Evaluation of the effect of unilateral mastication on the morphology of temporomandibular joint from the perspective of dynamic joint space

BACKGROUND

Unbalanced alterations of temporomandibular joint morphology were associated with unilaterally masticatory habits.

OBJECTIVE

This study aimed to investigate the effect of unilateral mastication on the remodelling of the temporomandibular joint using dynamic joint space.

METHODS

Twelve volunteers with non-maxillofacial deformity and healthy temporomandibular joints were recruited. The 3D models of the mandible and the maxilla were reconstructed according to computed tomography. The subjects were asked to masticate French fries and peanuts unilaterally, which was recorded by a 3D motion capture system. The dynamic joint space during unilateral mastication was analysed.

RESULTS

During early closure, the joint space reduction on the non-masticatory side was significantly greater than on the masticatory side (p < .05). During later closure, the joint space reduction on the non-masticatory side was significantly lower than that on the masticatory side (p < .05). The difference in joint space reduction between both sides was greater than the French fries while masticating the peanuts.

CONCLUSIONS

Unilateral mastication resulted in a different major pressure area on the bilateral TMJs. Therefore, unilateral mastication might be an essential factor in the bilateral asymmetrical remodelling of the TMJ.

Poor condyle position after mandibular reconstruction and a classification system for patients with "VSCU" based on computed tomography: a cross-sectional study with retrospective data collection

Background

Although the application of vascularized free bone muscle flap to reconstruct the mandible has become a standardized approach for mandible reconstruction, the results of its reconstruction are not always satisfactory. The purpose of this study was to identify the types of mandibular and condylar defects by analyzing the unsatisfactory cases of mandibular reconstruction in clinical practice, and to provide some clinical experience of reconstruction.

Methods

Our study retrospectively analyzed 364 patients who underwent mandibular resection and vascularized free bone flap reconstruction of the mandible and temporomandibular joint (TMJ). We innovatively proposed a "VSCU" classification system (V: vertical position, S: sagittal position, C: coronal position, U: condylar resection is not required) by analyzing computed tomography (CT) scans of mandibular branches and TMJs.

Results

In all, 221 cases of free iliac muscle flap and 143 cases of fibula muscle flap were included in this study, of which 23 cases had unsatisfactory results after TMJ reconstruction. We classified 23 patients with unsatisfactory mandibular reconstruction according to the "VSCU" classification system. The most common type was U + V + SfC (n=8), followed by V - SfC + U + (n=4), V - s + C + U + (n=3), V - sbcou - (n=3), V - SBC + U + (n=2), V - s + C + U - (n=1). The most common classification was insufficient mandibular rami length, followed by condylar sagittal anteriorization. There was no significant change in the position of condyle on the healthy side during mandibular reconstruction involving condyle. P1 on the affected side was 52.28±4.17 mm before operation and 58.94±5.65 mm after operation, P<0.01; P2 was 12.83±3.49 mm before operation and 24.90±7.15 mm after operation. S2 was 4.54±2.84 mm before operation and 19.10±8.54 mm after operation. A2 was 11.46±3.35 mm before operation and 24.15±8.29 mm after operation. The P values were all less than 0.01, and the differences were statistically significant.

Conclusions

We propose to use the "VSCU" classification system for accurate 3-dimensional (3D) analysis and positioning, and then obtain accurate models through computer-aided design and manufacturing (CAD/CAM), which can reduce the occurrence of poor reconstruction effect and unreasonable joint position, and is worthy of clinical promotion.

Occurrence of Cervical Spine Pain and Its Intensity in Young People with Temporomandibular Disorders

Background: The main aim of this cross-sectional study was to compare the occurrence and severity of cervical spine pain in young adults diagnosed with TMDs with a healthy control group (without TMDs). Methods: The study was conducted from June to July 2023. Inclusion criteria were age (18-30 years), cervical spine pain (for at least 1 month), and consent to participate in the study. The study was conducted based on RDC/TMD protocol, an original questionnaire, and a physiotherapeutic examination focused on detecting TMDs. The cervical pain level was assessed using the Visual Analogue Scale (VAS). Thus, a total of 95 subjects were registered for the trials, 51 people (53.7%) constituted the control group (without TMDs), while 44 (46.3%) people constituted the study group (with TMDs). Results: The mean age of people participating in the study was 22.2 ± 2.2 years in the study group and 22.5 ± 3.1 years in the control group. The largest group was people aged 21-25 (n = 51 people, 53.7%). Patients from the study group more often experienced pain in the stomatognathic system during palpation (both in the muscle, joint, and musculoskeletal groups) and had reduced mobility of the temporomandibular joints in every movement (p < 0.001). People from the study group were also characterized by less mobility of the cervical spine (p < 0.05), apart from extension movement (p > 0.05). The analysis showed that of the 95 people participating in the study, 85.4% reported problems in the cervical spine area (n = 81), of which almost all people in the study group struggled with this problem (n = 43, 97.7%). It was found that cervical spine pain was significantly more common in people with TMDs (p < 0.05, chi2 = 10.118, df = 1, rc = 0.31). The level of pain was significantly higher in people from the study group (p < 0.001, chi2 = 45.765, df = 4, rc = 0.57). Conclusions: Our research has shown that the occurrence of cervical spine pain is more common in the group of young people with temporomandibular disorders (TMDs). In young people, this problem is rarely recognized and properly treated.

