Oxidative stress and degenerative temporomandibular joint disease: a proposed hypothesis

Temporomandibular disorders seen in rheumatology practices: A review

Temporomandibular disorders are recognized as the most common nontooth-related chronic orofacial pain conditions. This article reviews the recent temporomandibular disorders literature and summarizes the temporomandibular disorders seen in rheumatology practices. Arthritis is a common condition affecting the temporomandibular joint. Although degenerative and rheumatoid arthritis are the most frequently encountered infectious arthritis, metabolic arthritis, spondyloarthropathies and the traumatic arthritis have also been reported. Distinguishing between different temporomandibular disorders is as important as the clinical course, long-term prognosis, and therapy. Diagnostic criteria are generally based on signs and symptoms of the patient. The American Academy of Orofacial Pain established the first well-defined diagnostic classification. In addition, Research Diagnostic Criteria for Temporomandibular Disorders have been developed using similar classification. In the treatment of temporomandibular disorders, conservative and noninvasive treatments are endorsed for the initial care of nearly all TMD patients because the majority of patients with TMD achieve good relief of symptoms with conservative treatment.

Pathogenesis of degenerative temporomandibular joint arthritides

Over the past decade, remarkable progress has been made in the study of molecular mechanisms involved in degenerative temporomandibular joint arthritides. Based on recent findings, models of degenerative temporomandibular joint disease predict that mechanical loads trigger a cascade of molecular events leading to disease in susceptible individuals. These events involve the production or release of free radicals, cytokines, fatty acid catabolites, neuropeptides, and matrix-degrading enzymes. Under normal circumstances, these molecules may be involved in the remodeling of articular tissues in response to changing functional demands. However, if functional demands exceed the adaptive capacity of the temporomandibular joint or if the affected individual is susceptible to maladaptive responses, then a disease state will ensue. An individual's susceptibility to degenerative temporomandibular joint disease may be determined by several factors, including genetic backdrop, sex, age, and nutritional status. It is hoped that, by furthering our understanding of the molecular events that underlie degenerative temporomandibular joint diseases, improved diagnostics and effective therapies for these debilitating conditions will be developed.

Free Radical Damage in Facsimile Synovium: Correlation with Adhesion Formation in Osteoarthritic TMJs

PURPOSE

The purpose of this study was to use the rat air pouch model of facsimile synovium to evaluate oxidative stress as a primary mechanism in the pathogenesis of degenerative temporomandibular joint (TMJ) disease.

MATERIALS AND METHODS

Forty-nine Sprague-Dawley adult female rats were used to generate the standard rat air pouch model of facsimile synovium. This was accomplished by daily air injections (20 cc) subdermally through the dorsal skin. Hydrogen peroxide and ferrous iron (components of the Fenton reaction which generate free radicals) were introduced into the pouches of the 4-, 7-, and 14-day groups to generate oxidative stress. Control rats were injected with phosphate-buffered solution (PBS), pH 7.4. Either N-acetylcysteine (NAC), a powerful free radical scavenger, or ibuprofen were simultaneously injected with the Fenton reagents into the pouches of the 14-day treatment groups to modulate free radical-mediated protein damage to the synovium. Animals were euthanized at appropriate experimental intervals and biopsies obtained from specimens to analyze: (1) proteins' amino acid modification (carbonyl group formation), (2) protein hydrophobicity, (3) detection of low molecular weight protein degradation products, and (4) histological and gross anatomical observations.

RESULTS

Free radicals introduced into the rat air pouch interacted with synovial tissues causing oxidation and breakdown of proteins. Clinical evidence of adhesion formation consistent with features found in osteoarthritis of the TMJ developed. The groups subjected to oxidative stress experienced statistically significant (p < 0.05) increases in carbonyl formation, carbonyls/protein, and low molecular weight protein fragments. These groups also showed significant (p < 0.05) hydrophobicity changes consistent with free radical attack. Control synovial tissues were statistically undamaged. The 14-day NAC and ibuprofen treatment groups experienced statistically significant (p < 0.05) decreases in total carbonyl formation, carbonyls/protein, and hydrophobicity. Histological and gross observations in free radical damaged synovium exhibited features consistent with known arthoscopic and arthrocentesis findings in diseased TMJs.

CONCLUSIONS

This study suggests that the rat air pouch model of facsimile synovium develops clinical evidence of adhesions and biochemical signs of protein modification when subjected to free radical attack. NAC and ibuprofen prevented carbonyl formation as well as hydrophobicity changes indicative of oxidative stress damage in facsimile synovium. These findings are consistent with features of degenerative human TMJ disease. Future direction may be taken from this study to postulate new analysis techniques and treatment modalities for patients with degenerative TMJ disease.

