Disk derangement and inflammatory changes in the posterior disk attachment of the temporomandibular joint. A histologic study

Temporomandibular Joint Facts and Foibles

The purpose of this article is to dispel some of the major foibles associated with the etiology and management of TMJ disorders, while presenting some of the facts based on the scientific literature to date. To appreciate this kind of update, the reader must be an "out of the box thinker" which requires openness to new ways of seeing the world and a willingness to accept new concepts based on evolving evidence.

Change of lateral pterygoid muscle and temporomandibular disc position after bi-maxillary surgery in class II and III patients

OBJECTIVES

The purpose of this study was to examine changes in lateral pterygoid muscle and temporomandibular joint (TMJ) disc position in classes II and III patients, before and after bi-maxillary surgery.

MATERIALS AND METHODS

The subjects were comprised of 48 patients (96 sides), 23 of whom were diagnosed as class II and 25 as class III patients who underwent Le Fort I osteotomy and sagittal split ramus osteotomy (SSRO). The cross-sectional measurements of the lateral pterygoid muscles were measured at two levels of horizontal plane images (condyle and mandibular notch levels) by computed tomography (CT), before and 1 year after the operation. The relationship between these measurements regarding lateral pterygoid muscle and disc position by magnetic resonance image (MRI) was also examined statistically.

RESULTS

Preoperatively, class II was significantly larger than class III in condylar angle at the upper level and in long diameter, square, condylar angle, and muscle angle at the lower level (P < 0.05). After 1 year, class II was significantly larger than class III in condylar angle, long diameter, and muscle angle at the upper level and in long diameter, short diameter, square, condylar angle, and muscle angle at the lower level (P < 0.05). TMJ disc position classification correlated significantly with condylar angle at the upper level and long diameter and condylar angle at the lower level (P < 0.0001).

CONCLUSION

This study suggested that there were differences in the cross-sectional measurements of the lateral pterygoid muscles between class II and class III patients, before and after bi-maxillary surgery.

The usefulness of diagnostic imaging for the assessment of pain symptoms in temporomandibular disorders

The causes of pain symptoms in the temporomandibular joint (TMJ) and masticatory muscle (MM) regions may not be determined by clinical examination alone. In this review, we document that pain symptoms of the TMJ and MM regions in patients with temporomandibular disorders (TMDs) are associated with computed tomography and magnetic resonance (MR) findings of internal derangement, joint effusion, osteoarthritis, and bone marrow edema. However, it is emphasized that these imaging findings must not be regarded as the unique and dominant factors in defining TMJ pain. High signal intensity and prominent enhancement of the posterior disk attachment on fat saturation T2-weighted imaging and dynamic MR imaging with contrast material are closely correlated with the severity of TMJ pain. Magnetic transfer contrast, MR spectroscopy, diffusion tensor imaging, and ultrasonography findings have helped identify intramuscular edema and contracture as one of the causes of MM pain and fatigue. Recently, changes in brain as detected by functional MR neuroimaging have been associated with changes in the TMJ and MM regions. The thalamus, the primary somatosensory cortex, the insula, and the anterior and mid-cinglate cortices are most frequently associated with TMD pain.

A critical review of Dr. Charles S. Greene's article titled "Managing the Care of Patients with Temporomandibular Disorders: a new Guideline for Care" and a revision of the American Association for Dental Research's 1996 policy statement on temporomandibular disorders, approved by the AADR Council in March 2010, published in the Journal of the American Dental Association September 2010

Dr. Charles Greene's article, "Managing the Care of Patients with TMDs A New Guideline for Care," and the American Association for Dental Research's (AADR) 2010 Policy Statement on Temporomandibular Disorders, published in the Journal of the American Dental Association (JADA) September 2010, are reviewed in detail. The concept that all temporomandibular disorders (TMDs) should be lumped into one policy statement for care is inappropriate. TMDs are a collection of disorders that are treated differently, and the concept that TMDs must only be managed within a biopsychosocial model of care is inappropriate. TMDs are usually a musculoskeletal orthopedic disorder, as defined by the AADR. TMD orthopedic care that is peer-reviewed and evidence-based is available and appropriate for some TMDs. Organized dentistry, including the American Dental Association, and mainstream texts on TMDs, support the use of orthopedics in the treatment of some TMDs. TMDs are not psychological or social disorders. Informed consent requires that alternative care is discussed with patients. Standard of care is a legal concept that is usually decided by a court of law and not decided by a policy statement, position paper, guidelines or parameters of care handed down by professional organizations. The 2010 AADR Policy Statement on TMD is not the standard of care in the United States. Whether a patient needs care for a TMD is not decided by a diagnostic test, but by whether the patient has significant pain, dysfunction and/or a negative change in quality of life from a TMD and they want care. Some TMDs need timely invasive and irreversible care.

Increased risk of temporomandibular joint closed lock: a case-control study of ANKH polymorphisms

Objectives

This study aimed to carry out a histological examination of the temporomandibular joint (TMJ) in ank mutant mice and to identify polymorphisms of the human ANKH gene in order to establish the relationship between the type of temporomandibular disorders (TMD) and ANKH polymorphisms.

Materials and Methods

Specimens from the TMJ of ank mutant and wild-type mice were inspected with a haematoxylin and eosin staining method. A sample of 55 TMD patients were selected. Each was examined with standard clinical procedures and genotyping techniques.

Results

The major histological finding in ank mutant mice was joint space narrowing. Within TMD patients, closed lock was more prevalent among ANKH-OR homozygotes (p = 0.011, OR = 7.7, 95% CI 1.6–36.5) and the elder (p = 0.005, OR = 2.4, 95% CI 1.3–4.3).

Conclusions

Fibrous ankylosis was identified in the TMJ of ank mutant mice. In the human sample, ANKH-OR polymorphism was found to be a genetic marker associated with TMJ closed lock. Future investigations correlating genetic polymorphism to TMD are indicated.

