Magnetic resonance evaluation of the temporomandibular joint disc position and configuration

Contribution of the complex comprising the masticatory fascia, disc, and capsule to temporomandibular joint stabilization: An anatomical study

BACKGROUND

Anterior displacement of the temporomandibular joint (TMJ) disc is the most typical pathological condition of TMJ disorders. Structures attached to the articular disc may support the disc in various directions and contribute to stabilizing the TMJ. However, the relationship between the articular disc, capsule, and masticatory muscles remains unclear. Therefore, this study aimed to clarify the relationship between the masticatory muscles, related masticatory fascia, articular disc, and capsule.

METHODS

We examined 10 halves from adult Japanese cadavers, with five halves macroscopically analyzed and the remaining five histologically analyzed. The TMJ was dissected from the lateral aspect for gross anatomical analysis. For histological analysis, the relationship between the temporal and masseteric fasciae and the articular capsule was observed in the coronal section. Additionally, we evaluated relationships among the disc, capsule, temporal fascia, and masseteric fascia in 10 living and healthy volunteers using magnetic resonance imaging.

RESULTS

The articular disc was attached to the capsule without a clear border. The capsule continued into the masseteric and temporal fasciae. Consequently, the articular disc, capsule, masseteric, and temporal fasciae were considered a single complex.

CONCLUSIONS

The single complex of the temporalis, masseter, capsule, masticatory fascia, and disc may antagonize the force in the posterolateral direction through the fascia.

Temporomandibular joint disc position and shape in patients submitted to two protocols of rapid maxillary expansion and face mask therapy: A randomized clinical trial

OBJECTIVE

The objective of this prospective study was to assess possible changes in the position and shape of the temporomandibular joint (TMJ) articular disc in patients treated with two protocols of rapid maxillary expansion (RME) and face mask (FM) therapy.

METHODS

A sample of 88 patients with Class III or Class III subdivision malocclusions, aged between 6 and 13 years, were consecutively selected and divided into three groups (G): G1-34 patients were treated with RME, followed by FM therapy; G2-34 patients were treated using RME according to modified alternate rapid maxillary expansion and constriction (ALT-RAMEC) protocol, followed by FM therapy. These treated groups were randomly (1:1 allocation ratio) distributed according to the two treatment protocols. G3 - Control Group - 20 untreated patients were followed. Magnetic resonance imaging (MRI) TMJs were obtained before (T1) and after (T2) a treatment period or follow-up. McNemar test, Fisher's exact test and intra- and inter-observer concordance (K) were performed (p ≤ .05).

RESULTS

There were no statistically significant differences in the baseline cephalometric variables at T1 between the groups. There were statistically significant differences between the groups (p < .001) in relation to the disc shape in T1, since G1 (8 TMJs -11.76%) presented higher occurrences of altered forms in comparison with G2 (no changes). No significant differences were observed in disc position CM and OM (G1 - p > .999; G2 - p = .063; G3 - p = .500) and shape (G1 - p > 0.999; G2 - p = .250; G3 - not calculable), between T1 × T2, in any of the groups studied.

CONCLUSION

The two treatment protocols did not have adverse effects on the position and shape of the TMJ disc, in a short-term evaluation.

Relationships between functional temporomandibular joint space and disc morphology, position, and condylar osseous condition in patients with temporomandibular disorder

OBJECTIVE

To investigate the correlations between joint space and temporomandibular joint (TMJ) components and the compressive states of the disc and condyle subsequent to joint space changes.

MATERIALS AND METHODS

A total of 240 TMJs were categorized according to disc morphology, disc position, and condylar osseous condition. The two-dimensional (2D) and three-dimensional (3D) measurements were compared. The functional joint space (FJS) and disc areas on closed- and open-mouth images (DA-C and DA-O) were also calculated, and the joint space was measured in five directions. Different groups of TMJ components were compared. A spring model was used to simulate the effect of condylar displacement on the disc and condyle.

RESULTS

Disc morphology was strongly correlated with its position. The measurements were equivalent between 2D and 3D methods. DA-C and FJS differed significantly between groups. The DA-C to FJS ratio differed between the Class 2 and Class 3 groups and between disc displacement groups with and without reduction. Altered disc morphology and position were correlated with significant changes in joint space in the 60°, 90°, and 120° directions. Despite minor discrepancies among condylar osseous conditions, reduced joint space was correlated with bone destruction at the corresponding site. The spring model stimulation revealed that condylar displacement caused elevated stresses on the disc and condyle.

CONCLUSIONS

Condylar displacement causes joint space alterations while exerting compressive pressure on both the disc and condyle.

CLINICAL RELEVANCE

Proper condylar positioning within the fossa is recommended to ensure sufficient articular disc accommodation.

Reconstructed magnetic resonance image-based effusion volume assessment for temporomandibular joint arthralgia

BACKGROUND

Joint effusion is often noticed in magnetic resonance image (MRI) and its diagnostic value for arthralgia of the temporomandibular joint (TMJ) remains obscure.

OBJECTIVE

To develop a method for quantitatively evaluating the joint effusion revealed in MRI and its diagnostic value for arthralgia of the TMJ.

METHODS

Two-hundreds and twenty-eight TMJs, 101 with arthralgia (Group P) and 105 without (Group NP) from 103 patients, and 22 TMJs (Group CON) from 11 asymptomatic volunteers were examined by using MRI. The effusion volume was measured after constructing a three-dimensional structure of the joint effusion revealed in MRI by using the ITK-SNAP software. The diagnostic capabilities of the effusion volume on arthralgia were evaluated with receiver operating characteristic (ROC) curve analysis.

RESULTS

Totally 146 joints showed MRI signs of joint effusion, including nine joints from Group CON. However, the medium volume was greater in Group P (66.65 mm3 ), but was much similar in Group CON (18.33 mm3 ) to Group NP (27.12 mm3 ). The effusion volume larger than 38.20 mm3 was validated to discriminate Group P from Group NP. The AUC value was 0.801 (95% CI 0.728 to 0.874), with a sensitivity of 75% and specificity of 78.9%. The median volume of the joint effusion was larger in those with than without bone marrow oedema, osteoarthritis, Type-III disc configurations, disc displacement and higher signal intensity of the retrodiscal tissue (all, p < .05).

CONCLUSION

The present method for evaluate joint effusion volume well discriminated painful TMJs from non-pain ones.

MRI changes and clinical characteristics in temporomandibular joints with displacement of the articular disk without reduction - a cross-sectional observational study

OBJECTIVES

This study examined changes in magnetic resonance imaging (MRI) of temporomandibular joints (TMJ) with anterior displacement disk without reduction (DDwoR) and its correlation to clinical symptoms.

