Oxidative stress and degenerative temporomandibular joint disease: a proposed hypothesis

Application of EPR Spectroscopy to Examination of the Effect of Sterilization Process on Free Radicals in Different Herbs

Free radicals in the original and sterilized caraway, curry, curcuma and cardamom were studied. An X-band (9.3 GHz) electron paramagnetic resonance (EPR) spectroscopy was the experimental technique. Effect of microwave power in the range of 2.2-70 mW on amplitudes, linewidths, and lineshape parameters of the EPR spectra was tested. Free radicals concentrations in the non- and sterilized herb samples were compared. The aim of this work was to determine properties and concentration of free radicals in steam sterilized caraway, curry, curcuma and cardamom. It was pointed out that free radicals (~1018 spin/g) exist in both the original and sterilized herbs. Complex free radical system with oxygen and carbon paramagnetic centers characterizes the examined herbs. Homogeneously dipolar broadened EPR spectra were measured for all the tested herbs. Slow spin-lattice relaxation processes exist in the examined samples. Practical usefulness of EPR method in food technology was discussed.

Cytoprotective and anti-inflammatory effects of melatonin in hydrogen peroxide-stimulated CHON-001 human chondrocyte cell line and rabbit model of osteoarthritis via the SIRT1 pathway

Melatonin has potent antioxidant, analgesic, and antinociceptive properties. However, the effects of melatonin against oxidative stress-induced cytotoxicity and inflammatory mediators in human chondrocytes remain poorly understood. This study examined the effects and underlying mechanism of melatonin in hydrogen peroxide (H(2) O(2) )-stimulated human chondrocytes and rabbit osteoarthritis (OA) model. Melatonin markedly inhibited hydrogen peroxide (H(2) O(2) )-stimulated cytotoxicity, iNOS, and COX-2 protein and mRNA expression, as well as the downstream products, NO and PGE(2) . Incubation of cells with melatonin decreased H(2) O(2) -induced Sirtuin 1 (SIRT1) mRNA and protein expression. SIRT1 inhibition by sirtinol or Sirt1 siRNA reversed the effects of melatonin on H(2) O(2) -mediated induction of pro-inflammatory cytokines (NO, PGE(2) , TNF-α, IL-1β, and IL-8) and the expression of iNOS, COX-2, and cartilage destruction molecules. Melatonin blocked H(2) O(2) -induced phosphorylation of PI3K/Akt, p38, ERK, JNK, and MAPK, as well as activation of NF-κB, which was reversed by sirtinol and SIRT1 siRNA. In rabbit with OA, intra-articular injection of melatonin significantly reduced cartilage degradation, which was reversed by sirtinol. Taken together, this study shows that melatonin exerts cytoprotective and anti-inflammatory effects in an oxidative stress-stimulated chondrocyte model and rabbit OA model, and that the SIRT1 pathway is strongly involved in this effect.

Temporomandibular disorders, facial pain, and headaches

Headaches and facial pain are common in the general population. In many cases, facial pain can be resultant from temporomandibular joint disorders. Studies have identified an association between headaches and temporomandibular joint disorders suggesting the possibility of shared pathophysiologic mechanisms of these 2 maladies. The aim of this paper is to elucidate potential commonalities of these disorders and to provide a brief overview of an examination protocol that may benefit the headache clinician in daily practice.

Human temporomandibular joint and myofascial pain biochemical profiles: a case-control study

Neurobiological mechanisms of human musculoskeletal pain are poorly understood. This case-control study tested the hypothesis that biomarkers within temporomandibular muscle and joint disorders (TMJD) subjects' masseter muscles or temporomandibular joint (TMJ) synovial fluid correlate with plasma biomarker concentrations. Fifty subjects were recruited and categorized into TMJD cases (n=23) and pain-free controls (n=27) at the University of Minnesota School of Dentistry. Prior to specimen collection, pain intensity and pressure pain threshold masseter muscles and the TMJs were assessed. We collected venous blood; biopsied masseter muscle; and sampled TMJ synovial fluid on the subjects' side of maximum pain intensity. We assayed these tissues for the presence of nerve growth factor (NGF), bradykinin (BK), leukotreine B(4) (LTB(4) ) and prostaglandin E(2) (PGE(2) ), F(2) -isoprostane (F(2) I) and substance P (SP). The data was analyzed using Spearman Correlation Coefficients. We found that only plasma concentrations of bradykinin statistically correlated with synovial fluid concentrations (ρ=-0·48, P=0·005), but no association was found between pain intensities. The data suggests that biomarkers used to assess TMJD need to be acquired in a site-specific manner. We also discovered that F(2) I concentrations were associated with muscle pain intensity and muscle pressure pain threshold (PTT) (β=0·4, 95%CI: 0·03-0·8) and joint PPT (β=0·4, 95%CI: 0·07-0·8) suggesting that muscle oxidative stress is involved in myofascial pain and that F(2) -I may be a biomarker for myofascial pain.