Condylar shape in relation to anterior disk displacement in juvenile females

The purpose of the study was to test the hypothesis that condylar shape varies based upon the condition of anterior disk displacement in young adolescent patients with temporomandibular disorder (TMD). The study design consisted of 96 juvenile female patients (aged 9 to 20; 15.1 +/- 2.3 yrs.) with clinical signs and/or symptoms of TMD. Bilateral high-resolution magnetic resonance imaging scans were performed in frontal and horizontal views with the mandible in the closed position. Disk positions were evaluated to classify the patients into three diagnostic groups. The results of the study, using ANOVA and Bonferroni tests, demonstrated significant differences among the groups. The conclusion drawn from the study was that condylar shape and size vary based on anterior disk position in juvenile females with TMD. The study's results suggest that disk displacement results in a smaller condyle.

Magnetic resonance signal intensity from retrodiscal tissue related to joint effusion status and disc displacement in elderly patients with temporomandibular joint disorders

Magnetic resonance imaging (MRI) on patients with temporomandibular joint disorders (TMD) has revealed that a decrease and/or increase in signal intensity from retrodiscal tissue, joint effusion (the excessive accumulation of joint fluid) and articular disc displacement are related to TMD. However, the effect of aging on these phenomena has yet to be clarified. This study was carried out to explore the relationship between changes in signal intensity from retrodiscal tissue, joint fluid status and pathological disc conditions in elderly patients with TMD. Twenty patients aged over 60 years were examined. They consisted of one man and 19 women, and ranged between 60 and 79 years in age (mean, 66.0 years). The relationships between decreased signal intensity on proton-density-weighted (PDW) images and increased signal intensity on T2-weighted (T2W) MR images from retrodiscal tissue, joint fluid status and state of articular disc were examined. Joint fluid status was classified into 5 levels by extent of high signal areas in upper and lower articular spaces on T2W images. Disc displacement status was evaluated by PDW images. The Wilcoxon test was applied for the statistical analysis. The group showing increased T2W signal intensities from the retrodiscal tissue consisted of 31 out of 40 joints (77.5%). This group showed a significant difference in comparison with the other groups in which no apparent joint fluid was shown (p<0.05). There were no statistically significant differences among other categories. The results suggest a negative relationship between joint fluid and increased signal intensity from retrodiscal tissue due to reflection of the inflammatory reaction in TM joints.

Magnetic resonance imaging evaluation of mandibular condyle bone marrow and temporomandibular joint disc signal intensity in anaemia patients

OBJECTIVES

To compare the signal intensity (SI) of mandibular condyle bone marrow (MCBM) and the temporomandibular joint (TMJ) disc in patients with chronic anaemia and healthy subjects, and to investigate the relationships between bone marrow changes, age, types of anaemia and severity of anaemia.

METHODS

MRIs of 18 patients with chronic anaemia were compared with those of 12 healthy subjects. The SI of MCBM and the TMJ disc were quantitatively evaluated. The SI of the grey matter (GM), white matter (WM) and the lateral pterygoid muscle were also investigated. Relationships between age, MCBM and TMJ disc signal-intensities and anaemia severity, and correlations between the groups, were analysed.

RESULTS

The mean MCBM SI was lower in anaemia patients (including both subgroups and also separately) than in healthy subjects (P < 0.05). No statistical significance was found for GM, WM and the muscle SI between the anaemia patients and healthy patient group (P > 0.05). No statistical significance was found between the groups with respect to the anterior band, whereas the mean SI value of the posterior band in the study group was significantly lower than in healthy subjects (P < 0.05). There were no correlations between age and MCBM SI, or between anaemia severity and MCBM SI.

CONCLUSIONS

Anaemia may cause bone marrow alterations without any internal derangement. Patients with chronic anaemia exhibit lower mandibular condyle bone marrow and posterior band SI than healthy subjects.

Characterization of a model of chronic orofacial hyperalgesia in the rat: contribution of NA(V) 1.8

The purpose of this study was to develop and characterize a model of orofacial inflammatory hyperalgesia. Injection of complete Freund's adjuvant (CFA) into the upper lip/whisker pad of the rat produced significant and long-lasting thermal (> or =14 days) and mechanical (> or =28 days) hyperalgesia in the area of CFA injection. Both indomethacin and morphine, given systemically, significantly attenuated thermal hyperalgesia; the effect of morphine was shown to be opioid receptor-mediated. We also examined the contribution of the tetrodotoxin-resistant voltage-gated sodium channel Na(v)1.8 in CFA-produced orofacial mechanical hypersensitivity. Na(v)1.8 mRNA was increased > or =2.5-fold in trigeminal ganglion neurons 1 and 2 weeks after CFA treatment, and Na(v)1.8 protein was increased in the infraorbital nerve over a similar time course. The changes observed were time-dependent and had returned to baseline when examined 2 months after inflammation; there were no changes in Na(v)1.9 mRNA in trigeminal ganglion neurons after CFA treatment. In support of this, Na(v)1.8 antisense oligodeoxynucleotide treatment significantly attenuated CFA-produced mechanical hypersensitivity. These results document development of a model of inflammatory orofacial hyperalgesia, which, consistent with other reports, indicate a contribution of tetrodotoxin-resistant, voltage-gated sodium channel Na(v)1.8.

PERSPECTIVE

Orofacial hypersensitivity develops postoperatively as a routine course of orofacial surgery, and mechanical allodynia is characteristic of temporomandibular joint disorder. The results described in this report are novel with respect to the duration of orofacial hypersensitivity produced and suggest that pharmacological targeting of the voltage-gated sodium channel Na(v)1.8 may be useful in managing hypersensitivity.

Histologic and histomorphometric analysis of posterior region of the human temporomandibular disc

OBJECTIVE

The aim of this study was to analyze histologic and histomorphometric features of the articular disc in groups with and without disc displacement.