METHODS

190 individuals with DDwoR were evaluated according to Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) and MRI. Pain's chronicity/intensity and limited mouth opening (locking) were correlated with: TMJ degeneration (MRI T1), effusion (T2), disc's shape and position (proton density).

RESULTS

In 103 TMJ with DDwoR, hemiconvex shape (41.6%), sclerosis (45.6%) and mild effusion (47.6%) were the most prevalent findings. There was not association (p > .05) between: different DDwoR positions with pain's intensity/chronicity; effusion with locking. Disk deformation was associated with degeneration (p = .034) and pain's intensity (p = .006). Locking was associated with degeneration (p = .05).

CONCLUSIONS

Condylar osteodegeneration is often related to DDwoR. Locking by DDwoR is associated with severe levels of chronic pain and articular disk deformation.

Biomechanics and Derangements of the Temporomandibular Joint

The human temporomandibular joint, is a ginglymo-arthrodial joint. The articular disk serves as a fibrous, viscoelastic structure that allows force distribution and smooth movement of the joint in its normal arrangement during mandibular movements. Most studies suggest that in the normal disk position the posterior band is located at the 12'o clock position within the glenoid fossa in the closed mouth posture. When the biomechanics of the joint is altered, the disk may be displaced creating an abnormal relationship between the disk, condyle, and the eminence that is often referred to as an internal derangement. This article reviews the various presentations of internal derangements.

Introducing a novice-friendly classification system for magnetic resonance imaging of the temporomandibular joint disc morphology

OBJECTIVE

To introduce a new classification, aiming to correspond TMJ disc configuration with diagnosis, meanwhile reduce difficulty and subjectivity in TMJ MRI evaluation and training of TMD diagnosis for dental students.

METHODS

90 patients sought for TMD treatment were enrolled in the study, whose MRIs were used to establish the new classification. A total of 180 discs were evaluated using MRI for position (normal, DDWR or DDWoR) and classified by morphology according to previous (Murakami's classification) and new classification respectively. 60 discs were selected and judged by two groups (2 TMJ specialists and 30 dental students) to assess the reliability and validity of the new classification. Questionnaires were acquired for all observers to assess the attitude toward two classification systems. Descriptive statistics, Spearman's rank correlation coefficient, and intraclass correlation coefficient were performed. P < 0.05 was considered statistically significant.

RESULTS

In the new classification, Class 1 disc was significantly correlated with DDWR and Class 3 disc was significantly correlated with DDWoR. Interobserver reliability/consistency for observers between TMJ specialists was 0.867 when Murakami's classification was applied and 0.948 when the new classification was applied. Interobserver ICC value for dental students was 0.656 when using Murakami's classification, and 0.831 when using the new classification. The difference in attitude toward different classification systems was statistically significant.

CONCLUSION

A new classification of TMJ disc configuration is presented. The correlation between disc morphology and position revealed helps diagnosis and management. The new classification improves TMJ MRI interpreting accuracy and provides a better learning and using experience.

Asporin levels in patients with temporomandibular joint disorders

BACKGROUND

Understanding the pathogenesis of temporomandibular joint disorder (TMD) is important for diagnosis and treatment planning. Thus, biochemical analysis is usually used for the detection of tissue damage.

OBJECTIVE

In this study, we aimed to investigate the serum asporin levels in patients with TMD.

METHODS

Our study was planned to be performed on 43 healthy individuals (control group) without any joint problems and 43 patients with temporomandibular joint internal derangement (TMJ-ID; patients group) according to the Wilkes classification (stages 3, 4 and 5). Serum asporin levels were determined by the enzyme-linked immunosorbent assay (ELISA) method and compared between groups. Asporin levels were analysed according to the demographic and clinical characteristics of the patients, and the differences between them were demonstrated.

RESULTS

Asporin levels were found to be significantly increased in the patients group compared to control group (p = .0303). The age and gender distributions of the samples in the control and patients groups were homogeneous, and there was no statistically significant difference between the groups. In addition, while there was no significant change in asporin levels in females in the patients group compared with the control group, the asporin levels were significantly increased in males in the patients group (p = .0403).

CONCLUSIONS

Consequently, asporin seems to be an important biomarker in the pathobiology of TMJ-ID as it is significantly upregulated in these patients.

MRI investigation of TMJ disc and articular eminence morphology in patients with disc displacement

PURPOSE

The aim of this study was to evaluate the morphology of the temporomandibular joint (TMJ) articular eminence and disc and the relationship between morphology and inclination in patients with disc displacement.

METHODS

TMJ magnetic resonance images (MRI) of 30 patients with disc displacement with reduction (DDWR) on one side and disc displacement without reduction (DDWOR) on the other side were analyzed. Articular eminence morphology was subdivided as box, sigmoid, flattened and deformed. Articular disc configuration was characterized as biconcave, biplanar, biconvex, hemiconvex and folded. The articular eminence inclination was measured as the angle between the Frankfurt plane and a line drawn from the glenoid fossa roof to the lowest point of the articular eminence.

RESULTS

Regarding articular eminence shape, in both DDWR and DDWOR groups, the most frequent articular eminence shape was flattened shape. Regarding to the disc morphology, biplanar shape was the most frequently observed in both DDWR side and DDWOR side. The mean articular eminence inclination was 32.62 and 33.85 in the DDWR and DDWOR side, respectively.

CONCLUSIONS

Disc and articular eminence morphology was found to have no relationship with TMJ internal derangement except the relationship between flattened type and internal derangement. The articular eminence inclination have no influence on disc reduction.

MRI characteristics of the asymptomatic temporomandibular joint in patients with unilateral temporomandibular joint disorder

OBJECTIVE

To determine the association between unilateral temporomandibular joint disorder (TMD) and the presence of imaging abnormalities in the contralateral, asymptomatic joint.

METHODS

MRI studies of 219 subjects with symptoms of unilateral TMD were examined for signs of disc displacement, osteoarthritis, disc deformation, and effusion in both temporomandibular joints (TMJ). The Chi-Square test and stepwise logistic regression analysis were performed.

RESULTS

Disc displacement, osteoarthritis, disc deformation, and effusion were more common on the symptomatic side. However, in the category of disc displacement with a reduction in open mouth position (DDWR), the difference was not significant between the symptomatic and the asymptomatic TMJs. Stepwise logistic regression showed that the presence of any imaging abnormality other than DDWR was related to osteoarthritis and disc deformity on the symptomatic side. On the other hand, the presence of any MRI abnormality (including DDWR) on the asymptomatic side was related only to the presence of osteoarthritis on the symptomatic side.