The influence of maxillary incisor angles on the stress distributions of temporomandibular joints under incisal biting

BACKGROUND AND OBJECTIVE

The incisal biting was one of the most regular jaw activities. The direction of bite force on the incisor tip and the mandible position were relevant to the incisor angle as biting. This study was carried out to explore the influence on the temporomandibular joint (TMJ) caused by the incisor angle.

METHODS

Twenty individuals belonging to three incisor subtypes of the buccal type were recruited. In addition, the 3D models including the maxillary, mandible and discs were established based on their cone-beam computed tomography and magnetic resonance imaging scannings. Then, the mandibular ligaments and the discal attachments were simulated in the finite element models to analyze the stress distributions of the TMJs under incisal biting.

RESULTS

The TMJ stresses of subtype I showed normal range and distribution. The stresses of the intermediate temporal bone tended to increase in subtype II. The intermediate and posterior bands of the discs sustained greater tensile stresses in subtype III.

CONCLUSIONS

Abnormal stress distributions are harmful to TMJs, so the incisor cusp was not suggested to incline to the palatal side too much.

Effect of bimaxillary surgery on the stress distributions in patients with mandibular retrognathia under unilateral molar clenching

To investigate the effect of bimaxillary surgery on the stress distribution of the temporomandibular joint (TMJ) in patients with mandibular retrognathia under unilateral molar clenching (UMC). Five patients with mandibular retrognathia (preoperative group) and ten asymptomatic subjects (control group) were recruited. In addition, patients treated with bimaxillary surgery were considered as the postoperative group. The muscle forces corresponding to UMC were applied. The results showed that the discal stresses in the postoperative group were significantly greater than those in the preoperative and control groups. Bimaxillary surgery plus UMC had a detrimental effect on the TMJ.

Evaluation of condylar osseous changes using a wireless detector with proton density-weighted imaging sequences

Background

Cone-beam computed tomography (CBCT) is the gold standard for evaluating condylar osseous changes. However, the radiation risk and low soft-tissue resolution of CBCT make it unsuitable for evaluating soft tissue such as the articular disc and lateral pterygoid muscle. This study aimed to qualitatively and quantitatively evaluate the feasibility and advantages of using wireless detectors (WD) with proton density-weighted imaging (PDWI) sequences to image condyle changes in patients with temporomandibular disorders (TMD).

Methods

This study involved 20 patients (male =8, female =12; mean age 31.65 years, SD 12.68 years) with TMD. All participants underwent a closed oblique sagittal PDWI scan with head/neck coupling coiling (HNCC) and wireless detector-HNCC (WD-HNCC) on a 3.0 T magnetic resonance imaging (MRI) scanner. Subsequently, the changes in the condyle bones in the scanned images for the 2 image types were scored subjectively and compared qualitatively. The contrast-to-noise ratio (CNR) of the 2 types of scanned images was compared quantitatively. The comparison of CNR differences between the 2 types of images was performed using the paired t-test. The kappa statistic was used to test the consistency of quantitative analyses of MRI images between observers. The subjective scores of condylar osseous changes in the 2 types of images were compared by paired rank-sum test. A P value <0.05 was considered statistically significant.

Results

A total of 40 condyles from 20 patients were scanned. Among them, 8 condyles showed no bone changes, and the other 32 condyles demonstrated condylar osseous changes of varying degrees and nature. These 32 condyles were used in the subsequent analysis. As compared to images acquired by HNCC in the PDWI sequence, the WD-HNCC images more clearly showed mandibular osteophyte, bone cortical erosion, subcortical cystic focus, and bone cortical hyperplasia and thickening. In addition, the WD-HNCC was demonstrated to improve image CNR by 158.9% compared to HNCC (28.17±16.01 vs. 10.88±6.53; t=8.63; P=0.001).

Conclusions

WD-HNCC in PDWI sequences is suitable for imaging the condylar bone changes of patients with TMD and significantly improves the image quality.

Relationship between bad oral habits, signs, and symptoms of temporomandibular joint disorders among Saudi population: A cross-sectional study

Background

According to the American Dental Association, temporomandibular disorders (TMD) refer to a group of disorders characterised by pain in the temporomandibular joint (TMJ), the periauricular area, or the muscles of mastication. TMJ noise/sounds, and any deviations or restriction during jaw movements. Many oral habits are common and usually do not harm the TMJ and associated structures. However, these habits may result in TMJ disorders, if the activity goes beyond someone's physiological tolerance. The causes of degenerative changes of TMJ are believed to be multifactorial and controversial too.

Objectives

This study aims to evaluate the prevalence of oral habits and its relationship with temporomandibular disorders in the Saudi population of Taif city.

Materials and Methods

This questionnaire-based cross-sectional study was conducted from March 2021 to July 2021 at Taif city, Kingdom of Saudi Arabia (KSA). The Arabic version of a standardized questionnaire (recommended by the American Academy of Orofacial Pain) was used and distributed randomly among 441 citizens of Taif city.