STUDY DESIGN

A sample of 39 temporomandibular joints TMJs (31 case specimens, 8 control specimens) from 28 patients (mean age 31.2 years) were recruited for this study. The patients were considered to be affected and treated surgically with disc repositioning when presenting painful clinical signs of disc displacement after unsuccessful nonsurgical treatment for at least 6 months. Of the control patients, 4 presented condyle fracture which required opening to be reduced for treatment, and 4 displayed active condyle hyperplasia. The posterior region of the disc was removed and sent for histologic and histomorphometric analysis. Histologic (hematoxylin-eosin) and histomorphometric (picro-Sirius red) analyses were performed. Statistically significant differences between the analyzed groups were accessed through the chi-squared test (P <or= .05). The Mann-Whitney U test was used to observe the differences between mean values when variables did not present normal distribution [Kolmogorov-Smirnov(a) test].

RESULTS

There were no significant differences between the groups in relation to the parameters studied by histologic and histomorphometric analysis (using or not using polarization).

CONCLUSIONS

To the limits of this study, there were no significant histologic and histomorphometric differences in the articular disc between groups with and without TMJ dysfunction.

Disc derangements of the temporomandibular joint

Disc-related derangement of the temporomandibular joint is common and epidemiological research has found that about 20% of the population may be affected. Although very few of these people have the more prominent symptoms, recent data indicate that the numbers who need treatment is increasing. The two clinical variants of disc derangement, reciprocal clicking and closed lock, have long been recognized, but the association between them and their aetiology and pathogenesis is still unclear. As a consequence, there is still uncertainty on how to treat the conditions, and this is even more evident when surgery is involved. This paper describes new tissue research related to disc derangement. A simplified scheme is presented and implications for surgical treatment are discussed.

Association between high signal intensity in the posterior disc attachment seen on T2 weighted fat-suppressed images and temporomandibular joint pain

OBJECTIVES

We sought to determine whether high signal intensity in the posterior disc attachment (PDA) seen on T2 weighted fat-suppressed MRI is associated with temporomandibular joint (TMJ) pain and joint pathology.

METHODS

This study was based on 283 TMJs of 177 patients (31 males and 146 females, mean age 32.7 years) with TMJ disorders showing anterior disc displacement. MRI evaluation included assessment of signal intensity in the PDA and TMJ status (disc displacement with reduction, disc displacement without reduction and disc displacement with bone changes). Clinical criteria that were considered positive indicators of TMJ pain included the presence of pre-auricular pain during palpation, jaw function and assisted or unassisted mandibular opening. Association of signal intensity in the PDA with joint pain and TMJ status was analysed using chi2 test.

RESULTS

Joint pain was reported in 47 (77.0%) out of 61 joints with high signal intensity in the PDA and in 97 (43.7%) out of 222 joints with low signal intensity in the PDA (P<0.0001). High signal intensity in the PDA correlated closely with more advanced joint pathology. In joints with anterior disc displacement with bone changes, TMJ pain was more commonly reported in joints with high signal intensity in the PDA than with low signal intensity in the PDA (P<0.0001).

CONCLUSIONS

High signal intensity in the PDA on T2 weighted fat-suppressed MRI is associated with TMJ pain in TMJ disorders with anterior disc displacement with bone changes in the mandibular condyles.

Visualization of anterior disc displacement in temporomandibular disorders on contrast-enhanced magnetic resonance imaging: comparison with T2-weighted, proton density–weighted, and precontrast T1-weighted imaging

OBJECTIVE

To compare postcontrast T1-weighted imaging (T1WI+) with precontrast T1-weighted (T1WI-), T2-weighted (T2WI), and proton density-weighted imaging (ProWI) in depiction of the anterior disc displacement (ADD) in temporomandibular disorders (TMDs).

STUDY DESIGN

A total of 120 joints with TMD were included in this study. Qualitatively, Receiver operating characteristic analysis was performed. Quantitatively, the ratio of the intensity in the retrodiscal tissue to intensity in the disc (intensity ratio) was measured.

RESULTS

One reader achieved superior performance in visualization of ADD with T1WI+ than with the other sequences. The other reader showed superiority with T1WI+ rather than T2WI or T1WI-. The intensity ratio on T1WI+ was significantly higher than the intensity ratio on other sequences. On T1WI,+ the intensity ratio in the joints with ADD was significantly higher than that in the joints without ADD.

CONCLUSION

Postcontrast T1-weighted imaging can improve the visualization of ADD in TMDs.

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.

Electrophoretically separation of the synovial fluid proteins in rabbit temporomandibular arthritis induced by mechanical loading

BACKGROUND

The concentration of protein in synovial fluid (SF) of temporomandibular joints (TMJs) with disorders tends to be increased. We investigated the protein composition of SF of rabbits in which arthritis of the TMJ was induced.

METHOD

Arthritis was induced in six TMJs in six rabbits by exertion of a load for 4 weeks. Six non-loaded TMJs in six rabbits served as controls. The protein concentration and content in TMJ SF of the two groups were compared.

RESULTS

The mean protein concentration was higher in the SF of the loaded group than in that of the non-loaded group (1824 microg/ml vs. 398 microg/ml, P = 0.002). Proteins with molecular weights of more than 95 kDa were abundant in the loaded group (P < 0.05).

CONCLUSION

Temporomandibular arthritis induced by mechanical loading in rabbit is accompanied by an increase in the abundance of relatively high molecular weight proteins in SF.

Relationship between internal derangement of the temporomandibular joint and dentofacial morphology in women with anterior open bite

INTRODUCTION

Anterior open bite is known to be associated with internal derangement of the temporomandibular joint (TMJ). This study examined the relationships between internal derangement and dentofacial morphology in women with anterior open bite.

METHODS

Fifty-one women with anterior open bite were enrolled in this study. The sample was divided into 3 groups based on magnetic resonance imaging of bilateral TMJs: normal disk position, disk displacement with reduction, and disk displacement without reduction. One-way analysis of variance was used to compare the 3 groups with respect to the cephalometric variables, and Duncan's multiple comparisons were performed at the 95% confidence level to identify the differences among the 3 groups.

