Objective: The purpose of this study was to determine the prevalence of anterior, sideways, rotational and partial anterior disc displacements, as well as degenerative changes in patients with clinical signs and symptoms of internal disorders.
Materials and methods: 732 MR Images of temporomandibular joints (TMJ) were produced for 366 symptomatic patients. Image analysis included assessment of disc positions and mobility, as well as recapture in coronal and mediolaterally divided sagittal planes in closed and open positions.
Results: Of these images, 545 TMJ showed an internal derangement comprised of 52% anterior disc displacements without reduction, 26% anterior disc displacements with reduction, 11% partial anterior disc displacement, 5% pure sideways displacements and 4% stuck discs. Rotational disc displacements were observed in 34% of the anterior disc displacements without reduction group and in 53% of the anterior disc displacements with reduction group. A total of 97% of the partial anterior disc displacement occurred laterally. Degenerative changes increased with age, mainly in the anterior disc displacements without reduction group.
Conclusion: Magnetic resonance imaging (MRI) investigations show that the disc is subject to a great variety of displacements and that there is a need for further research to refine the clinical therapy for TMJ internal derangements.