Elevated levels of nitric oxide in synovial fluid from patients with temporomandibular disorders

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

The novel relationship between polycystic ovary syndrome and temporomandibular joint disorders

INTRODUCTION

Studies investigating the relationship between sex hormones, inflammatory mediators and joint disorders have reported that sex hormones affect the pathogenesis of joint disorders. We aimed to investigate temporomandibular joint disorder (TJD) in polycystic ovary syndrome (PCOS) and the possible role of systemic mediators and sex hormones in TJD pathogenesis.

MATERIAL AND METHODS

PCOS patients (n = 45) and controls (n = 30) aged 20-40 years, were enrolled in this case-control study. TJD diagnosis was performed by the specialist and blood samples were tested in the early follicular phase and on the 21 st (midluteal) day to investigate the levels of estrogen, progesterone, matrix metalloproteinase (MMP) 1-8-9, interleukin (IL)-1ß and Tumor necrosis factor (TNF)-α.

RESULTS

TJD incidence was significantly higher in PCOS than the control group (51.1% and 6.9% respectively, p < 0.01). Midluteal progesterone (p < 0.01) was lower in PCOS group than the controls (p < 0.01). TNF-α (p < 0.01), MMP 1 (p < 0.01) and MMP 8 (p = 0.02) levels were found significantly higher in PCOS than the control group. Further, Progesterone levels were found significantly lower in TJD (+) PCOS patients than TJD (-) PCOS patients. However, significant difference was not found between the PCOS TJD (+) and PCOS TJD (-) patients for estrogen, MMP 1, MMP 8, MMP 9, TNF-α and IL-1ß.

CONCLUSIONS

TJD frequency was found significantly increased in PCOS patients. Related with this, TJD co-occurrence should be kept in mind in the diagnosing and treatment process of PCOS due to hormonal alteration.

Association between oxidative stress and temporomandibular joint dysfunction: A narrative review

BACKGROUND

The role of oxidative stress in temporomandibular disorders (TMDs) has been studied using synovial fluid, to evaluate oxidative stress (im)balance and its potential role in the onset and/or progression of the disease.

OBJECTIVE

This review aimed to evaluate the association between oxidative stress markers and the etiopathogenesis of TMJ dysfunction by means of synovial fluid analysis.

METHODS

Two independent reviewers searched the electronic databases from inception to March 2019: PubMed/MEDLINE, LILACS, SciELO, EMBASE, TRIPDATABASE, SCOPUS, and Google Scholar. The following key search terms were used: Temporomandibular Joint Disorders OR Temporomandibular Joint Disc OR Temporomandibular Joint Dysfunction Syndrome OR Temporomandibular Joint OR Facial Pain AND Free Radicals OR Oxidative Stress. Data were extracted from the selected articles, including study design, sample profile, TMJ disease reported, diagnostic method, reactive oxygen and nitrogen species evaluated, enzymatic and non-enzymatic antioxidants evaluated, and techniques used to measure free radicals and antioxidants.

RESULTS

After title and abstract screening of 6974 results, and full-text reading, 19 studies were included. All selected articles were cross-sectional observational studies. Enzymatic and non-enzymatic antioxidant defences appeared to be reduced in these patients, resulting in the establishment of the oxidative stress process. In addition, the studies showed a positive correlation between the severity of the intra-articular TMD and the increase in oxidative damage.

CONCLUSION

The establishment of oxidative stress, whether by an increase in reactive oxygen/nitrogen species or by a decrease in antioxidant defences, or a combination of both, may be associated with the establishment and maintenance of intra-articular damage.

Analysis of synovial fluid visfatin level in temporomandibular joint disorders

Background: Biochemical analysis of synovial fluid (SF) is an important means of understanding the pathogenesis of temporomandibular disorder (TMD) and confirming diagnoses made using traditional methods. Objective: The aim of this study was to determine whether or not SF visfatin levels can serve as a biochemical marker in the diagnosis of TMD. Method: Sixty samples of SF were obtained from 60 patients with internal derangement (ID) or osteoarthritis (OA). Visfatin in the SF was examined by enzyme-linked immunosorbent assay (ELISA). Result: Visfatin levels showed positive correlations with TMD pain and ID stage and a negative correlation with maximum mouth opening. In addition, Visfatin levels in joints with OA changes in the condyle were significantly higher in comparison to joints with no OA changes. Conclusion: Within the limitations of this study, it can be concluded that visfatin may play a role in the pathogenesis of TMD.

Expression of chemerin in the synovial fluid of patients with temporomandibular joint disorders

The synovial membrane and fluid are significantly involved in the pathogenesis of temporomandibular joint (TMJ) disorders. This study aimed to investigate the relation between levels of chemerin in the synovial fluid (SF) of patients with TMJ disorder and their relationship. Sixty samples of SF were obtained from patients with an internal derangement (ID) or osteoarthritis (OA). Chemerin in the SF was examined by enzyme-linked immunosorbent assay (ELISA). The results showed greater levels of chemerin in the SF of patients with OA than ID. While chemerin levels were positively correlated with pain scores, they were inversely correlated with MMO. Chemerin levels increased progressively as the disorder stage became more severe. The findings of this study suggest that chemerin in SF may play role as a predisposing factor and may represent a novel potential prognostic biochemical marker in the pathogenesis of TMJ disorders.

Effect of hyaluronic acid on the regulation of inflammatory mediators in osteoarthritis of the temporomandibular joint: a systematic review

Osteoarthritis is one of the most frequent pathologies affecting the temporomandibular joint (TMJ). There is evidence that the use of intra-articular hyaluronic acid (HA) for the treatment of this disorder achieves positive effects through a reduction in inflammatory mediators. A systematic review of the available evidence regarding the regulation of inflammatory mediators when applying HA in osteoarthritis of the TMJ in humans was performed. The Web of Science, Embase, ScienceDirect, MEDLINE, Scopus, EBSCOhost, and LILACS databases, SciELO library, and search engine Trip Database were searched systematically. Two thousand eight hundred and sixty-three related articles were found, of which only two met the selection criteria (both were clinical trials and evidence level 2b for treatment studies). These two articles represented a population of 87 patients. Both articles reported that the application of HA had a positive effect on the regulation of inflammatory mediators; the mediators studied were those of the plasminogen activator system and levels of nitric oxide. The limited evidence available suggests that the application of HA regulates various inflammatory mediators in osteoarthritic processes in the TMJ. Nevertheless, further evidence in this regard is required, through the study of specific pathologies of the TMJ, complementing the assessment of clinical parameters with molecular studies, and generating good quality clinical studies with larger sample sizes.