Results

Our study showed that many respondents had different TMJ disorders, such as pain during eating, sound in jaw joint, pain around ear, temples, and cheek, headache and neck pain, change in bite, and pain during opening and closing of the mouth. On the other hand, many respondents answered that they had TMD, pain associated with nail biting/object biting, lip biting, clenching teeth, and chewing gum.

Conclusion

In the present study, a relationship between harmful oral habits and the development of signs and symptoms of TMDs among adolescents who lived in Taif city, KSA was noted. In the present study, no clinical examinations were conducted and only consisted of closed-ended questions, all of which may have a lower the validity rate. An effort was made to overcome these limitations by using a well-designed standardized questionnaire by the American Academy of the Orofacial Pain. We conclude that further studies are required and using of clinical examination to measure the severity of the signs and symptoms for better understanding the association of oral habits with TMJ disorders.

Trifid Mandibular Condyle: Case Report and Current Review of the Literature

Trifid mandibular condyle (TMC) is a rare anatomical variation characterized by the duplication of the mandibular condyle. The aim of this study is to report a new case of a 26-year-old female patient with a left TMC and to review the current existing literature on TMC, the relevant cases, etiology, symptoms and different treatment modalities. The database engines PubMed, EMBASE, Scopus, Web of science, Scientific Electronic Library Online, Cochrane and CINAHL were searched for TMC cases from inception until April of 2022. Only 13 previous cases of TMC were found. Although it is a rare anatomical entity, TMC is increasingly being detected due to more advanced imaging techniques, especially computed tomography (CT), cone beam CT (CBCT) and magnetic resonance imaging (MRI) emerging in the field of dentistry. The etiology and pathogenesis of TMC and its relationship with TMD are still unclear. Further studies and follow-up may help to better understand this anatomic variant and possible interactions with local pathologies.

Three-dimensional assessment of temporomandibular joint in skeletal Class I malocclusion with variable degrees of overbite and overjet

OBJECTIVE

To three-dimensionally evaluate the position and morphology of the TMJ in skeletal Class I with variable degrees of overbite and overjet in comparison with normal peers.

METHODS

Pretreatment CBCT scans of 126 adults were retrieved. Based on the severity of overjet and overbite, the sample was divided into three main groups and six subgroups (18 patients each): the first group with a normal overbite and variable overjet degree and the second group with normal overjet and variable overbite degree. These six subgroups were compared with a third control group of normal overjet and overbite.

RESULTS

There were significant differences in vertical condylar position, vertical and anteroposterior condylar inclinations, condylar height, and significant posterior condylar positioning in severe deep overbite, compared with the control group.

CONCLUSION

There were significant changes in the TMJ components in severe deep overbite cases. Therefore, sever deep overbite could be considered a predisposing factor for temporomandibular disorders.

Chondrocyte Adipogenic Differentiation in Softening Osteoarthritic Cartilage

A chondrocyte-to-osteoblast lineage continuum exists in the growth plate. Adipogenic differentiation of chondrocytes in vivo should be investigated. Here, unilateral anterior crossbite (UAC), which can induce osteoarthritic lesions in the temporomandibular joint (TMJ), was applied to 6-wk-old C57BL/6 mice. Matrix loss in TMJ cartilage was obvious, as demonstrated by safranin O staining, and the condylar cartilage elastic modulus values, detected by using atomic force microscopy (AFM), were reduced, indicating cartilage softening that might be linked with loss of the highly charged proteoglycan. By crossing the Rosa26/tdTomato (TdT) mice with Sox9;Cre^ERT2 mice or with Col10;Cre^ERT2 mice, we obtained the Sox9-TdT and Col10-TdT strains, respectively, in which the Sox9- or Col10-expressing cells, accordingly, were labeled by TdT. A few TdT-labeled cells in both strains expressed AdipoQ or DMP-1. The Sox9-TdT⁺AdipoQ⁺ cells were primarily located in the deep zone cartilage and then in the whole cartilage. Col10-TdT⁺AdipoQ⁺ cells, Sox9-TdT⁺DMP-1⁺ cells, and Col10-TdT⁺DMP-1⁺ cells were located in the deep zone region. UAC promoted AdipoQ and DMP-1 expression in cartilage. The percentages of Sox9-TdT⁺AdipoQ⁺ and Col10-TdT⁺AdipoQ⁺ cells to Sox9-TdT⁺ and Col10-TdT⁺ cells, respectively, were increased (both P < 0.05), implying that more chondrocytes were undergoing adipogenic differentiation in the UAC group, the cartilage of which was softened. The percentages of Sox9-TdT⁺DMP-1⁺ and Col10-TdT⁺DMP-1⁺ cells to Sox9-TdT⁺ cells and Col10-TdT⁺ cells, respectively, were increased (both P < 0.05), consistent with our report that UAC enhanced deep zone cartilage calcification, causing stiffening of the deep zone cartilage. Our present data demonstrated that TMJ chondrocyte descendants can become adipogenic in vivo in addition to becoming osteogenic. This potential was promoted in osteoarthritic cartilage, in which deep zone cartilage calcification-associated cartilage stiffening and proteoglycan loss-associated cartilage softening were both stimulated.

