Scanning electoronmicroscopical analysis of the loose bodies of synovial chondoromatosis in temporomandibular joint.

The aim of this study is to reveal the morphological property about the loose bodies (LBs) of temporomandibular joint (TMJ) by scanning electron microscope (SEM). We obtained specimens from two female cases of released loose body by surgical operation. These specimens were fixed by soaking in a mixture of 5% glutaraldehyde or 4% formaldehyde for one week. They were cut into half pieces. These specimens were observed at an accelerating voltage of 3 kV under a SEM (JSM-5500, JEOL, Tokyo). In the electron microscopic findings, it seems to be separated into two different parts as inside part and outside part. On the inside part, collagen fibers were running very densely in the same direction in an orderly neatly manner. Whereas, we observed waved collagen fibers running irregularly with many spaces on the outside part. Outside part seems to be porous pattern compared with inside part. It might be that the surface and outside part included many active fibroblasts. As results, it seems that the LBs might develop in a multi-layer style, in which fibrous tissues were piled up loosely around the inside part. The proliferating activity of LBs grows from the inside to outside of SC in TMJ.

Unilateral anterior crossbite induces aberrant mineral deposition in degenerative temporomandibular cartilage in rats.

OBJECTIVE: To investigate whether mechanical stress induces mineral deposits that contribute to matrix degradation at the onset of osteoarthritis (OA) in temporomandibular joint (TMJ) cartilage. DESIGN: Female Spraguee-Dawley rats were subjected to an unilateral anterior crossbite (UAC) procedure. Histology, electron microscopy, and energy dispersive spectrometer (EDS) were used to examine cartilage matrix structures and composition of mineral deposit in the affected TMJ cartilage. Protein and/or RNA expression of phenotypic markers and mineralization modulators and matrix degradation was analyzed by immunohistochemistry and/or real-time PCR. Synthetic basic calcium phosphate (BCP) and calcium pyrophosphate dehydrate (CPPD) crystals were used to stimulate ATDC5 cells for their impact on cell differentiation and gene expression. RESULTS: Fragmented and disorganized collagen fibers, expanded fibrous spaces, and enhancement of matrix vesicle production and mineral deposition were observed in matrices surrounding hypertrophic chondrocytes in cartilage as early as 2-weeks post-UAC and exacerbated with time. The mineral deposits in TMJ cartilage at 12- and 20-weeks post-UAC had Ca/P ratios of 1.42 and 1.44, which are similar to the ratios for BCP. The expression of mineralization inhibitors, NPP1, ANK, CD73, and Matrix gla protein (MGP) was decreased from 2 to 8 weeks post-UAC, so were the chondrogenic markers, Col-2, Col-X and aggrecan. In contrast, the expression of tissue-nonspecific alkaline phosphatase (TNAP) and MMP13 was increased 4-weeks post-UAC. Treating ADTC5 cells with BCP crystals increased MMPs and ADAMTS5 expression, but reduced matrix production in a time-dependent manner. CONCLUSION: UAC induces deposition of BCP-like minerals in osteoarthritic cartilage, which can stimulate matrix degradation by promoting the expression of cartilage-degrading enzymes to facilitate OA progression.

The influence of psychological stress on the rat temporomandibular joint with the application of countermeasures.

OBJECTIVE: This study aimed to provide an experimental theoretical basis for the treatment of temporomandibular disorders by observing the effects of psychological stress and countermeasures on the rat temporomandibular joint (TMJ). METHODS: Rats were exposed to psychological stress via a communication box and the lateral pterygoid muscle and TMJ were observed with transmission electron microscopy and scanning electron microscopy. Furthermore, the expression of interleukin-1 and tumor necrosis factor-α was assessed in control animals and psychological stress (PS) and stress with diazepam (PS+DI) groups. RESULTS: Transmission electron microscopy of the lateral pterygoid muscle fibers in the PS showed vacuolar changes in the mitochondria, loss of cristae, and reduced matrix density to variable degrees after 1, 3, and 5 wk of stress. After 5 wk stress+recovery, the cristae and matrix were normal in the PS and PS+DI groups. Scanning electron microscopy of PS rats showed some synovial membranes were detached from the surface of the articular disc after 1 wk. After 3 wk, collagen fibers appeared to have wider waves and worn strips changing in size on the articular disc; after 5 wk, the distribution of collagen fibers was distorted. In PS+recovery and PS+DI rats, no obvious changes were observed on the surface of the articular disc after 1 to 5 wk stress. In PS rats, interleukin-1 and tumor necrosis factor-α expression increased significantly but was at control levels in the PS+DI and PS+recovery groups. CONCLUSION: Counteracting psychological stress can antagonize its effects on the TMJ and provide a reference for the treatment of stress-related temporomandibular disorders.

Psychological stress induces alterations in temporomandibular joint ultrastructure in a rat model of temporomandibular disorder.