Clinical factors affecting the outcome of arthrocentesis and hydraulic distension of the temporomandibular joint

OBJECTIVE

Significant psychosocial distress and substantial cost are associated with the diagnosis and management of chronic temporomandibular joint (TMJ) pain conditions. Successful intervention based on identified risk factors has potential functional and financial benefits. Arthrocentesis and hydraulic distension of the TMJ has been described as an effective modality in the treatment of patients demonstrating clinical findings consistent with the diagnosis of disc displacement without reduction. The purpose of this study was to investigate whether clinical variables such as age, gender, time since pain onset (TSO), visual analog scale (VAS) pain level, and mandibular range of motion (ROM) may predict treatment outcomes of arthrocentesis and hydraulic distension of the TMJ.

STUDY DESIGN

The study comprised 64 consecutive patients presenting with TMJ pain, who were diagnosed with a unilateral clinical TMJ disorder of "TMJ pain associated with an internal derangement (ID) type III (disc displacement without reduction)." TMJ pain level of function and mandibular range of motion were assessed initially and then compared with the respective 2-month follow-up findings after arthrocentesis and hydraulic distension. Outcome criteria of success included an absence of signs and symptoms characteristic of a diagnosis of ID type III. A multiple logistic regression analysis of pretreatment data was used to compute the odds ratio for variables of age, gender, TSO, VAS pain level, and ROM for successful outcomes (n = 34) vs nonsuccessful (n = 30) outcomes.

RESULTS

At 2-months follow-up, clinical evaluation showed a significant reduction in TMJ pain during function (P < .001), a significant reduction in clinical diagnoses of TMJ disorders (P < .001), and a significant increase in mandibular range of motion (P < .001). For the outcome criteria of "absence of ID type III," there was a significant difference between the clinical outcome groups for the variables of age (P = .029) and VAS pain level (P < .001). Significant increase in benefit of a successful outcome occurred with an age of < or = 25 years (11.8 odds ratio; P = .044), a VAS pain level of > 75 mm (6.5 odds ratio; P = .026), and an ROM of < 25 mm (6.9 odds ratio; P = .029).

CONCLUSION

Clinical variables predicted TMJ "ID type III and pain" patients who went on to show successful treatment outcomes of arthrocentesis and hydraulic distension. Predictive modeling may provide clinicians with the opportunity to identify "at-benefit" patients early and initiate specific treatments.

Molecular correlates of temporomandibular joint disease

OBJECTIVE

The relation between disease severity and the known mediators of pain, inflammation, and tissue damage-prostaglandin E 2 (PGE 2 ), leukotriene B 4 (LTB 4 ), malondialdehyde (MDA), nitric oxide (NO), and myeloperoxidase (MPO)-was examined in the synovial fluid of patients with internal derangement (ID) of the temporomandibular joint (TMJ).

STUDY DESIGN

Thirty-two patients with ID were classified according to Wilkes by clinical and radiological examinations, and TMJ synovial fluid samples were obtained by arthrocentesis. PGE 2 and LTB 4 levels were measured by ELISA kits, MDA levels were determined by a fluorometric method, myeloperoxidase activity was determined by an end-point method, and NO levels were measured by Griess reaction.

RESULTS

The earliest significant increase was observed in NO levels (stage II) and this elevation persisted in the subsequent stages. The first significant elevation in PGE 2 and LTB 4 levels and MPO activity were observed in stage III. Both PGE 2 and LTB 4 levels were increased in stage III and were correlated with each at this stage and in the subsequent stage. Significant increases in MDA levels were observed only in stage IV. At stage IV there was correlation between MDA and PGE 2 , MDA and LTB 4 , and MDA and MPO. The relation between PGE 2 and MDA was the most powerful one.

CONCLUSION

Results of this cross-sectional study point out the relation between disease severity and levels of some molecular mediators in synovial fluid of TMJ. Longitudinal studies are needed to explore the role of these molecular mediators in the progression of ID.

The role of surgery in the management of disorders of the Temporomandibular Joint: a critical review of the literature. Part 1

Despite the controversy surrounding the role of surgery in the management of Temporomandibular Disorders (TMD), studies in peer review journals continue to support the role of surgery as a legitimate means of treating pain and dysfunction in the Temporomandibular Joint (TMJ). To better understand the role of surgery in the management of TMJ disorders, a critical review of the literature will be presented in two parts. Part 1 reviews the evolution of TMJ surgery together with the biological evidence for surgical disease. History teaches us that we are destined to repeat the mistakes of the past if we fail to properly reflect on what has already been achieved and where the failures have occurred. With the help of molecular biology, the future of TMD management may comprise more carefully targeted and less radical treatment modalities.

Role of hypoxia and interleukin-1β in gene expressions of matrix metalloproteinases in temporomandibular joint disc cells

The aim of this study was to test the hypothesis that hypoxia and interleukin-1 (IL-1)beta played a substantial role in gene expressions of matrix metalloproteinases (MMPs) in temporomandibular joint (TMJ) disc cells. The TMJ disc cells were isolated from rabbit TMJ, and cultured in Dulbecco's modified Eagle's medium (DMEM). The experiment was performed for 24 h in hypoxic (2% O2) and IL-1beta stimulated conditions. To examine the effect of hypoxia and IL-1beta on gene expression of MMPs and tissue inhibitors of metalloproteinase (TIMPs), we performed reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-RCR. The results showed that the combination of hypoxia and IL-1beta caused a significant increase of MMP-1, MMP-3, MMP-9 and MMP-13 mRNA (P < 0.05). Hypoxia caused a significant increase of MMP-2 mRNA (P < 0.05). The combination of hypoxia and IL-1beta caused a significant decrease of TIMP-3 compared to hypoxia (P < 0.05). These findings suggest that hypoxia and IL-1beta may contribute to the degradation or remodelling of the extracellular matrix (ECM) of the disc and may have a role in the pathogenesis of TMJ disorders.