Automated Indentation Demonstrates Structural Stiffness of Femoral Articular Cartilage and Temporomandibular Joint Mandibular Condylar Cartilage Is Altered in FgF2KO Mice

OBJECTIVE

Employ an automated indentation technique, using a commercially available machine, to assess the effect of fibroblast growth factor 2 (FGF2) expression on structural stiffness over the surface of both murine femoral articular cartilage (AC) and temporomandibular joint (TMJ) mandibular condylar cartilage (MCC).

DESIGN

Experiments were performed using 3-month-old female homozygote Fgf2KO mice with wild type (WT) littermates. After euthanization, isolated mandibles and hindlimbs were either processed for histology or subjected to automated indentation on a Biomomentum Mach-1 v500csst with a 3-axis motion controller in a phosphate buffered saline bath using a 0.3 mm spherical tip indenter. The effect of indentation depth on normal force was characterized, then structural stiffness was calculated and mapped at multiple positions on the AC and MCC.

RESULTS

Automated indentation of the AC and TMJ MCC was successfully completed and was able to demonstrate both regional variation in structural stiffness and differences between WT and Fgf2KO mice. Structural stiffness values for Fgf2KO AC were significantly smaller than WT at both the medial/anterior (P < 0.05) and medial/posterior (P < 0.05) positions. Global Fgf2KO also lead to a decrease in MCC thickness of the TMJ compared with WT (P < 0.05) and increased structural stiffness values for Fgf2KO at both the posterior and anterior location (P < 0.05).

CONCLUSIONS

Automated indentation spatially resolved differences in structural stiffness between WT and Fgf2KO tissue, demonstrating FGF2 expression affects femoral AC and TMJ MCC. This quantitative method will provide a valuable approach for functional characterization of cartilage tissues in murine models relevant to knee joint and TMJ health and disease.

Diffuse-Type Tenosynovial Giant Cell Tumor Arising in the Temporomandibular Joint Extending to the External Auditory Canal: A Case Report and Literature Review

A 74-year-old Japanese woman with a 1-year history of right preauricular pain and a 2-month history of bleeding from the right ear was admitted to our department. Tumor was observed in the anterior wall in the right external auditory canal. Bony swelling of the right preauricular area was palpated. Computed tomography revealed an ill-defined, osteogenic tumor around the mandibular condyle with a destructive bony lesion involving the temporal bone. Magnetic resonance imaging revealed a 2.0 × 1.5 × 1.3-cm solid tumor around the mandibular condyle, exhibiting a low-intensity signal on T1-weighted imaging and an isointense central area surrounded by low-signal intensity on T2-weighted imaging. Histological examination of biopsy specimens revealed diffuse-type tenosynovial giant cell tumor (D-TGCT). After the feeding arteries for the tumor were embolized, the patient underwent surgery with combined temporal craniotomy and mandibular condylectomy. The soft and cystic tumor with calcification located in the extradural space was totally resected along with the mandibular condyle. No facial paralysis or recurrence was evident as of 6 months postoperatively. To date, only 23 cases of D-TGCT arising in the temporomandibular joint (TMJ) with ear involvement have been reported since 2011. We report successful resection of a rare case of D-TGCT arising in the TMJ.

Impact of mandibular prognathism on morphology and loadings in temporomandibular joints

Loadings in temporomandibular joints (TMJs) are essential factors in dysfunction of TMJs, and are barely noticed in treatment of maxillofacial deformity. The only approach, which can access stresses in TMJs, could expend day's even weeks to complete. The objective of the study was to compare the differences of the morphological and biomechanical characteristics of TMJs between asymptomatic subjects and patients with mandibular prognathism, and to preliminarily analyze the connection between the two kinds of characteristics. Morphological measurements and finite element analysis (FEA) corresponding to the central occlusion were carried out on the models of 13 mandibular prognathism patients and 10 asymptomatic subjects. The results indicated that the joint spaces of the patients were significantly lower than those of the asymptomatic subjects, while the stresses of patients were significantly greater than those of asymptomatic subjects, especially the stresses on discs. The results of Pearson correlation analysis showed that weak or no correlations were found between the von Mises stresses and the joint spaces of asymptomatic subjects, while moderate, even high correlations were found in the patients. Thus, it was shown to be a feasible way to use morphological parameters to predict the internal loads of TMJs.

Biomechanical behaviour of temporomandibular joints during opening and closing of the mouth: A 3D finite element analysis

Temporomandibular joints (TMJs) constitute a pair of joints that connect the jawbone to the skull. TMJs are bilateral joints which work as one unit in conducting daily functions such as speaking, mastication, and other activities associated with the movement of the jaw. Issues associated with the TMJs may arise due to various factors-one such factor being the internal load on the TMJ. These issues may contribute to temporomandibular disorders (TMD). This study aims to evaluate the mandibular trajectories and the associated stress changes during the process of opening the mouth on the TMJs of an asymptomatic subject. The mouth opening motion was recorded by a motion capturing system using models of the mandible and maxilla constructed based on the computed tomography (CT). Two discs constructed based on magnetic resonance imaging (MRI). Finite element analysis was performed on the relative motion of the mandible to the maxilla and validated. The process modelled by these displacements provided less than 10% error in terms of deformation. The simulation results indicate that the lateral intermediate zone-the head and neck of the mandible-and the articular eminence sustained the most significant stresses during the mouth opening motion. The results also suggested that the stresses increase as the range of opening increases with the greatest von Mises stress, tensile, and compressive stress found at the position of maximal opening.

