Unilateral Anterior Disc Displacement Research Articles

Clinical outcomes of patients with unilateral internal derangement of the temporomandibular joint following arthrocentesis and stabilization splint therapy

BackgroundThe management of internal derangement (ID) of the TMJ is challenging because of multiple etiologic factors and varying degrees of severity. The aim of this study was to evaluate the clinical outcomes of patients with unilateral ID treated with arthrocentesis and stabilization splint therapy during a 6-month period.MethodsA total of 105 patients (87 females, 18 males) with unilateral ID were included in this study. Patients were divided into unilateral anterior disc displacement with reduction (ADDwR) and unilateral anterior disc displacement without reduction (ADDwoR). Patients with ADDwoR were subdivided according to the erosive bone changes. Objective parameters on mandibular movement and subjective parameters on pain were obtained and assessed.Their clinical outcomes before and after arthrocentesis and stabilization splint therapy were compared with the chi-square, Fisher’s exact test, paired t-test, or Wilcoxon singed-rank test.ResultsAll objective parameters of unilateral ID patients significantly increased at the 6-month follow-up. The differences in mean visual analog scale (VAS) pain scores were statistically significant in all subjective variables (p < 0.01). In joints with ADDwoR, preoperative maximal mouth opening, and maximal protrusive movement in both groups, with erosive and non-erosive changes were significantly increased after 6 months (p < 0.01). However, right and left maximal lateral movement increased after treatment in both groups but without significant differences. All VAS pain scores on jaw movement and palpation of associated muscles showed a significant decrease regardless of erosive changes.ConclusionsThe combination of arthrocentesis and subsequent stabilization splint therapy was shown to be highly effective in pain reduction and improvement of mandibular movements in both unilateral ADDwR and ADDwoR, as well as in cases with both erosive and non-erosive bony changes associated with unilateral ADDwoR.

The utilization of decision trees on orthopantomographic and lateral panoramic graphs for the diagnosis of unilateral anterior disc displacement of the temporomandibular joint

BackgroundInvestigation is to utilize decision trees in conjunction with orthopantomography (OPT) and lateral panoramic graphy (LPG) to diagnose unilateral anterior disc displacement (ADD) of the temporomandibular joint.MethodsIn this study, 161 patients with images obtained through all three imaging methods, MRI, OPT, and LPG, were selected from the archives. The participants were categorized into two groups: the study group, comprising 89 patients with unilateral anterior disc displacement, and the control group, consisting of 72 healthy individuals. Measurements, including 2 angles (antero-posterior angle and superior-inferior angle) and 3 distance parameters (anterior joint space distance, superior joint space distance, and posterior joint space distance), were conducted on each imaging modality dataset. To assess the obtained measurement data within each patient, the differences from each measurement were calculated. Statistical analysis of the measurement differences between the control and study groups was carried out with independent t test, and decision trees were generated using the SPSS 25 decision tree module 5.0.ResultsIn ADD patients, it was statistically significantly found that the APA increased while the SIA decreased for angle measurements. But for linear measurements, AS increased while the SS and PS decreased in MRI, OPT, and LPG.ConclusionADD can be diagnosed in OPT and LPG. The identification of the specific type of ADD that occurs in the temporomandibular joint is not feasible.

Comparison of T2 values of the displaced unilateral disc and retrodiscal tissue of temporomandibular joints and their implications

Unilateral anterior disc displacement (uADD) has been shown to affect the contralateral joints qualitatively. This study aims to assess the quantitative T2 values of the articular disc and retrodiscal tissue of patients with uADD at 1.5 Tesla (T). The study included 65 uADD patients and 17 volunteers. The regions of interest on T2 maps were evaluated. The affected joints demonstrated significantly higher articular disc T2 values (31.5 ± 3.8 ms) than those of the unaffected joints (28.9 ± 4.5 ms) (P < 0.001). For retrodiscal tissue, T2 values of the unaffected (37.8 ± 5.8 ms) and affected joints (41.6 ± 7.1 ms) were significantly longer than those of normal volunteers (34.4 ± 3.2 ms) (P < 0.001). Furthermore, uADD without reduction (WOR) joints (43.3 ± 6.8 ms) showed statistically higher T2 values than the unaffected joints of both uADD with reduction (WR) (33.9 ± 3.8 ms) and uADDWOR (38.9 ± 5.8 ms), and the affected joints of uADDWR (35.8 ± 4.4 ms). The mean T2 value of the unaffected joints of uADDWOR was significantly longer than that of healthy volunteers (P < 0.001). These results provided quantitative evidence for the influence of the affected joints on the contralateral joints.

