The role of PETRA MRI sequences in the diagnosis of chondromatosis of the temporomandibular joint with erosion of the glenoid fossa.

Synovial chondromatosis is a benign condition characterised by the presence of small cartilaginous nodules in the joint; its aetiology is unknown. Only a few cases of temporomandibular chondromatosis are described in the literature. In some cases, the synovial chondromatosis can erode the adjacent bone structures, such as the glenoid fossa, middle cranial fossa, and internal carotid canal. In these cases, besides MRI, the gold standard to verify the erosion of the glenoid fossa is a computed tomography scan. The aim of this study is to report the use of MRI with PETRA (pointwise encoding time reduction with radial acquisition) sequences for the diagnosis and follow-up of temporomandibular joint chondromatosis with suspected erosion of the glenoid fossa.

A proposed novel digital condylar position adjustment technique to help restore a normal disc-condyle relationship.

Objectives: To demonstrate a novel digital technique that enables real-time visualisation of occlusal transfer and adjustment of condyle position, to (1) improve the repeatability of occlusal transfer and the accuracy of condyle position adjustment and (2) be clinically effective in helping to restore the disc-condyle relationship. Materials and methods: Three participants were included in the study and underwent facebow transfers using two different methods. The digital method used patient-related three-dimensional imaging data matched with digital dental casts for occlusal transfer. The conventional method used anatomical facebows. The condylar position was adjusted based on occlusal transfer results. The results were evaluated and compared in three dimensions. In addition, clinical application data from 36 patients were analysed before and after condylar position adjustment. Statistical significance was set at p < 0.05. Results: Differences in the spatial positions of the three anatomical structures reproduced by both methods were statistically significant (p = 0.000). After adjusting the rotation of the condylar position, the positional deviation of the condylar point along the X- and Z-axes was significantly lower in the digital group (p < 0.05). After adjustment for translation (X and Z), the positional deviation showed no difference along the X- and Z-axes (p > 0.05) but a significant difference along the Y-axis (p < 0.001). Conclusion: A novel digital technique for occlusal transfer and condylar position adjustment was presented. This technique simplifies clinical practice, improves the accuracy of results, and can help restore a normal disc-condyle relationship.

Biomimetic Scaffolds for Regeneration of Temporomandibular Joint Disc: A Narrative Review.

Defects and dysfunctions of temporomandibular joint (TMJ) disc are responsible for the majority of TMJ diseases. Current treatments in this matter are usually short-term and only palliative, thus an alternative treatment that offers long-lasting repair is in great demand. In recent years great attempts have been made to prepare an ideal scaffold, which best resembles the native TMJ disc in characteristics such as mechanical, physical and biological properties. This narrative review focuses on developments of the recent ten years in fabrication of scaffolds using decellularized tissues, natural and synthetic biomaterials for regeneration of TMJ disc and compared their properties. PubMed and Google Scholar databases were searched using the following keywords ("TMJ" OR "temporomandibular joint" OR "TMD" OR "temporomandibular disease") AND ("scaffold" OR "hydrogels"). Randomized controlled trials, randomized clinical trials, case-controls, case reports, and animal studies were included. Comments, systematic reviews, meta-analyses, and non-English papers were excluded. The study concluded that hybrid scaffolds have exhibited favorable cell attachment and proliferation. Synthetic scaffolds have shown promise in providing better control over structural properties; however, additional processes are often required to provide biomimetic cell signaling. While there is still much to learn about the ideal scaffold for TMJ disc regeneration, both natural and synthetic scaffolds have shown promise in achieving the functional, structural, biological, and mechanical properties of a native TMJ disc.

Superficial musculoaponeurotic system interpositional graft after temporomandibular joint discectomy.