Antinociceptive and anti-inflammatory effects of electroacupuncture on experimental arthritis of the rat temporomandibular joint

This study investigated the antinociceptive and anti-inflammatory effects of electroacupuncture (EA) on zymosan-induced acute arthritis of the rat temporomandibular joint (TMJ). Male Wistar rats were injected with saline or zymosan (control group; 2 mg) into the left TMJ. Low frequency EA (10 Hz, 30 min) was performed at acupoints (LI4, LI11, ST36, ST44) or sham points 2 h after or 1 h before zymosan administration. Mechanical hypernociception was accessed by the electronic Von Frey method after zymosan administration. Rats were sacrificed 6 h after zymosan administration and the joint was removed for histopathological analysis, myeloperoxidase activity assessment, vascular permeability observations, and immunohistochemical verification of inflammatory mediators. The results showed that EA inhibited zymosan-induced hypernociception, compared with the control group and with the sham group (p < 0.05). The results showed that EA inhibited inflammatory parameters such as neutrophil migration, vascular permeability, and tumour necrosis factor α (TNF-α), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) expression in the TMJ compared with the sham group (p < 0.05). Histopathological analysis showed that EA significantly inhibited edema and periarticular infiltration (p < 0.05) compared with the control and sham groups. EA at acupoints produced antinociceptive and anti-inflammatory effects on zymosan-induced arthritis in the rat TMJ.

Role of intra-articular ozone gas injection in the management of internal derangement of the temporomandibular joint

OBJECTIVES

This study was carried out to compare intra-articular ozone gas injection and drug therapy as conservative treatment modalities for internal derangement of the temporomandibular joint (TMJ).

STUDY DESIGN

Sixty patients (49 female and 11 male) with bilateral internal derangement of the TMJs, disc displacement with reduction, were included in this study. They were divided randomly into 2 equal groups. The first group was treated by a direct injection of ozone gas into the superior joint space. Each joint received 2 mL ozone-oxygen mixture (ozone gas concentration 10 μg/mL). The injections were repeated 2 times per week for 3 weeks. The second group received nonsteroidal antiinflammatory drugs and muscles relaxants. The clinical signs and symptoms before and after the treatment were assessed according to Helkimo's clinical dysfunction index.

RESULTS

The results showed that 87% of the patients who received ozone gas injections into the superior joint space (n = 26) either completely recovered (37%; n = 11) or improved (50%; n = 15). In the second group, 33% of the patients who were treated with nonsteroidal antiinflammatory drugs and muscle relaxants (n = 10) showed only an improvement in their clinical dysfunction indexes.

CONCLUSIONS

Based on the findings of the present study, we can consider that intra-articular ozone gas injection is a promising new treatment modality for internal derangement of the TMJ. However, further clinical and experimental studies are required to provide direct evidence for its mechanism of action and to substantiate our results.

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.

Evidence of oxidative stress in temporomandibular disorders: a pilot study

Oxidative stress is involved in the pathogenesis of many conditions and is caused by free radicals in concentrations that overwhelm the natural scavenging mechanisms and cause pain and inflammation. This investigation sought to determine whether pain from temporomandibular disorders was associated with increased oxidative stress as measured by biomarkers in saliva and serum. Both salivary and serum levels of the oxidative stress biomarkers including 8-hydroxydeoxyguanosine, malondialdehyde and total antioxidant status were compared in patients with mild and severe TMJD pain and with healthy controls. These biomarkers were determined spectrophotometrically in saliva and serum from 10 high TMJD pain patients, 10 low TMJD pain patients, and 10 healthy control subjects from National Institute of Dental Research's TMJ Implant Registry and Repository. Linear and logistic regression analyses were used to evaluate the association between each biomarker and TMJD pain. The mean levels of log 8-hydroxydeoxyguanosine (saliva P < 0·0001, serum P = 0·0008), malondialdehyde (saliva P = 0·002, serum P = 0·004) and total antioxidant status (saliva P = 0·005; serum P = 0·001) achieved statistically significant differences between groups. In linear regression analysis, both salivary and serum levels of each biomarker were associated with TMJD pain. In a multivariable analysis, again, both salivary levels and serum levels were also different between groups. Salivary levels of oxidative stress ratios of 8-hydroxydeoxyguanosine, malondialdehyde and total antioxidant status were significantly different between patients with TMJD pain and controls and was comparable to that in serum. These biomarkers hold promise as a potential diagnostic and therapeutic strategy.

The effects of high molecular weight hyaluronic acid (Hylan G-F 20) on experimentally induced temporomandibular joint osteoartrosis: part II

The aim of this study was to determine the efficacy of Hylan G-F 20 on experimentally induced osteoarthritic changes in rabbit temporomandibular joint (TMJ). A 3mg/ml concentration of sodium mono iodoacetate (MIA) had been injected into both joints of 24 rabbits to create osteoartrosis. The study group was injected with Hylan G-F 20 in one joint and saline in the contralateral joint as a control (once a week for 3 weeks). Histological changes in articular cartilage, osteochondral junction, chondrocyte appearance and subchondral bone were determined at 4, 6, and 8 weeks. Regarding cartilage, there was a statistically significant difference between the two groups at 4 weeks. Degenerative bony changes to subchondral bone were significantly higher in the controls. No statistical difference was found in the study group at 6 weeks. A positive correlation was found between osteochondral junction and subchondral bone in the study group at 8 weeks. The changes in chondrocyte appearance were significantly decreased in the study group at all follow-up times. Intra-articular injection of Hylan G-F 20 decreased cartilage changes in early stage TMJ osteoartrosis and clustering of chondrocytes showed the chondroprotective effects of Hylan G-F 20 caused by hypertrophic responses.