Oxidative Stress-induced DNA Damage in the Synovial Cells of the Temporomandibular Joint in the Rat

Synovial hyperplasia is a feature of degenerative temporomandibular joint (TMJ) disease. However, the mechanism by which hyperplasia progresses in the TMJ is unknown. Based on the hypothesis that the oxidative stress generated by mechanical loading causes degenerative changes in the TMJ synovium, we investigated the generation of the highly reactive species, peroxynitrite, and the occurrence of DNA damage in the synovium. After condylar hypermobility of rat TMJs, a marker of peroxynitrite, nitrotyrosine, was localized to the nuclei and cytoplasm of the synovial lining cells and fibroblasts in synovitis-induced TMJ. DNA single-strand breaks were found in the nuclei of the synovial cells only after enzyme treatment, whereas DNA double-strand breaks were not detected. These findings indicate that condylar hypermovement induces the proliferation of synovial cells, and suggest that oxidative stress leads to the progression of synovial hyperplasia via DNA damage of the synovial cells in TMJs after mechanical loading.

Changes in the salivary oxidative status in individuals with temporomandibular disorders and pain

Temporomandibular joint disorders are quite common among the general public. Free radicals may play a role in the pathogenesis of joint diseases, and the oxidative stress is an important aspect in the mechanism of TMDs. The use of new biotechnologies has enabled the use of saliva as a diagnostic method. This is the first paper that aims to investigate changes in the oxidative status, through saliva analysis, in individuals who suffer from temporomandibular disorder and pain. Sixty individuals, 54 women and 06 men, aged between 10 and 60, participated in this research. The questionnaire 'Research Diagnostic Criteria for Temporomandibular Disorders' (RDC/TMD) was filled out in order to determine the presence and the type of TMD, and the Visual Analogue Scale (VAS) was conducted in order to measure the pain perception caused by TMD. In addition, the total oxidant status (TOS), and the total antioxidant capacity (TAC) were measured, and the oxidative stress index (OSI) was calculated. The t-test and the Pearson Correlation Test were used with the significance level of p < 0.05. The TAC in individuals with TMD and pain was significantly reduced (p < 0.001). There was no difference regarding the levels of TOS (p = 0.765) between both groups. As a result, the OSI was significantly higher in the group TMD and pain (p = 0.011). There was no correlation between VAS, TAC, and TOS values. Within the limits of this study, oxidative changes seem to influence the pathogenesis of pain in TMDs.

Recent Advancements in Temporomandibular Disorders (TMDs)

TMDs are a group of conditions affecting the joint and or the muscles of mastication.TMDs consist of three main groups of conditions: myofascial pain; disc disorders; TMJ arthritides.The gold standard diagnostic criteria for research involving TMDs are the Research Diagnostic Criteria for TMDs (RDC/TMD). A pragmatic clinically applicable alternative is the Clinical examination protocol for TMDs (CEP-TMD).Signs and symptoms can include: pain in masticatory musculature and or the joint; noises associated with joint movements; locking; headache; otalgia.TMDs' aetiology is multifactorial and biopsychosocial in nature.Reversible conservative management as defined by the American Association of Dental Research is the initial management of choice for all subgroups of TMDs.

ANKH Polymorphisms and Clicking of the Temporomandibular Joint in Dental Residents

AIM

This study aimed to carry out a case-control research study to assess occurrence of clicking of the temporomandibular joint (TMJ) in order to establish the relationship between TMJ clicking and the genotype of "ANKH inorganic pyrophosphate transport regulator" (ANKH) polymorphisms.

MATERIALS AND METHOD

A sample of 41 first-year dental residents was selected. Each was examined using standard clinical procedures and genotyping techniques.

RESULTS

The participation rate was 91.8 %. The prevalence of TMJ clicking was 51.2 % (95 % CI: 35.7-66.7 %). Occurrence of TMJ clicking was not related to age, gender and genotypes of ANKH-OR as well as ANKH-TR polymorphisms (p ≥ 0.165).

CONCLUSION

A similar distribution of ANKH genotypes in TMJ clicking and asymptomatic individuals has been demonstrated by this study. A high percentage of TMJ clicking has been confirmed. Future investigations are indicated.

Total antioxidant capacity and total oxidant status of synovial fluids in patients with temporomandibular joint pain and dysfunction

OBJECTIVES

The objective of this study was to investigate whether a relationship exists between total antioxidant capacity (TAC) and total oxidant status (TOS) of synovial fluids (SFs) of temporomandibular joint (TMJ) pain patients with pain and dysfunction.

MATERIALS AND METHODS

Forty-two patients with TMJ pain were included in this study. TAC and TOS values of SFs were measured with a novel colorimetric method. Independent t test and correlations were used to analyze the data.

RESULTS

TAC of SFs in patients with TMJ pain and limited mouth opening (LMO; n = 21) were significantly lower (P = 0.03) than patients without LMO (n = 21). TOS of SF was negatively correlated with duration of the disease. There was no correlation between TAC, TOS, and VAS scores of the patients as well as age and maximum mouth opening values.

CONCLUSIONS

Antioxidant response to oxidative changes (TAC and TOS) in SF decreased as the stage of dysfunction increased.

CLINICAL RELEVANCE

Local administration of antioxidant agents might be considered in management of TMJ pain and dysfunction to prevent possible increased oxidative stress.

Effects of hyaluronan on carrageenan-induced synovitis in rat TMJ

Nitric oxide is one of many proinflammatory mediators that are involved in temporomandibular joint (TMJ) inflammatory disorder and is synthesized by inducible nitric oxide synthase (iNOS). iNOS is transcriptionally regulated by nuclear factor-κB (NF-κB) in cases of inflammation, proliferation, and apoptosis. It has also been reported that nitric oxide is positively regulated by carrageenan and negatively regulated by hyaluronan in the knee joint. The aim of this study was to histologically evaluate how inflammation and cell proliferation of the synovial membrane are affected by the exogenous administration of carrageenan and hyaluronan in the rat TMJ by investigating iNOS, NF-κB, and anti proliferating cell nuclear antigen (PCNA) immunoreactivity. As results, immunoreactive cells to iNOS, NF-κB, and PCNA were normally localized only in the synovial membrane of wild type TMJs. The numbers of immunoreactive cells were extensively larger in the carrageenan-injected synovial membranes exhibiting excessive folding, and smaller in the hyaluronan-injected synovial membranes showing a few folds. These results indicate that a carrageenan injection induced inflammation and cell proliferation especially in the synovial membrane and that hyaluronan relieved the inflammation by decreasing inflammatory molecules in the synovial membrane.