Arthroplasty with discectomy is a proven treatment for internal derangement of the temporomandibular joint (TMJ), however there is no consensus on the type of interpositional graft that should be used after the disc is removed. While an ideal graft should be easy to obtain and provide an adequate buffer between the articular surfaces, the authors suggest that it should also minimize donor site morbidity. This Technical Note highlights the technique for harvesting and utilizing the superficial musculoaponeurotic system (SMAS) as an interpositional graft. Three patients were treated with a SMAS graft after TMJ arthroplasty with discectomy. The average pain score decreased from 9/10 preoperatively to 2/10 at 6 weeks postoperatively, while the average maximum incisal opening increased from 31 mm to 36.7 mm. Since these patients were concurrently treated with a facelift, they were asked about their esthetic outcome on a scale of 1-10, with 1 representing extremely dissatisfied and 10 representing extremely satisfied. The average esthetic rating at 6 weeks postoperatively was 9.3/10. The SMAS interpositional graft technique eliminates a second surgical site, improves function, reduces pain, and provides the opportunity for concurrent esthetic facial rejuvenation if desired.

Clinical benefit of botulinum toxin for treatment of persistent TMD-related myofascial pain: A randomized, placebo-controlled, cross-over trial.

BACKGROUND: Injections of botulinum toxin type A (BoNT-A) have been proposed as an additional treatment modality for patients suffering chronic temporomandibular disorder (TMD)-related myofascial pain (MFP). BoNT-A impairs muscle function, along with its analgesic effect, and a minimal effective dose should be used. The objective of this randomized placebo-controlled crossover study was to evaluate the clinical benefit of a moderate dose (50 U) of BoNT-A. METHODS: Sixty-six subjects were randomized into two groups, one which received BoNT-A first and a second which received a saline solution (SS) first. Follow-ups were performed 2, 11, and 16 weeks after the injections. Diagnostic criteria for temporomandibular disorders (DC/TMD) diagnostic algorithms were used to evaluate characteristic pain intensity (CPI) and pain-related disability based on the Graded Chronic Pain Scale (GCPS). Electromyographic and bite force were also evaluated. RESULTS: The within-group analysis showed a significant improvement in pain intensity and pain-related disability after BoNT-A (p < 0.001, p = 0.005, p = 0.011) and SS (p = 0.003, p = 0.005, p = 0.046) injections up to week 16. The between-group analysis of pain-related variables revealed no differences between groups at any time. Nonetheless, BoNT-A, but not SS, caused a significant decline in muscle performance. The number needed to treat (NNT) regarding a clinically significant pain reduction (≥30%) was 6.3, 57.0, and 19.0 at 2, 11, and 16-week follow-ups favoring BoNT-A. CONCLUSIONS: Injections of 50 U of BoNT-A might improve MFP symptoms, but the specific effect of the drug on pain compared to the placebo is not obvious.

The effects of lumbar stabilization exercises with and without jaw movements in non-specific low back pain (A randomized controlled trial).

Objective: This study aimed to investigate the added effect of jaw clenching on the efficacy of lumbar stabilization exercises to manage chronic non-specific low back pain. Methods: This randomized controlled trial was conducted at the Sindh Institute of Physical Medicine and Rehabilitation (SIPM&R) Karachi from April 2021 to April 2023. Eighty patients with chronic non-specific low back pain participated in this study. Forty patients each were randomly allocated to the lumbar stability exercise (LSE) group' and the lumbar stability exercise with teeth clenching (LSETC) group. Patients in both groups performed respective exercises twice weekly for 12 weeks. The Numeric Pain Rating Scale (NPRS), Roland Morris Disability Questionnaire (RMDQ), and Pressure Biofeedback Unit (PBU) were used to assess pain, disability, and muscle endurance respectively. Data were collected at the baseline, after six weeks and 12 weeks of intervention. A p-value of <0.05 was considered statistically significant. Results: Both groups showed statistically significant improvements in pain, disability, and muscle endurance. Upon further stratification, participants aged 20-30 years in the LSETC group showed significantly higher scores than the LSE group for NPRS, RMDQ, and PBU after 12 weeks. Overall, the LSETC group showed relatively higher improvement in mean scores for NPRS, RMDQ, and PBU than the LSE group. Conclusion: Lumbar stabilization exercises with and without jaw movement are effective for the treatment of chronic non-specific low back pain. The addition of teeth clenching enhanced the effectiveness of lumbar stability exercises, especially in young adults. Trial Registration: Clinicaltrials.gov (NCT04801212), Prospectively registered on March 16, 2021.

Muscle oxygenation and pain in different types of temporomandibular disorders.