CONCLUSIONS

Unilateral symptomatic TMD is related to the presence of imaging abnormalities on the contralateral, asymptomatic side, suggesting that the development and progression of joint changes in symptomatic and contralateral asymptomatic TMJs are interrelated.

Does clinical findings correlate with magnetic resonance imaging (MRI) findings in patients with temporomandibular joint (TMJ) pain? A cross sectional study

Background

Although magnetic resonance imaging (MRI) helps to clearly visualize the disorders in temporomandibular joint (TMJ), the relationship between cross-sectional and clinical findings has not been precisely established. The aim of this study was to evaluate the relationship between clinical symptoms and MRI findings in individuals with TMJ pain.

Material and Methods

This cross-sectional study, conducted on the clinical and MRI findings of the patients, who applied to Uşak University, Oral and Maxillofacial Surgery Clinic with TMJ pain between the years 2016-2019. The primary predictor variables were MRI findings; disc position (normal, disc displacement with reduction (DDWR), disc displacement without reduction (DDWOR)), disc structural distortion (normal, folded, lengthened, round, biconvex, thick), condyle degeneration type (normal, moderate, severe) and joint effusion (JE) (absent, present). The primary outcome variable was pain, recorded on a visual analog scale (VAS) (numbered between 0-10). The other variables were demographic variables (age/gender). The relationship between clinical and MRI findings were statistically evaluated. The data were analysed by Kruskal Wallis and Mann Whitney U test. Chi-square (x2) test was used for categorical variable comparisons. P values < .05 were considered to indicate statistical significance.

Results

Clinical and MRI records of 700 TMJ, from 350 patients with the mean age of the 31 (12-65) were evaluated in this study. Statistically significant differences were found between; disc position and pain, disc position and JE; JE and pain; disc structural distortion and pain; and disc structural distortion and disc position. JE was seen more common in DDWOR group. The most common disc distortion, seen in patients with JE, is the folded type.

Conclusions

The present study can infer that pain is associated with disc position, JE, disc structural distortion, and DDWOR is associated with JE. Folded type disc is the most common disc type in TMJ with JE.

Key words:Internal derangement, TMJ, MRI evaluation, disc morphology, disc position, condyle degeneration, joint effusion.

Temporomandibular joint morphology does not influence the presence of arthralgia in patients with disk displacement with reduction: a magnetic resonance imaging-based study

OBJECTIVE

The aim of this study was to compare, by using magnetic resonance imaging (MRI), temporomandibular joint (TMJ) morphology between patients with disk displacement with reduction (DDWR) with or without arthralgia and a control group and to identify which factors are associated with the concomitant presence of arthralgia in DDWR patients.

STUDY DESIGN

In this investigation, 36 TMJ MRIs were divided into 3 groups. Group 1 (n = 12) comprised patients with DDWR and arthralgia; group 2 (n = 12) comprised patients with DDWR without arthralgia; and group 3 (n = 12) was the control group. Disk and mandibular condyle morphologies; articular eminence morphology and inclination; size of the mandibular fossa; joint space size; joint effusion; bone marrow of the mandibular condyle; and the relative signal intensity of retrodiscal tissue were evaluated.

RESULTS

Fisher's exact test and 1-way analysis of variance (ANOVA) revealed no significant differences (P > .05) between groups for any variable. Logistic regression analysis showed that no anatomic variables were related to the concomitant presence of arthralgia in patients with DDWR (P > .05).

CONCLUSIONS

As evaluated on MRI scans, no significant differences in the anatomic characteristics of the TMJ were detected between DDWR patients with or without concomitant arthralgia and the control group. There were no factors associated with the concomitant presence of arthralgia in patients with DDWR.

Evaluation of serum prolidase activity and oxidative stress in patients with temporomandibular joint internal derangement

Objective: To investigate serum prolidase activity and oxidative stress in patients with temporomandibular joint internal derangement (TMJ-ID).Methods: Seventy patients with Wilkes stage III, IV, and V joints and 70 healthy controls were included. Serum prolidase activity and oxidative stress parameters, including total antioxidant status (TAS), total oxidant status (TOS), oxidative stress index (OSI), advanced oxidation protein products (AOPP), glutathione (GSH), ferric reducing antioxidant power (FRAP), and lipid hydroperoxide (LOOH) were measured.Results: The levels of prolidase, TOS, OSI, AOPP, and LOOH were significantly higher in the TMJ-ID group than in the control (p = .0001). TAS and FRAP level was significantly lower in the TMJ-ID group than in the control (p = .0001). There was no significant difference in GSH between groups.Conclusion: Significantly increased prolidase activity and oxidative stress in patients with TMJ-ID may be related to long-term collagen tissue damage, and inflammation and can be effective in the etiology of TMJ-ID.

Temporomandibular joint disc displacement with reduction: a review of mechanisms and clinical presentation

Disc displacement with reduction (DDWR) is one of the most common intra-articular disorders of the temporomandibular joint (TMJ). Factors related to the etiology, progression and treatment of such condition is still a subject of discussion. This literature review aimed to address etiology, development, related factors, diagnosis, natural course, and treatment of DDWR. A non-systematic search was conducted within PubMed, Scopus, SciELO, Medline, LILACS and Science Direct using the Medical Subjective Headings (MeSH) terms “temporomandibular disorders”, “temporomandibular joint”, “disc displacement” and “disc displacement with reduction”. No time restriction was applied. Literature reviews, systematic reviews, meta-analysis and clinical trials were included. DDWR is usually asymptomatic and requires no treatment, since the TMJ structures adapt very well and painlessly to different disc positions. Yet, long-term studies have shown the favorable progression of this condition, with no pain and/or jaw locking occurring in most of the patients.

Effectiveness of Sequential Viscosupplementation in Temporomandibular Joint Internal Derangements and Symptomatology: A Case Series

Viscosupplementation is a minimally invasive technique that replaces synovial fluid by intra-articular injection of hyaluronic acid (HA). Although effective in some joints, there is not conclusive evidence regarding temporomandibular disorders. This case series described the efficacy of a viscosupplementation protocol in intra-articular temporomandibular disorders. Ten patients with a diagnosis of disc displacement and/or osteoarthritis by Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were submitted to four monthly injections of low or medium molecular weight HA. Pain, mandibular function, image analysis by tomography and magnetic resonance, and quality of life were assessed at baseline and follow-ups (1 and 6 months). Pain, jaw range-of-motion, mandibular function, and quality of life improved at follow-up evaluations. Osteoarthritis changes decreased, and 20% of patients improved mandibular head excursion after treatment. Resolution of effusion and improvement in disc morphology were observed for most patients. This viscosupplementation protocol reduced pain and symptoms associated with internal derangement of temporomandibular joint, improved quality of life, and showed benefits from both low and medium molecular weight HA in alternate cycles.