Intra-articular oxidative state correlated with the pathogenesis of disorders of the temporomandibular joint

We investigated the redox state of albumin in the synovial fluid from patients with temporomandibular joint (TMJ) disorders (TMD) to evaluate the relation between the cause of the TMD and the number of types of oxygen in synovial fluid. The albumin was fractionated into three components, human mercaptalbumin (HMA, reduced form) and two types human non-mercaptalbumin (HNA, oxidized form), by high-performance liquid chromatography (HPLC). The 63 patients were divided into three groups radiologically, and the ratios of the redox state of the synovial fluid in each group were compared. The fraction of HNA was significantly higher in patients with advanced disease than in patients with early disease. This indicates that the TMJ is affected by intra-articlular oxidative stress, and the severity of TMD correlates closely with the number of oxidative factors. Oxidative stress was thought to be responsible for the genesis of TMD.

Determining predictor variables for treatment outcomes of arthrocentesis and hydraulic distention of the temporomandibular joint

PURPOSE

Arthrocentesis and hydraulic distention of the temporomandibular joint (TMJ) has been described as an effective modality in the treatment of patients demonstrating clinical findings consistent with the diagnosis of disc displacement without reduction. The purpose of this study was to investigate whether the clinical variable of TMJ pain chronicity and the magnetic resonance (MR) imaging variable of osteoarthrosis (OA) may predict treatment outcomes of arthrocentesis and hydraulic distention of the TMJ.

PATIENTS AND METHODS

The study consisted of 29 TMJ pain patients, who were assigned a unilateral clinical temporomandibular disorder (TMD) of "TMJ pain associated with an internal derangement (ID) type III (disc displacement without reduction)," and a TMJ pain side-related MR imaging diagnosis of disc displacement without reduction. Bilateral sagittal and coronal MR images were obtained immediately preoperatively to establish the presence or absence of ID and OA. TMJ pain level of function and mandibular range of motion were assessed preoperatively and compared with the respective 2-month follow-up findings. Outcome criteria of success were 1). an absence of signs and symptoms characteristic of a diagnosis of ID type III and/or 2). a reduction in pain level of 85% or greater. A multiple logistic regression analysis was used to compute the odds ratio for TMJ pain chronicity (duration >6 months and <2 years) and OA for successful outcomes versus nonsuccessful outcomes.

RESULTS

The pretreatment data revealed no significant relationship between the clinical disorder "TMJ pain associated with ID type III" and the MR imaging finding of OA (P =.103). At 2-month follow-up, clinical evaluation showed a significant reduction in TMJ pain during function (P =.000), a significant reduction in clinical diagnoses of TMDs (P =.000), and a significant increase in mandibular range of motion (P =.000). Significant increase in risk of a nonsuccessful outcome (pain reduction <85%) occurred with TMJ pain chronicity (odds ratio of 41.0) (P =.018). Significant increase in benefit of a successful outcome (absence of ID type III) occurred with TMJ OA (odds ratio 1:16.7, P =.06) (P =.044).

CONCLUSIONS

Arthrocentesis in chronic TMJ pain patients was less successful than in nonchronic patients with regard to treatment outcome of pain reduction. Arthrocentesis in patients with TMJ OA was more beneficial with regard to the disappearance of ID type III than in non-OA patients. Predictive modeling may provide clinicians with the opportunity to identify "at-benefit" patients early and initiate specific treatments.

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.

Validation of the clinical diagnostic criteria for temporomandibular disorders for the diagnostic subgroup of degenerative joint disease

Research is needed to assess the validity of the Clinical Diagnostic Criteria for Temporomandibular Disorders (CDC/TMD). The purpose of this study was to test the reliability of the clinical diagnosis of temporomandibular joint (TMJ) degenerative joint disease (DJD) as compared with the magnetic resonance imaging (MRI) 'gold standard'. The TMJ DJD group comprised 48 joints in 24 consecutive patients who were assigned a clinical bilateral diagnosis of TMJ DJD. The TMJ non-DJD group consisted of 82 joints in 41 consecutive patients without a TMJ-related diagnosis of TMD. Bilateral sagittal and coronal MR images were obtained subsequently to establish the corresponding diagnosis of degenerative joint changes. An MRI diagnosis of osteoarthrosis (OA) was defined by the presence of flattening, subchondral sclerosis, surface irregularities, and erosion of the condyle or presence of condylar deformities associated with flattening, subchondral sclerosis, surface irregularities, erosion and osteophyte. For the CDC/TMD interpretations, the positive predictive of DJD for OA was 67%, and for the presence of degenerative joint changes 88%. The overall diagnostic agreement for DJD was 44.6% with a corresponding K-value of 0.01. Most of the disagreement was due to false-negative interpretations of asymptomatic joints. The results suggest CDC/TMD to be predictive for degenerative joint changes but insufficient for determination of OA. Patients assigned a clinical TMJ-related diagnosis of DJD may need to be supplemented by evidence from MRI to determine the presence or absence of OA.