Effect of sagittal split ramus osteotomy on stress distribution of temporomandibular joints in patients with mandibular prognathism under symmetric occlusions

Sagittal split ramus osteotomy (SSRO) is the representative orthognathic surgery for the patients with mandibular prognathism. It is essential to understand the biomechanical environment of temporomandibular joint (TMJ) to analyse the effects of SSRO. This study aimed to investigate the influence of SSRO on the stress distributions in the TMJs of the patients with mandibular prognathism under symmetric occlusions. Thirteen patients with mandibular prognathism and ten asymptomatic volunteers were recruited. Finite element models of the asymptomatic, preoperative, and postoperative subjects were established, based on the CT of the asymptomatic volunteers and preoperative and postoperative scans of patients with mandibular prognathism. Contact was used to simulate the interactions between discs and articular surfaces, and between the upper and lower dentition. Muscle forces and boundary conditions corresponding to the centric and anterior occlusions were applied on the models. Under both occlusions, the maximum and minimum principal stresses of the articular disc and condyle in the preoperative group were significantly greater than those in the control group. After SSRO, the maximum and minimum principal stresses of the articular disc and condyle of the patients under both occlusions were greatly reduced, but the principal stresses of the articular disc were not significantly higher than those in the control group. Mandibular prognathism led to excessive stress on the TMJ. Severe asymmetric compression between the TMJs on both sides might cause temporomandibular disorder (TMD) symptoms. SSRO could improve the stress distribution of the TMJ and partially relieve the symptoms of TMD.

Lesions of the lateral pterygoid muscle-an overestimated reason for temporomandibular dysfunction: a 3T magnetic resonance imaging study

The aim of this study was to examine the lateral pterygoid muscle (LPM) parenchyma, myotendinous junction, and tendon in temporomandibular disorder (TMD) patients using 3T magnetic resonance imaging (MRI). Results were compared with findings reported in the literature, in which the LPM has been attributed a major role in triggering TMD. 3T MRI was used for temporomandibular joint (TMJ) imaging. The MRI images of 63 patients were analysed for muscle contracture and atrophy, tendon rupture, signal alterations of the tendon, tendon contrast enhancement, and peritendinous fluid collection. Descriptive statistics and the coefficient estimate method were used for statistical analysis. Focus was placed on the association between LPM tendon pathology and TMJ lesions like osteoarthritis and disc displacement. Severe lesions of the LPM tendon and muscle parenchyma, like rupture or fibrosis, were detected in very few cases. Only moderate signs of tendinosis were found in TMD patients. In contrast, there was a clear correlation between tendon lesions and osteoarthritis or anterior disc displacement. These results indicate the need to discuss and question the role of the LPM and its tendon in TMD. Data suggest that LPM and tendon lesions are part of complex degenerative changes of the TMJ, and it seems less likely that a LPM disorder is causative in TMD.

Estrogen-Related Receptor γ Induces Angiogenesis and Extracellular Matrix Degradation of Temporomandibular Joint Osteoarthritis in Rats

The main causes of cartilage destruction during temporomandibular joint osteoarthritis (TMJOA) are extracellular matrix degradation and angiogenesis, accompanied by an increased level of matrix-degrading enzymes and proangiogenic factors. Interleukin 6 and extracellular signal–regulated kinase (ERK) signaling pathways may play a critical role in these two processes simultaneously, but researchers have not clearly determined the mechanism. We hypothesized that estrogen-related receptor γ (ERRγ) is involved in both cartilage degeneration and angiogenesis in TMJOA. The interactions between ERRγ and the Mmp9 and Vegfa promoter regions were investigated using a chromatin immunoprecipitation (ChIP) assay. A chick embryo chorioallantoic membrane (CAM) assay was performed to investigate the inhibitory effects of U0126 and GSK5182 on angiogenesis. Western blotting, reverse transcription–quantitative PCR (RT-qPCR), immunofluorescence staining, toluidine blue staining, and transfection with cDNAs or small interfering RNAs (siRNAs) were performed on primary mandibular condylar chondrocytes (MCCs). Unilateral anterior crossbite–induced TMJOA models were established in rats, and Western blotting, RT-qPCR, immunohistochemistry, and Safranin O-Fast Green staining were performed to evaluate changes in vivo. ERK1/2 activated matrix metalloproteinase 9 (MMP9) and vascular endothelial growth factor A (VEGFA), which are involved in cartilage destruction, through ERRγ. Based on the ChIP assay results, ERRγ directly activated the transcription of the Mmp9 and Vegfa genes. In chick embryo CAM models, U0126 and GSK5182 significantly inhibited angiogenesis. In conclusion, ERRγ is a downstream transcription factor of ERK1/2, and its upregulation leads to extracellular matrix degradation and angiogenesis in TMJOA. This study identified a common factor between inflammation and vascularization in OA as well as a new therapeutic target for OA: ERRγ.