Correlation between clinical variables and magnetic resonance imaging findings in symptomatic patients with chronic temporomandibular articular disc displacement with reduction: A retrospective analytical study

Objective: To correlate the clinical aspects of symptomatic patients with chronic articular disc displacement with reduction with alterations in the articular disc (AD) morphology and sagittal position. Methods: Records from 109 patients were selected that included data on AD morphology and sagittal position as determined by MRI. According to the MRI results, the sagittal position and AD morphology with opened and closed mouth were correlated with many clinical variables. Results: More than half of the patients studied were female, and the biconcave and hemiconvex morphologies were most common. Thirty-four patients (31.3%) presented with restricted maximum interincisal distance (MID). The biplanar morphology was associated with eccentric bruxism and MID (p < 0.05). Visual analog scale (VAS) scores between 2 and 7 were shown to be risk factors (p < 0.05). Conclusion: The mouth position can influence AD morphology and eccentric bruxism. VAS scores and unknown etiology were risk factors.

Clinical study of splint therapeutic efficacy for the relief of temporomandibular joint discomfort

PURPOSE

This study aimed to evaluate the relationship between displacement of the mandibular condyle/disc due to occlusal splint insertion with splint therapy and changes in discomfort of the temporomandibular joint (TMJ), and to clarify the relationships between the outcomes over time of temporomandibular discomfort and TMJ magnetic resonance imaging (MRI) findings at the initiation of splint therapy.

MATERIALS AND METHODS

A total of 75 patients admitted to hospital with discomfort around the TMJ were evaluated. A visual analogue scale for TMJ discomfort was administered during visits for approximately 3 months following the initiation of splint therapy. At the start of splint therapy, magnetic resonance imaging (MRI) was performed with and without splint insertion, and condyle and disc movements were evaluated. Disc balance, disc position and function, disc configuration, joint effusion, osteoarthritis, and bone marrow were evaluated. Linear regression and multiple regression analyses were used to clarify relationships between changes in discomfort and the factors evaluated.

RESULTS

There was no significant correlation between TMJ discomfort and condyle/disc movement with splint insertion. TMJ discomfort was significantly relieved by splint therapy regardless of temporomandibular MRI findings. Unilateral anterior disc displacement and marked or extensive joint effusion fluid were significantly improved with splint therapy.

CONCLUSION

Discomfort tended to remit with splint therapy regardless of temporomandibular MRI findings. Improvement of TMJ discomfort appears more likely to occur in patients with unilateral anterior disc displacement and with an apparent organic disorder, such as a joint effusion.

Characteristics of temporomandibular joint structures after mandibular condyle fractures revealed by magnetic resonance imaging

Background

This study aimed to evaluate the structural changes of temporomandibular joint immediately after condylar fractures with magnetic resonance imaging (MRI).

Method

We evaluated 34 subjects of condylar fractures with MRI. The position, shape, and signal intensity of the condyle, disc, and retrodiscal tissue were analyzed with MR images.

Results

Immediately after trauma, the disc was displaced with the fractured segment in almost all cases. And, the changes of signal intensity at the retrodiscal tissue were found but less related to the degree of fracture displacement. And, the high signals were observed almost at all fractured joint spaces and even at some contralateral joints.

Conclusions

The displaced disc as well as the increased signal intensity of the joint space, condylar head, and retrodiscal tissue demands more attention to prevent the possible sequela of joint.

Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation

OBJECTIVE

The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs.

DESIGN

Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs.

RESULTS

Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface.

CONCLUSIONS

The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering.

Radiological follow-up results of untreated anterior disc displacement without reduction in adults

The aim of this study was to assess the radiographic changes in untreated adults with bilateral anterior disc displacement without reduction. A cohort study was designed to compare the bone changes, effusion, disc configuration, and pseudo-disc changes on two magnetic resonance images obtained at least 24 months apart. Twenty-eight patients (22 female, six male) with a mean age of 33.1 years (range 20-57 years) were included. The mean interval between the initial visit and the follow-up visit was 36.2 months. At the initial visit, the frequencies of bone changes, effusion, disc deformation, and pseudo-disc changes were 51.79%, 35.71%, 100%, and 0%, respectively. At follow-up, the frequency of effusion had decreased significantly. The frequency of bone changes had increased significantly to 75%, but newly formed cortical bone was present in five condyles. All discs remained deformed. Pseudo-disc changes were detected in five joints. Over a long period of observation, there was a significant decrease in effusion and a significant increase in bone changes. However, some adaptive changes occurred.

Correlation between clinical symptoms and magnetic resonance imaging findings in patients with temporomandibular joint internal derangement

Objectives

The purpose of this study was to clarify which findings in magnetic resonance imaging (MRI) are good predicators of pain and mouth opening limitation in patients with temporomandibular joint (TMJ) internal derangement (ID).

Materials and Methods

Clinical examinations for pain and mouth opening limitation were conducted for suspected TMJ ID. MRI scans were taken within a week of clinical examinations. On the oblique-sagittal plane image, readings were obtained in terms of the functional aspect of disc position, degree of displacement, disc deformity, joint effusion, and osteoarthrosis. Multiple logistic regression analyses were conducted to identify the predictors of pain and mouth opening limitation.

Results

A total of 48 patients (96 TMJs) were studied, including 39 female patients and 9 male patients whose ages ranged from 10 to 65 years. The resultant data showed significant correlations between pain and the MR imaging of the degree of disc displacement (P<0.05). The probability of there being pain in moderate to significant cases was 9.69 times higher than in normal cases. No significant correlation was found between mouth opening limitation and MRI findings.

Conclusion

We identified a significant correlation between clinical symptoms and MRI findings of ID. The degree of anterior disc displacement may be useful for predicting pain in patients with TMJ ID.

Correlation between temporomandibular joint morphology and disc displacement by MRI

OBJECTIVES

The aim was to evaluate the morphology of the temporomandibular joint's (TMJs) disc and condyle as well as its correlation with disc displacement, using MRI.