Morphologic changes in the unloaded temporomandibular joint after mandibulectomy

PURPOSE

The aim of this study was to examine intra-articular conditions in unloaded temporomandibular joints (TMJs) after mandibulectomy including the condyle or segmental mandibulectomy.

PATIENTS AND METHODS

Seventeen joints were defined as unloaded TMJs. Eleven of the 17 joints were classified into the "without condyle" (WOC) group in which TMJs had the condyle removed but the disc and superior joint compartment were preserved, and remaining 6 joints were classified into the "with condyle" (WC) group in which TMJs were connected to the condylar process. Disc configuration, bony changes, and joint effusion were examined by magnetic resonance imaging. In 8 of the 17 joints, arthroscopic examination of the superior joint compartment was performed. Correlation between data of the WOC and WC groups was evaluated. The relationship between arthroscopic findings and joint effusion was also analyzed.

RESULTS

Deformed discs were observed in 7 of the 11 joints (63.6%) of the WOC group but were not observed in the WC group, in which there was a normal relationship between the disc and condyle. Bony changes were not detected in any joints. Joint effusion and arthroscopically diagnosed fibrous adhesion were observed in nearly all joints of both groups.

CONCLUSIONS

We conclude that alteration of the relationship between the disc and condyle is more important for the initiation of disc deformation than loading conditions on the disc. The present findings suggest that, in the unloaded TMJs, articular degeneration is induced by disturbance of synovial fluid metabolism but that bony conditions are not affected.

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.

Magnetic resonance imaging analysis on the relationship between anterior disc displacement and balancing-side occlusal contact

The purpose of this study was to evaluate the relationship between balancing-side occlusal contact patterns and the prevalence of the internal derangement of the temporomandibular joint (TMJ). Forty-one patients were used for the magnetic resonance image (MRI) analysis of TMJ and occlusal examination. Balancing-side occlusal contact patterns observed during mandibular lateral excursive movements were classified into the three following categories: group A, simultaneous balancing-side contact, group B, balancing-side contact (with clenching only) and Group C, no balancing-side contact (with or without clenching). By the occlusal examination of 57 sides, 31.6% showed group A, 8.8% showed group B and 59.6% showed group C contact. Group A could not be observed in the patient group with normal disc position. In the disc displacement group, the prevalence of group A, group B and group C were 40.9, 6.8 and 52.3%, respectively. The higher prevalence of simultaneous balancing-side contact was revealed to be associated with articular disc dislocation.

Crosslinking of fibrinogen and fibronectin by free radicals: a possible initial step in adhesion formation in osteoarthritis of the temporomandibular joint

PURPOSE

Adhesion formation in osteoarthritis (OA) of the temporomandibular joint (TMJ) typically results in a sustained limitation of joint movement. We propose the hypothesis that free-radical-mediated crosslinking of proteins underlies this adhesion formation in affected joints. Free radicals may cause oxidative modification of proteins, creating an opportunity for the formation of intramolecular and intermolecular crosslinks via covalent bonds. This may stabilize protein aggregates, rendering them more resistant to degradation. In this study, the free-radical-mediated crosslinking of model proteins (fibrinogen and fibronectin) was investigated to test our hypothesis that free radicals contribute to adhesion formation via this mechanism in OA of the TMJ.

MATERIALS AND METHODS

Physiological clot formation of fibrinogen by thrombin and free-radical-induced crosslinking of fibrinogen and of fibronectin were analyzed using spectrophotometric turbidity measurements, light-scattering techniques, polyacrylamide gel electrophoresis (PAGE), and rotary shadowing.

RESULTS

Fibrinogen was shown to aggregate after free radical treatment, as detected using turbidity measurements and light-scattering techniques. Using PAGE, fibrinogen as well as fibronectin was shown to degrade under low oxidative stress. Under high oxidative stress, however, fragments from both proteins were found to be covalently crosslinked, resulting in high-molecular-weight protein aggregates. The aggregation was shown to be at random with rotary shadowing.

CONCLUSION

The study shows that high oxidative stress contributes to the formation of crosslinked proteins that may serve as an initial scaffolding for the development of adhesions frequently seen in OA of the TMJ.