RESULTS

Internal derangement of the TMJ was much more prevalent in subjects with a more posteriorly rotated mandibular ramus, a smaller mandible, and a greater tendency for a skeletal Class II pattern, although all subjects had an anterior open bite. These patterns were more severe as the internal derangement progressed to disk displacement without reduction.

CONCLUSIONS

Some cephalometric characteristics, such as a decrease in posterior facial height, decrease in ramus height, and backward rotation and retruded position of the mandible, are associated with TMJ internal derangement in women with anterior open bite.

Tempromandibular joint (TMJ) response to intra-articular dexamethasone injection following mechanical arthropathy: a histological study in rats

The purpose of this study was to evaluate as well as to compare the effect of intra-articular versus intra-peritoneal injection of dexamethasone on synovitis induced by trauma to the rat's TMJ. Twenty-seven male Wister rats were included in the present study. Induced forced condylar hypermobility achieved through opening the rat's mouth manually 10 times for 10 consecutive days. Rats were randomized into three groups (3 rats in the control group, and 24 rats in both experimental groups). Group I (control group): Rats of this group were left without any treatment after induction of synovitis. Group II: Rats were injected with a single dose of 1.2 mg/kg dexamethasone intra-articularly (after 10 days). Group III: Rats were injected with a single intra-peritoneal injection of 1.2 mg/kg dexamethasone (after 10 days). Control rats were sacrificed at 6 weeks, while rats in Groups II and III were sacrificed at 1 and 6 weeks after drug injection, then joints were dissected and processed for histological study. The condylar head of the rats injected with intra-articular dexamethasone showed resorption with active osteoclastic activity, although the drug was given only once. This might be an alarming sign of the severe adverse effect(s) of the local injection of dexamethasone.

Histologic evaluation of temporomandibular arthritis induced by mild mechanical loading in rabbits

BACKGROUND

We still lack knowledge of causative factors in arthritis related to temporomandibular disorders (TMD). The goal of the present study was to investigate whether applying a mechanical loading on the glenoid fossa can induce arthritis.

METHODS

Coil springs were placed in 24 rabbits so as to exert a force of 100 g between the orbital edge and the antegonial notch. At 1, 2, 4 and 8 weeks after the surgery, six samples of the temporomandibular joint (TMJ) were removed for histologic examination.

RESULTS

The results showed that mild synovitis began 1-2 weeks after the start of loading, and the degree of synovitis was significant at 4 weeks, and that morphologic changes occurred in the articular eminence and condyle, while type II collagen in the cartilage of the articular eminence degraded prior to that in the condyle.

CONCLUSIONS

Our results revealed that mild, continuous mechanical loading to the glenoid fossa induces synovitis of the articular capsule, and induces organic changes of the articular cartilage without destroying these tissues.

The prevalence of osteoarthrosis in cases of advanced internal derangement of the temporomandibular joint: a clinical, surgical and histological study

INTRODUCTION

The articular disk has a central role in the pathology of internal derangement of the Temporomandibular Joint (TMJ). What is less clear is the role of osteoarthrosis in the development of internal derangement. The aim of this study is to determine the prevalence of osteoarthrosis in cases of advanced and recalcitrant TMJ internal derangement that were treated by diskectomy.

MATERIALS AND METHODS

This study involved 22 joints in 18 patients who underwent surgery for the treatment of advanced and recalcitrant internal derangement of the TMJ. All patients included in the study failed to respond to at least 6 months of pre-operative conservative treatment and the clinical diagnoses of advanced TMJ internal derangement were confirmed on pre-operative MRI's. Tissue specimens were obtained from all 22 joints for histopathology. The specimens included articular disks that were excised from all 22 joints which were found to have severely displaced and deformed disks that were judged to be irreparable at the time of surgery. Also included were eight tissue samples from the mandibular condyles that were judged to be diseased on pre-operative tomograms and at the time of surgery. All samples were prepared in serial sections in the standard way and examined under light microscopy by two experienced Oral Pathologists.

RESULTS

There were 22 specimens of articular disk examined together with 8 specimens from the mandibular condyle. All 22 joints (100%) showed histological evidence of disk pathology and eight of the 22 joints (34.4%) were found to have condylar pathology. The most common disk pathology was hyalinization indicative of disk degeneration (12/22). The most common condylar pathology found was articular surface degeneration indicative of osteoarthrosis (8/22).

CONCLUSION

The clinical and radiological diagnoses of advanced TMJ internal derangement correlated with histological findings of degeneration and inflammation of the articular disk in all 22 specimens. The 8 specimens obtained from the condylar head showed histological features consistent with osteoarthrosis. This study showed that osteoarthrosis and internal derangement were found to co-exist in the same joint in about one-third of cases. The fact that osteoarthrosis was not found in all cases suggests that perhaps the widely held view that subclinical osteoarthrosis may lead to pathologic tissue responses in the form of internal derangement will need to be re-examined.

Inflammatory cell and cytokine patterns in patients with painful clicking and osteoarthritis in the temporomandibular joint

The occurrence of a subset of cytokines and leukocytes in the posterior disc attachment area of the temporomandibular joint (TMJ) was investigated in two patient groups, i.e, one group with painful clicking and one with osteoarthritis. Synovial biopsies were taken during discectomy in 19 patients with painful clicking and 20 with osteoarthritis. One set of specimens was examined with immunohistochemistry, using frozen sections postfixed by para-formaldehyde and with the cell membranes permeablized in saponin. These sections were incubated with antibodies against cytokines IL-1alpha, IL-1beta, IL-1ra, TNFalpha, IFNgamma, IL2 in all patients and TGFbeta1,2,3 in 16. The other set of specimens was used to characterize cell infiltrates using immunohistochemistry with monoclonal antibodies against antigens CD68 and CD45RO, respectively. Moreover, PCNA was included as a marker for cell proliferation. The cytokine staining was most frequently positive for IL-1alpha and IL-1beta in both patient groups. However, joints with OA showed a more complex cytokine pattern, also involving IFN-gamma (P = 0.019), IL-ra (P = 0.047), and apparently but without reaching the chosen level of significance, IL-2, TNF-alpha and TGF-beta1,2,3. Positive staining for CD45RO was frequent in both groups. OA patients showed more frequently positive staining for CD68 (P = 0.025) and apparently for PCNA.

