Experimental Analysis of the Temporomandibular Disc Movement During Mouth Opening

The main aim of this work was to determine the relative displacement of the temporomandibular (TM) disc and the mandible during mouth opening. The movement of the TM disc was studied using a magnetic resonance imaging (MRI) FFE dynamic scan sequence with a customised mono-directional "spreader" device. Six sagittal static images in revolved sections of the temporomandibular joint (TMJ) were obtained in various positions of jaw opening from 0 to 50 mm (distance between lower and upper incisors). The results provided a description of the TM disc displacements as a function of jaw opening. The anatomical marker movement data was transformed and the motions of the TM disc and the mandible were observed. The displacements of the mandible and TM disc were about 31 mm and 18 mm respectively at mouth opening of 50 mm. The maximum rotation of the mandible was 34.4°. While the movement of the mandible has already been published, though only for a small mouth opening, the behaviour of the disc during the same movement has not been well depicted. The results of these measurements can be used for clinical diagnostics and also as inputs for finite element analysis (FEA).