Presence of denatured hemoglobin deposits in diseased temporomandibular joints

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.

Is Hyaluronic Acid or Corticosteroid Superior to Lactated Ringer Solution in the Short-Term Reduction of Temporomandibular Joint Pain After Arthrocentesis? Part 1

PURPOSE

Arthrocentesis has been used for the management of patients with temporomandibular joint (TMJ) pain, with good success. The additional use of hyaluronic acid (HA) or corticosteroid (CS) remains controversial. The purpose of this study was to compare HA, CS, and lactated Ringer solution (LR; placebo) after arthrocentesis.

MATERIALS AND METHODS

This was a prospective multicenter double-blinded randomized clinical trial. Consecutive patients presenting to the oral and maxillofacial departments at Emory University, the University of Pennsylvania, the University of California-Los Angeles, the University of Cincinnati, and the Oregon Health Sciences University were enrolled in the study. Patients were randomized to HA, CS, or LR. All patients underwent arthrocentesis and then the instillation of HA, CS, or LR. Patients were evaluated clinically at 1 and 3 months. The primary outcome variable was pain at 1 month (by visual analog scale). Secondary outcome variables were pain at 3 months and analgesic consumption. Univariate, bivariate, and multivariate statistics were computed, with a P value less than .05 considered significant.

RESULTS

One hundred two patients were enrolled in the study. Four were lost to follow-up, leaving 98 patients for the final analysis. The mean age of patients in the HA, CS, and LR groups was 39.6, 44.3, and 51.8 years, respectively (P = .02). There was no difference among groups in time to follow-up at 1 month (P = .11). The mean decrease in pain in the CS group was 19% for right-side procedures (P = .12) and 36% for left-side procedures (P = .02). The mean decrease in pain in the HA group was 31% for right-side procedures (P = .01) and 34% for left-side procedures (P = .01). The mean decrease in pain in the LR group was 43% for right-side procedures (P < .01) and 37% for left-side procedures (P < .01). There was no difference in pain decrease among groups (P = .55). There was no difference in the use of narcotic (P = .52) or nonsteroidal anti-inflammatory drugs (P = .71) among groups.

CONCLUSION

Arthrocentesis alone is as efficacious as arthrocentesis with HA or CS in decreasing TMJ pain.

Temporomandibular joint: disorders, treatments, and biomechanics

Temporomandibular joint (TMJ) is a complex, sensitive, and highly mobile joint. Millions of people suffer from temporomandibular disorders (TMD) in USA alone. The TMD treatment options need to be looked at more fully to assess possible improvement of the available options and introduction of novel techniques. As reconstruction with either partial or total joint prosthesis is the potential treatment option in certain TMD conditions, it is essential to study outcomes of the FDA approved TMJ implants in a controlled comparative manner. Evaluating the kinetics and kinematics of the TMJ enables the understanding of structure and function of normal and diseased TMJ to predict changes due to alterations, and to propose more efficient methods of treatment. Although many researchers have conducted biomechanical analysis of the TMJ, many of the methods have certain limitations. Therefore, a more comprehensive analysis is necessary for better understanding of different movements and resulting forces and stresses in the joint components. This article provides the results of a state-of-the-art investigation of the TMJ anatomy, TMD, treatment options, a review of the FDA approved TMJ prosthetic devices, and the TMJ biomechanics.

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.

Electrophoretic separation of the synovial fluid proteins in patients with temporomandibular joint disorders

OBJECTIVE

The present study was performed to characterize the patterns of protein expression in the synovial fluid (SF) of patients with temporomandibular joint disorders (TMD) by electrophoretic fractionation.

STUDY DESIGN

Samples of the SF of 26 consecutive patients consisting of 16 with closed locking (CL group) and 10 with osteoarthritis (OA group), as well as 7 asymptomatic control subjects (AS group), were analyzed in the present study. SF samples were obtained from the upper compartment of the temporomandibular joint (TMJ) and equal quantities of SF protein were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).

RESULTS

The mean total protein concentrations in the SF from both of the TMD groups were higher than that in the AS group (1353 microg/mL in the CL group and 2485 microg/mL in the OA group vs 615 microg/mL in the AS group; P < .01). Moreover, the mean total SF protein concentration was higher in the OA group than in the CL group (P < .01). There was a correlation between the total protein concentration in the SF from both patient groups and the degree of expanded joint effusion (P = .003, r = 0.685). Approximately 22 different protein bands with molecular weights ranging from 14 to 700 kd were clearly discernible on electrophoresis. The relative amounts of specific proteins in the SF of the TMD group were also different from those in the AS group (P < .05). The major difference in total protein concentration appeared to be due to the increased abundance of relatively high molecular weight proteins (>140 kd) in the TMD patients as compared to the AS group.

CONCLUSIONS

The SF of patients with TMD showed significant quantitative differences in total protein abundance as compared to healthy subjects. Moreover, this protein abundance was correlated strongly with the degree of expanded joint effusion. The major difference in total protein concentration appeared to be due to the increased abundance of relatively high molecular weight polypeptides in the TMD patients as compared to the healthy control subjects. These observations of changes in the pattern of protein expression may help in understanding the etiological factors involved in the pathophysiology of TMD.

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.

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.

Iron-dependent generation of free radicals: plausible mechanisms in the progressive deterioration of the temporomandibular joint

PURPOSE

The purposes of this study were 1) to determine whether iron concentrations detected in temporomandibular joint (TMJ) lavage fluid samples obtained from symptomatic patients are sufficient to catalyze the degradation of specific extracellular matrix (ECM) molecules in vitro, and 2) to provide evidence of oxidative stress in symptomatic TMJs by the detection of protein carbonyls in lavage fluids.

PATIENTS AND METHODS

Iron concentrations in TMJ lavage samples (19 joints in 14 patients) were determined colorimetrically, and the ability of the sample to produce free radicals in the presence of hydrogen peroxide was determined with the chromogen 2,2'-azinobis (3-ethylbenzothizoline-6-sulfonic acid), diammonium salt (ABTS). The presence of oxidized proteins was measured fluorimetrically using Bodipy FL hydrazide (Molecular Probes, Eugene, OR). Degradation of fibronectin was visualized by Western blot. Relative susceptibilities of fibronectin and collagen I to free radical cleavage were measured with the Fenton reaction.

RESULTS

Redox-active iron concentration in lavage samples was found to be as high as 3.66 micromol/L. A 70-kd protein band, presumed to be albumin, was found to contain higher levels of carbonyls than peripheral serum albumin, which correlated with a greater degree of oxidative damage. Fibronectin was found to be more susceptible than collagen I to free radical degradation, and fragments of the former were found in the lavage. The TMJ lavage fluid was capable of producing free radicals in the presence of peroxide.

CONCLUSION

Circumstantial evidence is provided that the presence of modified and cleaved proteins isolated from lavage of symptomatic TMJs may have been subjected to oxidative stress.