Sudden onset of temporomandibular joint swelling and limited mouth opening: a rare case of ganglion cyst

Preauricular swelling followed by limited mouth opening can be a challenging diagnosis. All anatomical structures and related pathologies should be examined. A 41-year-old woman presented to the Emergency Room complaining of limited mouth opening, severe pain that was worse on chewing, and swelling over her right temporomandibular joint (TMJ) that had started 3 days previously. Physical examination revealed localized swelling and redness over her right TMJ. Her right masticatory muscles were very painful and tender on palpation. Mouth opening was slightly limited. A computed tomography (CT) scan demonstrated a collection adjacent to her right TMJ, and reactive arthritis was diagnosed. Aspiration and arthrocentesis were performed, leading to immediate improvement. When symptoms returned 6 months later, magnetic resonance imaging (MRI) demonstrated a cystic lesion adjacent to the TMJ. Under general anesthesia an excisional biopsy was performed, and the pathologic examination revealed fibrous connective tissue with pseudocyst-like formation compatible with ganglion cyst. This case report demonstrates that a CT scan might lead to an incorrect diagnosis, whereas MRI scanning led to the correct diagnosis, thereby emphasizing the importance of choosing the right imaging modality. When a pathologic process of the TMJ is suspected, MRI is the gold standard imaging modality to diagnose the exact TMJ pathology. Complete surgical excision of ganglion cyst is recommended to determine a definite diagnosis. The final diagnosis should eventually be made by combining standard histology and MRI findings.

Inflammation and Temporomandibular Joint Derangement

Temporomandibular disorders (TMD) are a common stomatognathic disease affecting all age groups. Patients with internal derangement (ID) or osteoarthritis (OA) of temporomandibular joint (TMJ) often have TMJ synovitis. When TMJ synovial membrane is damaged, many inflammatory cytokines are produced and secreted from TMJ synoviocytes to synovial fluid of TMJ. It has been widely reported that many kinds of biologic factors are produced from TMJ synoviocytes stimulated with interleukin (IL)-1beta and tumor necrosis factor (TNF)-alpha. One of the major symptoms of TMD is pain of the TMJ. Many study groups have studied relations between the development of TMJ pain and biologic factors secreted into synovial fluid of TMJ. Here, we summarize previous reports trying to elucidate this correlation. On the other hand, it has been reported that a new molecular mechanism of IL-1beta secretion called inflammasome is involved in several diseases with sterile inflammation. Because TMJ synovitis with ID and OA of TMJ is also sterile inflammation, inflammasome may be involved in the development of TMJ synovial inflammation. This review describes some molecular mechanisms underlying inflammation in TMJ, especially in TMJ synovitis, which may be useful for the development of new therapies against TMD.

Biomarker expression related to chondromatosis in the temporomandibular joint

Background: Synovial chondromatosis is usually detected at a late stage based on free bodies in joint space. The purpose of this study was to identify biomarkers for cell proliferation and chondrogenesis in the primary stage of synovial chondromatosis in the temporomandibular joint (TMJ).Clinical Presentation: A 67-year-old female was referred for right side TMJ pain. Magnetic resonance imaging (MRI) findings suggested an intra-joint space lesion, but no free bodies were observed intraoperatively. Pathological examination led to diagnosis of Milgram stage 1 synovial chondromatosis. Biomarkers related to mesenchymal stem cells (MSCs), cell proliferation, and chondrogenesis were observed in immunohistopathological examination of specimens.Clinical Relevance: The findings suggest that MSCs with chondrogenic potential and growth activity are present at the start of cartilage formation in the synovial membrane. These cells may be the origin of disease. Those findings improve understanding of the etiology and disease progression of synovial chondromatosis in the TMJ.

Temporal mandibular joint chondrocalcinosis (tophaceous pseudogout) diagnosed by ultrasound-guided fine-needle aspiration

Tophaceous pseudogout is a calcium pyrophosphate dihydrate crystal (CPPD) deposition disease that frequently affects elderly patient in the temporomandibular joint (TMJ). A diagnosis of CPPD deposition disease in the TMJ is challenging due to its mimicking of other benign and malignant entities. Surgical exploration followed by histologic examination is by far the most frequently used diagnostic modality. We present a case of an 87-year-old female who presented with a right TMJ mass. A final diagnosis of tophaceous pseudogout was made on cellular material obtained by ultrasound-guided fine-needle aspiration (US-guided FNA). Based on our case and current available literature, ultrasound-guided FNA is a reliable tool for diagnosing tophaceous pseudogout of the TMJ.