Magnetic resonance imaging findings of osteoarthrosis and effusion in patients with unilateral temporomandibular joint pain

The purpose of this study was to investigate the relationship between the presence of temporomandibular joint (TMJ) pain and the magnetic resonance (MR) imaging findings of osteoarthrosis (OA), and effusion. The study comprised 112 consecutive TMJ pain patients. Criteria for including a patient were report of unilateral pain near the TMJ, with the presence of unilateral TMJ pain during palpation, function, and/or unassisted or assisted mandibular opening. Bilateral sagittal and coronal MR images were obtained to establish the presence or absence of TMJ OA, and/or effusion. Comparison of the TMJ side-related data showed a significant relationship between the clinical finding of TMJ pain and the MR imaging diagnoses of TMJ OA (P=0.000), and TMJ effusion (P=0.000). Further, there was a significant relationship between the MR imaging diagnosis of TMJ OA and TMJ effusion (P=0.000). Use of the Kappa statistical test indicated poor diagnostic agreement between the presence of TMJ pain and the MR imaging diagnosis of TMJ OA (K=0.22), TMJ effusion (K=0.29), and TMJ 'OA and effusion' (K=0.30). The study's findings suggest that while clinical pain is correlated to TMJ-related MR imaging findings, clinical pain in and of itself, is not reliable for predicting the presence of TMJ OA and/or effusion. Validation of MR imaging diagnoses would involve the investigation of cross-sectional and longitudinal evidence to assess decisive differences in terms of prognosis and/or treatment outcome.

Dietary vitamins and selenium diminish the development of mechanically induced osteoarthritis and increase the expression of antioxidative enzymes in the knee joint of STR/1N mice

OBJECTIVE

To study the influence of dietary vitamins and selenium on mechanically-induced osteoarthritis (OA) and the expression of antioxidative enzymes in male STR/1N and Balb/c mice. Male STR/1N mice are prone to develop OA caused by a varus deformity-induced mechanical overload of the medial tibial plateau.

METHODS

After 12 months of feeding (special diet supplemented with the vitamins E, C, A, B6, B2, and selenium) serial histological sections of the knee joints were evaluated for development of osteoarthritic changes (grade 0-4). Serum glutathione peroxidase activity (GSH-px) was measured photometrically. Expression of antioxidative enzymes was demonstrated by immunohistochemistry.

RESULTS

All control STR/1N mice showed OA lesions (grade 3-4) while the special diet decreased OA incidence significantly down to approximately 65% (mostly grade 2). Even in Balb/c mice the incidence was decreased by the special diet from approximately 21% (control animals; grade 1) to approximately 14%. Serum GSH-px activity increased diet-dependently in both mouse strains but was generally higher in Balb/c mice. In both mouse strains the special diet increased the expression of GSH-px and Cu/Zn-SOD in articular cartilage while there was no expression of Mn-SOD. There was also a special diet-dependent increase in expression of GSH-px in the synovium of both mouse strains while an increase in expression of Mn-SOD and Cu/Zn-SOD could only be seen in the synovium of STR/1N mice.

CONCLUSIONS

A diet supplemented with vitamins/selenium might be important in prevention or therapy of mechanically induced OA. We hypothesize that free oxygen radical species might be involved in the mechanical induction of OA.

The biological concept of "internal derangement and osteoarthrosis": a diagnostic approach in patients with temporomandibular joint pain?

OBJECTIVES

We sought to investigate whether the finding of temporomandibular joint (TMJ)-related pain may be linked to magnetic resonance (MR) imaging findings of TMJ internal derangement and TMJ osteoarthrosis.

STUDY DESIGN

The study consisted of 194 consecutive TMJ patients. Criteria for including a patient with a painful TMJ were as follow: report of orofacial pain in the TMJ, with the presence of unilateral or bilateral TMJ pain during palpation, function, and unassisted or assisted mandibular opening. Criteria for including a patient with a nonpainful TMJ were as follow: absence of a TMJ with pain during palpation, function, and unassisted or assisted mandibular opening. Application of the criteria resulted in a study group of 150 patients with unilateral TMJ pain, 10 with bilateral TMJ pain, and 34 without TMJ pain. Bilateral sagittal and coronal MR images were obtained to establish the presence or absence of TMJ internal derangement or osteoarthrosis, or both.

RESULTS

A comparison of the TMJ-related data showed a significant relationship between the clinical finding of TMJ pain and the MR imaging diagnoses of TMJ internal derangement (P =.002) and TMJ osteoarthrosis (P =.004). Significant increases in risk of pain occurred with "disk displacement without reduction and osteoarthrosis" (P =.000), "disk displacement without reduction and absence of osteoarthrosis" (P =.000), and "disk displacement with reduction and osteoarthrosis" (P =.036).

CONCLUSIONS

The results suggest that TMJ-related pain is correlated with TMJ-related MR imaging diagnoses of internal derangement and osteoarthrosis. The data confirm the biological concept of "internal derangement and osteoarthrosis," yet re-emphasize that internal derangement and osteoarthrosis may not be regarded as the unique and dominant factors in the definition of TMJ pain.

Clinical versus magnetic resonance imaging findings with internal derangement of the temporomandibular joint: an evaluation of anterior disc displacement without reduction

PURPOSE

The purpose of this study was to investigate whether the clinical finding of anterior disc displacement without reduction (ADWOR) and pain in the temporomandibular joint (TMJ) is correlated to the magnetic resonance imaging (MRI) findings of TMJ internal derangement (ID).