Superoxide Dismutase Activity in Synovial Fluids in Patients With Temporomandibular Joint Internal Derangement

PURPOSE

To measure the activity of superoxide dismutase (SOD) in the synovial fluid of patients with temporomandibular joint internal derangement and to show the relationship between the activity of SOD and the severity of the disease.

MATERIALS AND METHODS

Twenty patients with internal derangement were classified according to Wilkes by clinical radiological examinations. SOD activity was measured by the method based on nitrobluetetrazolium reduction rate.

RESULTS

The activity of SOD seemed to be progressively decreased as the stage of the disease increased.

CONCLUSION

The reduction of SOD activity observed may result from insufficient scavenging capacity of free radicals. Further investigation and longitudinal studies are required to determine the role of antioxidants that scavenge the free radicals in temporomandibular joint disorders.

In vivo measurement of facet joint nitric oxide in patients with chronic low back pain

STUDY DESIGN

Prospective case-control study testing a new diagnostic method.

OBJECTIVE

The aim of the present study was to investigate the concentration of nitric oxide (NO) in the perifacetal region in patients with chronic low back pain and healthy controls.

SUMMARY OF BACKGROUND DATA

Facet joint arthrosis may be a pain source in chronic back pain. Increased concentrations of NO, an oxygen-free radical, have been demonstrated in temporomandibular and knee joints with osteoarthritis.

PATIENTS AND METHODS

Patients with at least 6 months' duration of chronic low back pain and signs of facet joint osteoarthrosis (n = 24) and healthy volunteers (n = 7) were included. A detailed questionnaire, including visual analogue scale, was completed before and 6 weeks after the measurements. NO was measured with a custom-designed electrochemical real-time NO sensor inserted under fluoroscopic guidance. All patients received corticosteroids and local anesthetics after NO measurements.

RESULTS

NO measurements were obtained from all participants. No adverse effects were noted. The patients with chronic low back pain demonstrated higher concentrations of NO in the perifacetal region compared with healthy controls (1.66 +/- 0.28 vs. 0.46 +/- 0.14 nmol/L, P = 0.007). No association between NO concentration and pain duration or pain level was detected. Patients with a positive response to local anesthetics and corticosteroid injection (defined as a >or=20 mm reduction of visual analogue scale at the 6-week follow-up visit) had higher NO concentrations than patients without positive response.

CONCLUSIONS

The study demonstrates that it is feasible and safe to measure NO with a real time-sensor in or around the facet joints. The findings of higher concentrations of NO in the perifacetal region in chronic low back patients compared with healthy controls indicate that the degenerative process of the joints in these patients may cause increased NO production. The observation of higher NO concentrations in the perifacetal region in patients responding to corticosteroid/local anesthetic infiltration indirectly suggest a more pronounced inflammatory process in these patients.

A multifaceted molecule, nitric oxide in oral and periodontal diseases

Nitric oxide (NO) is a molecule with multiple effects on different tissues. NO takes important roles in vasodilatation, bacterial challenge and cytokine stimulation, regulation of mineralized tissue function, neurotransmission, and platelet aggregation, etc. However, under pathological conditions, NO has damaging effects. NO is synthesized by NO synthases (NOS) and inducible isoform of NOS (iNOS) is closely related to the pathophysiological characteristics of inflammatory diseases such as periodontal diseases. The expression of iNOS has been investigated in salivary gland-related diseases, temporomandibular joint disorders and oral cancer as well. The beneficial and damaging effects of NO in diseases related with periodontal, dental and maxillofacial area are discussed in this review. The biological pathways involved with NO and NO inhibitors may be good drug targets to have a role in the future management of patients with diseases in orofacial region.

Capsaicin receptor expression in the rat temporomandibular joint

Experimentally, temporomandibular joint (TMJ) nerve units respond to capsaicin, which is used clinically to treat TMJ pain. However, the existence of capsaicin receptors in the TMJ has not previously been clearly demonstrated. Immunohistochemical analysis has revealed the presence of transient receptor potential vanilloid subtype 1 (TRPV1) expression in the nerves and synovial lining cells of the TMJ. TRPV1-immunoreactive nerves are distributed in the synovial membrane of the joint capsule and provide branches to the joint compartment. The disc periphery is supplied by TRPV1 nerves that are mostly associated with small arterioles, and occasional nerves penetrate to the synovial lining layer. Double immunofluorescence has shown that many TRPV1-immunoreactive nerves are labeled with neuropeptide calcitonin gene-related peptide, whereas few are labeled with IB4-lectin. The results provide evidence for the presence of TRPV1 in both nerves and synovial lining cells, which might thus be involved in the mechanism of nociception and inflammation in the TMJ.

Synovial nitric oxide concentrations are increased and correlated with serum levels in patients with active Behçet's disease: a pilot study

Behçet's disease (BD) is a relapsing immunoinflammatory vasculitis of unknown etiology characterized by endothelial dysfunction. Articular symptoms and signs are present in about 75% of cases and characterized by seronegative arthritis and nonspecific synovitis. We demonstrated that both serum and erythrocyte nitric oxide (NO(.)) levels, the most abundant free radical in the body, were elevated in BD and associated with disease activity. This study further investigated NO(.) levels in the synovial fluid and serum from patients with active and inactive BD. A total of 23 BD patients with articular involvement (14 men and 9 women) satisfying International Study Group criteria and 15 age- and sex-matched healthy control subjects (9 men and 6 women) undergoing elective arthroscopy were included in this case-control investigation. The synovial fluid and serum were obtained from BD patients and controls. Clinical and laboratory findings including neutrophil count and erythrocyte sedimentation rate (ESR) were used to classify BD patients as active (n = 11) or inactive (n = 12). Synovial as well as serum NO(.) levels were compared between the groups and correlation analysis was performed. Acute phase reactant levels were significantly higher (for each, p < 0.01) in BD patients than control subjects in the active period. The mean synovial NO(.) level in active Behçet's patients (mean +/- SD 76.61 +/- 11.95 micromol/l) was significantly higher than in inactive patients (46.16 +/- 8.89 micromol/l, p < 0.001) and healthy control subjects (39.60 +/-8.03 micromol/l, p < 0.001). The difference between inactive patients and controls was not significant (p > 0.05). Active BD patients had significantly higher serum NO(.) levels (38.84 +/- 9.15 micromol/l) than inactive patients (30.91 +/- 5.88 micromol/l, p = 0.018) and control subjects (28.86 +/- 5.91 micromol/l, p = 0.002). In addition, synovial NO(.) levels were positively correlated with serum levels (r(2) = 0.621, p < 0.001). Increased synovial NO(.) levels in active BD patients probably reflect a nonspecific inflammatory process of the synovium and, therefore, arthralgia and arthritis as a common finding of BD.

