Materials and Methods:
This prospective study was conducted at the Department of Oral and Maxillofacial Radiology, performed from October 2016 to October 2019. The Institutional Review Board and the local ethical committee have approved the study after registration with the Research Center (protocol HMU # RC/IRB/2016/1040). This study followed the criteria as declared by Helsinki. All participants signed provided written informed consent after a full explanation of the process’s procedure and safety. According to the set criteria, those who were not ready or failed to report were excluded from the stu­dy.
In this study, adult patients without any systemic complications, who strictly met the inclusion criteria, were included. The subjects’ clinical inclusion criteria were assessed on the following five clinical characteristics that were/are the modification of those described initially by Okeson10. The inclusion criteria were; Limited mouth opening; Deflection of the mandible to the affected side at the maximal mouth opening, TMJ pain at the pre-auricular region during mandibular movement; Limitation of condylar translation to the maximal mouth opening; Crepitation during mouth opening and/or closing movement. The exclusion criteria were patients with cerebral aneurysm clip, cardiac pacemaker, skeletal jaw deformity, undergoing orthodontic treatment, history of traumatic extraction, claustrophobic and uncooperative, pregnant patient, and metallic prosthesis heart valves, ferromagnetic foreign bodies in a critical location like the eye.
Each patient was subjected to the clinical diagnostic process. In accord with the Research Diagnostic Criteria (RDC/TMD) 11, the diagnostic process used a standardized clinical head and neck examination that included palpation of the TMJ and muscles of mastication for pain, palpation of joint sounds, and measurement of the range of motion3.
According to the RDC/TMD criteria, a total of 14 symptomatic patients with clinically diagnosed internal derangement of TMJ according to the RDC/TMD criteria were included in this study group. All volunteers were examined and were accepted for the study after completing the following evaluation-
A subjective questionnaire to document the absence of jaw pain, joint noise, locking and history of TMD.
Clinical TMJ and dental examination for signs and symptoms usually associated with internal derangement.
The symptomatic patients were selected from 14 consecutive subjects who were evaluated at the Department of Oral Medicine, Diagnosis, and Radiology.
Bilateral TMJ magnetic resonance images were obtained of all 14 patients employing Higher 1.5 Tesla magnet (General Electric). Pulse sequences were obtained from all patients in closed-mouth position and maximal mouth opening positions on corrected sagittal and coronal T1 weighted; proton density (PD) and T2 weighted images.3
MRI images were prescribed graphically perpendicular (sagittal images) and parallel (coronal images) to the condyle’s horizontal long axis. The maximum intercuspation position was used for closed mouth images and maximum mouth opening for open mouth images.
The disc’s position was analyzed and grouped into one of the categories described by Tasaki et al. 12. Disc function was analyzed as usual, displaced with reduction or without reduction, or indeterminate. The normal function was noted when a disc in the superior position in the closed mouth position interposed between the condyle and the articular eminence in the open mouth position. The reduction was noted when a displaced disc in the closed mouth position assumed a position interposed between the condyle and the articular eminence in the open mouth position. No reduction was noted when the displaced disc in the closed mouth position did not achieve a position between the condyle and the articular eminence in the open mouth position.
Indeterminate disc function was noted when the disc could not be identified because of the artifact or post-surgical scaring13. Osseous components were classified as normal or abnormal.
The TMJs were classified according to the following MR criteria8-
Normal state (No Disc Displacement; NDD) - in the sagittal plane of imaging, the disc had a biconcave shape (an anterior band; an intermediate zone, the thinnest portion; a posterior band, the thickest portion). In a closed-mouth position, the posterior band’s junction with the bilaminar zone was located above the apex of the condylar head (12 o’clock position). When the jaw opens, the condyle rotates under the disc, and the disc-condyle complex translates inferiorly under the temporal tubercle. The disc remains interposed between the osseous component and moves anteriorly in a synchronized fashion. The disc has an arc-shaped configuration in the coronal plane of imaging due to its insertions at the condylar pole. The disc is perfectly centered on the condylar head in an open and closed-mouth position.
(Figure 1).
Anterior disc displacement with reduction (ADDWR):- In the closed position, the disc’s posterior band is anterior to the condylar head in all the sagittal sections. When the jaw is opened, the disc is recaptured by the condyle, and the disc condyle relation appears normal. Figure 2
Anterior disc displacement without reduction (ADDWOR):- In close and open mouth position, the disc’s posterior band is anterior to the condylar head’s superior aspect in all sagittal sections. When the jaw is opened, the disc is anteriorly compressed, whether its shape is modified or not. Figure 2
Sideways displacement (medial or lateral):- Sideways displacements of the disc are well documented in the coronal plane. The disc crosses over one of the sagittal plane tangents to one of the condylar poles. Figure 3
Rotational displacement was present when the disc was anteriorly displaced in all sagittal sections, together with a sideway component (medial or lateral), whether it is reduced or not, according to the definition of Katz berg.
Stuck disc or disc adhesion:- During jaw movement, the disc remains in the same place in relation to the mandibular fossa or the articular tubercle. The stuck disc may be fixed in a normal or displaced position and may or may not be associated with the condyle’s normal mobility.
Degenerative changes: Flattening, erosion, changes in the shape of the articular surfaces, anterior osteophytes, and/or subchondral lacunas were classified as a degenerative joint disease (osteoarthritic joint). The sharpness of the cortical limits was not considered: chemical shifting may produce artifacts in the MR images.
Restricted condylar translation: Limitation of translation was identified when the condylar head did not reach the apex of the articular tubercle of the temporal bone during the opening, with or without the disc – condyle complex dislocation.
All radiograph s and images were evaluated for a set criterion to determine osseous and soft tissue changes in the TMJ.
Statistical Analysis .
Data were subjected to statistical analysis using SPSS 22.0 (SPSS, Inc., Chicago, IL). Statistical tests used for analyzing data were mean and standard deviation and unpaired t-test.
Statistical analyses were undertaken to correlate the radiography/imaging findings to the clinical signs and symptoms in the internal derangement according to RDC/TMD criteria. Data were subjected to statistical analysis using SPSS 22.0 (SPSS, Inc., Chicago, IL). Statistical tests used for analyzing data were sensitivity&specificity tests and inter-observer reliability correlation through the Kappa test.