PATIENTS AND METHODS

The TMJ group was composed of 55 TMJ pain patients who were assigned a clinical diagnosis of unilateral ADWOR. The control group consisted of 58 nonpainful TMJ patients. Sagittal and coronal MR images were obtained to establish the incidence and type of ID.

RESULTS

Using chi-square analysis, the results showed a significant relationship between the presence of pain and the MRI diagnosis of ID (P =.000) and its type (P =.000). Use of the kappa statistical test indicated poor diagnostic agreement between the presence of pain and the MRI diagnosis of ID (kappa = 0.37) and disc displacement with reduction (kappa = 0.20). The diagnostic agreement for disc displacement without reduction was 78.8%, with a corresponding kappa-value of 0.58, indicating fair agreement between the clinical and the MRI diagnosis.

CONCLUSION

The results suggest that TMJ pain associated with ADWOR is correlated with MRI diagnoses of ID and the ID type. These data confirm the use of the clinical diagnostic criteria for disc displacement without reduction as a reliable method of predicting similar MRI diagnoses.

Substance P and mast cells: preliminary histologic analysis of the human temporomandibular joint

PURPOSE

Neuropeptide-containing nerves can serve as a mechanism for nervous system regulation of host defense responses. Because bacteria associated with reactive arthritis have been identified in the temporomandibular joint (TMJ), this study investigates whether the presence of substance P (SP) neuropeptide-containing nerves and mast cells can be identified in the TMJ.

MATERIAL AND METHODS

Posterior bilaminar tissue removed during TMJ surgery from 9 women was evaluated for the presence of neuropeptide-containing nerves by staining with a monoclonal antibody to SP. Staining of the TMJ tissue sections with 0.5% toluidine blue was performed to identify the presence of mast cells.

RESULTS

SP-containing nerves and mast cells were identified within the posterior bilaminar tissue associated with the vasculature.

CONCLUSIONS

The presence of neuropeptide nerves and mast cells within the TMJ has been shown. Mast cell degranulation products and SP release can contribute to TMJ inflammation.

Temporomandibular joint internal derangement type III: relationship to magnetic resonance imaging findings of internal derangement and osteoarthrosis. An intraindividual approach

The purpose of this study was to investigate whether in patients with a clinical unilateral temporomandibular joint (TMJ)-related finding of internal derangement type (ID)-III (disk displacement without reduction) in combination with TMJ-related pain, the intraindividual variable of 'unilateral TMJ ID-III pain' may be linked to subject-related magnetic resonance (MR) imaging findings of TMJ ID, and TMJ osteoarthrosis (OA). The study comprised 48 consecutive TMJ pain patients, who were assigned a clinical unilateral TMJ pain side-related diagnosis of ID-III. Bilateral sagittal and coronal MR images were obtained to establish the presence or absence of TMJ ID and/or OA. Comparison of the TMJ side-related data showed a significant relationship between the clinical finding of TMJ ID-III pain and the MR imaging diagnoses of TMJ ID (P=0.000) and TMJ ID type (P=0.000). There was no correlation between the clinical finding of TMJ ID-III pain and the MR imaging diagnosis of TMJ OA (P=0.217), nor between the MR imaging diagnosis of TMJ OA and that of TMJ ID (P=0.350). Regarding the diagnostic subgroups of TMJ ID, a significant relationship was found between the presence of TMJ OA and the MR imaging diagnoses of TMJ ID type(P=0.002). Use of the Kappa statistical test indicated a fair diagnostic agreement between the presence of TMJ ID-III pain and the MR imaging diagnosis of disk displacement without reduction (DDNR) (K=0.42). The results suggest that TMJ ID-III pain is related to TMJ-related MR imaging diagnoses of ID. Further, the data confirm the biological concept of 'DDNR and OA' as an underlying mechanism in the etiology of TMJ-related pain and dysfunction.

The use of arthrocentesis for the treatment of osteoarthritic temporomandibular joints

PURPOSE

The purpose of this retrospective study was to determine the efficacy of arthrocentesis in restoring the functional capacity of osteoarthritic temporomandibular joints (TMJ).

PATIENTS AND METHODS

This study involved 36 patients (29 females, 7 males; age range, 16 to 54 years, mean, 37.36 +/- 14.60 years) presenting with 38 dysfunctional joints that had not responded to conservative treatment. The postarthrocentesis status (follow-up period 6 to 62 months, mean 20.7 +/- 20.5 months) of the TMJs was determined by patient self-evaluation using visual analog scales and clinical examination.

RESULTS

Of the 38 TMJs treated with arthrocentesis, 26 joints reacted favorably to the treatment; pain and dysfunction scores were reduced from 9.86 +/- 0.73 to 3.39 +/- 0.76 and from 11.34 +/- 0.66 to 3.4 +/- 0.69, respectively (P <.001). Self-assessed general improvement/deterioration was +4.90 +/- 2.10 (on a scale of -7 to +7). Maximal mouth opening increased from 24.40 +/- 2.70 mm to 43.20 +/- 3.10 mm (P <.001). Lateral and protrusive jaw movements also increased in magnitude. In 14 patients in whom no improvement was noted, arthrocentesis acted as a diagnostic tool before surgical treatment.