Can infrared thermography be a diagnostic tool for arthralgia of the temporomandibular joint?

This paper presents a review of the use of infrared thermography in diagnosis of temporomandibular joint (TMJ) arthralgia. The question examined was whether the infrared thermography could be reliably used as a tool to diagnose arthralgia by objectively assessing the site of origin and the degree of irritation. Controlled studies were performed by using advanced thermographic devices to show both diagnostic validity and reliability of infrared thermography as a screening test for selecting healthy subjects from patients with unilateral TMJ arthralgia. The study revealed that thermography fails to meet the criteria of high level of evidence. Further studies are required to confirm these results in order to specify analysis of facial thermal patterns and to better understand the relationship between TMJ arthralgia and regional temperature changes. Until then infrared thermography cannot be recommended for routine use as a diagnostic technique to identify TMJ disorders.

Comparative study of intra-articular irrigation and corticosteroid injection versus closed reduction with intermaxillary fixation for the management of mandibular condyle fractures

OBJECTIVE

To evaluate the clinical outcome of a modified conservative treatment protocol involving intra-articular irrigation and corticosteroid injection into the superior joint compartment (SJC) of patients with fresh mandibular condyle fractures. Study design A total of 26 consecutive unilateral fresh condylar fractures in 26 patients were divided into the intra-articular irrigation (IR) group (14 patients, 14 joints) and the conventional conservative treatment (CC) group (12 patients, 12 joints). In the IR group, the SJCs of the fractured joints were irrigated with saline solution and injected dexamethazone sodium, followed by conventional rehabilitation. In the CC group, patients were treated by closed reduction with intermaxillary fixation (IMF) for 2 weeks, followed by conventional rehabilitation. Clinical outcome at 1 month, 3 months, 6 months, and 1 year after injury was determined by clinical examination of jaw motion, joint pain, and occlusal changes. The posttreatment results were compared with the pretreatment baseline data. Between-group differences in clinical parameters were analyzed.

RESULTS

There were significant between-group differences in the range of mandibular motion at 1 month and 3 months after injury (1 month, P=.0022; 3 months, P=.0022). In the IR group, joint pain was well relieved from the early stage of treatment. Occlusal changes were found in 1 patient in the IR group and 4 patients in the CC group at 1 year after injury.

CONCLUSIONS

The modified treatment protocol involving intra-articular irrigation and corticosteroid injection into the SJC is a more effective and quick-acting modality than conventional closed reduction with IMF for functional recovery and control of clinical symptoms of patients with unilateral fresh condylar fractures.

Immunohistochemical localization of cyclooxygenase-1 and -2 in synovial tissues from patients with internal derangement or osteoarthritis of the temporomandibular joint

This study examined the immunohistochemical expression and localization of cyclooxygenase-1 and -2 (COX-1 and COX-2) in synovial tissues from patients with internal derangement (ID) or osteoarthritis (OA) of the temporomandibular joint (TMJ). Synovial tissues from patients with condylar fractures of the mandible were studied as control. Synovial tissues from 13 TMJs of 10 patients with ID or OA and from 5 TMJs of 4 patients with fractures were examined for COX-1 and COX-2 expression by immunohistochemical staining using two monoclonal antibodies. In addition, whether the COX-2 expression grade correlated with the synovitis score and clinical findings was assessed. COX-2 was expressed in the synovial lining, infiltrating mononuclear cells, fibroblast-like cells, and blood vessels, including CD31-positive endothelial cells, in the synovium of patients with ID or OA. Expression levels of COX-1 in synovial lining cells and endothelial cells were similar in the specimens obtained from the patients with ID or OA and those obtained from the controls. The expression of COX-2 positively correlated with arthroscopic findings of synovitis (p = 0.55, P = 0.023) and with joint pain (p = 0.56, P = 0.021). These results suggest that up-regulation of COX-2 in synovium may play a part in the pathogenesis of synovitis in patients with ID or OA of the TMJ.

Synovial membrane in the temporomandibular joint--its morphology, function and development

This paper reviews recent findings of the synovial membrane, in particular the morphology, function and development of synovial lining cells, in the temporomandibular joint (TMJ). Electron microscopic studies have confirmed the synovial membrane in TMJ consists of macrophage-like type A cells and fibroblast-like type B cells identical to those in other systematic joints. The macrophage-like type A cells react with anti-macrophage and macrophage-derived substances including the major histocompatibility class II molecule, and show a drastic increase in their number in the inflamed synovial membrane. In addition, they have the ability to produce substances involved in the progression of TMJ inflammation such as nitric oxide and inducible nitric oxide synthase. Observation of osteopetrotic mice revealed that macrophage-like type A cells in TMJ are derived from monocyte lineage. Immunocytochemistry for 25kDa heat shock protein was able to depict the entire shape of fibroblast-like type B cells including their unique processes. The expression of an estrogen receptor alpha-immunoreaction in the fibroblast-like type B cells may explain the etiology of temporomandibular disorders at a higher frequency in females than in males, suggesting that TMJ is a target tissue for estrogen. Furthermore, fibroblast-like type B cells are equipped with a basement membrane to serve as an adhesion molecule for the fibroblast-like type B cells to keep their epithelial arrangement. A clear understanding of the morphology of the intact synovial membrane will serve to clarify the etiology and development of temporomandibular disorders.

The effects of intraarticularly injected sodium hyaluronate on levels of intact aggrecan and nitric oxide in the joint fluid of patients with knee osteoarthritis

OBJECTIVE

Intraarticular injections of sodium hyaluronate (Na-HA) appear effective in reducing subjective symptoms of osteoarthritis (OA) and may also have protective effects on the cartilage matrix. The present study analyzed the suppressive effects of Na-HA on the release and degradation of aggrecan and on levels of nitric oxide (NO) in the joint fluid of patients with knee OA.

