Reliability of Measuring Mandibular Movement and Condylar Position Using an Optical Jaw Registration System

Aim: The aim of this study was to evaluate the reliability of a digital jaw registration system for measuring mandibular movement and condylar position.
Materials and methods: Data on mandibular movement and condylar position were collected from a consecutively recruited sample of 20 functionally healthy adults (age range: 19–77 years; 45% female) using an optoelectronic registration system (Tizian JMA optic, zebris Medical GmbH, Isny, Germany). Participants were randomly assigned to one of two calibrated examiners, who exclusively performed the measurements for the entire study period. Condylar position was measured five times on two separate days, approximately one week apart, while mandibular movements were recorded once per appointment. The measurement results were analyzed within (intra-appointment) and compared across both measurement appointments (inter-appointment). Analysis of condylar position involved comparing the condylar positions in the resting position to the maximum intercuspation. Reliability was assessed using the intraclass correlation coefficients (ICCs).
Result: For mandibular movement, ICCs indicated high reliability for mouth opening (0.95) and protrusion (0.94), with slightly lower values for laterotrusion (0.89 to 0.87), without significant differences between appointments. The condylar position showed an overall intra-appointment ICC value of 0.98. No significant differences were found within or between the examiners, intraappointment as well as inter-appointment.
Conclusion: The evaluation of mandibular movements and condylar position relative to habitual occlusion using the tested digital registration system proved to be a reliable procedure. The measurements were not significantly influenced by different examiners. The results confirm the applicability of the device in clinical settings, particularly in functional diagnostics and the digital prosthetic workflow. Although the actual benefits of the application for patients have yet to be established, this study provides a scientific foundation for future research considering more vulnerable cohorts, particularly patients with a higher average age, reduced dentition, or the presence of temporomandibular disorders.