In vivo prediction of temporomandibular joint disc thickness and position changes for different jaw positions

Abstract

Temporomandibular joint disorders (TMD) are common dysfunctions of the masticatory region and are often linked to dislocation or changes of the temporomandibular joint (TMJ) disc. Magnetic resonance imaging (MRI) is the gold standard for TMJ imaging but standard clinical sequences do not deliver a sufficient resolution and contrast for the creation of detailed meshes of the TMJ disc. Additionally, bony structures cannot be captured appropriately using standard MRI sequences due to their low signal intensity. The objective of this study was to enable researchers to create high resolution representations of all structures of the TMJ and consequently investigate morphological as well as positional changes of the masticatory system. To create meshes of the bony structures, a single computed tomography (CT) scan was acquired. In addition, a high-resolution MRI sequence was produced, which is used to collect the thickness and position change of the disc for various static postures using bite blocks. Changes in thickness of the TMJ disc as well as disc translation were measured. The newly developed workflow successfully allows researchers to create high resolution models of all structures of the TMJ for various static positions, enabling the investigation of TMJ disc translation and deformation. Discs were thinnest in the lateral part and moved mainly anteriorly and slightly medially. The procedure offers the most comprehensive picture of disc positioning and thickness changes reported to date. The presented data can be used for the development of a biomechanical computer model of TMJ anatomy and to investigate dynamic and static loads on the components of the system, which could be useful for the prediction of TMD onset.

Keywords: magnetic resonance imaging; temporomandibular joint; temporomandibular joint disc; temporomandibular joint morphology.

Figure 1

Registered CT (rendered) and MRI volumes.

Figure 2

Examples of achieved MRI image quality: (a) coronal slice, (b) sagittal slice with segmentation (green).

Figure 3

Workflow of disc mesh creation. Leftmost pictures show segmentation from MRI; middle pictures show interpenetration with cartilage borders, and right pictures show the smooth final meshes in comparison with the MRI segmentation.

Figure 4

Example of qualitative verification of mandible position (protrusion shown) using the scanned bite blocks (yellow, bite block; green, articular disc; light blue, condylar cartilage; dark blue, articular fossa cartilage).

Figure 5

Disc and condyle position for the different postures (Rightwards and Leftwards describe corresponding mandible movements. Dark blue, fossa articularis; green, disc; light blue, condyle).

Figure 6

Visualization of disc thickness for the right disc from top view (gray/yellow/blue area is thinner than 1/1.5/2 mm, respectively).

Figure 7

Visualization of disc thickness for the left disc from top view (gray/yellow/blue area is thinner than 1/1.5/2 mm, respectively).

Figure 8

Visualization of disc position (green area) relative to fossa articularis (dark blue) and mandibular condyle (light blue) for the right and left disc (top view for condyle and bottom view for fossa).