METHODS

190 TMJs were retrospectively analysed. The condyle morphology of each TMJ was evaluated by two observers using both axial and coronal views, as were their disc morphology and displacement, using sagittal view. Condyle morphology was classified as flat, convex, angled or rounded in the coronal sections and as anterior side flat/posterior side convex, biconvex, anterior side concave/posterior side convex, flat or biconcave in the axial view. Disc morphology was determined as biconcave, biplanar, biconvex, hemiconvex or folded. χ2, Fisher exact and Bonferroni correction tests were used to evaluate the data. ANOVA followed by post hoc Tukey's test was used to evaluate the interaction between age and disc displacement.

RESULTS

Anterior disc displacement with reduction; convex condyle morphology in the coronal view; anterior side concave/posterior side convex morphology in the axial view; and biconcave discs were found to be the most prevalent findings. An association was observed between disc morphology and disc displacement (p<0.001). No correlation between condyle morphology and TMJ disc displacement was found (p=0.291 for axial and p=0.14 for coronal views).

CONCLUSIONS

The results of this study suggest that TMJ disc morphology is associated with disc displacement.

Assessing the reliability of MRI-CBCT image registration to visualize temporomandibular joints

OBJECTIVES

To evaluate image quality of two methods of registering MRI and CBCT images of the temporomandibular joint (TMJ), particularly regarding TMJ articular disc-condyle relationship and osseous abnormality.

METHODS

MR and CBCT images for 10 patients (20 TMJs) were obtained and co-registered using two methods (non-guided and marker guided) using Mirada XD software (Mirada Medical Ltd, Oxford, UK). Three radiologists independently and blindly evaluated three types of images (MRI, CBCT and registered MRI-CBCT) at two times (T1 and T2) on two criteria: (1) quality of MRI-CBCT registrations (excellent, fair or poor) and (2) TMJ disc-condylar position and articular osseous abnormalities (osteophytes, erosions and subcortical cyst, surface flattening, sclerosis).

RESULTS

75% of the non-guided registered images showed excellent quality, and 95% of the marker-guided registered images showed poor quality. Significant difference was found between the non-guided and marker-guided registration (χ(2) = 108.5; p < 0.01). The interexaminer variability of the disc position in MRI [intraclass correlation coefficient (ICC) = 0.50 at T1, 0.56 at T2] was lower than that in MRI-CBCT registered images [ICC = 0.80 (0.52-0.92) at T1, 0.84 (0.62-0.93) at T2]. Erosions and subcortical cysts were noticed less frequently in the MRI-CBCT images than in CBCT images.

CONCLUSIONS

Non-guided registration proved superior to marker-guided registration. Although MRI-CBCT fused images were slightly more limited than CBCT alone to detect osseous abnormalities, use of the fused images improved the consistency among examiners in detecting disc position in relation to the condyle.

Influence of temporomandibular joint disc displacement on craniocervical posture and hyoid bone position

INTRODUCTION

The purpose of this study was to evaluate craniocervical posture and hyoid bone position in orthodontic patients with temporomandibular joint (TMJ) disc displacement.

METHODS

The subjects consisted of 170 female orthodontic patients who consented to bilateral magnetic resonance imaging of their TMJs. They were divided into 3 groups based on the results of magnetic resonance imaging of their TMJs: bilateral normal disc position, bilateral disc displacement with reduction, and bilateral disc displacement without reduction. Twenty-five variables from lateral cephalograms were analyzed with 1-way analysis of variance to investigate differences in craniocervical posture and hyoid bone position with respect to TMJ disc displacement status. Pearson correlation coefficients were calculated to analyze the relationships between craniofacial morphology and craniocervical posture or hyoid bone position.

RESULTS

Subjects with TMJ disc displacement were more likely to have an extended craniocervical posture with Class II hyperdivergent patterns. The most significant differences were found between patients with bilateral normal disc position and bilateral disc displacement without reduction. However, hyoid bone position in relation to craniofacial references was not significantly different among the TMJ disc displacement groups, except for variables related to the mandible. Pearson correlation coefficients indicated that extended craniocervical posture was significantly correlated with backward positioning and clockwise rotation of the mandible.

CONCLUSIONS

This suggests that craniocervical posture is significantly influenced by TMJ disc displacement, which may be associated with hyperdivergent skeletal patterns with a retrognathic mandible.

Correlation between the disc status in MRI and the different types of traumatic temporomandibular joint ankylosis

OBJECTIVES

We aimed to investigate the correlation between the disc status in MRI and the different types of traumatic temporomandibular joint (TMJ) ankylosis.

METHODS

51 consecutive patients (69 joints), diagnosed with traumatic TMJ ankylosis with a residual condyle (Types A2 and A3), were included in this study. All patients had pre-operative MRI, which was reviewed to determine the disc shape, length and position. The results were compared using the Mann-Whitney test.

RESULTS

There were 37 joints of Type A2 ankylosis and 32 joints of Type A3. All joints of Type A2 and 27 joints of Type A3 (84.4%) definitely had a discernible disc, while 5 joints of Type A3 had no discernible discs. Among the discernible discs, the lateral disc of Type A2 and the whole disc of Type A3 had severe deformity, while the medial disc of Type A2 had mild deformity. The mean (standard deviation) disc length was 10.88 (1.19) mm in Type A2, but 7.50 (0.82) mm in Type A3. There was a significant difference between Types A2 and A3 (p < 0.05). As for the disc position, the intermediate position was found in all joints.

CONCLUSIONS

There is a correlation between the disc status and the different types of traumatic TMJ ankylosis. Therefore, MRI examination is needed to help treatment planning and predict post-operative TMJ function.

Comparison of the T2 relaxation time of the temporomandibular joint articular disk between patients with temporomandibular disorders and asymptomatic volunteers

BACKGROUND AND PURPOSE

T2 relaxation time is a quantitative MR imaging parameter used to detect degenerated cartilage in the knee and lumbar intervertebral disks. We measured the T2 relaxation time of the articular disk of the temporomandibular joint in patients with temporomandibular disorders and asymptomatic volunteers to demonstrate an association between T2 relaxation time and temporomandibular disorder MR imaging findings.

MATERIALS AND METHODS

One hundred forty-four patients with temporomandibular disorders and 17 volunteers were enrolled in this study. An 8-echo spin-echo sequence for measuring the T2 relaxation times was performed in the closed mouth position, and the T2 relaxation time of the entire articular disk was measured. Patients were classified according to the articular disk location and function, articular disk configuration, presence of joint effusion, osteoarthritis, and bone marrow abnormalities.

RESULTS

The T2 relaxation time of the entire articular disk was 29.3 ± 3.8 ms in the volunteer group and 30.7 ± 5.1 ms in the patient group (P = .177). When subgroups were analyzed, however, the T2 relaxation times of the entire articular disk in the anterior disk displacement without reduction group, the marked or extensive joint effusion group, the osteoarthritis-positive group, and the bone marrow abnormality-positive group were significantly longer than those in the volunteer group (P < .05).

