Directional characteristics of incipient temporomandibular joint disc displacements: A magnetic resonance imaging study

Classification of the temporomandibular joint disc displacement without reduction using MRI in the mouth-opening position

OBJECTIVES

This study aimed to analyze the positional characteristics of the temporomandibular joint (TMJ) disc in patients with anterior disc displacement without reduction (ADDWoR) using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

2,827 MRI images from 2,168 ADDWoR patients were collected and categorized into two groups: without limited opening (WoLO) group and with limited opening (WLO) group. The position of TMJ disc and their distribution characteristics in these two groups were analyzed from the oblique sagittal planes of MRI.

RESULTS

The disc positions were classified into 11 types based on oblique sagittal MRI images during maximum mouth opening. Anterior displacement was the most common in both groups, with 39.65% in WoLO and 41.96% in WLO. Anteroinferior displacement and anteroinferior displacement in the lateral part were also prevalent, particularly in the WLO group. While the MRI imaging features of superior displacement did not appear in the WLO group, due to mouth opening limitation. The effect of masticatory muscles and condylar excursion during mouth opening play a crucial role in the displacement of TMJ disc.

CONCLUSIONS

ADDWoR patients of WoLO group primarily manifest disc anterior displacement, anteroinferior in the lateral part, and anteroinferior displacement. ADDWoR patients of WLO group are more likely to exhibit disc anterior displacement and anteroinferior displacement, without the manifestation of superior displacement.

CLINICAL RELEVANCE

The position of the anterior displaced disc can guide treatment strategies, conservative treatment alleviating restricted mouth opening for anteroinferior displacement patients, or controlling excessive mouth opening to relieve ligamentous laxity for anterosuperior displacement patients.

Correlation between TMJ Space Alteration and Disc Displacement: A Retrospective CBCT and MRI Study

This study aims to determine if a large anterior and reduced posterior/superior joint space is highly predictable for disc displacement. From patients with temporomandibular disorders symptoms, fifty-two experimental joints and fourteen control joints were included. The cone beam computed tomography (CBCT) images were used to calculate posterior-to-anterior (P-A) and superior-to-anterior (S-A) joint space ratios, while disc position was determined using magnetic resonance imaging (MRI). One-way analysis of covariance test and receiver operating characteristics analysis were carried out. The results showed that among the 52 experimental joints, 45 were diagnosed as disc displacement and 7 as normal disc positions (N). All 14 control joints showed normal disc positions. The P-A ratio was 1.46 ± 0.21, 0.99 ± 0.23, and 0.86 ± 0.30 in the control, N, and DD groups, respectively (p < 0.001). The S-A ratio was 1.80 ± 0.27, 1.44 ± 0.33, and 1.08 ± 0.35 in the control, N, and DD groups, respectively (p < 0.001). When an altered P-A ratio and/or S-A ratio are observed on the CBCT, the diagnosis of disc displacement is quite predictable with high sensitivity and specificity.

Magnetic resonance imaging assessment of articular disc position in temporomandibular disorder subjects with various bite registrations

Objective

This study aimed to evaluate the validity and reliability of three bite registrations on articular disc position in temporomandibular disorder patients using magnetic resonance imaging (MRI).

Materials and Methods

Fifteen clinically symptomatic and orthodontically untreated temporomandibular disorder patients within the age range of 17-40 years (mean age: 28.5 years) were examined. Each patient was subjected to three bite registrations, namely maximum intercuspation, initial contact bite and Roth power centric bite, and evaluated with MRI.

Results

On the right side, the mean vertical and horizontal measurement values of the point in the most posterior aspect of the posterior band of the articular disc in relation to horizontal reference line (HRL) and vertical reference line (VRL) in the sagittal view in the Roth power centric bite were lesser (2.720 ± 1.239 mm and 2.380 ± 1.185 mm, respectively), in comparison with the other two bites, and on the left side too, it was lesser in the Roth power centric bite (2.293 ± 0.979 mm and 2.360 ± 1.078 mm, respectively), when compared to the other two bites. Statistical analysis also showed the significance of Roth power centric bite over the other two bites.

Conclusions

Favourable articular disc positional changes were observed in the Roth power centric bite followed by the initial contact bite and that maximum disc recapture was observed in most patients with the Roth power centric bite rather than in initial contact bite and maximum intercuspation positions. The Roth power centric bite could be assumed to be the ideal method for articulation and fabrication of gnathological splints for treating patients with temporomandibular disorders.