DESIGN

Sixteen OA patients with knee joint effusion were treated by 5 weekly intraarticular injections of Na-HA. Prior to each Na-HA injection, joint fluid was collected to determine the levels of chondroitin 4-sulfate (C4S) and chondroitin 6-sulfate (C6S), intact aggrecan and NO.

RESULTS

One week after the final injection, the joint fluid levels of C4S, C6S, and NO were significantly decreased. In contrast, the joint fluid level of intact aggrecan was stable during the series of Na-HA injections. A trend was seen for a positive correlation (P < 0.1) between the clinical score and C4S or C6S joint fluid levels, and for a negative correlation between the joint fluid levels of intact aggrecan and C4S or C6S. No significant correlations were observed between joint fluid levels of NO, the clinical score, and levels of C4S, C6S, and intact aggrecan.

CONCLUSION

The results of this study suggest that intraarticularly injected Na-HA is able to improve the clinical symptoms of OA partially based on its ability to reduce the release and degradation of aggrecan and/or to enhance the synthesis of aggrecan in the joint tissues of the patients with knee OA. While Na-HA also reduces the NO level in the joint fluid of patients with knee OA, this effect may be independent from the other effects of Na-HA.

Synovial fluid nitric oxide levels in patients with knee osteoarthritis

Nitric oxide (NO) has an important role in the inflammatory arthropathies. This study investigated NO levels in the synovial fluid and plasma of patients with primary osteoarthritis (OA) of the knee. Twenty-seven cases with primary knee OA and 13 controls were recruited for the study. Nitrate/nitrite levels of synovial fluid and plasma were measured by Griess reaction, and interleukin-1 beta (IL-1 beta) levels were measured quantitatively by a sandwich immunoassay technique. We found a significant increase in the synovial fluid nitrate/nitrite levels in cases with primary OA of the knee compared to controls (50.26+/-23.63 microg/l vs 32.49+/-10.05 microg/l, p=0.002) as well as increased plasma nitrate/nitrite levels (57.06+/-23.32 microg/l vs 39.98+/-16.36 microg/l, p=0.012). There was no difference in plasma and synovial fluid IL-1 beta concentrations between the study and control groups. These results may be considered as supporting evidence that NO might be one of the factors responsible for cartilage destruction in primary osteoarthritis of the knee.

Effects of a single arthrocentesis and a COX-2 inhibitor on disorders of temporomandibular joints

Our aim was to examine the short-term effect of combined treatment with single arthrocentesis and a COX-2 inhibitor on 26 patients with severe symptoms of temporomandibular joint (TMJ) disorders. The severity of the disorders was graded according to the degree of restriction of mouth opening and pain score on a visual analogue scale. Synovial fluid was collected from the superior joint space of the affected TMJ, and arthrocentesis was done with isotonic saline, 200ml. Subsequently, etodolac, 400mg/day, was given for 2 weeks. At 14 days, patients were re-examined and further specimens of synovial fluid were collected. Patients generally lost their symptoms and the severity of the disorders improved significantly (P<0.01). The concentrations of total protein and albumin in synovial fluid decreased with no statistical significance. However, the concentration of matrix metalloproteinase-3 and its ratios to total protein and albumin did decrease significantly (P<0.05). Our results suggest that a larger controlled study is necessary to clarify the contributory effect of arthrocentesis and etodolac for patients with severe symptoms of TMJ disorders.

Inducible nitric oxide synthase and apoptosis-related factors in the synovial tissues of temporomandibular joints with internal derangement and osteoarthritis

PURPOSE

In this study, we investigated the relationship between oxidative stress and apoptosis in synovial tissues in temporomandibular joint diseases (TMDs), including internal derangement (ID) and osteoarthritis (OA), comparing immunohistochemical, arthroscopic, and histologic findings.

MATERIALS AND METHODS

Synovial specimens obtained from patients with ID (31 patients), osteoarthritis (11 patients), and condylar fractures of the mandible (5 patients) during arthroscopy were examined immunohistochemically using antibodies against CD68, inducible nitric oxide synthase (iNOS), Fas, and single-stranded DNA (ssDNA).

RESULTS

CD68 and iNOS immunoreactivity were detected mainly in synovial lining cells and subintimal macrophages, and tended to increase with synovial hyperplasia. Fas and ssDNA immunoreactivity was detected mainly in synovial lining cells, and Fas-positive regions exhibited a number of ssDNA-positive cells. Fas expression was significantly greater in fractures than in OA, and ssDNA expression was significantly greater in OA than in ID. Fas expression was significantly greater in iNOS-positive versus iNOS-negative TMJs, and ssDNA expression tended to increase with iNOS expression.

CONCLUSION

These immunohistochemical findings suggest that oxidative stress and apoptosis in synovial tissues are involved in the onset and progression of TMDs.

The effects of mechanical strain on synovial fibroblasts

PURPOSE

Arthritic diseases of the temporomandibular joint, such as rheumatoid arthritis and osteoarthritis, suggest that inflammatory mediators and metalloproteinases may play a role in their pathogenesis. Recent clinical evidence from physical therapy and other modalities has shown a significant decrease in temporomandibular joint symptoms in patients with early disease. This project examines the effect of mechanical strain on synovial fibroblasts' production of inflammatory mediators including prostaglandin E(2) (PGE(2)) and proteinases.

MATERIALS AND METHODS

An established synovial fibroblast cell line (HIG-82) was grown to confluency in modified Eagle's medium supplemented with 10% fetal calf serum. The monolayer of fibroblasts was then subjected to mechanical strain using the Flexercell Strain Unit (Flexcell International Corporation, McKeesport, PA) at 3 cycles per minute, with 10 seconds' elongation of up to 24% and 10 seconds of relaxation. Levels of PGE(2) were determined by radioimmunoassay using commercially available product and measured in nanograms per milliliter of supernatant. Proteinases collagenase, gelatinase, and stromelysin were measured by H(3) radioactive labeling of acidic anhydride to the specific substrate. Enzymatic proteolysis of the radiolabeled substrate was then measured in supernate as units per milliliter. Statistical analysis of all results was performed using Student's t test in triplicate.

RESULTS

PGE(2) levels of mechanically activated cells was 18.1 +/- 13.4 ng/mL, with control levels being 58.0 +/- 9.2 ng/mL. This is a statistically significant decrease, between strained and unstrained cells with P <.05. In control cells, proteinase activity that degrades collagen, gelatin, or casein was 4.27 +/- 1.5, 4.62 +/- 0.11, or 0.11 +/- 0.01 U/mL, respectively. Levels for mechanically strained cells were 3.99 +/- 1.90, 4.02 +/- 0.90, and 0.12 +/- 0.01 U/mL, respectively. These results show that there is a significant decrease in PGE(2) levels of synovial fibroblasts undergoing mechanical strain. Proteinases examined show no difference in levels between mechanically activated fibroblasts and their controls.