OBJECTIVES: Studies exploring variations in peripheral muscle oxygenation and pressure pain thresholds (PPT) of masticatory muscles in individuals with Temporomandibular Disorders (TMDs) are limited. The purpose of this study was to compare variations in peripheral oxygenation of the masseter muscle; PPT of the masseter and temporal muscles and correlate peripheral muscle oxygenation and PPT of the masseter muscle in individuals with different types of TMDs. MATERIALS AND METHODS: Cross-sectional study involving 116 participants classified into three groups: muscle group (MG, n = 32), joint group (JG, n = 30) and muscle-joint group (MJG, n = 54). Individuals aged 26.97 ± 6.93, 68.97% female, 31,03% males were included. All participants were evaluated using the Diagnostic Criteria for Temporomandibular Disorders, Near-infrared spectroscopy (NIRS) for peripheral muscle oxygenation and pressure algometer for PPT. RESULTS: There was no difference in masseter muscle oxygenation among groups. In the masseter muscle, a weakly positive correlation was observed between PPT and variation in tissue saturation index in the MG (rho = 0.365) and JG (rho = 0.317). In addition, the MJG expressed lower PPT (p = 0.004) than JG, demonstrating that MJG had more pain in this muscle. CONCLUSIONS: MJG have lower PPT in the masseter muscle. Although the PPT is dependent on the type of TMDs, the correlation between PPT and oxygenation is weak. All TMDs groups evaluated (MG, JG, MJG) showed hemodynamic similarities of the masseter muscle. CLINICAL RELEVANCE: Understanding pain thresholds and the hemodynamic behavior of the masticatory muscles contributes to a more assertive physiotherapeutic assessment in TMDs, serving as a basis for careful and individualized interventions.

Hormone replacement therapy did not alleviate temporomandibular joint inflammatory pain in ovariectomized rats.

This study had the aim of examining the relationships between variations in estrogen levels resulting from ovariectomy, and estrogen hormone replacement therapy (HRT) in rats subjected to an orofacial inflammatory pain model. Eighty adult female Wistar rats were initially divided into 2 groups: Sham or ovariectomy (OVX-D1). Seven days later (D7), the rats were subjected to an unilateral infiltration of Freund's Complete Adjuvant (CFA) or saline solution into the right temporomandibular joint (TMJ). Then, rats received 17ß-estradiol (28 µg/kg/day) or placebo for 21 days (D10-D31). Nociception was evaluated by the von Frey (VF) and the Hot Plate (HP) tests, and depressive-like behavior by the Forced Swimming (FS) test. On D32 all rats were euthanized and serum, hippocampus and brainstem were collected. The CFA groups presented a mechanical hyperalgesia until day 21 (p ≤ 0.05). No differences were observed among groups in the HP (p = 0.735), and in the immobility and swimming time of the FS (p = 0.800; p = 0.998, respectively). In the brainstem, there was a significant difference in the TNF-ɑ levels (p = 0.043), and a marginal significant difference in BDNF levels (p = 0.054), without differences among groups in the hippocampal BDNF and TNF-ɑ levels (p = 0.232; p = 0.081, respectively). In conclusion, the hormone replacement therapy did not alleviate orofacial pain in ovariectomized rats. However, there is a decrease in brainstem TNF-ɑ levels in the animals submitted to both models, which was partially reverted by HRT.

The role of nutraceuticals in the management of temporomandibular disorders.

OBJECTIVES: Temporomandibular disorders (TMDs) are usually treated with occlusal appliances and supportive treatments such as physical therapy and drugs. Supplements can be included among potential supportive therapies, with the aim of reducing the use of drugs. To evaluate the efficacy of nutraceuticals' short-term treatment in subjects with temporomandibular disorders. METHODS: The study started in January 2021 and ended in January 2022. Subjects with temporomandibular disorders and a verbal numeric scale >40 were recruited and randomly assigned to one of the following groups. If waiting to start a therapy, to the nutraceutical group or to the no treatment group, while if already undergoing splint therapy, to nutraceautical+splint group or to splint therapy group. Nutraceutical used was composed by Boswellia Serrata Casperome, Magnesium, Tryptophan and vitamins B2 and D with a posology of one tablet/day before sleep for 40 days. Presence of temporomandibular pain, headache, neck pain and sleep/emotional disorders were assessed at T0 and at T1, after 40 days. ANOVA was performed to compare treatments with nutraceuticals and their respective controls, as for the variables related to painful symptomatology. Chi- Squared was conducted to assess differences in sleep/emotional disorders between groups. The statistical significance was p<0.05. RESULTS: The groups using nutraceuticals showed statistically significant improvements over controls for most of the variables analyzed. CONCLUSIONS: The use of nutraceutical seems to be a valuable support for TMD therapy in the short term either alone or combined with occlusal splint therapy.