CONCLUSIONS

Arthrocentesis is a safe and rapid procedure that in many instances results in the osteoarthritic TMJs returning to a healthy functional state. Failure of arthrocentesis suggests that the painful limitation is most probably caused by changes such as fibrous adhesions or osteophytes that require surgical intervention for their removal.

Relationship between temporomandibular joint pain and magnetic resonance imaging findings of internal derangement

In terms of clinical decision-making in instances of temporomandibular disorders (TMD) and orofacial pain, there is controversy in the literature over the diagnostic significance of the temporomandibular joint (TMJ)-related variable disk-condyle relationship (DCR). The purpose of this study was to investigate whether in patients with TMJ-related pain, the variable of TMJ pain may be linked to magnetic resonance (MR) imaging findings of internal derangement (ID). The study comprised 163 consecutive TMJ pain patients. Criteria for including a patient were report of orofacial pain referred to the TMJ, and the presence of uni- or bilateral TMJ pain during palpation, during function, and/or during unassisted or assisted mandibular opening. Bilateral sagittal and coronal MR images were obtained to establish the prevalence of TMJ ID types. Analysis of the data revealed the presence of TMJ pain to be associated with significantly more MR imaging diagnoses of ID than an absence of ID (P<0.001), and disk displacement without reduction than disk displacement with reduction (P<0.001). Using chi-square analysis, the results showed a significant relationship between the presence of TMJ-related pain and the MR imaging diagnosis of TMJ ID (P=0.001), and TMJ ID type (P=0.000). Use of the Kappa statistical test indicated poor diagnostic agreement between the presence of TMJ pain and the MR imaging diagnosis of ID (K=0.16). The results suggest that the clinical variable of TMJ pain may have a significant effect on the prevalences of MR imaging diagnoses of TMJ ID. The data confirm the biological concept of DCR as a diagnostic approach in patients with signs and symptoms of TMJ-related pain.

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.

Temporomandibular joint pain: relationship to internal derangement type, osteoarthrosis, and synovial fluid mediator level of tumor necrosis factor-alpha

OBJECTIVES

The purpose of this study was to investigate whether patients with temporomandibular joint (TMJ)-related pain classified as capsulitis/synovitis may be linked to magnetic resonance imaging (MRI) findings of internal derangement, osteoarthrosis, or the synovial fluid aspirate findings of tumor necrosis factor-alpha (TNF-alpha) level.

STUDY DESIGN

The study comprised 23 patients with temporomandibular disorders (TMD), who had nonchronic pain (pain onset < or =6 months) and a unilateral TMJ-related diagnosis of capsulitis/synovitis. Bilateral sagittal and coronal magnetic resonance images were obtained to establish the presence or absence of internal derangement, osteoarthrosis, or both. TMJ synovial fluid aspirates were obtained from the pain and contralateral nonpain sides to determine the TNF-alpha level.

RESULTS

Comparison of the TMJ side-related data showed a significant relationship between the clinical TMD diagnosis of capsulitis/synovitis and the MRI diagnoses of TMJ internal derangement (P =.002) and of TMJ internal derangement type (P =.04). The mean TNF-alpha level in synovial fluid aspirates from TMJs assigned a clinical TMD diagnosis of capsulitis/synovitis was significantly higher than in those obtained from contralateral nonpain sides (P =.001). There was no correlation between the clinical diagnosis of capsulitis/synovitis and the MRI diagnosis of TMJ osteoarthrosis (P =.13) or between the MRI diagnosis of TMJ osteoarthrosis and that of TMJ internal derangement (P =.70) or TMJ internal derangement type (P =.33).

CONCLUSIONS

The results suggest that the TMJ pain condition of capsulitis/synovitis is related to TMJ-side specific MRI diagnoses of internal derangement and internal derangement type, and synovial fluid aspirate findings of TNF-alpha level. The data confirm the concept of elevated mediator level as a diagnostic approach for patients presenting with TMJ-related pain. MRI and synovial fluid aspirates may be used as diagnostic methods for evaluating TMJ-related pain conditions.

Reactive oxygen species participation in experimentally induced arthritis of the temporomandibular joint in rats

