, X. Sun, J. Li, W. Liu, Is dynamic occlusal design necessary for anterior guidance recovery in the computer-aided design process? An in vitro study, J Dent 142 (2024) 104833. https://doi.org/10.1016/j.jdent.2024.104833.
[14] S. Rosenstiel, M. Land, R. Walter, Contemporary Fixed Prosthodontics, 6th edition, Elsevier, 2022.
[15] J. Kunii, Y. Hotta, Y. Tamaki, A. Ozawa, Y. Kobayashi, A. Fujishima, T. Miyazaki, T. Fujiwara, Effect of sintering on the marginal and internal fit of CAD/CAM-fabricated zirconia frameworks, Dent Mater J 26 (2007) 820–826. https://doi.org/10.4012/dmj.26.820.
[16] A. Abdulmajeed, T.A. Sulaiman, A.A. Abdulmajeed, T.O. Närhi, Strength and phase transformation of different zirconia types after chairside adjustment, J Prosthet Dent 132 (2024) 455–463. https://doi.org/10.1016/j.prosdent.2022.06.015.
[17] R. Ghanem, A. Adel, W. Al-Zordk, Effect of simulated intraoral adjustment on the color and translucency of gradient multilayered monolithic zirconia, J Prosthet Dent 132 (2024) 1313.e1-1313.e8. https://doi.org/10.1016/j.prosdent.2024.08.025.
[18] M.T. Kattadiyil, A.A. Alzaid, S.D. Campbell, The Relationship Between Centric Occlusion and The Maximal Intercuspal Position and Their Use as Treatment Positions for Complete Mouth Rehabilitation: Best Evidence Consensus Statement, J Prosthodont 30 (2021) 26–33. https://doi.org/10.1111/jopr.13316.
[19] L.H. Lux, G.A. Thompson, K.J. Waliszewski, G.J. Ziebert, Comparison of the Kois Dento-Facial Analyzer System with an earbow for mounting a maxillary cast, J Prosthet Dent 114 (2015) 432–439. https://doi.org/10.1016/j.prosdent.2015.02.022.
[20] J.C. Kois, D.E. Kois, Y. Chaiyabutr, Occlusal errors generated at the maxillary incisal edge position related to discrepancies in the arbitrary horizontal axis location and to the thickness of the interocclusal record, J Prosthet Dent 110 (2013) 414–419. https://doi.org/10.1016/j.prosdent.2013.06.005.
[21] P. Ntovas, O. Ladia, J.C. Kois, C. Rahiotis, M. Revilla-León, Digital workflow for the fabrication of custom-fit additively manufactured sports mouthguards with balanced occlusion using an optical jaw tracking system: A dental technique, J Prosthet Dent (2024) S0022-3913(24)00505–5. https://doi.org/10.1016/j.prosdent.2024.07.021.