Influence of examiner calibration on clinical and mri diagnosis of temporomandibular joint disc displacement: a systematic review and meta-analysis.

OBJECTIVES: This study aimed to verify the accuracy of clinical protocols for the diagnosis of disc displacement (DD) compared with magnetic resonance imaging (MRI), considering examiners' calibration. METHODS: PubMed, Cochrane (Central), Scopus, Web of Science, LILACS, Embase, Science Direct, Google Scholar, and DANS EASY Archive databases were searched. Two reviewers independently screened and selected the studies. A meta-analysis was conducted using the R Statistical software. Results are shown using sensitivity and specificity, and 95% confidence intervals. RESULTS: Of the 20 studies included in the systematic review, only 3 were classified as low risk of bias. Seventeen studies were included in the meta-analysis. Compared to MRI, clinical protocols showed overall sensitivity and specificity of 0.75 (0.63-0.83) and 0.73 (0.59-0.84) for DD diagnosis, respectively. For DD with reduction, sensitivity was 0.64 (0.48-0.77) and specificity was 0.72 (0.48-0.87). For DD without reduction, sensitivity was 0.58 (0.39-0.74) and specificity 0.93 (0.83-0.97). Only 8 studies reported examiner calibration when performing clinical and/or MRI evaluation; nevertheless, calibration showed a tendency to improve the diagnosis of DD. CONCLUSION: The sensitivity and specificity of clinical protocols in the diagnosis of DD are slightly below the recommended values, as well as the studies lack calibration of clinical and MRI examiners. Examiner calibration seems to improve the diagnosis of DD.

Poly(p-coumaric acid) nanoparticles alleviate temporomandibular joint osteoarthritis by inhibiting chondrocyte ferroptosis.

Oxidative stress and inflammation are key drivers of osteoarthritis (OA) pathogenesis and disease progression. Herein we report the synthesis of poly(p-coumaric) nanoparticles (PCA NPs) from p-courmaic acid (p-CA), a naturally occurring phytophenolic acid, to be a multifunctional and drug-free therapeutic for temporomandibular joint osteoarthritis (TMJOA). Compared to hyaluronic acid (HA) that is clinically given as viscosupplementation, PCA NPs exhibited long-term efficacy, superior anti-oxidant and anti-inflammatory properties in alleviating TMJOA and repairing the TMJ cartilage and subchondral bone in a rat model of TMJOA. Notably, TMJ repair mediated by PCA NPs could be attributed to their anti-oxidant and anti-inflammatory properties in enhancing cell proliferation and matrix synthesis, while reducing inflammation, oxidative stress, matrix degradation, and chondrocyte ferroptosis. Overall, our study demonstrates a multifunctional nanoparticle, synthesized from natural p-coumaric acid, that is stable and possess potent antioxidant, anti-inflammatory properties and ferroptosis inhibition, beneficial for treatment of TMJOA.

The reliability and minimal detectable change of common tests and measures for temporomandibular disorders.