Platelet-Rich Plasma in Treatment of Temporomandibular Joint Dysfunctions: Narrative Review

Background: The aims of this narrative review were to examine up-to-date literature in order to evaluate the effectiveness of arthrocentesis or injections with platelet-rich plasma in temporomandibular affections and to compare them to arthrocentesis alone or with hyaluronic acid (HA) or to hyaluronic acid injections. Methods: The search of international literature was made on the PMC, PubMed and Cochrane databases, including all full-length text of studies on humans focused on osteoarthritis and disc displacements and their treatment with platelet-rich plasma arthrocentesis or injections. All design studies were included in the review and they were examined for three different outcomes: pain, joint sound and mandibular motion. English papers were only selected. Results: Even though the low number of studies in this field, arthrocentesis with platelet-rich plasma and platelet-rich plasma injections in temporomandibular disorders’ management were found to be effective in reducing pain and joint sound as well as in improving mandibular motion in a maximum follow-up of 24 months. Conclusion: Comparison to arthrocentesis alone or to HA use in arthrocentesis or by injections provided encouraging results in terms of the effectiveness of platelet-rich plasma use.

Deletion of Axin1 in condylar chondrocytes leads to osteoarthritis-like phenotype in temporomandibular joint via activation of β-catenin and FGF signaling

Osteoarthritis (OA) in the temporomandibular joint (TMJ) is a degenerative disease in the adult, which is characterized by the pathological degeneration of condylar cartilage. Axin1 plays a critical role in the regulation of cartilage development and homeostasis. To determine the role of Axin1 in TMJ tissue at the adult stage, we generated Axin1^Agc1ER mice, in which Axin1 was deleted in aggrecan-expressing chondrocytes at 2 months of age. Histology, histomorphometry, and immunostaining analyses were performed using TMJ tissues harvested from 4- and 6-month-old mice after tamoxifen administration. Total RNA isolated from TMJ cartilage of 6-month-old mice was used for gene expression analysis. Progressive OA-like degeneration was observed in condylar cartilage in Axin1 knockout (KO) mice with loss of surface continuity and the formation of vertical fissures. In addition, reduced alcian blue staining in condylar cartilage was also found in Axin1 KO mice. Immunostaining and reverse transcription quantitative polymerase chain reaction (qRT-PCR) assays revealed disturbed homeostasis in condylar cartilage with increased expressions of MMP13 and Adamts5 and decreased lubricin expression in Axin1-deficient chondrocytes. Less proliferative cells with increased hypertrophic and apoptotic activities were presented in the condylar cartilage of Axin1^Agc1ER KO mice. As a scaffolding protein, the deletion of Axin1 stimulated not only the β-catenin but also the fibroblast growth factor (FGF) signaling via extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) activation. The qRT-PCR results showed an increased expression of Fgfr1 in Axin1 KO cartilage. Overall, the deletion of Axin1 in condylar chondrocytes altered the β-catenin and FGF/ERK1/2 signaling pathways, thus cooperatively contribute to the cartilage degeneration.

Adolescent internal condylar resorption (AICR) of the temporomandibular joint, part 1: A review for diagnosis and treatment considerations

BACKGROUND

Adolescent internal condylar resorption (AICR) is a temporomandibular joint (TMJ) pathology that develops predominately in teenage females during pubertal growth (onset between ages 11 and 15 years), with a distinct clinical, radiographic, and magnetic resonance imaging (MRI) presentation. Clinical and imaging presentation: The condition usually occurs bilaterally with: (1) Progressive retrusion of the mandible; (2) High occlusal plane angle facial morphology; (3) Worsening Class II occlusion; and (4) TMJ symptoms such as pain, headaches, noises, etc. MRI imaging demonstrates decreased condylar head size and anterior disc displacement. Treatment protocol: AICR can be successfully treated when the condyles and discs are salvageable with the following surgical protocol: (1) Removal of bilaminar tissue surrounding the condyle; (2) Reposition the disc with the Mitek anchor technique; and (3) Orthognathic surgery to advance the maxillo-mandibular complex in a counterclockwise direction.

CONCLUSION

AICR can be successfully treated using the specific protocol presented herein to provide stable and predictable outcomes.

Diagnostic imaging modalities and surgical anatomy of the temporomandibular joint in rabbits

The temporomandibular joint (TMJ) is a condylar synovial joint that, together with the masticatory muscles, controls mandibular movement during mastication. The rabbit is often used as a model species for studying the mechanisms of TMJ diseases, and in regenerative research. However, there are significant differences between rabbit and human TMJs that should be taken into account before using this model for experimental research. Here, we use several analytical approaches (radiography, computed tomography and magnetic resonance imaging) to enable a detailed description and analysis of the rabbit TMJ morphology. Moreover, possible surgical approaches have been introduced with a focus on available access into the rabbit TMJ cavity, which relate our findings to clinical usage.

A Case of Glenoid Fossa Fracture, Progressive Ankylosis, Total Joint Reconstruction with Alloplastic Prosthesis to Normalized Function Including Evaluation with F18-PET/CT-a Four Year Follow-up

Temporomandibular joint replacement (TJR) with alloplastic prosthesis has shown promising long-term results in end stage joint disorders. We present a case of young woman with painful ankylosis that where reconstructed with TJR, due to a complex mandibular fracture with dislocation of the left condyle into the middle cranial fossa two years earlier. At the age of 18 the subject underwent a total joint replacement with custom-made alloplastic TMJ prosthesis. To determine the bone response and remodeling activity around the prosthesis, a F18 PET/CT-scan was used. No sign of increased remodeling or pathology were seen in the imaging after the reconstruction. Four years postoperatively the subject reports no pain and excellent jaw function.