The Asymmetry of the Mandible in Patients with Unilateral Temporomandibular Joint Disc Displacement Confirmed by Magnetic Resonance Imaging.

The study aimed to determine the relationship between the mandibular asymmetry index according to Kjellberg between patients with painful unilateral anterior disc displacement (DD) and asymptomatic volunteers without disc displacement. Vertical measurements were performed on a panoramic single-image radiograph, and the disc status was confirmed by magnetic resonance imaging (MRI). Two groups of subjects were retrospectively selected, 40 patients (the overall mean age was 35.5 years; 75% female) with temporomandibular disorder symptoms confirmed by RDC/TMD axis I and manual functional analysis. Unilateral DD was determined by MRI. A comparative group of asymptomatic volunteers (20 dental students with a mean age of 23.4 years; 72% female) had the physiological position of the disc determined by MRI. The vertical asymmetry of the condyle was determined by the method of Kjellberg et al. The symmetry of the gonial angle of the mandible was also measured. A comparison of the mean of the asymmetry index between patients (average 90.89±7.08%) and asymptomatic volunteers (mean 95.86±4.44%) showed a statistically significant difference (p=0.0029). There was no difference (p=0.088) in gonial angle symmetry between the patients (mean 96.48±2.96°) and the asymptomatic volunteers (mean 97.52±2.31°). The distribution of the presence of individual DD diagnoses (partial and total displacement with reduction, displacement without reduction) in patients diagnosed with asymmetry of the mandible was without statistical significance (p>0.05). This study actually points to the asymmetry of the mandible as a potential morphological risk of anterior DD.

Finite element analysis of various thickness occlusal stabilization splint therapy on unilateral temporomandibular joint anterior disc displacement without reduction

Occlusal stabilization splint is the most common treatment modality for temporomandibular joint disorders, but the optimal thickness is still uncertain. This study investigated the effect of the occlusal splint with different thicknesses on the stress distribution of the temporomandibular joint. Cone-beam computed tomography and magnetic resonance images were used to reconstruct the maxillofacial and disc, and the unilateral anterior disc displacement without reduction was established manually as the basic model. Occlusal splint with 5 different thickness levels (2, 3, 4, 5, and 6 mm) was added to the basic model as the study models. The displacement and stress distribution of the disc were evaluated. The maximum von Mises stress of the condylar cartilage was the largest on the affected side, whereas the maximum von Mises stress of the disc was the largest on the unaffected side. The disc stress on the affected side was mainly distributed on the posterior zone and the intermediate zone for the unaffected side. The maximum von Mises stress of the bilaminar region on the affected side was greater than the unaffected side. The stress of the disc and bilaminar region was the lowest on the affected side in the 2 mm model. The disc displacement on the affected side gradually increased, whereas, on the unaffected side, it fluctuated. These results showed that occlusal stabilization splint could decrease the stress of disc and bilaminar region, and 2 mm was considered the optimal thickness for the treatment of unilateral temporomandibular joint anterior disc displacement without reduction.

The effect of arthroscopic disc repositioning on facial growth in juvenile patients with unilateral anterior disc displacement

ObjectiveTo investigate the effect of arthroscopic disc repositioning on condylar development and mandibular asymmetry in juvenile patients with unilateral temporomandibular joint (TMJ) anterior disc displacement (ADD). Patients and methodsA retrospective cohort study was conducted on unilateral juvenile anterior disc displacement (UJADD) patients of 10–20 years of age treated in Shanghai Ninth People's Hospital from 2010 to 2017. The primary predictor was TMJ arthroscopic disc repositioning surgery, according to which patients were divided into a surgery group and a control group. Initial and re-examined (with at least 6-month interval) magnetic resonance imaging (MRI) and posteroanterior cephalometric radiographs (PA) were collected. The condylar heights on both sides of the TMJ were measured by MRI and the difference between them was calculated. Menton (Me) deviation was measured based on PA. Changes in condylar height difference and Me deviation were compared between the two groups. ResultsA total of 108 UJADD patients were collected in this study, including 55 patients in the surgery group and 53 patients in the control group. There were no significant differences in age, sex and follow-up time between the two groups. The condylar height difference was (−0.61 ± 2.02) mm in surgery group and (1.68 ± 1.73) mm in control group (P < 0.0001); while the Me deviation was (−1.00 ± 1.15) mm in surgery group and (1.81 ± 1.96) mm in control group (P < 0.0001), indicating that TMJ arthroscopic disc repositioning surgery could significantly improve condylar height difference and Me deviation. ConclusionsUJADD should be treated as early as possible, especially in juvenile patients, in order to improve condylar development and avoid jaw deformities.