Relationship between rotational disc displacement of the temporomandibular joint and the dentoskeletal morphology

Objective

The purpose of this study was to evaluate the relationship between rotational disk displacement (DD) of the temporomandibular joint (TMJ) and the dentoskeletal morphology.

Methods

Women aged > 17 years were included in this study. Each subject had a primary complaint of malocclusion and underwent routine cephalometric examinations. They were divided into five groups according to the findings on sagittal and coronal magnetic resonance images of their TMJs bilateral normal disk position, bilateral anterior DD with reduction (ADDR), bilateral rotational DD with reduction (RDDR), bilateral anterior DD without reduction (ADDNR), and bilateral rotational DD without reduction (RDDNR). Twenty-three cephalometric variables were analyzed, and the Kruskal–Wallis test was used to evaluate differences in the dentoskeletal morphology among the five groups.

Results

Patients with TMJ DD exhibited a hyperdivergent pattern with a retrognathic mandible, unlike those with a normal disk position. These specific skeletal characteristics were more severe in patients exhibiting DD without reduction than in those with reduction, regardless of the presence of rotational DD. Rotational DD significantly influenced horizontal and vertical skeletal patterns only in the stage of DD with reduction, and the mandible exhibited a more backward position and rotation in patients with RDDR than in those with ADDR. However, there were no significant dentoskeletal differences between ADDNR and RDDNR.

Conclusions

The results of this study suggest that rotational DD of TMJ plays an important role in the dentoskeletal morphology, particularly in patients showing DD with reduction.

The importance of multisection sagittal and coronal magnetic resonance imaging evaluation in the assessment of temporomandibular joint disc position

OBJECTIVES

The aim of this study was to evaluate diagnoses of temporomandibular (TMJ) disc displacement by comparing evaluations done on the basis of central sagittal scans only, the most often used in temporomandibular disorder (TMD) patients, with a multisection evaluation done with both sagittal and coronal scans.

MATERIALS AND METHODS

Multisection MRI analysis of 382 TMJs was conducted in 191 patients with disc displacement according to RDC/TMD criteria. Disc position in the intercuspal position (IP) was assessed two times using two different methods. The first method involved a TMJ disc position evaluation on the central slide in the oblique sagittal plane only. In the second method, the TMJ disc position was assessed on all oblique sagittal and coronal images. McNemar's χ² test was used to evaluate the differences between the sensitivities of two methods.

RESULTS

The first method (central oblique sagittal scans assessment) identified 148 TMJs (38.7%) with normal disc position compared with 89 TMJs (23.3%) with normal disc position found by the second method (all oblique sagittal and coronal scans assessment). The sensitivity of analysis in both planes was significantly higher than in the sagittal plane only (p < 0.001).

CONCLUSIONS

The multisection analysis in the sagittal and coronal plane allows to distinguish the correct disc position from disc displacement and thus improve evaluation of TMJ internal derangement.

CLINICAL RELEVANCE

The multisection sagittal and coronal images should be recommended as a standard in MRI of the TMJ disc displacement in patients with TMD to avoid false-negative diagnoses.

Diagnostic accuracy of synovial chondromatosis of the temporomandibular joint on magnetic resonance imaging

The purpose of this study was to evaluate the diagnostic accuracy of magnetic resonance imaging (MRI) for synovial chondromatosis (SC) of the temporomandibular joint (TMJ). In this study, 1415 patients (2109 joints) with temporomandibular joint disorders were collected between January 2012 and January 2017. All patients had a preoperative MRI examination and were treated by either arthroscopy or open surgery. On reviewing all MRI images, the number of "positive", "suspicious", and "negative" cases was collected afterwards, then the number of reported SC cases in operative data was recorded. The SPSS software was used to process all collected data. The kappa coefficient and ROC curve (AUC-index) with sensitivity and specificity were calculated to evaluate the consistency between MRI and arthroscopy/open surgery. Compared to 156 joints with SC detected by arthroscopy and open surgery, the results of MRI examination showed "positive" in 117 joints, and "negative" in 1938 joints. The number of "true positive", and "true negative" cases was 95, and 1897 respectively. The AUC-index was 0.86 (0.82-0.90) with a kappa coefficient of 0.74 (P < 0.05). In conclusion, the incidence of synovial chondromatosis diagnosed on MRI was in accordance with the arthroscopic and open surgery. Therefore, being a relatively non-invasive tool, MRI could be recommended as an effective diagnostic modality for SC.