BACKGROUND: Temporomandibular disorders are a source of orofacial pain. Understanding clinimetric properties of evaluation procedures is necessary for assessing impairments and determining response to interventions. PURPOSE: Reliability, minimal detectable change (MDC95), and 95% limits of agreement of TMJ examination procedures were investigated. METHODS: Occlusion (central incisor alignment, overjet, overbite), mandibular dynamics (maximal incisor opening, laterotrusion, protrusion active range of motion (AROM)), auscultation, tenderness, and joint play were measured on 50 asymptomatic adults (30 females), mean age 24.8. The inter-rater reliability assessment used an intra-session design. Participants returned 24-48 h later for intra-rater assessments. Intraclass correlation coefficients (ICC) and Kappa values were used to determine reproducibility. RESULTS: Intra-rater reliability for occlusion and AROM was ICC 3,1 ≥ 0.75, whereas interrater reliability was ICC 2,1 ≥ 0.68. Kappa values for inter-rater agreement of joint mobility was K = .18, whereas auscultation and palpation were K ≥ 0.48. Intra-rater Kappa values were ≥ 0.24, with lateral pterygoid region palpation having poor agreement. The MDC95 for occlusion was 1 mm, whereas AROM ranged from 3 to 6 mm. Mean AROM differences between raters were -1.16, -0.42, -0.18, and -0.8 mm for maximal incisor opening, left and right laterotrusion, and protrusion, respectively. CONCLUSION: AROM and occlusion measurements may be used with confidence; however, poor agreement for joint mobility measurements and lateral pterygoid region palpation must be recognized. When re-assessing measurements, a 3-6 and 1-mm change in AROM and occlusion, respectively, is required to be 95% certain change is not due to error. Future symptomatic population research is needed (250/250).

N-methyl-D-aspartate Receptor Subunits 2A and 2B Mediate Connexins and Pannexins in the Trigeminal Ganglion Involved in Orofacial Inflammatory Allodynia during Temporomandibular Joint Inflammation.

Temporomandibular joint osteoarthritis (TMJOA) is a severe form of temporomandibular joint disorders (TMD), and orofacial inflammatory allodynia is one of its common symptoms which lacks effective treatment. N-methyl-D-aspartate receptor (NMDAR), particularly its subtypes GluN2A and GluN2B, along with gap junctions (GJs), are key players in the mediation of inflammatory pain. However, the precise regulatory mechanisms of GluN2A, GluN2B, and GJs in orofacial inflammatory allodynia during TMJ inflammation still remain unclear. Here, we established the TMJ inflammation model by injecting Complete Freund's adjuvant (CFA) into the TMJ and used Cre/loxp site-specific recombination system to conditionally knock out (CKO) GluN2A and GluN2B in the trigeminal ganglion (TG). Von-frey test results indicated that CFA-induced mechanical allodynia in the TMJ region was relieved in GluN2A and GluN2B deficient mice. In vivo, CFA significantly up-regulated the expression of GluN2A and GluN2B, Gjb1, Gjb2, Gjc2 and Panx3 in the TG, and GluN2A and GluN2B CKO played different roles in mediating the expression of Gjb1, Gjb2, Gjc2 and Panx3. In vitro, NMDA up-regulated the expression of Gjb1, Gjb2, Gjc2 and Panx3 in satellite glial cells (SGCs) as well as promoted the intercellular communication between SGCs, and GluN2A and GluN2B knocking down (KD) altered the expression and function differently. NMDAR regulated Gjb1 and Panx3 through ERK1/2 pathway, and mediated Gjb2 and Gjc2 through MAPK, PKA, and PKC intracellular signaling pathways. These findings shed light on the distinct functions of GluN2A and GluN2B in mediating peripheral sensitization induced by TMJ inflammation in the TG, offering potential therapeutic targets for managing orofacial inflammatory allodynia.

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

BACKGROUND: The 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. METHODS: A 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. RESULTS: All 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. CONCLUSIONS: The 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 dynamic progression of temporomandibular joint osteoarthritis-like lesions elicited by mandibular shift in a rat model.