Analysis of the Correlation between Morphology and Kinematics of Anteriorly Displaced TMJ Discs Using Cine-MRI and ARCUSdigma Systems

Background: Studies of mandibular movement trajectories have provided a good understanding of the motion of the condyle but little information on the geometric relationships of the disc because they have not related the movements to anatomic structures. Objective: This study investigated the morphology and kinematic characteristics of the Temporomandibular Joint (TMJ) using Cine-MRI and ARCUSdigma systems. Methods: For this study population, preliminary clinical diagnoses were asymptomatic in 15 cases, unilateral anterior disc displacement with reduction (ADDWR) in 17 cases, and unilateral Anterior Disc Displacement Without Reduction (ADDWoR) in 14 cases. Patients were investigated with Cine-MRI and ARCUSdigma systems during physiological opening and closing of the mouth. Results: In these groups, there were 13 healthy subjects, 19 patients with unilateral ADDWR and 14 patients with unilateral ADDWoR classified by Cine-MRI. (1) To assess morphology by MRI, disc deformities were evaluated as follows: biplanar, rounded, thickening in the posterior band, lengthened and folded. (2) The opening trajectory for healthy subjects was close to the closing trajectory. Conversely, the incisal and condylar trajectories during opening and closing were obviously bounced, deviated or shortened in the ADDWR and ADDWoR groups. The pathway of the kinematic axis was not parallel, and the condylar trajectory had an inflexion. (3) The mean values of the incisal and condylar paths of the ADDWoR group were significantly different from those in the healthy group (P&lt;0.05), whereas there were no significant differences between the ADDWR and the healthy group (P&gt;0.05). Conclusion: This study combined analysis of the condylar pathways and disc-condylar relationship to provide good visualization of morphology and kinematics during jaw movement. This process helps improve our understanding of the complexity of disk-condylar movements in subjects with TMJ internal derangement and may also contribute to our knowledge of the etiology of TMJ internal derangement.

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

PurposeThis 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 methodsA 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. ResultsThere 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. ConclusionDiscomfort 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.

The images of osteoarthrosis associated with anterior disc displacement without reduction detected by cone-beam CT

Objective: To analyze the radiological characteristics of the condylar bone in patients with anterior disc displacement without reduction of temporomandibular joint using cone-beam CT (CBCT), and to further investigate the clinical factors possibly associated with the early-stage osteoarthritic changes. Methods: Two hundred and four individuals (≤30 years old) diagnosed as unilateral anterior disc displacement without reduction (disease duration≤1 year) were recruited. CBCT images of bilateral condyles were independently evaluated by two assessors and documented. Correlation between the early-stage osteoarthritic (OA) changes and gender, age, disease duration and mouth opening were analyzed using SPSS 21.0 software. Results: About sixty percent were presented with OA changes in the symptomatic joints, and most of them (47.1%) (96/204) were early-stage OA changes characterized by loss of continuity of articular cortex (Ⅰ) and/or surface erosion (Ⅱ). Logistics regression analyses indicated that disease duration (P =0.000) and mouth opening (P =0.002) were correlated significantly with early-stage OA changes. Conclusions: Disc displacement without reduction was closely related to OA occurrence. OA changes occurred in more than half of the patients after one month of the joint locked and more possibly in patients with increased mouth opening.

Is mandibular asymmetry more frequent and severe with unilateral disc displacement?

PurposeTo investigate the prevalence of mandibular asymmetry (MA) within the symptomatic unilateral anterior disc displacement (ADD) patients, and analyze the influence TMJ factors of the MA severity. MethodsPatients aged under 20 years old with symptomatic unilateral ADD and asymptomatic volunteers with normal disc-condyle relationship diagnosed by magnetic resonance imaging (MRI) were included in this study. Posteroanterior cephalometric radiographs were taken to measure MA. Condylar height, disc length and disc displacement were measured by MRI. The prevalence and severity of MA were compared between the ADD and the control groups. The correlation between the severity of MA with the amount of condylar height shortage, disc deformity and distance of disc displacement were also evaluated within the ADD group. ResultsThere were 165 cases in the unilateral ADD group, and 156 cases in the control group. One hundred and nineteen cases had MA which accounted 72.12% (119/165) in the ADD group; while in the control group, only 25.64% (40/156) exhibited MA. The mean horizontal menton deviation and condylar height shortage in the unilateral ADD group were significantly larger than that in the control group (5.62 mm vs. 4.19 mm; 3.14 mm vs. 1.32 mm, p < 0.01). The severity of MA was significantly correlated with the amount of disc displacement, disc deformity and condylar height shortage (correlation coefficient: 0.80, 0.70, and 0.82). ConclusionMA is much more common and severe in young unilateral ADD patients. The severity of MA is correlated with the height of condyle and the status of the disc.