Apoptosis in displaced temporomandibular joint disc with and without reduction: an immunohistochemical study

Internal derangement (ID) of the temporomandibular joint (TMJ) is due to an abnormal relationship of the articular disc to the mandibular condyle, glenoid fossa and articular eminence. The two most common types of internal derangement are anterior disc displacement with (ADDwR) and without reduction (ADDwoR). Disc displacement is associated with degenerative tissue changes. The histological features of discs from patients with TMJ ID reflect a general remodelling caused by abnormal loading. A correlation has been demonstrated between TMJ ID and apoptosis. Few investigations have addressed the role of apoptosis or caspase activity in TMJ ID. The apoptosis activation process was studied in different areas of discs from 18 patients with ID (both ADDwR and ADDwoR) and four cadavers (controls), with emphasis on the expression of caspase 3, whose activation makes the death process irreversible. The results showed a greater proportion of caspase 3-positive cells in ADDwR and ADDwoR than in control discs. Immunopositivity also varied between disc areas; in particular, in ADDwoR sections labelled cells were significantly more numerous (P < 0.01) in the posterior disc attachment than in the anterior and intermediate bands. In addition, a significantly greater proportion of labelled cells was seen in the anterior (+) and intermediate (++) band of ADDwR compared with ADDwoR discs both bands (P < 0.05). These data suggest the importance of programmed cell death in the progression of TMJ ID.

Genetic polymorphisms in folate pathway enzymes, DRD4 and GSTM1 are related to temporomandibular disorder

Background

Temporomandibular disorder (TMD) is a multifactorial syndrome related to a critical period of human life. TMD has been associated with psychological dysfunctions, oxidative state and sexual dimorphism with coincidental occurrence along the pubertal development. In this work we study the association between TMD and genetic polymorphisms of folate metabolism, neurotransmission, oxidative and hormonal metabolism. Folate metabolism, which depends on genes variations and diet, is directly involved in genetic and epigenetic variations that can influence the changes of last growing period of development in human and the appearance of the TMD.

Methods

A case-control study was designed to evaluate the impact of genetic polymorphisms above described on TMD. A total of 229 individuals (69% women) were included at the study; 86 were patients with TMD and 143 were healthy control subjects. Subjects underwent to a clinical examination following the guidelines by the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). Genotyping of 20 Single Nucleotide Polymorphisms (SNPs), divided in two groups, was performed by multiplex minisequencing preceded by multiplex PCR. Other seven genetic polymorphisms different from SNPs (deletions, insertions, tandem repeat, null genotype) were achieved by a multiplex-PCR. A chi-square test was performed to determine the differences in genotype and allelic frequencies between TMD patients and healthy subjects. To estimate TMD risk, in those polymorphisms that shown significant differences, odds ratio (OR) with a 95% of confidence interval were calculated.

Results

Six of the polymorphisms showed statistical associations with TMD. Four of them are related to enzymes of folates metabolism: Allele G of Serine Hydoxymethyltransferase 1 (SHMT1) rs1979277 (OR = 3.99; 95%CI 1.72, 9.25; p = 0.002), allele G of SHMT1 rs638416 (OR = 2.80; 95%CI 1.51, 5.21; p = 0.013), allele T of Methylentetrahydrofolate Dehydrogenase (MTHFD) rs2236225 (OR = 3.09; 95%CI 1.27, 7.50; p = 0.016) and allele A of Methionine Synthase Reductase (MTRR) rs1801394 (OR = 2.35; 95CI 1.10, 5.00; p = 0.037). An inflammatory oxidative stress enzyme, Gluthatione S-Tranferase Mu-1(GSTM1), null allele (OR = 2.21; 95%CI 1.24, 4.36; p = 0.030) and a neurotransmission receptor, Dopamine Receptor D4 (DRD4), long allele of 48 bp-repeat (OR = 3.62; 95%CI 0.76, 17.26; p = 0.161).

Conclusions

Some genetic polymorphisms related to folates metabolism, inflammatory oxidative stress, and neurotransmission responses to pain, has been significantly associated to TMD syndrome

Differential diagnosis of temporomandibular disorders and other orofacial pain disorders

There are many types of pain conditions that are felt in the orofacial structures. Most of the conditions treated by the dentist are associated with the teeth, periodontal structures, and associated mucosal tissues. This article focuses on the differential diagnosis of other common pain conditions the dentist will likely face, such as temporomandibular disorders, neuropathic pain disorders, and common headaches; and the clinical presentation of each. Controlling or reducing pain can be accomplished by controlling perpetuating factors such as parafunctional habits and by some simple behavioral modifications. Finally, this article offers some simple treatment considerations.