BACKGROUND: Temporomandibular joint osteoarthritis (TMJ-OA) presents significant challenges due to its complex etiology, often insidious onset, high incidence, and progressive structural deterioration. While research has explored genetic and molecular factors, treatment outcomes remain suboptimal, emphasizing the need for a deeper understanding of disease progression. OBJECTIVE: This study employs a specific mandibular shift rat model to explore the dynamic progression of TMJ-OA-like lesions and evaluate the potential for self-repair at different stages, aiming to inform early diagnosis and preventative strategies. METHODS: Seventy-two female Sprague-Dawley rats were randomized into three groups: a control group (n=24; average weight: 157.23±1.63 g) receiving sham surgery. an experimental group (n=24; average weight: 157.78±1.88 g) subjected to mandibular shift induction, and a removal group (n=24; average weight: 158.11±2.20 g) experiencing mandibular shift for one, two, or four weeks followed by a one-month recovery period (designated as 1w Removal, 2w Removal and 4w Removal, respectively). Histomorphological and molecular analyses were conducted at designated time points. RESULTS: Rats in the 1-week removal group exhibited substantial recovery in condylar morphology, cartilage thickness, extracellular matrix composition, and expression of OA-related genes. Conversely, the 4-week removal group mirrored the experimental group, indicating limited self-repair capacity at later stages. The 2-week removal group presented with variable outcomes, with some animals showing signs of recovery and others resembling the experimental group, indicating a potential transitional phase in the disease process. CONCLUSION: Recovery from early-stage TMJ-OA involves eliminating provoking factors such as occlusal interference or reducing joint loading. However, advanced stages exhibit diminished self-repair capabilities, necessitating additional therapeutic interventions. These findings emphasize the importance of early diagnosis and intervention in TMJ-OA management.

Deep learning classification performance for diagnosing condylar osteoarthritis in patients with dentofacial deformities using panoramic temporomandibular joint projection images.

OBJECTIVE: The present study aimed to assess the consistencies and performances of deep learning (DL) models in the diagnosis of condylar osteoarthritis (OA) among patients with dentofacial deformities using panoramic temporomandibular joint (TMJ) projection images. METHODS: A total of 68 TMJs with or without condylar OA in dentofacial deformity patients were tested to verify the consistencies and performances of DL models created using 252 TMJs with or without OA in TMJ disorder and dentofacial deformity patients; these models were used to diagnose OA on conventional panoramic (Con-Pa) images and open (Open-TMJ) and closed (Closed-TMJ) mouth TMJ projection images. The GoogLeNet and VGG-16 networks were used to create the DL models. For comparison, two dental residents with < 1 year of experience interpreting radiographs evaluated the same condyle data that had been used to test the DL models. RESULTS: On Open-TMJ images, the DL models showed moderate to very good consistency, whereas the residents' demonstrated fair consistency on all images. The areas under the curve (AUCs) of both DL models on Con-Pa (0.84 for GoogLeNet and 0.75 for VGG-16) and Open-TMJ images (0.89 for both models) were significantly higher than the residents' AUCs (p < 0.01). The AUCs of the DL models on Open-TMJ images (0.89 for both models) were higher than the AUCs on Closed-TMJ images (0.72 for both models). CONCLUSIONS: The DL models created in this study could help residents to interpret Con-Pa and Open-TMJ images in the diagnosis of condylar OA.

Deletion of Bmal1 in aggrecan-expressing cells leads to mouse temporomandibular joint osteoarthritis.

INTRODUCTION: Articular cartilage is the major affected tissue during the development of osteoarthritis (OA) in temporomandibular joint (TMJ). The core circadian rhythm molecule Bmal1 regulates chondrocyte proliferation, differentiation and apoptosis; however, its roles in condylar cartilage function and in TMJ OA have not been fully elucidated. MATERIALS AND METHODS: TMJ OA mouse model was induced by unilateral anterior crossbite (UAC) and Bmal1 protein expression in condylar cartilage were examined by western blot analysis. To determine the role of Bmal1 in TMJ OA, we generated cartilage-specific Bmal1 conditional knockout (cKO) mice (Bmal1Agc1CreER mice) and hematoxylin and eosin staining, toluidine blue and Safranin O/fast green, immunohistochemistry, TUNEL assay, real-time PCR analysis and Western blot assay were followed. RESULTS: Bmal1 expression was reduced in condylar cartilage in a TMJ OA mouse model induced by UAC. The Bmal1 cKO mice displayed decreased cartilage matrix synthesis, reduced chondrocyte proliferation, increased chondrocyte hypertrophy and apoptosis as well as the upregulation of YAP expression in TMJ condylar cartilage. CONCLUSIONS: We demonstrated that Bmal1 was essential for TMJ tissue homeostasis and loss-of-function of Bmal1 in chondrocytes leads to the development of TMJ OA.