Norepinephrine Regulates Condylar Bone Loss via Comorbid Factors

Degenerative changes of condylar subchondral bone occur frequently in temporomandibular disorders. Although psychologic stresses and occlusal abnormalities have been implicated in temporomandibular disorder, it is not known if these risks represent synergistic comorbid factors that are involved in condylar subchondral bone degradation that is regulated by the sympathetic nervous system. In the present study, chronic immobilization stress (CIS), chemical sympathectomy, and unilateral anterior crossbite (UAC) were sequentially applied in a murine model. Norepinephrine contents in the subjects' serum and condylar subchondral bone were detected by ELISA; bone and cartilage remodeling parameters and related gene expression in the subchondral bone were examined. Subchondral bone loss and increased subchondral bone norepinephrine level were observed in the CIS and UAC groups. These groups exhibited decreased bone mineral density, volume fraction, and bone formation rate; decreased expressions of osterix, collagen I, and osteocalcin; but increased trabecular separation, osteoclast number and surface, and RANKL expression. Combined CIS + UAC produced more severe subchondral bone loss, higher bone norepinephrine level, and decreased chondrocyte density and cartilage thickness when compared to CIS or UAC alone. Sympathectomy simultaneously prevented subchondral bone loss and decreased bone norepinephrine level in all experimental subgroups when compared to the vehicle-treated counterparts. Norepinephrine also decreased mRNA expression of osterix, collagen I, and osteocalcin by mesenchymal stem cells at 7 and 14 d of stimulation and increased the expression of RANKL and RANKL/OPG ratio by mesenchymal stem cells at 2 h. In conclusion, CIS and UAC synergistically promote condylar subchondral bone loss and cartilage degradation; such processes are partially regulated by norepinephrine within subchondral bone.

Primary intra- and juxta-articular vascular malformations of the temporomandibular joint: a clinical analysis of 8 consecutive patients

OBJECTIVE

To analyze primary intra- and juxta-articular vascular malformations of the temporomandibular joint.

PATIENTS AND METHODS

This study retrospectively reviewed eight patients (seven venous malformations and one lymphatico-venous malformation) who were treated for intra- or juxta-articular vascular malformations of the temporomandibular joint from November 2005 to January 2011. All patients underwent magnetic resonance imaging (MRI) preoperatively.

RESULTS

According to MRI findings, vascular malformations involving TMJ could be divided into 3 types; homogenous, lacunar and mixed types. All patients underwent surgical resection, and the final clinical diagnoses were confirmed by postoperative histopathology and immunohistochemical examinations. All treated patients had no clinical or radiographic signs of recurrence.

CONCLUSION

Owing to the lower incidence and nonspecific clinical presentations, preoperative diagnosis of vascular malformations involving the TMJ region is very difficult. The classification based on MRI manifestations is proposed first, then it may greatly help in the initial diagnosis. Surgical resection is considered the first option for these TMJ lesions with excellent results.

Dynamic MRI of the TMJ under physical load

OBJECTIVES

The objective of this study was to examine the kinematics of structures of the temporomandibular joint (TMJ) under physiological load while masticating.

METHODS

Radial MRI was chosen as a fast imaging method to dynamically capture the motions of the joint's anatomy. The technique included a golden ratio-based increment angle and a sliding window reconstruction. The measurements were performed on 22 subjects with and without deformation/displacement of the intra-articular disc while they were biting on a cooled caramel toffee.

RESULTS

The reconstructed dynamic images provided sufficient information about the size and localization of the disc as well as the change of the intra-articular distance with and without loading.

CONCLUSIONS

The feasibility of the golden ratio-based radial MRI technique to dynamically capture the anatomy of the TMJ under physical load was demonstrated in this initial study.

Evaluation of temporomandibular joint total replacement with alloplastic prosthesis: observational study of 27 patients

Background Temporomandibular joint (TMJ) total replacement with alloplastic prostheses has been performed since 1960s. Research in these last two decades has achieved important improvement in the development of biomaterials, design, adaptation, and fixation of the prosthesis components. Objective To evaluate total TMJ replacement with alloplastic prostheses. Methods We studied 27 patients, between 19 and 73 years old, who had total TMJ uni- or bilateral replacement surgery with custom-made alloplastic prostheses manufactured by TMJ Concepts, Inc. (Ventura, CA) between 1996 and 2011. The general data and preoperative measurements were taken from medical records. Subjective data related to pain, diet consistency, and current quality of life were collected with a questionnaire answered by the patients; measures of maximum interincisal opening and lateral mandibular movements were obtained from direct examination. Results We found significant difference (p < 0.05) comparing pre- to postoperative results about improvement in mouth opening, pain relief, and satisfaction with the surgery and diet consistency. Conclusion The results of this study show that total alloplastic TMJ prostheses are an efficient, safe, and stable long-term solution for patients who need TMJ total replacement.