Biophoton detection and low-intensity light therapy: a potential clinical partnership

Low-intensity light therapy (LILT) is showing promise in the treatment of a wide variety of medical conditions. Concurrently, our knowledge of LILT mechanisms continues to expand. We are now aware of LILT's potential to induce cellular effects through, for example, accelerated ATP production and the mitigation of oxidative stress. In clinical use, however, it is often difficult to predict patient response to LILT. It appears that cellular reduction/oxidation (redox) state may play a central role in determining sensitivity to LILT and may help explain variability in patient responsiveness. In LILT, conditions associated with elevated reactive oxygen species (ROS) production, e.g. diabetic hyperglycemia, demonstrate increased sensitivity to LILT. Consequently, assessment of tissue redox conditions in vivo may prove helpful in identifying responsive tissues. A noninvasive redox measure may be useful in advancing investigation in LILT and may one day be helpful in better identifying responsive patients. The detection of biophotons, the production of which is associated with cellular redox state and the generation of ROS, represents just such an opportunity. In this review, we will present the case for pursuing further investigation into the potential clinical partnership between biophoton detection and LILT.

Possíveis fatores etiológicos para desordens temporomandibulares de origem articular com implicações para diagnóstico e tratamento

Os fatores envolvidos na etiologia, diagnóstico e tratamento das desordens temporomandibulares (DTM) de origem articular foram revisados. Critérios específicos de inclusão e exclusão para o diagnóstico de DTM são essenciais, mas apresentam utilidade limitada. Atualmente, os Critérios Diagnósticos de Pesquisa para Desordem Temporomandibular (RDC/TMD) oferecem a melhor classificação baseada em evidências para os subgrupos mais comuns de DTM. O RDC/TMD inclui não apenas métodos para a classificação diagnóstica física, presentes em seu Eixo I, mas ao mesmo tempo métodos para avaliar a intensidade e a severidade da dor crônica e os níveis de sintomas depressivos e físicos não-específicos, presentes em seu Eixo II. Embora historicamente as más oclusões tenham sido consideradas como fatores de risco para o desenvolvimento das DTM, incluindo as predominantemente articulares, em muitos casos a associação estabelecida entre essas variáveis parece ter tomado direção oposta. No que diz respeito aos desarranjos internos da ATM, os resultados de estudos prévios sobre a redução induzida do ramo mandibular, secundária ao deslocamento anterior do disco articular, indicam que o reposicionamento do disco deslocado em crianças ou adolescentes jovens pode fazer mais sentido do que previamente imaginado. O uso terapêutico de suplementos alimentares, como o sulfato de glicosamina, parece uma alternativa segura ao uso dos medicamentos anti-inflamatórios normalmente utilizados para controlar a dor relacionada à osteoartrite da articulação temporomandibular (ATM), embora a evidência em torno de sua eficácia para a maioria dos pacientes de DTM não tenha sido completamente estabelecida.

Modulation of hyaluronan catabolism in chondrocytes by mechanical stimuli

Hyaluronan (HA) is a component of the extracellular matrices of cartilage contributing to the structural and functional integrity. HA metabolism is regulated by both anabolic and catabolic processes; however, a great deal more of the detail has been unknown yet. The purpose of this study was to clarify the effect of excessive mechanical load on the expression and activity of hyaluronidase (HYAL) in chondrocytes with a special reference to the expressions of IL-1beta and tumor necrosis factor (TNF)-alpha. A cyclic tensile load of 22.8% cell elongation, regarded as an excessive mechanical stimulus, was applied to cultured rabbit knee articular chondrocytes. HYAL1, HYAL2, IL-1beta, and TNF-alpha mRNA levels were examined by quantitative real-time PCR analysis. The HYAL activity in culture medium was examined by HA zymography. Both HYAL1 and HYAL2 mRNA levels were upregulated significantly by the loading in cultured chondrocytes. HYAL activity was also enhanced as compared with unloaded controls. The IL-1beta mRNA level was upregulated significantly by the loading, and TNF-alpha mRNA level was slightly upregulated. HYAL1 and HYAL2 mRNA levels were upregulated significantly by IL-1beta treatment, resulting in a slight increase in HYAL activity. These results show that the expression of HYAL1 and HYAL2 in articular chondrocytes is enhanced by excessive mechanical stimuli and affected in part by induction of IL-1beta, leading to HA catabolism in articular cartilage.

The levels of vascular endothelial growth factor in the synovial fluid correlated with the severity of arthroscopically observed synovitis and clinical outcome after temporomandibular joint irrigation in patients with chronic closed lock

OBJECTIVE

This study aimed to investigate the level of vascular endothelial growth factor (VEGF) in the temporomandibular joint (TMJ) synovial fluid (SF) and the severity of arthroscopically observed synovitis before and after visually guided TMJ irrigation (VGIR) in patients with chronic closed lock (CCL). In addition, the findings were correlated with the clinical outcome.

STUDY DESIGN

Twenty-four patients with unilateral CCL, who underwent a second VGIR either as a repeated therapeutic TMJ irrigation or as a follow-up arthroscopy, were enrolled in the study. They were divided into either successful (s-group; n = 11) and unsuccessful (u-group; n = 13) groups. The VEGF level in the aspirated SF and the severity of synovitis were compared between the s- and u-groups. In each group, the same parameters were compared before and after VGIR. The correlation of the VEGF level with the severity of synovitis was also studied.

RESULTS

At the first VGIR, the VEGF levels showed no significant differences when comparing s- and u-groups. At the second VGIR, the VEGF level was significantly higher in the u-group. The VEGF level significantly decreased after the first VGIR in the s-group but remained unchanged in the u-group. There was no significant correlation between the VEGF level and the severity of synovitis.