Movement of the mandibular condyle and articular disc on placement of an occlusal splint

The aim of this study was to evaluate, with the use of magnetic resonance images, mandibular condyle and articular disc movement on occlusal splint application. Thirty-five subjects were classified into "Pain" and "No-pain" groups based on visual analog scale scoring of temporomandibular joint (TMJ) pain and were categorized as bilateral normal disc (ND), unilateral anterior disc displacement (ADD), or bilateral ADD position. t test and analysis of variance with multiple comparisons were used for statistical analyses. Pain and No-pain groups showed significant anteroinferior and rotated movement of the condyle on splint application, but the disc did not significantly move in the Pain group. Of all groups, anteroposterior movement of the condyle and disc with the splint was significantly less in the unilateral ADD group. TMJ pain was associated with decreased movement of the articular disc. Disc and condyle movement was different in the unilateral ADD group in the presence of a splint compared with the ND and bilateral ADD groups.

Use of Artificial Neural Network in Differentiation of Subgroups of Temporomandibular Internal Derangements: A Preliminary Study

Artificial neural networks (ANNs) have been developed in the past few decades for many different applications in medical science and in biomedical research. The use of neural networks in oral and maxillofacial surgery is limited. The aim of this study was to determine the use of ANNs for the prediction of 2 subgroups of temporomandibular joint (TMJ) internal derangements (IDs) and normal joints using characteristic clinical signs and symptoms of the diseases. Clinical symptoms and diagnoses of 161 patients with TMJ ID were considered the gold standard and were employed to train a neural network. After the training process, the symptoms and diagnoses of 58 new patients were used to verify the network's ability to diagnose. The diagnoses obtained from ANNs were compared with diagnoses of a surgeon experienced in temporomandibular disorders. The sensitivity and specificity of ANNs in predicting subtypes of TMJ ID were evaluated using clinical diagnosis as the gold standard. Eight cases evaluated as bilaterally normal in clinical examination were evaluated as normal by ANN. In detecting unilateral anterior disc displacement with reduction (ADDwR; clicking), the sensitivity and specificity of ANN were 80% and 95%, respectively. In detecting unilateral anterior disc displacement without reduction (ADDwoR; locking), the sensitivity and specificity of ANN were 69% and 91%, respectively. In detecting bilateral ADDwoR, the sensitivity and specificity of ANN were 37% and 100%, respectively. In detecting bilateral ADDwR, the sensitivity and specificity of ANN were 100% and 89%, respectively. In detecting cases of ADDwR at 1 side and ADDwoR at the other side, the sensitivity and specificity of ANN were 44% and 93%, respectively. The application of ANNs for diagnosis of subtypes of TMJ IDs may be a useful supportive diagnostic method, especially for dental practitioners. Further research, including advanced network models that use clinical data and radiographic images, is recommended.

Muscular and condylar response to rapid maxillary expansion. Part 3: Magnetic resonance assessment of condyle-disc relationship

The aim of this prospective study was to assess temporomandibular joint (TMJ) condyle-disc positions at the sagittal and coronal planes of magnetic resonance images (MRIs) before and after rapid maxillary expansion (RME). The study included 18 subjects (11 girls, 7 boys) with a mean age of 12.54 years with unilateral or bilateral posterior crossbite that included at least 3 posterior teeth. The clinical and radiographic assessments of the TMJ were done before (T1) and 18 weeks after (T2) RME. A Haas-type expansion appliance was used for an average treatment time of 3.5 weeks. A visual MRI analysis of pretreatment condyle-disc positions showed that 8 TMJs had medial disc displacement, 3 had anteromedial disc displacement, and 2 had lateral disc displacement. The disc positions remained unchanged at T2 except in 1 subject, who developed unilateral anterior disc displacement. Unilateral joint sounds developed in 3 subjects without changes in the disc positions. Posterior crossbite can be considered a minor risk factor for temporomandibular disorder (TMD). RME is neither a risk factor nor a prevention for TMD. Coronal MRIs contribute complementary information for optimal diagnosis of TMD.