Does decreased T1 signal intensity in the retrodiscal tissue of the temporomandibular joint reflect increased density of collagen fibres?

OBJECTIVE

To evaluate whether decreased signal intensity on T(1) weighted MR images of the retrodiscal tissue of the temporomandibular joint (TMJ) reflects increased density of collagen fibres.

METHODS

Corrected sagittal T(1) weighted MR images of six TMJs from six fresh cadavers (three males and three females; age range 76-87 years, mean 80.8 years) were obtained. Following MRI, slices of tissue samples were taken from the cadavers that exactly matched the planes of the MR image. These samples were fixed, decalcified and stained (haematoxylin-eosin stain, Elastica van Gieson's stain) for light microscopy. The samples were evaluated for density of collagen fibres according to Hall et al (1984) and for vascularity, arterial wall thickness, fat content and elastin. In these sagittal samples, the retrodiscal tissue was divided anteroposteriorly and vertically into six areas and each area was classified by histological parameters. The MR images were similarly divided into six areas. Areas with reduced signal intensity were classified as the low signal group and those with no reduced signals were classified as the control group.

RESULTS

Collagen density assessed histologically differed between the low signal intensity group and the control group, and loose collage density on the histological samples was observed significantly more often in the low signal group (Fisher's exact test, P=0.03). There were no statistically significant differences in the other categories between the two groups.

CONCLUSION

The results suggest that reduced T1 signals of retrodiscal tissue do not necessarily reflect a dense distribution of collagen fibres.

Does joint effusion on T2 magnetic resonance images reflect synovitis? Part 3. Comparison of histologic findings of arthroscopically obtained synovium in internal derangements of the temporomandibular joint

OBJECTIVES

To evaluate the relationship between the volume of joint effusion (JE), determined by T2-weighted magnetic resonance imaging (MRI), and microscopic findings of synovial inflammation in internal derangement of the temporomandibular joint (TMJ).

STUDY DESIGN

Magnetic resonance images of 53 symptomatic TMJs (53 patients) associated with painful hypomobility were taken to evaluate the degree of JE on a scale of 0 to 3. Within 2 months after MRI, biopsy specimens obtained by arthroscopy were quantitatively assessed, on the basis of Gynther's grading system, for severity of hyperplasia of synovial lining cell layers, vascularity, and the presence of inflammatory cells. Each synovitis score was compared among the 4 JE grades, as well as between 2 groups-effusion present (grades 2 and 3) and effusion absent (grades 0 and 1)-by using the Spearman correlation coefficiency and the Mann-Whitney U test.

RESULTS

The distribution of JE was as follows: 14 joints had grade 0, 9 joints had grade 1, 19 joints had grade 2, and 11 joints had grade 3. Significant relationships were found between the grades of JE and scores of synovial lining cell layers (P =.0012) as well as between the grades of JE and scores of presence of inflammatory cells (P =.0064). The joints with effusion had significantly higher scores for synovial lining cell layers (2.0 +/- 0.2) than the joints without effusion (1.3 +/- 0.2) (P =.029). There was no statistically significant correlation between the scores of vascularity and JE (P =.394).

CONCLUSIONS

The evidence of JE on MRI might correlate with synovial inflammatory activity. It confirms the common consensus that JE probably reflects synovitis, especially when synovial hyperplasia has a key role in the pathogenesis of JE.

Correlation between the arthroscopic diagnosis of synovitis and microvessel density in synovial tissues in patients with internal derangement of the temporomandibular joint

OBJECTIVE

To elucidate the correlation between the arthroscopic diagnosis of synovitis and microvessel density in synovial tissues in patients with internal derangement of the temporomandibular joint (TMJ).

STUDY DESIGN

Forty-three joints in 41 patients with internal derangement were examined and biopsies taken. Microvessel density was evaluated using the immunohistochemical method for CD 34 antibody. Arthroscopically diagnosed synovitis was evaluated according to Murakami's criteria.

RESULTS

In patients with internal derangement, arthroscopically diagnosed synovitis scores averaged 5.2+/-2.0, according to Murakami et al. (1991). Small to large blood vessels were observed clearly with CD 34 stain. The mean microvessel density was 22.7+/-15.6 per two high power fields (magnification x200). Synovitis scores correlated significantly with microvessel density (p=0.002, r=0.43).

CONCLUSION

Synovitis evaluated using Murakami's scores correlated well with the number of blood vessels in synovial tissues in patients with internal derangement of the TMJ. This demonstrates that synovitis is linked to inflammation-related blood vessel density of the synovial tissues.

Ultrastructural study of synovitis induced by trauma to the rat temporomandibular joint (TMJ)

BACKGROUND

Electron microscopy was used to examine the histologic effect of trauma on the rat temporomandibular joint synovial membrane.

METHODS

Trauma to the TMJ in male Wister rats (100-200 g) was introduced through repeated forced condylar hypermobility. Ultrastructural observations were made 5 days and 6 weeks after the trauma.

RESULTS

The early response of the synovial membrane was synovial hyperplasia, type A synovial cell loss, dilation of the r-ER in the type B synovial cells and fibrin deposition on the synovial surfaces. The late response included degeneration of synovial cells with swollen mitochondria and cell projections, and cell fragmentation. Large amount of fibrin deposition on opposing surface layers was also noticed.

CONCLUSION

The type A cell loss and fibrin deposition followed by the occurrence of fibrinous materials at opposing surface layers of the synovial membrane suggest that traumatic synovitis causes synovial adhesions.