CONCLUSIONS

The level of VEGF in TMJ SF seems to reflect the clinical status in patients with CCL. Moreover, VEGF may be an important target molecule in future chemotherapy of TMJ CCL.

Effects of mechanical stimuli on the synthesis of superficial zone protein in chondrocytes

Superficial zone protein (SZP) has been demonstrated to contribute to the boundary lubrication in synovial joints. This study was designed to clarify the modulation of SZP expression by mechanical stress in articular chondrocytes. Cyclic tensile strains of 7 and 21% cell elongation were applied to cultured chondrocytes obtained from porcine mandibular condylar cartilage. The mRNA levels of SZP, IL-1 beta, and TGF-beta1 were examined by a quantitative real-time PCR analysis. Protein level of SZP was examined by Western blotting. The SZP mRNA level was significantly upregulated after 12, 24, and 48 h by 7% elongation. Although SZP mRNA level was upregulated by 21% elongation after 12 h, it decreased to a lower level than the control after 48 h. The TGF-beta1 mRNA level exhibited an almost similar change to SZP. The IL-1 beta mRNA level was not changed markedly by 7% elongation. However, the IL-1 beta mRNA level was significantly increased by a 12-h application of 21% elongation. Western blot analysis revealed that the SZP expression was increased by 7% elongation, but decreased remarkably by 21% elongation. It is suggested from these findings that the SZP expression level in the chondrocytes is enhanced by optimal mechanical stimuli, but inhibited by excessive loading partly affected by TGF-beta1 and IL-1 beta, leading to the deterioration of joint lubrication.

Quantification of disc displacement in internal derangement of the temporomandibular joint using magnetic resonance imaging

Many measures have been developed to determine the extent of disc displacement in internal derangements of the temporomandibular joint (TMJ) using magnetic resonance imaging. The purpose of this study was to develop a quantitative method of analyzing disc position and to evaluate the positions of the disc in internal derangements of the TMJ (group 1, with reduction; group 2, without reduction). Magnetic resonance images of 150 TMJs in 20 healthy volunteers and 55 patients with internal derangements were evaluated. The anatomical points of interest of the TMJ, including the anterior (DA) and posterior (DP) points of the disc, were marked on parasagittal magnetic resonance images of the TMJ disc taken in both the closed- and the open-mouth positions. All points were recorded using an x-y coordinate system, with reference to a referral line. In the closed-mouth position, the DP in patients in group 1 was situated in a more-anterior direction than the DP in volunteers. The DP in group 2 was located further anterior and inferior than the DP in group 1. However, the position of the DA did not differ between group 1 and group 2. In the open-mouth position, the DP was displaced anteroinferiorly to a greater extent in group 2 than in group 1 (one-way ANOVA, followed by Scheffe's test; P < 0.0001). The distance between the disc points in the closed- and open-mouth positions was also evaluated. Comparison of the disc point position in the closed- and open-mouth positions in symptomatic and asymptomatic displaced TMJ discs revealed no significant difference. In conclusion, most of our results quantitatively support previously reported findings in imaging, surgical, and histopathological studies of TMJ internal derangement. We suggest that our measure of disc position of the TMJ would be useful to assess the status and response to treatment of internal derangements of the TMJ.

Oligonucleotides are potent antioxidants acting primarily through metal ion chelation

We report on a rather unknown feature of oligonucleotides, namely, their potent antioxidant activity. Previously, we showed that nucleotides are potent antioxidants in Fe(II)/Cu(I/II)-H(2)O(2) systems. Here, we explored the potential of 2'-deoxyoligonucleotides as inhibitors of the Fe(II)/Cu(I/II)-induced *OH formation from H(2)O(2). The oligonucleotides [d(A)(5,7,20); d(T)(20); (2'-OMe-A)(5)] proved to be highly potent antioxidants with IC(50) values of 5-17 or 48-85 microM in inhibiting Fe(II)/Cu(I)- or Cu(II)-induced H(2)O(2) decomposition, respectively, thus representing a 40-215-fold increase in potency as compared with Trolox, a standard antioxidant. The antioxidant activity is only weakly dependent on the oligonucleotides' length or base identity. We analyzed by matrix-assisted laser desorption/ionization time of flight mass spectrometry and (1)H-NMR spectroscopy the composition of the d(A)(5) solution exposed to the aforementioned oxidative conditions for 4 min or 24 h. We concluded that the primary (rapid) inhibition mechanism by oligonucleotides is metal ion chelation and the secondary (slow) mechanism is radical scavenging. We characterized the Cu(I)-d(A)(5) and Cu(II)-d(A)(7) complexes by (1)H-NMR and (31)P-NMR or frozen-solution ESR spectroscopy, respectively. Cu(I) is probably coordinated to d(A)(5) via N1 and N7 of two adenine residues and possibly also via two phosphate/bridging water molecules. The ESR data suggest Cu(II) chelation through two nitrogen atoms of the adenine bases and two oxygen atoms (phosphates or water molecules). We conclude that oligonucleotides at micromolar concentrations prevent Fe(II)/Cu(I/II)-induced oxidative damage, primarily through metal ion chelation. Furthermore, we propose the use of a short, metabolically stable oligonucleotide, (2'-OMe-A)(5), as a highly potent and relatively long lived (t(1/2) approximately 20 h) antioxidant.

