2023 Volume 35 Issue 2 Pages 93-98
Purpose: A model that expresses the movement of the mandibular condyle during mouth opening was developed. Using this model, the accuracy of measuring mandibular condyle movement in X-ray images was evaluated.
Methods: A robotic system to replicate the condylar movement of the TMJ was developed to evaluate the geometric elements of the appropriate X-ray projection to observe the movement of the condyle. Then, the linear distance of condylar movement was measured in the panoramic radiograph (TMJ imaging mode) and lateral oblique radiograph (Schüller method). Five dried mandibles (ten TMJs) were used as the objects to be imaged. The distances of condylar movement in the radiographs were compared with the actual movement distance of the dried mandibular condyles. The amount of error in the radiographic measurement value was calculated based on the actual measurement value and the magnified factor of radiographs.
Results and Conclusion: Using the robotic system and Schüller method radiograph, the mouth-opening movement was imaged by dividing it into 13 frames from the closed position to the maximum opening amount of 40 mm. The median condylar movement distance of the ten temporomandibular joints was 19.53 mm in actual measurement, 14.38 mm in the Schüller method, and 18.81 mm in panoramic TMJ imaging mode. The amount of error in the radiographic measurement was 3.34 mm in the panoramic TMJ imaging and 5.32 mm in the Schüller method. The results of this study suggested that panoramic TMJ imaging is superior to the Schüller method in the accuracy of measuring mandibular condylar movement.