Co-expression of interleukin-1beta and tumor necrosis factor alpha in synovial tissues and synovial fluids of temporomandibular joint with internal derangement: comparison with histological grading of synovial inflammation

BACKGROUND

It has been clarified that interleukin-1 (IL-1)beta and tumor necrosis factor (TNF)alpha play an important role in pathogenesis of various joint disease. The purpose of this study was to investigate the cellular source of IL-1beta and TNFalpha in temporomandibular joint (TMJ), and to analyze the relation between the expression of these cytokines and the intensity of TMJ synovial inflammation.

METHODS

We examined 33 synovial biopsy specimens from patients with internal derangement of the TMJ by an immunohistochemical technique using specific antibodies to IL-1beta and TNFalpha. We also studied 20 synovial fluids from the patients by enzyme-linked immunosorbent assay method. These data are compared with histological grading of synovial inflammation by Gynther's system.

RESULTS

Both IL-1beta and TNFalpha were predominantly localized in the synovial lining cell layer and the blood vessels of synovial biopsy specimens obtained from patients with TMJ internal derangement. A statistically significant correlation was found between the intensity of IL-1beta expression and that of TNFalpha. Additionally, the intensity of TNFalpha expression was statistically correlated with histological grading by Gynther's system.

CONCLUSION

These results supported that IL-1beta and TNFalpha may be involved in the occurrence of TMJ internal derangement and that they coordinately play an role in pathogenesis of TMJ internal derangement.

Characterization of tissue components in the temporomandibular joint disc and posterior disc attachment region: internal derangement and control autopsy specimens compared by morphometry

PURPOSE

Our aim was to morphologically investigate the occurrence of fibroblasts, chondrocytes, and blood vessels in the tissue of the temporomandibular joint (TMJ) disc, the intermediate zone, and the posterior disc attachment region in control autopsy specimens and to compare the results with those observed in corresponding tissues from patients with TMJ internal derangement.

PATIENTS AND METHODS

First, 20 bilateral TMJ disc specimens from selected autopsy cases were analyzed by conventional morphometry. Thus, the volume density of fibroblasts, chondrocytes, and blood vessels was determined. Second, the obtained results from the right joint of the autopsy disc specimens were compared with 12 TMJ disc specimens obtained at surgery from patients with internal derangement.

RESULTS

The tissue compartments of interest (disc, intermediate zone, and posterior disc attachment region) were identified unequivocally in all specimens. None of the autopsy cases showed any significant difference between the right and left joints or related to gender. The only variable that differed between autopsy and patient specimens was volume density of blood vessels, which was higher in patient specimens.

CONCLUSIONS

We found that the volume density of blood vessels was significantly higher in the posterior disc attachment region in patient specimens than in autopsy controls. Whether this reflects a role for vessels in the pathogenesis of TMJ internal derangement or merely is a reaction to another type of injury remains to be settled. In both the autopsy control and patient specimens, chondrocytes and fibroblasts were characteristic for disc respective posterior disc attachment region. Thus it appears that the occurrence of these cells can be used to distinguish TMJ disc from posterior disc attachment in small biopsy specimens.

Interleukin-1beta stimulates interleukin-8 production and gene expression in synovial cells from human temporomandibular joint

PURPOSE

The aims of the present study were to isolate and characterize cultured synovial cells from human temporomandibular joint (TMJ) specimens and to investigate the effect of interleukin (IL)-1beta on IL-8 production and gene expression in those cells.

MATERIALS AND METHODS

Synovial cells (HTS cells) were isolated from TMJ synovial tissues using an outgrowth method and then primary cultured. The cells were examined for cell-specific markers of fibroblast, macrophage, and dendritic cells using immunocytochemistry. HTS cells were then treated with IL-1beta, and amounts of IL-8 were measured by enzyme-linked immunosorbent assay. IL-8 production and expression were also investigated using immunocytochemistry and a reverse transcription-polymerase chain reaction method.

RESULTS

HTS cells were positive for the fibroblast-specific markers, such as vimentin and propyl 4-hydroxylase. The macrophage or dendritic cell markers and HLA class II antigen were negative. Furthermore, IL-1beta enhanced IL-8 production in HTS cells in a time- and dose-dependent manner and stimulated IL-8 gene expression.

CONCLUSIONS

HTS cells may provide important advantages for studies of the cellular and molecular mechanisms in the TMJ. In addition, we found that IL-1beta stimulated IL-8 production through an increase in IL-8 gene expression in HTS cells, which may be associated with the increase of infiltrating inflammatory cells seen in the synovial membrane of TMJ disorders.

Microscopic analysis of the temporomandibular joint in rabbits (Oryctolagus cuniculus L.) using an occlusal interference

The purpose of this study was to assess the tissue alterations in the temporomandibular joint (TMJ) of the New Zealand White rabbit (Oryctolagus cuniculus L.), after a unilateral occlusal interference insertion on the animal's right side back teeth. A total of 36 animals were used, thirty of which belonged to the experimental group and six to the control group. We established three experimental periods: 24 hours, three days and seven days. The control group animals were divided two by two; each pair followed the same experimental periods of the former one. The experimental group animals were submitted to the use of a 0.3 mm thick metallic cap with a visor. All animals were euthanized, and the TMJs were removed. Using a microscope for examination we observed, in all experimental periods, the presence of intra-articular hemorrhage in the supra- and infra-disk compartments as well as in the retro-disk zone. There were no inflammatory cells detected. The thickness of the condylar fibrocartilage presented significant alterations among the animals of the three experimental groups. In the left TMJs no inflammatory cells were detected. The results suggest that the insertion of a unilateral occlusal interference in rabbit back teeth does not cause any inflammatory intra-articular process within seven days; however, it does cause bilateral intra-articular hemorrhage and a larger compression of the condylar fibrocartilage in the joint opposite the side where the interference is placed. We also concluded that, in order to do research on the temporomandibular joint using animals, it is necessary have an independent (or separate) group of animals as controls.