Mechanical stretch enhances NF-kappaB-dependent gene expression and poly(ADP-ribose) synthesis in synovial cells

Temporomandibular joint disorders (TMD) show complex symptoms associated with inflammation, pain and degeneration of the peripheral tissues including synovium. Although it is believed that excessive mechanical stress on synovium causes development of TMD, the molecular mechanism by which mechanical stress triggers TMD has still remained unclear. In order to examine the effect of mechanical stress on synoviocytes, rabbit synovial cells were cyclically stretched in vitro. The stretch efficiently increased the gene expressions of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) and NF-kappaB responsive reporter gene constructs. The interruption of NF-kappaB activating pathway by inhibitors resulted in the abrogation of those expressions, indicating the pivotal role of NF-kappaB in the mechanical stretch-mediated COX-2 and iNOS expressions. In parallel, the stretch remarkably increased NO production and poly(ADP-ribose) (PAR) synthesis, suggesting that excessive amounts of NO causes DNA injury and in turn activates PAR synthesis by poly(ADP-ribose) polymerase (PARP). The inhibition of PAR synthesis by a PARP inhibitor or a radical scavenger enhanced the mechanical stretch-induced gene expressions in a NF-kappaB-independent manner, implying an involvement of PARP in the gene expression. Taken together, these results demonstrate that mechanical stress on synovial cells not only induces gene expressions of COX-2 and iNOS but also affects PAR synthesis.

A biomechanical basis for primary arthroplasty of the temporomandibular joint

Biomechanical principles of temporomandibular joint (TMJ) loading are unique, particularly in an orthopedic system that exhibits curvilinear general plane motion. Certain type-specific derangements can be surgically challenging and may primarily require open arthrotomy techniques rather than arthroscopy. This article discusses the basic biomechanical principles in normal and pathologic function. Three-dimensional preoperative imaging of TMJs is necessary for appropriate assessment of all patients and when open techniques are necessary as the initial surgical procedure.

Temporomandibular joint pain and synovial fluid analysis: a review of the literature

The pathophysiology of temporomandibular joint pain is not well understood. A significant amount of research has been conducted to evaluate synovial fluid in these patients and in healthy controls. Qualitative and quantitative analyses of the synovial fluid have shown a significant difference between these groups. A multitude of inflammatory mediators and degradation products have been identified. The concentration of these products has been shown to correlate with several clinical parameters including pain, chronicity, severity of degenerative change, and response to treatment. A common inflammatory pathway would appear to be involved in most patients. At the present time, synovial fluid analysis does not have the sensitivity or specificity to allow specific diagnoses and targeted treatment. Continued research with the specific aim of establishing more appropriate therapeutic modalities based on the biochemical pathways is warranted.

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.

Low-intensity light therapy: exploring the role of redox mechanisms

Low-intensity light therapy (LILT) appears to be working through newly recognized photoacceptor systems. The mitochondrial electron transport chain has been shown to be photosensitive to red and near-infrared (NIR) light. Although the underlying mechanisms have not yet been clearly elucidated, mitochondrial photostimulation has been shown to increase ATP production and cause transient increases in reactive oxygen species (ROS). In some cells, this process appears to participate in reduction/oxidation (redox) signaling. Redox mechanisms are known to be involved in cellular homeostasis and proliferative control. In plants, photostimulation of the analogous photosynthetic electron transport chain leads to redox signaling known to be integral to cellular function. In gene therapy research, ultraviolet lasers are being used to photostimulate cells through a process that also appears to involve redox signaling. It seems that visible and near visible low-intensity light can be used to modulate cellular physiology in some nonphotosynthetic cells, acting through existing redox mechanisms of cellular physiology. In this manner, LILT may act to promote proliferation and/or cellular homeostasis. Understanding the role of redox state and signaling in LILT may be useful in guiding future therapies, particularly in conditions associated with pro-oxidant conditions.

Masseter muscular weakness affects temporomandibular synovitis induced by jaw opening in growing rats

OBJECTIVE

To evaluate the influence of impaired masseter function during growth on the development of temporomandibular synovitis.

MATERIALS AND METHODS

Sixteen 3-week-old male Wistar rats were classified into four groups. The first group served as control; and in the second group, jaw opening was forced for 3 hours when the rats were 9 weeks old. In the third and fourth groups, the masseter muscles were bilaterally resected at 3 weeks of age, and the rats in the fourth group were additionally forced to open their jaw at 9 weeks of age. All rats were sacrificed at 9 weeks. Temporomandibular joint (TMJ) tissue samples were processed for histology, and evaluated for cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions by immunohistochemistry to examine the inflammatory changes in the synovial membrane.

RESULTS

The control group showed noninflammatory changes. In the jaw-opening group, vascular dilation and weak COX-2 immunoreactivity were induced by jaw opening in the synovium. In the masseter-resection group, the masseter-resected rats exhibited moderate synovial changes while in the resection with opening group, the masseter-resected rats revealed more significant inflammatory changes including synovial hyperplasia, dilated vasculature, fibrin deposits, and intense immunoreactivity for COX-2 and iNOS, all caused by jaw opening.

CONCLUSIONS

These results suggest that masseter activity in the growth period is an important factor in the induction of temporomandibular synovitis.