CONCLUSION

This decrease in PGE(2) production in synovial fibroblasts could help elucidate the mechanism by which physical therapy, and in particular continuous passive motion, may decrease inflammatory mediators of the temporomandibular joint.

NF-kappaB activation and iNOS expression in the synovial membrane of rat temporomandibular joints after induced synovitis

NF-kappaB plays a pivotal role in pathogenesis in general arthritis. However, the participation of NF-kappaB in inflammation of the temporomandibular joint (TMJ) is poorly understood. We examined NF-kappaB expression in rat TMJs with synovitis induced by condyle hypermobility. By immunohistochemistry, NF-kappaB immunoreactivity was found mainly in the cytoplasm, not the nucleus, of the synovial lining cells of induced-synovitis and control TMJs. Southwestern histochemistry, a new method for detecting transcription factors, showed greater NF-kappaB expression in the nucleus of the synovial lining cells in the hypertrophic synovium than in control synovium. Increased numbers of the synovial lining cells with immunoreactivity for inducible nitric oxide synthase (iNOS), which is transcriptionally regulated by NF-kappaB, were also seen in the inflamed synovium. These findings indicate that excess mechanical stress increases NF-kappaB activation in the TMJ and suggest that active NF-kappaB is involved in the progression of TMJ inflammation.

Specific expression of inducible nitric oxide synthase in the synovium of the diseased temporomandibular joint

OBJECTIVE

The expression of inducible nitric oxide synthase (iNOS) in temporomandibular joint (TMJ) specimens obtained arthroscopically from diseased TMJs was investigated by using immunohistochemistry and compared with clinical, arthroscopic, and histologic findings.

STUDY DESIGN

Synovial biopsies were obtained arthroscopically from 18 TMJs in 15 patients with symptomatic internal derangement (ID) or osteoarthritis (OA). We also obtained arthroscopic biopsies from 8 control TMJs (3 with habitual luxation of the mandible, one with ID with clicking, and 4 with mandibular condyle fractures). The expression of iNOS was examined by immunohistochemistry and was compared with clinical, arthroscopic, and histologic findings.

RESULTS

Definite or intense iNOS immunoreactivity was observed in both the synovial lining cells and the endothelial cells of TMJs with symptomatic ID or OA. Weaker immunoreactivity was present in synovial fibroblasts. In contrast, in TMJs without synovitis (eg, those with habitual luxation of the mandible) the expression of iNOS was weak or marginal. The expression of iNOS correlated significantly with arthroscopic evidence of synovitis (r = 0.406, P <.05) but not with cartilaginous degeneration (P >.05). The expression of iNOS also correlated with the histologic grade of the synovial lining cell layers (r = 0.530, P <.05). However, in patients with ID or OA of the TMJ, there was no statistically significant correlation between the intensity of iNOS immunoreactivity and clinical, arthroscopic, or histologic findings (P >.05).

CONCLUSION

These data clearly suggest that nitric oxide is locally produced in the synovial lining of the TMJ in ID and OA.

Relationships between pain-related mediators and both synovitis and joint pain in patients with internal derangements and osteoarthritis of the temporomandibular joint

OBJECTIVE

The purpose of this study was to investigate the correlations between the concentrations of pain-related mediators in synovial fluid and the degree of synovitis and between the concentrations of pain-related mediators and the degree of joint pain in patients with internal derangement and osteoarthritis of the temporomandibular joint.

STUDY DESIGN

The concentrations of substance P, serotonin, bradykinin, leukotriene B(4) (LTB(4)), and prostaglandin E(2) in SF and the degree of arthroscopic synovitis of 32 joints with internal derangement and osteoarthritis were assessed. The correlations between the concentration of each mediator and the score of arthroscopic synovitis and between the concentration of each mediator and the score of joint pain were analyzed statistically.

RESULTS

The detection rates of substance P, serotonin, bradykinin, LTB(4), and prostaglandin E(2) were 25%, 25%, 91%, 53%, and 16%, respectively. Positive correlations were found between the concentrations of bradykinin and LTB(4) and the score of synovitis.

CONCLUSION

Bradykinin in SF might be useful as an index of the degree of synovitis.

Temporomandibular disorders: relationship between joint pain and effusion and nitric oxide concentration in the joint fluid

OBJECTIVES

To evaluate the relationship between joint effusion, contrast enhancement of effusion, nitric oxide concentration in TMJ fluid and TM joint pain.

METHODS

Nonenhanced T1- and T2-weighted and gadolinium-enhanced T1-weighted spin-echo sequences were performed in 77 patients with TMD. The nitric oxide concentration in TMJ fluid was analysed spectrophotometrically by the Griess reaction.

RESULTS

Some or marked effusion was seen in five (9%) of the 56 asymptomatic joints and in 55 (56%) of the 98 symptomatic joints. The prevalence of contrast enhancement of joint effusion was significantly higher in the joint pain group than in the joint sound or asymptomatic joint groups (chi2 test, P<0.001). On postcontrast T1-weighted images, there was no evidence of synovial proliferation in patients with TMD. Anterior disk displacement without reduction was detected in 93% of the TMJs with marked effusion. The degree of joint pain correlated with raised nitric oxide concentration (Spearman's rank correlation, P<0.05).

CONCLUSIONS

Painful joints are more likely to demonstrate contrast enhancement of joint effusion. Nitric oxide concentration in TMJ fluid is closely associated with inflammatory changes and painful TM joints.

Temporomandibular Disorders: MR Assessment of Inflammatory Changes in the Posterior Disk Attachment During the Menstrual Cycle

PURPOSE

Our goal was to correlate the menstrual cycle with joint pain, MR evidence of the disk, and posterior disk attachment in patients with temporomandibular disorders.

METHOD

Forty-two women underwent MRI involving conventional T1-and T2-weighted gadolinium-enhanced fat-suppressed SE imaging sequences.

RESULTS

There was a strong statistical difference in the degree of joint pain between proliferated phase and secretory phase groups (p < 0.005). Joint pain had a tendency to increase at the secretory phase. Significantly less contrast enhancement of the posterior disk attachment was observed in the proliferated phase than in the secretory phase (p < 0.001) or menstrual phase (p < 0.01). In addition, anterior disk displacement without reduction of the temporomandibular joint was closely associated with joint pain.

