Comparison of Condylar Position Discrepancies Assessed Using an Optical Jaw Tracking System and a Conventional Condylar Position Indicator

Background: Assessment of functional occlusion is crucial in orthodontics and prosthodontics. With scientific advancements, optical jaw tracking systems are increasingly used to evaluate mandibular kinematics. Objectives: To compare the performance of an optical jaw tracking system (Modjaw®) and a traditional condylar position indicator (CPI) in identifying condylar position discrepancies within an orthodontic population. A secondary objective was to explore the association between condylar discrepancies and temporomandibular disorders (TMD). Methods: Measurements were collected from 132 patients consecutively recruited from the private practice of a coauthor, using Modjaw and CPI, analyzing discrepancies in the sagittal, vertical, and transverse planes. TMD presence was determined clinically and using the DC-TMD questionnaire. Receiver operating characteristic (ROC) curves and diagnostic metrics were used to evaluate the tools’ performance. Results: No correlation was found between CPI and Modjaw measurements. CPI did not effectively discriminate between patients with and without TMD, with areas under the curve (AUC) not statistically significant. In contrast, the AUCs for Modjaw were 0.683 for the vertical plane (p = 0.001), 0.654 for the sagittal plane (p = 0.004), and 0.777 for the transverse plane (p < 0.001). The cut-off values for TMD screening using Modjaw were established at 2 mm (vertical), 1 mm (sagittal), and 0.5 mm (transverse), exhibiting some specificity, especially in the transverse dimension, but very low sensitivity. Conclusions: No correlation was found between Modjaw and CPI for assessing condylar position discrepancies. While these discrepancies may aid orthodontic treatment planning, they lack sufficient sensitivity for reliable TMD diagnosis. Modjaw’s cut-off points may help exclude TMD risk in orthodontic patients.