Internal derangements of the temporomandibular joint

This article discusses several types of internal derangements of the temporomandibular joint. It includes definitions, clinical characteristics, and management options. Nonsurgical and surgical treatment strategies are discussed taking into consideration the latest evidence-based literature.

Freqüência de relatos de parafunções nos subgrupos diagnósticos de DTM de acordo com os critérios diagnósticos para pesquisa em disfunções temporomandibulares (RDC/TMD)

INTRODUÇÃO: as disfunções temporomandibulares (DTM) podem ser definidas como um conjunto de condições dolorosas e/ou disfuncionais, que envolvem os músculos da mastigação e/ou as articulações temporomandibulares (ATM). Um dos meios usados para o diagnóstico é o "Critério Diagnóstico para Pesquisa em Disfunções Temporomandibulares" (RDC/TMD). Hábitos parafuncionais são aqueles não relacionados à execução das funções normais do sistema estomatognático. O bruxismo é caracterizado por atividade parafuncional noturna involuntária dos músculos mastigatórios, enquanto o apertamento dentário é considerado uma parafunção diurna envolvendo esta musculatura, embora possa ocorrer também à noite. OBJETIVOS: o objetivo do presente estudo foi avaliar a freqüência do relato de parafunções orais diurna e/ou noturna em pacientes com DTM nos diferentes subgrupos diagnósticos do RDC/TMD. METODOLOGIA: foram utilizados dados provenientes de 217 pacientes que procuraram tratamento na Clínica de DTM e Dor Orofacial da Faculdade de Medicina de Petrópolis, sendo avaliados através do questionário e exame físico que compõem o RDC/TMD. RESULTADOS: dos 182 pacientes com DTM estudados, 76,9% relataram algum tipo de parafunção, podendo ser diurna, noturna ou a associação de ambas. A parafunção diurna foi a mais freqüentemente relatada entre os subgrupos de DTM, sendo encontrada em 64,8% dos casos contra 55,5% dos casos com relato de bruxismo. O relato de ambas as parafunções foi constatado em 43,4% dos pacientes com DTM. CONCLUSÕES: considerando cada subgrupo diagnóstico, os relatos de parafunções diurna e noturna foram mais freqüentes nos pacientes com dor miofascial.

Degenerative Disorders of the Temporomandibular Joint: Etiology, Diagnosis, and Treatment

Temporomandibular joint (TMJ) disorders have complex and sometimes controversial etiologies. Also, under similar circumstances, one person’s TMJ may appear to deteriorate, while another’s does not. However, once degenerative changes start in the TMJ, this pathology can be crippling, leading to a variety of morphological and functional deformities. Primarily, TMJ disorders have a non-inflammatory origin. The pathological process is characterized by deterioration and abrasion of articular cartilage and local thickening. These changes are accompanied by the superimposition of secondary inflammatory changes. Therefore, appreciating the pathophysiology of the TMJ degenerative disorders is important to an understanding of the etiology, diagnosis, and treatment of internal derangement and osteoarthrosis of the TMJ. The degenerative changes in the TMJ are believed to result from dysfunctional remodeling, due to a decreased host-adaptive capacity of the articulating surfaces and/or functional overloading of the joint that exceeds the normal adaptive capacity. This paper reviews etiologies that involve biomechanical and biochemical factors associated with functional overloading of the joint and the clinical, radiographic, and biochemical findings important in the diagnosis of TMJ-osteoarthrosis. In addition, non-invasive and invasive modalities utilized in TMJ-osteoarthrosis management, and the possibility of tissue engineering, are discussed.

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.

Screening seeds of some Scottish plants for free radical scavenging activity

From a consideration of ethnobotanical and taxonomic information, seeds of 45 Scottish plant species encompassing 23 different families were obtained from authentic seed suppliers. The n-hexane, dichloromethane (DCM) and methanol (MeOH) extracts were assessed, both qualitatively and quantitatively, for free radical scavenging activity in the DPPH assay. The MeOH extracts of 37 species exhibited low to high levels of free radical scavenging activity (RC50 values ranging from 2.00 to 4.7 x 10(-4) mg/mL), and Alliaria petiolata, Prunus padus and Prunus spinosa were the most potent antioxidant extracts. The DCM extracts of 17 species showed similar levels of activity, and among those, Prunus padus and Prunus spinosa extracts were the most active with RC50 values of 2.5 x 10(-4) and 5.0 x 10(-4) mg/mL, respectively. The n-hexane extracts were much less active than the MeOH and DCM extracts, and 17 species, with the exception of Glechoma hederacea (RC50 = 1.94 x 10(-4)) displayed low to moderate levels of free radical scavenging property (RC50 values ranging from 2.00 to 8.7 x 10(-3) mg/mL).

Temporomandibular joint soft-tissue pathology, I: Disc abnormalities

The internal derangements are the most common noninflammatory abnormalities of the disc, observed even in asymptomatic subjects. Because the temporomandibular joint shows large adaptative and compensatory mechanisms over dysfunctional disc motion, these disorders may be asymptomatic or minimally evident for a long time. A careful clinical evaluation, reinforced by imaging findings, should help differentiate asymptomatic derangements from painful conditions that may require treatment.