CONCLUSION

Our results suggest that positional changes of the disk and the menstrual cycle may play a role in the degree of joint pain and inflammatory pathology of the posterior disk attachment.

Immunohistochemical localization of inducible nitric oxide synthase in synovial tissue of human temporomandibular joints with internal derangement

The expression and distribution of inducible nitric oxide synthase (iNOS) was examined in 12 samples of human temporomandibular joint (TMJ) with internal derangement (ID) and four control specimens. In the diseased joints, strong or definite iNOS reactivity was expressed in synovial lining and endothelial cells; weaker activity was present in synovial fibroblasts. In contrast, although there was weak expression of iNOS in synovial fibroblasts and endothelial cells in the two control specimens, there was no iNOS staining in the synovial lining cell layers. This original report that iNOS is expressed in the synovial tissue of the temporomandibular joint indicates that nitric oxide is produced locally at least in the synovial lining in these joints when affected by internal derangement.

The process of lubrication impairment and its involvement in temporomandibular joint disc displacement: a theoretical concept

PURPOSE

This article re-evaluates the chain of events leading to temporomandibular joint (TMJ) disc displacement. The joint lubrication system and the process of its breakdown are clarified and an attempt is made to evaluate the possible effect of increased friction between the disc and fossa on the anterior displacement of the disc.

MATERIALS AND METHODS

The study is based on the author's accumulated clinical data and results obtained from laboratory investigations regarding TMJ lubrication and its possible breakdown, coupled with pertinent information culled from the literature.

RESULTS

Translation of the disc in the TMJ is enabled due to the presence of phospholipids and hyaluronic acid, which constitute an efficient lubrication system. This system may break down in the presence of uncontrolled free radicals. In the absence of lubricants, the articular surfaces are smooth, elastic in texture, and possess strong surface energy. Such opposing planes, especially in the presence of a thin fluid film (sub-boundary lubrication) tend to generate high friction while the disc is sliding against the fossa. Such friction is probably the prime mover in loosening the disc attachments to the condyle, with subsequent disc displacement.

CONCLUSIONS

Increased friction of the contiguous parts may well be a major causative factor in displacement of the articular disc. This should be taken into account in considering the appropriate treatment approach. It also raises some doubts regarding the validity of using repositioning techniques.

Reactive arthritis: preliminary microbiologic analysis of the human temporomandibular joint

PURPOSE

The presence of Chlamydia trachomatis has been previously shown in the temporomandibular joint (TMJ). This study investigated whether the presence of other bacteria associated with reactive arthritis (ReA) can be identified in the TMJ.

MATERIALS AND METHODS

Posterior bilaminar tissue removed during TMJ surgery from 26 patients (24 F, 2 M) was evaluated for the presence of C. trachomatis, Mycoplasma fermentans, Mycoplasma genitalium, Campylobacter jejuni, Yersinia enterocolitica, Salmonella spp, and Shigella spp by highly specific polymerase chain reaction (PCR) assays.

RESULTS

Bacterial DNA was identified in the TMJ as follows: C. trachomatis, 11 of 26 (42%); M. fermentans/orale, 6 of 26 (23%); M. genitalium, 9 of 26 (35%). Nine of 26 TMJs (35%) had the presence of a single bacterial species. Eight of 26 TMJs (31%) had more than 1 species, as follows: C. trachomatis with either M. genitalium or M. fermentans/orale in 5 of 26 (19%), M. fermentans/orale with M. genitalium 2 of 26 (8%), and C. trachomatis/M. fermentans/orale/M. genitalium, 1 of 26 (4%). A total of 17 of 26 (65%) of TMJs had the presence of bacteria identified in the TMJ. Campylobacter jejuni, Y. enterocolitica, Salmonella spp, and Shigella spp were not identified in any samples.

CONCLUSIONS

The presence of M. genitalium in the human TMJ has not been previously reported. The presence of bacteria in the TMJ, either singly or concurrently with other bacteria, may serve as the pathogenetic mechanism of TMJ inflammation. The presence of 2 bacteria from the urogenital tract in the TMJ suggests that internal derangement of the TMJ may occur as a result of a sexually acquired infection.

Effect of arthrocentesis and sodium hyaluronate injection on nitrite, nitrate, and thiobarbituric acid-reactive substance levels in the synovial fluid

OBJECTIVE

To evaluate the effect of arthrocentesis and sodium hyaluronate (SH) injections on nitrite, nitrate, and thiobarbituric acid-reactive substance (TBA-RS) levels in temporomandibular joint internal derangements.

STUDY DESIGN

Arthrocentesis was performed on 10 patients, and 15 patients received a supplemental injection of SH after arthrocentesis. All these patients received an SH injection 15 days after the first intervention. The synovial fluid samples were obtained before arthrocentesis on the first appointment and before the SH injection 15 days later. Nitrite and nitrate levels were measured with a highly sensitive and specific chemiluminescence detection method, and the concentration of lipid peroxidation products was assessed by means of the thiobarbituric acid reaction.

RESULTS

Symptomatic improvement was seen in both groups. Nitrite, nitrate, and TBA-RS levels only decreased significantly (P <.05) with a supplemental SH injection after arthrocentesis.

CONCLUSIONS

Intra-articular injections of SH may reduce nitrite, nitrate, and TBA-RS levels that play a role in the pathogenesis of various temporomandibular disorders.

Relationship between joint effusion, joint pain, and protein levels in joint lavage fluid of patients with internal derangement and osteoarthritis of the temporomandibular joint

PURPOSE

The purpose of this study was to investigate the relationship between the presence of joint effusion, joint pain, and protein levels in joint lavage fluid (JL) of patients with internal derangement (ID) and osteoarthritis (OA) of the temporomandibular joint (TMJ).

PATIENTS AND METHODS

Thirty-eight joints in 26 patients with ID and OA of the TMJ were studied. Magnetic resonance imaging (MRI) evidence of joint effusion was evaluated in T2-weighted images. Samples of JL were collected from the superior joint space during pumping manipulation, and the protein concentration was measured. The presence of pain was based on joint tenderness or a complaint of pain in the preauricular region during mouth opening or closing.