MR grading of temporomandibular joint fluid: association with disk displacement categories, condyle marrow abnormalities and pain

The purpose of this study was to investigate temporomandibular joint (TMJ) effusion on magnetic resonance (MR) images, and its association with specific categories of disk displacement, bone marrow abnormalities and pain. From a series of 523 consecutive TMJ MR imaging studies of patients referred to imaging because of pain and dysfunction, those with TMJ effusion, defined as an amount of fluid that exceeded the maximum amount seen in a control group of asymptomatic volunteers, were analysed. The selected patients were reassessed and the amount of TMJ fluid was graded bilaterally according to a set of reference films. Other parameters recorded included disk displacement categories and condyle marrow abnormalities. Pain self-records were obtained from the patients immediately before MR imaging. The association between the recorded parameters and TMJ pain was analysed with t-tests and regression analysis. Of the 523 patients, 70 (13%) had TMJ effusion, which was unilateral in 61%. Only 9% of the 70 patients had effusion bilaterally, whereas bilateral disk displacement was found in 80%. In the 76 joints with effusion, 83% showed two specific categories of disk displacement at closed mouth. Condyle marrow abnormalities were found in 31% of the 70 patients, mostly on one side, and in 24% of the 76 joints. An in-patient regression analysis of the side difference in TMJ pain showed that effusion and condyle marrow abnormalities were significant pain-increasing factors. In conclusion, patients with TMJ effusion represent a subgroup with pain and dysfunction with more severe intra-articular pathology than those with disk displacement but no other joint abnormalities.

Male adolescent facial pattern associated with TMJ disk displacement and reduction in disk length: Part II

Dental practitioners continually strive to understand and determine which factors influence craniofacial morphology and how these factors may be controlled to provide the best treatment outcome for patients. Recently, an association between internal derangement of the TMJ and altered facial morphology was shown in an adolescent female sample by means of multiple regression techniques. The present study aims to determine whether similar associations are present between facial patterns exhibited by a preorthodontic male sample (n = 70) and varying degrees of TMJ internal derangement as assessed by magnetic resonance imaging. Multiple regression techniques were used to test the associations in 5 facial regions. Associations between internal derangement and craniofacial morphology differed in 3 of the facial regions when males and females were compared. However, associations between internal derangement and alteration in mandibular morphology and positioning were consistent in both gender groups.

Orofacial deep and cutaneous tissue inflammation differentially upregulates preprodynorphin mRNA in the trigeminal and paratrigeminal nuclei of the rat

Preprodynorphin (PPD) and preproenkephalin (PPE) gene expression in a rat model of orofacial inflammation were examined in order to further characterize the neurochemical mechanisms underlying orofacial inflammation and hyperalgesia. Deep and cutaneous orofacial inflammation was produced by a unilateral injection of complete Freund's adjuvant (CFA) into the rat temporomandibular joint (TMJ) or perioral skin (PO), respectively. RNA blot analysis of the tissues including the spinal trigeminal complex revealed that the PPD mRNA level ipsilateral to TMJ inflammation was increased by 56.5+/-14.7% (n=4) when compared to the Naive group, and was significantly greater than the contralateral PPD mRNA level (p<0.05). The distribution of neurons that exhibited PPD mRNA after inflammation was localized by in situ hybridization (naive approximately 0). In TMJ-inflamed rats (n=6) PPD mRNA-positive neurons were found ipsilaterally in the medial portion of laminae I-II of the upper cervical dorsal horn (4.5+/-0.3), the dorsal portion of the subnucleus caudalis and caudal subnucleus interpolaris (5.2+/-0.3), and the paratrigeminal nucleus (6.4+/-1.2). A very localized induction of PPD mRNA was also identified in a group of neurons in the intermediate portion of the subnucleus caudalis (2.4+/-0.4) in PO-inflamed rats (n=6). The distribution of these PPD mRNA-positive neurons was somatotopically relevant to the site of injury. There were no significant changes in PPE mRNA expression in both TMJ- and PO-inflamed rats. These results indicate that TMJ inflammation resulted in a more intense and widespread increase in PPD mRNA expression when compared to PO inflammation. These changes may contribute to persistent central hyperexcitability and pain associated with temporomandibular disorders.

Arthroscopic findings in osteoarthritic temporomandibular joints

PURPOSE

This article reports on the results of a study of the arthroscopic findings in the joint surfaces of osteoarthritic temporomandibular joints (TMJs).

PATIENTS AND METHODS

Arthroscopy was performed in the upper joint compartment of 40 TMJs in 40 patients. Thirty-one TMJs that were diagnosed with osteoarthritis (OA) constituted the OA group. On the basis of the presence of symptoms related to disc displacement and perforation, OA subgroups were defined. Nine TMJs that were not involved with OA constituted the control group. During the examination, various arthroscopic variables were recorded. Differences between groups and between subgroups were tested statistically.

RESULTS

In the OA group, several arthroscopic variables were found significantly more frequently than in the control group. These included retrodiscal tissue redundancy, adhesions, and heightened attachment to the posterior wall of the glenoid fossa; articular disc displacement and limited mobility; and cartilage degeneration in the articular eminence. Moreover, in the OA group, disc displacement was found significantly more frequently in the period after 6 months than during the first 6 months of clinical signs and symptoms. Anterodiscal hypervascularity was found significantly more frequently during the first year than after the first year, as well as more during the first 2 years than after the first 2 years of clinical signs and symptoms, whereas a lowered attachment on the anterior slope of the articular eminence was found significantly more often after 2 years than during the first 2 years of clinical signs and symptoms.

CONCLUSIONS

The findings in this study suggest that OA of the TMJ may initially result in synovial tissue hypervascularity, creeping synovitis, and redundancy, and subsequently in adhesion formation and a reduction of the posterior and anterior recess. Because of cartilage fibrillation on the articular eminence, and the subsequently reduced surface smoothness, the articular disc may become displaced. Eventually, disc mobility is limited, and adhesions and a reduced posterior and anterior recess prevail.