The majority of patients report satisfaction more than 24 years after temporomandibular joint discectomy.

PURPOSE: To retrospectively evaluate long-term outcomes after temporomandibular joint (TMJ) discectomy. METHODS: Included patients (n = 64) had undergone discectomy during 1989-1998 at Umeå University Hospital. A questionnaire was used to evaluate pre- and postoperative symptoms, postoperative complications, general pain, and subjective opinion about the outcome of the surgery. RESULTS: The results are based on responses from 47 patients (40 women/7 men), including 36 (30 women/6 men) who completed the questionnaire and 11 (10 women/1 man) who were contacted by telephone and answered selected questions. Seventeen patients were excluded because of death, a move abroad, declining to participate, or no available patient information. Among the respondents, 41 (87%) were satisfied with the results, five (11%) were unsatisfied, and one (2%) patient did not answer the question. The results showed a significant long-term improvement in locking, clicking/crepitation, and pain when chewing or opening the jaw (p = 0.001). The prevalence of headaches had decreased significantly at follow-up (p = 0.001). Reported impaired jaw-opening capacity showed no significant improvement (p = 0.08). Of the 47 respondents, 19 (40%) had asked for additional treatment after the discectomy, and six of the 19 patients (13%) had undergone more surgery of the joint. CONCLUSION: The results of this retrospective long-term follow-up study indicate that TMJ discectomy has a high success rate, as most patients were satisfied with the postoperative results. Discectomy is thus an effective surgical intervention for patients with disabling TMJ pain and dysfunction when conservative interventions have been unsuccessful.

Temporomandibular joint ankylosis suspected to be associated with ankylosing spondylitis based on cervical computed tomography images: A pictorial essay.

This report showed a case of temporomandibular joint (TMJ) ankylosis suspected to be associated with ankylosing spondylitis based on the observation of bony ankylosis of the cervical spine on computed tomography (CT) images. A 53-year-old man presented with a chief complaint of difficulty in opening his mouth. His medical history indicated that in his 20s, he became aware of the difficulty in moving his neck. CT revealed marked osteoarthritic changes in the right mandibular condyle, suggesting fibrotic TMJ ankylosis. In addition, bony ankylosis of the cervical vertebral body and facet joints from the axis (C2) to C5 in continuity was observed. CT of the entire spine also showed bony deformity of the sacroiliac joints and bony ankylosis. Based on these findings, ankylosing spondylitis was suspected. The possibility of an ankylosing spondylitis complication should be considered in cases of TMJ ankylosis if bony ankylosis of the cervical spine is observed.

Bi-directional two-sample Mendelian randomization identifies causal association of depression with temporomandibular disorders.

BACKGROUND: Depression and anxiety have been suggested to be associated with temporomandibular disorders (TMD) in observational studies. However, the causal association and the direction in the relationship between depression/anxiety and TMD remain unknown. OBJECTIVES: This study investigated the potential causal relationship between depression/anxiety and TMD with two-sample bi-directional Mendelian randomization (MR). METHODS: Summary statistics of depression (N = 500 199), anxiety disorder (N = 17 310) and TMD (N = 195 930) were sourced from large-scale genome-wide association studies (GWAS). The primary Mendelian randomization (MR) estimation employed the inverse-variance weighted meta-analysis (IVW). Additional MR sensitivity methods and multivariate MR (MVMR) were applied to address pleiotropy. RESULTS: IVW results indicated a causal effect of genetically predicted depression on TMD (OR = 1.887, 95% CI = 1.504-2.367, p < .001), which was supported by other sensitivity MR approaches. MVMR results suggested that the negative effect of depression on TMD persisted after conditioning on other potential confounders. The association of anxiety disorder with TMD was not supported by our findings. In the reverse direction, we did not find compelling evidence suggesting the causal effect of TMD on depression and anxiety disorder. CONCLUSIONS: The present study suggests a potential causal association between genetic liability for depression and the risk of TMD. Our MR findings align with prior epidemiological research, underscoring the significance of early detection and prevention of depression in the treatment of TMD.