RESULTS

Joint effusion was demonstrated in 20 of 25 (80%) painful joints; a significantly higher incidence than in pain-free joints (5 of 13, 38.5%). The mean protein concentration (2.15 mg/mL) in JL from painful joints was significantly higher than in pain-free joints (1.22 mg/mL) (P < .05). Furthermore, the mean protein concentration (2.12 mg/mL) in JL from joints with effusion was significantly higher than in joints without joint effusion (1.27 mg/mL) (P < .05).

CONCLUSIONS

These data demonstrate that painful joints are more likely to show joint effusion on MRI, and the protein levels in JL recovered from these joints is higher than in pain-free joints. These data also suggested that joint effusion may be related to the inflammatory changes seen in patients with ID and OA.

Association between arthroscopic diagnosis of temporomandibular joint osteoarthritis and synovial fluid nitric oxide levels

OBJECTIVE

The purpose of this study was to determine whether there is a relationship between synovial fluid levels of nitric oxide and clinical and arthroscopic findings of synovitis or cartilaginous degeneration.

STUDY DESIGN

Arthroscopic surgery was performed on 20 joints in 15 female patients with internal derangement and osteoarthritis of the temporomandibular joint. Synovial fluid aspirates were obtained immediately before arthroscopy. Synovial fluid was also obtained from 14 joints of 11 female asymptomatic volunteers. The concentration of nitrite in the fluid recovered from each temporomandibular joint was measured through use of a highly sensitive and specific chemiluminescence detection method, calibrated per 1 mg of synovial fluid protein and expressed as nitric oxide; the result was then compared with clinical and arthroscopic findings of synovitis and cartilaginous degeneration.

RESULTS

Significantly higher levels of nitric oxide (median, 0.331 micromol/mg) were seen in the patients with internal derangement and osteoarthritis than in the control group (median, 0.001 micromol/mg; P<.0001). Synovial fluid from joints with pain in the joint area had significantly higher levels of nitric oxide than did fluid from joints without such pain. Synovial fluid from joints with degenerative changes (median, 0.467 micromol/mg) had significantly higher levels of nitric oxide than did fluid from joints without osteoarthritis (median, 0.057 micromol/mg; P<.05). Although the levels of nitric oxide in synovial fluid aspirates were markedly elevated in some joints with synovitis, there was no correlation between the levels of nitric oxide and the presence of synovitis.

CONCLUSIONS

The findings indicate that increased levels of nitric oxide are involved in the pathogenesis of cartilaginous degeneration of the temporomandibular joint.

The prevalence of some joint disorders in craniomandibular disorder (CMD) and bruxers as compared to CMD nonbruxer patients and controls

The objective of this study was to assess and compare the frequency of some joint disorders in 130 CMD + bruxing behavior patients, 66 CMD/nonbruxing behaviors patients referred for diagnosis and treatment to the Center for the Study of Craniomandibular Disorders and 130 control subjects seeking routine dental care. Both patients and controls were consecutive referrals to the clinic occurring over a five year period. The mean age of the CMD + bruxing behavior group was about 35.48 years (range 14-54, SD = 8.45), and 36.84 years (range 17-60, SD = 9.30) in the 66 CMD nonbruxing behavior group, and 34.34 years (range 14-62, SD = 9.92) in the control group of 130 subjects. Information gathered included a questionnaire, history of signs and symptoms, and a clinical examination. Different types of joint disorders, muscle signs and symptoms and bruxing behavior were assessed in the CMD groups and in the corresponding control group. The study concluded that capsulitis/synovitis, retrodiskal pain and disk-attachment pain predominated in CMD + bruxing behavior patients. The data reinforces the need to assess CMD + bruxing behavior patients to evaluate signs and symptoms of such disorders in order to obtain additional information about the true source of pain and the need for proper management.

The possible role of nitric oxide in the physiopathology of pain associated with temporomandibular joint disorders

Temporomandibular joint disorders (TMD) pose a significant challenge to the practice of oral and maxillofacial surgery. When painful, TMD are generally associated with hyperthermia of the overlying skin. It is hypothesized that this skin hyperthermia, caused by regional vasodilation, is induced by nitric oxide (NO) produced in the extravascular space of the joint. Extravascular NO can be produced by osteoblasts, chondrocytes and macrophages, or by stimulated neurons. It is suggested that this kind of pain is associated with NO-enhanced sensitivity of the peripheral nociceptors. Verification and clinical implications of the proposed mechanism are discussed.

Oxidative stress and degenerative temporomandibular joint disease: a proposed hypothesis

The molecular events that underlie degenerative temporomandibular joint diseases are poorly understood. Recent studies have provided evidence that a variety of molecular species, including cytokines, matrix degrading enzymes, neuropeptides, and arachidonic acid catabolites may be involved. This paper advances the theory that mechanical stresses lead to the accumulation of damaging free radicals in affected articular tissues of susceptible individuals. This condition is called oxidative stress. The authors postulate mechanisms that may be involved in the production of free radicals in the temporomandibular joint and in the subsequent induction of molecular events that may amplify damage of articular tissues initiated by free radicals. If the proposed model is correct, then future therapeutic strategies directed at the control of oxidative stress could be effective in the management of degenerative temporomandibular joint diseases.

Proinflammatory cytokines detectable in synovial fluids from patients with temporomandibular disorders

OBJECTIVE

To measure the levels of the proinflammatory cytokines, interleukin (IL)-1 beta, IL-6, tumor necrosis factor- (TNF) alpha, IL-8, and interferon- (IFN) gamma in synovial fluid samples taken from patients with temporomandibular disorders (TMD).

STUDY DESIGN

We studied 6 asymptomatic volunteers and 51 patients with TMD. The IL-1 beta, IL-6, TNF-alpha, IL-8, and IFN-gamma levels in temporomandibular joint synovial fluid were measured using enzyme-linked immunosorbent assay.

RESULTS

Measurable level of at least one cytokine in the synovial fluid was found in 40 (64.5%) of 62 joints in the patients: IL-1 beta and IFN-gamma were each detected in 18 (29.0%) of 62 joints; IL-6 in 13 (21.0%) of 62 joints; IL-8 in 11 (19.3%) of 57 joints; and TNF-alpha in only 5 (8.1%) of 62 joints. None of these cytokines was detectable in the synovial fluid in the control group. Furthermore, there was a strong correlation between the detection of IL-1 beta and pain in the joint area.

CONCLUSIONS

These data clearly demonstrate increased levels of several proinflammatory cytokines in certain patients with TMD and suggest that these cytokines may play a role in the pathogenesis of synovitis and degenerative changes of the cartilaginous tissue and bone of the temporomandibular joint.