Influence of unilateral disc displacement on the stress response of the temporomandibular joint discs during opening and mastication

The temporomandibular joint plays a crucial role in human mastication acting as a guide of jaw movements. During these movements, the joint is subjected to loads which cause stresses and deformations in its cartilaginous structures. A perfect balance between the two sides of the joint is essential to maintain the physiological stress level within the tissues. Therefore, it has been suggested that a derangement of the joint is a contributing factor in the development of mandibular asymmetry, especially if problems of the temporomandibular joint start in childhood or adolescence. To analyze the movement of the mandible and the stresses undergone by the discs, two finite element models of the human temporomandibular joint including the masticatory system were developed, one corresponding to a healthy joint and the other with a unilateral anterior disc displacement with their movement controlled by muscle activation. A fibre-reinforced porohyperelastic model was used to simulate the behaviour of the articular discs. The stress distribution was analyzed in both models during free opening and closing, and during the introduction of a resistant force between incisors or molars. It was found that a slight unilateral anterior disc displacement does not lead to mandibular asymmetry but to a slight decrease of the maximum gape. With the introduction of a restriction between incisors, the maximum stresses moved to the anterior band in contrast to what happened if the restriction was imposed between molars where maximum stresses were located more posteriorly. Finally, the presence of a unilateral displacement of the disc involved a strong change in the overall behaviour of the joint including also the healthy side, where the maximum stresses moved to the posterior part.

Simple disc reshaping surgery for internal derangement of the temporomandibular joint: 5-year follow-up results

Purpose: The goal of this study was to evaluate the clinical results of simple disc reshaping (SDR) surgery alone for treating dysfunctional internal derangement of the temporomandibular joint. Patients and Methods: Eleven patients with symptomatic unilateral anterior disc displacement with disc deformation were treated using reshaping of the inferior surface of the disc without disc repositioning. This was performed as an open-joint procedure. All patients were evaluated clinically for joint pain and jaw motion 5 years after surgery. Structural changes of the joint tissues such as disc displacement and deformation were evaluated using magnetic resonance imaging. The postoperative results were compared with preoperative findings. Results: Joint pain during mastication or opening was reported by all patients before surgery. In 10 of 11 patients (91%), the joint pain disappeared postoperatively. Preoperatively, all 11 patients had limitation of mouth opening: the mean opening was 24.9 mm (standard deviation [SD], 4.13 mm). Postoperatively, the mean opening increased to 43.0 mm (SD, 3.00 mm). Based on the preoperative magnetic resonance imaging, all cases were diagnosed as anterior disc displacement without reduction and with disc deformation. Five years postoperatively, the disc configuration had maintained the reshaped status with decreased thickness of the deformed disc in 5 patients, and was changed to an almost normal biconcave shape in 3 patients. In the remaining 3 patients, the disc was unchanged from its preoperative condition. The position of the disc was unchanged in 8 patients, and in 3 patients disc position improved to near normal. Conclusion: The 5-year follow-up results suggest that SDR is a stable and favorable surgical procedure. Successful outcomes were attained in 91% of the patients. © 2003 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 61:41-48, 2003

An animal model for studying mechanisms in human temporomandibular joint disc derangement

Purpose : A method for producing disc displacement is presented in which remodeling events in the disc and posterior attachment (PA) are similar to those occurring in patients suffering from disc displacement (DD). Method : Thirty-three adult New Zealand White rabbits were used in this study. A unilateral anterior DD was surgically induced in 18 animals. Six animals were sham operated and nine animals served as controls. Results : Macroscopically, DD was associated with gross thickening of the posterior band (PB), shortening of the disc anteroposteriorly, flexure of the intermediate zone (IZ), and loss of the biconcave shape. Microscopically, dramatic internal structural changes were observed in displaced discs, including extensive collagenous fiber reorganization and changes in cell morphology associated with a generalized loss of metachromatic staining. As in humans, the disc displacement caused abnormal loading of the PA and remodeling of this tissue into a disc-like structure characterized by the appearance of coarse collagenous fiber bundles and scattered chondrocytes surrounded by a matrix-containing cartilage-like glycosaminoglycans (GAGs). Conclusion : These pathoanatomic changes bear a remarkable similarity to those described in human disc derangements and support the use of this method as an experimental model for the study of remodeling events in human DD arthropathies.