Development and histologic characteristics of synovitis induced by trauma in the rat temporomandibular joint

Histopathological changes caused by trauma to the rat temporomandibular joint synovium were examined by light microscopy. The trauma was induced by forced hypermobility of the condyle. Pathological changes of the synovium were found primarily in the anterior pouch of the upper joint compartment. The main findings included surface cell proliferation, increased capillary hyperemia, fibrin deposits on the surfaces of inflamed synovial membranes, and fibrinous adhesion between closely opposed synovial membranes. A gradual change from fibrinous adhesion to fibrous adhesion was also seen.

Histologic study of synovitis induced by trauma to the rat temporomandibular joint

OBJECTIVE

The purpose of this study was to establish and histologically examine the time course of synovitis induced by trauma to the rat temporomandibular joint.

STUDY DESIGN

Synovitis of the temporomandibular joints of 8-week-old male Wister rats was induced by forced condylar hypermobility, which was administered 10 times successively once a day for 10 days. Pathologic changes were observed microscopically at 2 and 5 days and 2, 4, 6, 8, 10, and 20 weeks after treatment.

RESULTS

Histologic findings from the 5th day to the 6th week after treatment were characterized by multiple layers of synovial cells, an increase of dilated vasculature, fibrin deposits, and synovial adhesion. These findings were in good agreement with those reported for the human temporomandibular joint. The pathologic changes decreased with advancing time, and synovitis was not observed at 20 weeks after treatment.

CONCLUSION

The present procedure for inducing synovitis of the temporomandibular joint in rats will be useful in understanding the pathogenesis of synovitis in human temporomandibular joints.

Synovial inflammation in arthroscopically obtained biopsy specimens from the temporomandibular joint: a review of the literature and a proposed histologic grading system

Data indicate that the synovial lining of the temporomandibular joint (TMJ) in some respects differs from other joints. The normal variation in morphology of the synovial lining of the TMJ is quite great, whereas the variation in pattern of pathologic changes appears to be relatively small (ie, synovial inflammation is not of the severity as that in other joints). In the current review, a system for histologic grading of synovial inflammation is proposed. The system is based on semiquantitative evaluation of the following set of parameters: 1) synovial lining cell layers; 2) vascularity (number or size of vascular profiles); and 3) Inflammatory cell infiltrate (commonly lymphocytes).

Synovial membrane involvement in osteoarthritic temporomandibular joints: a light microscopic study

OBJECTIVE

To study the light microscopic characteristics of the synovial membrane of osteoarthritic temporomandibular joints to evaluate synovial membrane involvement in the osteoarthritic process.

STUDY DESIGN

Synovial membrane biopsies were obtained during unilateral arthroscopy in 40 patients. Thirty-one temporomandibular joints were diagnosed with osteoarthritis. Osteoarthritis subgroups were defined on the basis of the presence of symptoms related to disk displacement and perforation. The control group consisted of nine temporomandibular joints that were not involved by osteoarthritis. During light microscopic examination of the synovial membranes, several light microscopic variables were recorded. Differences between groups and between subgroups were tested with chi 2 or Fisher's exact tests with Mann-Whitney U tests and with Student's t tests.

RESULTS

In the osteoarthritis group, the number of synovial intima cell layers was significantly higher, and fibrous intima matrix and fibrous subintima were found significantly more frequently than in the control group. Moreover, in the osteoarthritis group, intima cell hypertrophy in combination with a closely packed cell composition was found significantly more often in the first year of clinical signs and symptoms, whereas intima hyperplasia, fibrous intima matrix, dense surface material, and subintima elastic fibers were found significantly more frequently in the first 2 years of clinical signs and symptoms.

CONCLUSIONS

The findings in this study suggest that osteoarthritis of the temporomandibular joint may initially result in synovial intima hyperplasia and cell hypertrophy, and subsequently in deposition of fibrous material in the intima matrix. Eventually, fibrosis of the subintimal tissue may occur in combination with degeneration and subsequent normalization of the synovial intima cell layer. Overall, fibrosis was the most characteristic feature of synovial membranes of osteoarthritic temporomandibular joints. In conclusion, the involvement of the synovial membrane in osteoarthritis of the temporomandibular joint is characterized by an early proliferative phase and a late fibrous phase. It appears that the intense and prolonged fibrous phase may not be a normal appropriate response to an initial insult but rather an aberrant counterproductive response.

Temporomandibular joint involvement in generalized osteoarthritis and rheumatoid arthritis: a clinical, arthroscopic, histologic, and immunohistochemical study

Twenty patients having generalized osteoarthritis (GOA) and symptomatic temporomandibular joints (TMJs) were compared with 22 patients having rheumatoid arthritis (RA) and TMJ symptoms, and also with an age-matched reference tissue material obtained at autopsy from 17 TMJs. Muscle tenderness was commoner in GOA. Arthroscopically, high frequencies of synovitis, degenerative changes, and fibrosis were observed in both groups, with more pronounced inflammatory and degenerative changes in RA patients, despite a shorter duration of TMJ symptoms. A correlation was noted between lateral joint tenderness and pronounced synovitis in RA patients. Histologic and immunohistochemical examinations added useful information to arthroscopy and showed similarly high frequencies of synovial inflammation in GOA and RA patients, differing clearly from those in the reference material. Connective-tissue degeneration was commoner in GOA patients. GOA and RA probably have different causes, but, interestingly, the tissue reaction was similar in the TMJs, although pronounced inflammatory and degenerative changes seemed to develop faster in RA.

Temporomandibular arthropathy: correlation between clinical signs and symptoms and arthroscopic findings

The clinical signs and symptoms of temporomandibular arthropathy were correlated with arthroscopic features of temporomandibular joint disease in 200 consecutive patients. The diagnostic accuracy of the selected clinical signs and symptoms was also tested with arthroscopy as the standard, and sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) were calculated. Pronounced osteoarthrosis was more frequently associated with joint crepitus (P < 0.001). Adhesions were more frequently associated with reduced maximum protrusion (P < 0.001). Crepitation was the only clinical sign that showed acceptable values for SE, SP, PPV, and NPV, and only in diagnosing advanced osteoarthrosis. The values for mild osteoarthrosis were low.