CONCLUSIONS

The T2 relaxation times of the articular disk of the temporomandibular joint in patients with progressive temporomandibular disorders were longer than those of healthy volunteers.

Correlation among the changes observed in temporomandibular joint internal derangements assessed by magnetic resonance in symptomatic patients

PURPOSE

The objective was to assess possible correlations among the anatomy and position of the articular disc, the morphology of the articular eminence and of the condyle, and the presence of joint effusion.

MATERIALS AND METHODS

Magnetic resonance images of 142 joints of symptomatic patients were assessed. The articular disc was classified as normal, elongated, or folded; displacement was classified as normal, anterior with reduction, anterior without reduction, or posterior, lateral, or medial; the condyle was classified as rounded, convex, flattened, or angulated; and the articular eminence was classified as box, sigmoid, flattened, or deformed.

RESULTS

The most frequent forms of the articular disc, articular eminence, and condyle were normal, box, and flattened, respectively. Associations were confirmed between the form of the articular disc and its anterior and lateral positions; between the form of the condyle and an anterior position of the disc; and between the form of the articular eminence and the form of the disc. The form of the articular eminence was the only variant that was not associated to the presence of joint effusion.

CONCLUSIONS

Magnetic resonance imaging allowed the clear observation of articular structures, without attributing a cause-and-effect relation. The prevalence of changes observed was associated with the diagnosis of internal derangement and was statistically proved.

Temporomandibular joints in patients with rheumatoid arthritis using magnetic resonance imaging

The aim of this study was to determine the relationship between the pathogenic duration of rheumatoid arthritis in joints other than the temporomandibular joint and bone and soft tissue involvement of the temporomandibular joint using magnetic resonance imaging. Twenty-six symptomatic patients diagnosed with rheumatoid arthritis were enrolled in this study. All patients were classified according to the duration of rheumatoid arthritis in joints other than the temporomandibular joint. The relationships between the duration of rheumatoid arthritis in these various joints and magnetic resonance findings in the temporomandibular joint were analyzed using the chi-square test. Bony changes in the mandibular condyle were observed in 43 of 52 (82.7 %) temporomandibular joints, but the frequency of such changes was not significantly correlated with the duration of rheumatoid arthritis in other joints. We found a significant correlation between the duration of rheumatoid arthritis in other joints and the type and number of bony changes in the mandibular condyle (P < 0.05). Superior disc positions were observed in 27 of 52 (51.9 %) temporomandibular joints. T2-weighted images demonstrated effusion in the joint space in 38 of 52 (73.1 %) temporomandibular joints. A biplanar disc configuration was the most frequent configuration in all groups. The duration of rheumatoid arthritis in other joints was significantly correlated with the mobility of the mandibular condyle (P < 0.05). The type and number of bony changes and mobility of the mandibular condyle showed significant relationships with the duration of rheumatoid arthritis in other joints in the body (P < 0.05).

How should the articular disk position be analyzed?

PURPOSE

To compare 2 methods used to determine the disk position based on sagittal magnetic resonance images.

PATIENTS AND METHODS

A cross-sectional study of patients with the signs and symptoms of temporomandibular disorders was conducted. The patients' ages and gender distributions were collected. The disk position diagnosis from the clinical examination was considered the primary outcome. Three observers evaluated the presence of anterior displacement on magnetic resonance images according to 2 criteria: method 1 (12-o'clock position) and method 2 (location of the intermediate zone). To assess the intraobserver variability of the 2 methods, the examiners evaluated the same magnetic resonance images at the beginning of the study (time 1) and 40 days later (time 2). The intraobserver agreement was assessed using the observed agreement and the kappa statistic. McNemar's test was used to assess the differences between each method and the clinical examination findings (P < .05). The accuracy, sensitivity, specificity, and positive and negative predictive values were calculated by comparing the diagnosis from each method with that from the clinical examination (considered the reference standard).

RESULTS

The final sample was composed of 20 subjects with a mean age of 33.0 ± 33.7 years; 3 were men (15%) and 17 were women (85%). A statistically significant difference between the 2 methods was found. Method 1 yielded a greater percentage of anterior displaced disks (52.5%). The agreement between the clinical diagnosis and method 1 was lower (70.0%) than that between the clinical diagnosis and method 2 (87.5%). No statistically significant difference was found between the clinical diagnosis and method 2.

CONCLUSION

The disk position should be judged according to the intermediate zone criterion.

Changes in temporomandibular joint disc position and form following Herbst and fixed orthodontic treatment

OBJECTIVE

To determine the changes in the position and form of the temporomandibular joint articular disc in adolescents with Class II division 1 malocclusion and mandibular retrognathism treated with the Herbst appliance (phase I) and fixed orthodontic appliance (phase II).

MATERIALS AND METHODS

Thirty-two consecutive adolescents went through phase I of treatment and 23 completed phase II. The temporomandibular joints were evaluated qualitatively by means of magnetic resonance images at the beginning of treatment (T1), during phase I (T2), at the end of phase I (T3), and at the end of phase II (T4).

RESULTS

Significant changes in disc position were not observed with the mouth closed between T1 x T3 (P = .317), T3 x T4 (P = .287), or T1 x T4 (P = .261). At T2, on average, the disc was positioned regressively. With the mouth open, no difference was observed between T1 x T3 (P = .223) or T1 x T4 (P = .082). We did observe a significant difference between T3 x T4 (P < .05). Significant changes in the disc form were found with the mouth closed between T1 x T2 (P < .001) and T2 x T3 (P < .001).

CONCLUSIONS

At the end of the two-phase treatment, in general terms, the position and form of the initial articular discs were maintained; however, in some temporomandibular joints some seemingly adverse effects were observed at T4.

Magnetic resonance imaging evaluation of mandibular condyle bone marrow and temporomandibular joint disc signal intensity in anaemia patients

OBJECTIVES

To compare the signal intensity (SI) of mandibular condyle bone marrow (MCBM) and the temporomandibular joint (TMJ) disc in patients with chronic anaemia and healthy subjects, and to investigate the relationships between bone marrow changes, age, types of anaemia and severity of anaemia.

METHODS

MRIs of 18 patients with chronic anaemia were compared with those of 12 healthy subjects. The SI of MCBM and the TMJ disc were quantitatively evaluated. The SI of the grey matter (GM), white matter (WM) and the lateral pterygoid muscle were also investigated. Relationships between age, MCBM and TMJ disc signal-intensities and anaemia severity, and correlations between the groups, were analysed.