In the temporomandibular joint (TMJ), it has been hypothesized that mechanical stresses lead to the oxidative stress of articular tissues. It has also been postulated that cells pertinent to arthritis-including endothelial cells and synovial cells-when stimulated by mechanical stresses and/or pro-inflammatory cytokines, promote oxidative damage. To determine the involvement of reactive oxygen species (ROS) in the diseased joint, we studied the generation of ROS in synovial fluid (SF) from interleukin-1alpha (IL-1alpha)-induced TMJ arthritis by electron spin resonance (ESR) spectroscopy, using the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO). The TMJ arthritis was experimentally induced in rats by the injection of human recombinant IL-1alpha into the TMJ; control rats were treated with normal saline solution. We found that the detected radicals in the collected SF were identified as a 1:2:2:1 quartet, characteristic of the hydroxyl radical-DMPO spin adduct. The ESR signal intensity of the hydroxyl radical-DMPO spin adduct in the SF from IL-1-treated rats was significantly higher than that from the control rats (P < 0.01). The results of ESR study also showed that hydroxyl radical (HO*) was increased in a time-dependent fashion in the presence of superoxide anion radical (O2*-) scavenger superoxide dismutase (SOD); the formation of DMPO-HO* was strongly inhibited by the iron chelater deferoxamine. We could measure higher levels of free iron (Fe2- and Fe3-) in the SF from TMJ arthritis than in that from controls (P < 0.05). Analysis of the data obtained from the present study suggests that the HO* radical detected in SF from IL-1-induced TMJ arthritis is generated via a modified Haber-Weiss reaction (biological Fenton reaction) in which O2*- can subsequently result in the production of H2O2 through dismutation reaction by SOD. Thus, HO* may be generated from the reaction of resultant H2O2 with free iron ions. The results presented here provide the first evidence of involvement of ROS in IL-1-induced TMJ arthritis.

Prostaglandin E2 in temporomandibular joint synovial fluid and its relation to pain and inflammatory disorders

PURPOSE

The aim of this study was to investigate temporomandibular joint (TMJ) synovial fluid (SF) levels of prostaglandin E2 and its relation to general inflammatory activity and its influence on specific TMJ pain in patients with inflammatory TMJ disorders.

PATIENTS AND METHODS

The study comprised 24 patients (30 joints) with inflammatory TMJ disorders and 4 healthy persons (6 joints). TMJ pain at rest, tenderness to palpation of the TMJ, and TMJ pressure pain threshold, as well as pain during joint movements (PM), were assessed. PGE2 levels were analyzed in synovial fluid samples (SF-PGE2) and blood plasma (P-PGE2). The erythrocyte sedimentation rate (B-ESR) as well as the serum levels of C-reactive protein (S-CRP) and antinuclear antibodies were determined.

RESULTS

PGE2 was undetectable in the plasma and in the TMJ SF of the healthy persons. In the patients, PGE2 was detectable in 20 of the 30 (67%) SF samples. SF-PGE2 was significantly and positively correlated to PM in the patients. There were significant correlations between P-PGE2 and B-ESR as well as the S-CRP.

CONCLUSIONS

This study shows that the synovial fluid in patients with TMJ inflammatory disorders frequently has a detectable level of PGE2 that is related to TMJ allodynia. The plasma levels of PGE2 seem to be related to the general inflammatory activity in these patients.

The relationship between parafunctional masticatory activity and arthroscopically diagnosed temporomandibular joint pathology

PURPOSE

The purpose of this investigation was to assess the relationship between parafunctional masticatory activity and arthroscopically visualized changes in patients with severe, unremitting symptoms caused by intra-articular temporomandibular joint pathology. The working hypothesis was that the presence of parafunctional activity leads to increased arthroscopically diagnosed pathology.

MATERIALS AND METHODS

Temporomandibular joint arthroscopy was performed on 124 joints in 83 patients (female:male, 5.4:1; mean age, 35 years; mean duration of symptoms, 49 months) with severe symptoms unresponsive to nonsurgical management. Preoperatively, the presence of parafunctional habits (bruxism, clenching) was assessed, and joints were classified as either with or without parafunctional influences. Joints were diagnosed arthroscopically and assessed for the presence or absence of osteoarthritis, synovitis, and adhesions. Analyses were performed to determine significant relationships between parafunctional activity and the presence of osteoarthritis, synovitis, and adhesions.

RESULTS

Parafunctional influences were present in 82 of 124 joints (66%). Clinically diagnosed osteoarthritis was present in 59 of 124 joints (48%) and arthroscopically diagnosed osteoarthritis was seen in 82 of 124 joints (66%). Arthroscopically, synovitis was diagnosed in 123 of 124 joints (99%) and adhesions in 93 of 124 joints (75%). Statistical analyses showed a significant relationship between parafunction and clinically diagnosed osteoarthritis, and suggested a close relationship between parafunction and arthroscopically diagnosed osteoarthritis. A significant association between clinically and arthroscopically diagnosed osteoarthritis and adhesions was also demonstrated. There also was no significant relationship detected between parafunction and the presence of synovitis or adhesions seen arthroscopically.

CONCLUSIONS

It was concluded that parafunctional masticatory activity and its influence on joint loading contribute to osteoarthritis of the temporomandibular joint. Such osteoarthritis is associated with adhesions of the joint. Arthroscopically diagnosed synovitis is not specifically associated with parafunction, and it appears that numerous other causative factors may contribute to its development in the TMJ. Because abnormal joint loading is a major causative factor in cartilage degradation, biochemical and biomechanical abnormalities, and intraarticular temporomandibular pathology, clinicians must identify and address parafunctional masticatory activity during nonsurgical, surgical, and postsurgical treatment regimens.