Up-regulation of vascular endothelial growth factor in synovial fibroblasts from human temporomandibular joint by hypoxia

INTRODUCTION

Enhanced expression of vascular endothelial growth factor (VEGF) has been described in patients with internal derangement (ID). Herein, we examined the expression of VEGF in synovial fibroblasts from temporomandibular joint (TMJ) under hypoxia and investigated the regulation of hypoxia-inducible factor-1alpha (HIF-1alpha) involved in the expression of VEGF.

METHODS

Synovial fibroblasts were prepared from human TMJ. These cells were incubated under hypoxia or normoxia for the indicated time periods. VEGF levels in cultured supernatant were measured by an ELISA. VEGF mRNA isoforms and stability were assessed using RT-PCR and Northern blot analysis respectively. HIF-1alpha accumulation was evaluated by Western blotting and immunofluorescence.

RESULTS

VEGF were significantly induced by hypoxia in synovial fibroblasts. In response to hypoxia, VEGF121 and VEGF165 mRNA were both remarkably increased, while there was no change in VEGF mRNA stability. The accumulation and nuclear translocation of HIF-1alpha occurred under hypoxia.

CONCLUSIONS

Hypoxia may mainly induce the expression of VEGF121 and VEGF165 in synovial fibroblasts to promote inflamed angiogenesis of TMJ. HIF-1alpha, which is clearly activated in response to hypoxia, may control the expression of VEGF in synovial fibroblasts from TMJ.

Temporomandibular Joint Internal Derangement and Osteoarthrosis: Are Effusion and Bone Marrow Edema Prognostic Indicators for Arthrocentesis and Hydraulic Distention?

PURPOSE

Arthrocentesis and hydraulic distention of the temporomandibular joint (TMJ) has proven to be an effective modality in treating patients exhibiting clinical findings consistent with the diagnosis of disc displacement without reduction. The purpose of this study was to investigate whether the magnetic resonance imaging (MRI) variables of effusion and/or bone marrow edema may predict treatment outcomes of arthrocentesis and hydraulic distention of the TMJ.

PATIENTS AND METHODS

The study group comprised 37 consecutive patients with TMJ pain, who were assigned a unilateral clinical TMJ disorder of TMJ pain associated with an internal derangement (ID) type III (disc displacement without reduction) and a TMJ pain side-related MRI diagnosis of disc displacement without reduction associated with osteoarthrosis (OA). Bilateral sagittal and coronal MRI images were obtained immediately before the operation to establish the presence or absence of ID, OA, TMJ effusion, and bone marrow edema. Pain level and mandibular range of motion (ROM) were assessed preoperatively and compared with the respective 2-month follow-up findings. Outcome criteria for success were a ROM >or=35 mm and pain reduction >50%. A logistic regression analysis was used to compute the odds ratio for TMJ effusion and bone marrow edema for successful outcomes (n = 21) versus unsuccessful (n = 16) outcomes.

RESULTS

At the 2-month follow-up, clinical evaluation showed a significant reduction in TMJ pain during function (P = .000), a significant reduction in clinical diagnoses of TMJ disorders (P = .016), and a significant increase in ROM (P = .000). A significant increase in the risk of an unsuccessful outcome of ROM <35 mm and/or pain reduction >or=50% occurred with MRI findings of effusion (odds ratio 1:10.8 = 0.09; P = .007).

CONCLUSIONS

TMJ effusion may prove to be an important prognostic determinant of successful arthrocentesis. However, the data re-emphasize the concept that the prediction of a specific outcome is not a matter of simple linearity, in which the presence of 1 factor may equate with predictive ability, but rather is a function of a complex interaction among different biological variables.

Temporomandibular joint pain and dysfunction

Pain caused by temporomandibular disorders originates from either muscular or articular conditions, or both. Distinguishing the precise source of the pain is a significant diagnostic challenge to clinicians, and effective management hinges on establishing a correct diagnosis. This paper examines terminology and regional anatomy as it pertains to functional and dysfunctional states of the temporomandibular joint and muscles of mastication. A review of the pathophysiology of the most common disorders is provided. Trends in evaluation, diagnosis, treatment, and research are presented.

Compressive mechanical stress promotes osteoclast formation through RANKL expression on synovial cells

OBJECTIVES

We investigated the effects of compressive mechanical stress on osteoclastogenesis of synovial cells to clarify the mechanism of osteoclast formation by those cells in temporomandibular joint (TMJ) disorders.

STUDY DESIGN

Synovial cells were isolated from rat knee joints and continuously compressed using a conventional method. The expression of receptor activator nuclear factor kappaB ligand (RANKL) mRNA and protein in synovial cells was analyzed by reverse transcriptase-polymerase chain reaction, immunoblotting, and immunofluorescence staining. Mouse bone marrow cells were cultured with synovial cells for 7 days to detect osteoclasts.

RESULTS

The expressions of RANKL mRNA and protein in synovial cells were increased with compressive force. When mouse bone marrow cells were cultured with continuously compressed synovial cells, tartrate-resistant acid phosphatase-positive multinucleated cells were formed. Osteoprotegerin completely inhibited osteoclast formation induced by culturing with compressed synovial cells.

CONCLUSION

Our results indicated that the expression of RANKL in compressed synovial cells enhanced osteoclast formation, whereas continuous compressive force may induce osteoclastic bone destruction in the TMJ.