RESULTS

The mean MCBM SI was lower in anaemia patients (including both subgroups and also separately) than in healthy subjects (P < 0.05). No statistical significance was found for GM, WM and the muscle SI between the anaemia patients and healthy patient group (P > 0.05). No statistical significance was found between the groups with respect to the anterior band, whereas the mean SI value of the posterior band in the study group was significantly lower than in healthy subjects (P < 0.05). There were no correlations between age and MCBM SI, or between anaemia severity and MCBM SI.

CONCLUSIONS

Anaemia may cause bone marrow alterations without any internal derangement. Patients with chronic anaemia exhibit lower mandibular condyle bone marrow and posterior band SI than healthy subjects.

Analysis of magnetic resonance images of disk positions and deformities in 1,265 patients with temporomandibular disorder

Objectives

To compare MRI manifestations according to gender and age and to identify correlations between clinical manifestations and MRI findings in patients with temporomandibular disorder (TMD) as based on a large series.

Materials and Methods

Fat suppressed oblique sagittal images of the open and closed mouth were acquired, and MRI scanning parameters were applied.

Results

The patients consisted of 946 females (average, 36.6 years old), and 319 males (average, 34.3 years old). In all TMD patients, 945 had symptoms in the unilateral temporomandibular joint (TMJ) and 320 in the bilateral TMJ. There were significant differences in the distribution of disk positions based on age, regardless of gender, in the unilaterally and bilaterally symptomatic groups; however, the results were not significant in the asymptomatic group. There were significant differences with respect to the distribution of disk positions between males and females in asymptomatic group and in the unilaterally symptomatic group, although the bilaterally symptomatic group did not show significant differences in this regard. As regards the disk positions in the joints of the three groups (asymptomatic group, unilaterally and bilaterally symptomatic groups), there were significant interactive effects of disk positions, regardless of gender. There were statistically significant age-related differences in disk deformities in all symptom groups, regardless of gender, except for in the group of males lacking symptoms in either joint. As regards disk deformities among the three groups studies here, there were significant interactive effects for disk positions, regardless of gender.

Evaluation of TMJ articular eminence morphology and disc patterns in patients with disc displacement in MRI

The aim of this study was to assess the shape of the temporomandibular joint (TMJ) articular eminence and the articular disc configuration and position in patients with disc displacement. TMJ magnetic resonance images (MRI) of 14 patients with bilateral disc displacement without unilateral reduction were analyzed. Articular eminence morphology was characterized as box, sigmoid, flattened, or deformed. Articular disc configuration was divided into biconcave, biplanar, biconvex, hemiconvex or folded, and its position, as "a" (superior), "b" (anterosuperior), "c" (anterior) or "d" (anteroinferior). The images were divided and the sides with disc displacement with reduction (DDWR) and without reduction (DDWOR) were compared. Regarding articular eminence shape, the sigmoid form presented the greatest incidence, followed by the box form, in the DDWR side, although this was not statistically significant. In the DDWOR side, the flattened shape was the most frequent (p = 0.041). As to disc configuration, the biconcave shape was found in 79% of the DDWR cases (p = 0.001) and the folded type predominated in 43% of the DDWOR cases (p = 0.008). As to disc position, in the DDWR side, "b" (anterosuperior position) was the most frequent (p = 0.001), whereas in the DDWOR side, "d" (anteroinferior position) was the most often observed (p = 0.001). The side of the patient with altered disc configuration and smaller shape of TMJ articular eminence seems to be more likely to develop non-reducing disc displacement as compared to the contralateral side.

Validity of temporomandibular disorder examination procedures for assessment of temporomandibular joint status

INTRODUCTION

This hypothesis-generating study was performed to determine which items in the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and additional diagnostic tests have the best predictive accuracy for joint-related diagnoses.

METHODS

One hundred forty-nine TMD patients and 43 symptom-free subjects were examined in clinical examinations and with magnetic resonance imaging (MRI). The importance of each variable of the clinical examination for correct joint-related diagnosis was assessed by using MRI diagnoses. For this purpose, "random forest" statistical software (based on classification trees) was used.

RESULTS

Maximum unassisted jaw opening, maximum assisted jaw opening, history of locked jaw, joint sound with and without compression, joint pain, facial pain, pain on palpation of the lateral pterygoid area, and overjet proved suitable for distinguishing between subtypes of joint-related TMD. Measurement of excursion, protrusion, and midline deviation were less important.

CONCLUSIONS

The validity of clinical TMD examination procedures can be enhanced by using the 16 variables of greatest importance identified in this study. In addition to other variables, maximum unassisted and assisted opening and a history of locked jaw were important when assessing the status of the TMJ.

Evaluation of disk position and prevalence of internal derangement, in a sample of the elderly, by gadolinium-enhanced magnetic resonance imaging

OBJECTIVES

To assess disk position and the prevalence of disk displacement (DD) in a sample of the elderly by use of contrast agent-enhanced magnetic resonance imaging (MRI).

STUDY DESIGN

Thirty subjects (73-75 years old) were drawn from a representative sample and examined clinically. The position and contours of the temporomandibular disk was assessed by using gadolinium-enhanced MR images which were evaluated by 2 independent raters. Statistical assessment was performed by using descriptive statistics and nonparametric tests.

RESULTS

Agreement between raters with respect to disk position was excellent. The MRI showed that 8 subjects (27%; 2 men, 6 women) had DD.

CONCLUSION

Gadolinum-enhanced MRI showed that DD is common in the elderly (27%) and that DD occurs more frequently in women than in men. In women without DD the disk is positioned more anteriorly than in men.

Influence of mouthguard on temporomandibular joint

The aim of this study is to examine whether wearing a mouthguard (MG) has an influence on temporomandibular joint (TMJ) components (i.e., the condyle and the articular disk) and whether clenching with a resilient MG has an effect on the same components. Twenty-six healthy volunteers (15 females, 11 males) with an age range of 26-42 years old (median 28 years) participated in this study. Among all 52 joints in the 26 subjects, anterior disk displacement (AntDD) was recognized in 15. Thus, we classified the 52 joints into two groups, the AntDD group and the Normal group. Resilient thermoplastic materials were used to fabricate two types of MG, one that raised the vertical dimension height by 3 mm and another that raised it by 6 mm. Subjects were scanned with/without two types of MG with/without clenching by magnetic resonance imaging (MRI). The movement of the condylar head and articular disk was measured in the magnetic resonance images using the special subtraction technique. Wearing the MG without clenching did not have a negative influence on the TMJ and clenching in the Normal group. In the AntDD group, however, the relationship between the disk and condyle was affected by clenching and the degree of disk displacement was worsened by clenching with the thicker MG. From our results, we recommend that athletes with an internal derangement of the TMJ not wear the thicker MG and attention should be paid to its setting. And the subtraction technique using MRI was thought as a good tool for detecting a slight change in the TMJ.

