Bilateral 4D visualization of human temporomandibular joints using a novel multi-slice real-time MRI procedure - A comparative analysis of the intraoral masticatory forces of subjects with and without anterior disk displacement

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The aim of the present study is the bilateral dynamic 4D real-time visualization of the temporomandibular joint structures of patients with anterior disk displacement during the chewing process. This includes the simultaneous visualization of both temporomandibular joints over time as well as the three-dimensional positional relationship, the dynamic changes of the discus articularis and all adjacent temporomandibular joint structures. The currently available conventional MRI techniques allow the visualization of static rather than dynamic processes (i.e., mandibular movements) because the corresponding data is not acquired in real time; pseudodynamic MRI sequences are also retrospectively produced only by time-consuming reconstruction of independent static MRI images. Clinically applicable measuring systems for the recording of mandibular pathways, such as the axiography, however, do not allow precise anatomical conclusions on the dynamic changes of the temporomandibular joint structures during movement. The development of real-time MRI technology at the Göttingen MPI for Biophysical Chemistry (Prof. Jens Frahm) enables an MRI acquisition time of approximately 20-60 milliseconds per frame with a high spatial resolution. As part of a collaboration with Prof. Frahm, our group has been able to implement this innovative technique to analyze high-resolution MRI video sequences of the temporomandibular joint in healthy volunteers during the chewing movement. Due to further advances in computer performance (bypass computers), image reconstruction techniques (FLASH, non-linear inverse reconstruction) as well as modified software and hardware components we have now succeeded in acquiring simultaneous bilateral MRI data in several image planes. We would like to apply this extended multi-slice real-time MRI procedure in the project presented here to enable four-dimensional real-time insights into physiological and pathophysiological processes of temporomandibular joint functions. For the first time, the interaction of both temporomandibular joints can be simultaneously visualized in order to investigate the biomechanical influence of unilateral and bilateral pathological changes in temporomandibular joint structures during mastication. This had not previously been an option due to technical limitations. The method presented here represents the state of the art in imaging diagnostics and enables conclusions to about biomechanical relationships in fundamental research on the human temporomandibular joint. By using this novel method, the biomechanics of the temporomandibular joint in subjects with and without disc displacements can be clearly described. On the basis of the results, the hypothesis should be tested that there is larger force on the articular surfaces in subjects with disc displacement in relation to subjects of the control group.