Temporomandibular joint soft-tissue pathology, I: Disc abnormalities

The internal derangements are the most common noninflammatory abnormalities of the disc, observed even in asymptomatic subjects. Because the temporomandibular joint shows large adaptative and compensatory mechanisms over dysfunctional disc motion, these disorders may be asymptomatic or minimally evident for a long time. A careful clinical evaluation, reinforced by imaging findings, should help differentiate asymptomatic derangements from painful conditions that may require treatment.

MR imaging of temporomandibular joint dysfunction: a pictorial review

Temporomandibular joint (TMJ) dysfunction is a common condition that is best evaluated with magnetic resonance (MR) imaging. The first step in MR imaging of the TMJ is to evaluate the articular disk, or meniscus, in terms of its morphologic features and its location relative to the condyle in both closed- and open-mouth positions. Disk location is of prime importance because the presence of a displaced disk is a critical sign of TMJ dysfunction. However, disk displacement is also frequently seen in asymptomatic volunteers, so that other findings may be required to help make the diagnosis. These findings include thickening of an attachment of the lateral pterygoid muscle, rupture of retrodiskal layers, and joint effusion and can serve as indirect early signs of TMJ dysfunction. It is important for the radiologist to detect early MR imaging signs of dysfunction, thereby avoiding the evolution of this condition to its final stage, an advanced and irreversible phase that is characterized by osteoarthritic changes such as condylar flattening or osteophytes. Further studies conducted with the latest MR imaging techniques will allow a better understanding of the sources of TMJ pain and of any discrepancy between imaging findings and patient symptoms.

Temporomandibular joint disc position and configuration in children with functional unilateral posterior crossbite: A magnetic resonance imaging evaluation

INTRODUCTION

Epidemiological studies have suggested an association between unilateral posterior crossbite (UPXB) and temporomandibular joint disc displacement. The purpose of this prospective study was to investigate articular disc positioning and its configuration in children with functional UPXB malocclusions and their counterparts with normal occlusions by using magnetic resonance imaging.

METHODS

The study sample included 9 girls and 6 boys (mean age, 9.3 years; SD, 2.1) with complete UPXB involving 3 or more posterior teeth and functional shift from centric relation to intercuspal position (patient group). The control group consisted of 10 girls and 6 boys (mean age, 9.6 years; SD, 2.1) with normal occlusion. All participants had no signs or symptoms of temporomandibular disorder. Sagittal and frontal magnetic resonance images of the temporomandibular joint with the jaw in closed and open positions were made bilaterally. Three investigators independently interpreted the magnetic resonance images.

RESULTS

No intergroup or intragroup differences regarding sex were found, and only 1 subject with articular derangement (disc displacement without reduction associated with disc distortion-folded disc) was found (patient group, same side of crossbite).

CONCLUSIONS

These findings suggest that temporomandibular joint derangements and functional UPXB are independent occurrences, or that the magnitude of such derangements is still not normally detected by magnetic resonance imaging in children in this age range. Another explanation for posterior crossbite not being reflected in disc displacement is the potential compensatory asymmetrical condyle growth or articular fossa remodeling that can hold the articular disc in position.

Comparison of altered signal intensity, position, and morphology of the TMJ disc in MR images corrected for variations in surface coil sensitivity

OBJECTIVE

The purpose of this study is to evaluate the corrections of signal intensity of the temporomandibular joint (TMJ) disc caused by variations in sensitivity of the magnetic resonance imaging (MRI) surface coil, to compare the modified signal intensities of the posterior and anterior bands, and then to evaluate the relationship of the signal intensity difference to altered disc position and morphology in a group of TMJ patients.

STUDY DESIGN

MRI was performed on 96 joints. All patients underwent imaging in axial, coronal, and sagittal planes using fast-spin echo sequences (FSE). The images were taken in the closed, partially opened, and maximum opened mouth positions in 2 sequences. Classifications were made according to the position and morphology of the disc. TMJs were divided into normal, anterior disc displacement with reduction (ADDwR), anterior disc displacement without reduction (ADDwoR), and partial anterior disc displacement with reduction (PDDwR). Disc morphology was subdivided as biconcave, lengthened, biconvex, thick posterior band, and others (defined as folded and rounded). The correction of the inhomogeneous sensitivity of the surface coil was done with the original software. The signal intensities (SI) of the posterior band and anterior band of TMJ discs were measured. The correlations among the groups of TMJs and disc morphologies and SI were statistically analyzed by using Bonferroni/Dunn multicomparison method test.

RESULTS

Of the total number of joints studied with the help of MRI, 37 were normal, 12 exhibited ADDwR, 32 ADDwoR, and 9 PDDwR. The corrected MR images indicated that SI of the posterior bands were higher than the anterior band of the discs. It can also be concluded that the SI of the posterior bands increased significantly in the following order: normal, PDDwR, ADDwR, and ADDwoR, while there is no statistical difference in the SI of the anterior band of the discs. In ADDwR and ADDwoR, thick posterior band is the most common shape. In normal TMJ, the biconcave shape is identified as the most frequently encountered shape.

CONCLUSIONS

It was demonstrated that the SI of the posterior bands increase with the progress of internal derangement, and was found to be higher than that of the anterior band of the discs. It appears that disc degeneration starts from the posterior band of the disc.

Relationship of condylar position to disc position and morphology

INTRODUCTION/OBJECTIVE

The purpose of this study was to assess whether condylar position, as depicted by magnetic resonance imaging, was an indicator of disc morphology and position.

METHODS AND MATERIAL

One hundred and twenty two TMJs of 61 patients with temporomandibular joint disorder were examined. Condylar position, disc deformity and degree of anterior disc displacement were evaluated by using magnetic resonance imaging.

RESULTS AND DISCUSSION

Posterior condyle position was found to be the main feature of temporomandibular joints with slight and moderate anterior disc displacement. No statistical significance was found between the condylar position, and reducing and nonreducing disc positions. On the other hand, superior disc position was found to be statistically significant for centric condylar position.

CONCLUSION

It was concluded that posterior condyle position could indicate anterior disc displacement whereas there was no relation between the position of condyle and the disc deformity.