OBJECTIVE: The objective of this study was to investigate the effects of psychological stress on temporomandibular disorder (TMD). STUDY DESIGN: A communication box was used to induce psychological stress (PS) in rats. Then, the ultrastructure of temporomandibular was observed using scanning electron microscopy. Interleukin-1 (IL-1) and IL-6 were measured with reverse transcription polymerase chain reaction. RESULTS: The PS group showed evidence of ultrastructural changes in the condyle and articular disk after stimulation, i.e., incomplete gelatinlike material was observed on the condyle after 1 week of PS, wider waves on the articular disk and exposed condylar collagen were observed after 3 weeks of PS, and cracks were apparent on the surface of the condyle. The expression of IL-1 and IL-6 in the condyle cartilage significantly increased after exposure to psychological stress. CONCLUSIONS: These results indicate that psychological stress induces ultrastructure alterations in the temporomandibular joint and plays an important role in TMD.

Masseter muscle inserted in the temporomandibular joint discocapsular complex, a case report

The presence of muscle insertions in the temporomandibular joint disc have a great importance in the dynamic joint. This article presents a case of bilateral insertion of deep fascicle of the masseter muscle in the temporomandibular joint capsule and disc in a spain corpse, describes the microscopic and macroscopic appearance of variation and a brief review of the functional implications.

La presencia de inserciones musculares en el disco de la articulación temporomandibular tiene gran importancia en la dinámica de la articulación. En este artículo se presenta un caso de la inserción bilateral del fascículo profundo del músculo masétero en la cápsula y disco de la articulación temporomandibular en un cadáver español, se describe el aspecto macroscópico y microscópico de la variación y se realiza una breve revisión de las implicancias funcionales.

Biomechanical properties of the condyle created by osteodistraction.

A new condyle can be reconstructed by osteodistraction, but the biomechanical properties of the neocondyle remain unknown. This study examined the hypothesis that the biomechanical properties of neocondylar cancellous bone could reach control levels 24 weeks after its creation by osteodistraction. The right mandibular condyles were removed and reconstructed by osteo-distraction in 16 adult goats. Their contralateral condyles served as controls. Microstructural and mechanical properties were examined by microcomputed tomography and mechanical testing. At 24 weeks after distraction, the neocondyle grew larger in size, but the shape and histological features were similar to those of the controls. The cancellous bone of the neocondyle even appeared to be more dense and stiffer in comparison with the control condyle. The results of this study suggest that the neocondyle created by osteodistraction develops nearly normal biomechanical properties for functional loading by 24 weeks after creation.

Immunocytochemical localization of caveolin-3 in the synoviocytes of the rat temporomandibular joint during development.

Caveolins -- caveolin-1, -2, -3 (Cav1, 2, 3) -- are major components of caveolae, which have diverse functions. Our recent study on the temporomandibular joint (TMJ) revealed expressions of Cav1 and muscle-specific Cav3 in some synovial fibroblast-like type B cells with well-developed caveolae. However, the involvement of Cav3 expression in the differentiation and maturation of type B cells remains unclear. The present study therefore examined the chronological alterations in the localization of Cav3 in the synovial lining cells of the rat TMJ during postnatal development by immunocytochemical techniques. Observations showed immature type B cells possessed a few caveolae with Cav1 but lacked Cav3 protein at postnatal day 5 (P5). At P14, Cav3-immunopositive type B cells first appeared in the synovial lining layer. They increased in number and immunointensity from P14 to P21 as occlusion became active. In immunoelectron microscopy and double immunolabeling with heat shock protein 25 (Hsp25) and Cav3, coexpressed type B cells developed rough endoplasmic reticulum and numerous caveolae, while the Cav3-immunonegative type B cell with Hsp25 immunoreaction possessed few of these. Results suggest that Cav3 expression, which is closely related to added functional stimuli, reflects the differentiation of the type B synoviocytes.

Matrix metalloproteinase and its inhibitor in temporomandibular joint osteoarthrosis after indirect trauma in young goats.

Our aim was to examine the change in expression of matrix metalloproteinases (MMP-13), matrix metalloproteinases-3 (MMP-3), and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in the articular cartilage of goats with experimentally-induced osteoarthrosis of the temporomandibular joint (TMJ) at various times. Osteoarthrosis was induced in 20 goats in the bilateral TMJ and 5 goats acted as controls. There were 5 goats in each group, and a group was killed at 7 days, and 1, 3, and 6 months postoperatively. The samples were collected, and the joints evaluated histologically. Immunofluorescence was used to detect the presence of MMPs and TIMP-1 in the articular disc and condylar cartilage. The ultrastructure of the articular disc and condylar surface at 1 month was examined with scanning electron microscopy (SEM). Osteoarthrosis of the TMJ progressed gradually over time. MMP-13, MMP-3, and TIMP-1 were expressed strongly in the TMJ soon after injury; MMP-13 became gradually weakened, and MMP-3 strengthened later. None of these were expressed in the normal condyle. After a month the surface of the arthrotic condyle was uneven, and the underlying collagen fibrils were exposed in irregular fissures on the surface. The secretion of TIMP-1 was related closely to the changes of MMPs during osteoarthrosis of the TMJ. The unbalanced ratio between them caused degradation of the matrix of the cartilage and might be the cause of osteoarthrosis of the TMJ.

Ultrastructural study of the temporomandibular joint after unilateral meniscectomy in Wistar rats.

Meniscectomy of the temporomandibular joint (TMJ) was frequently performed until a few years ago but now is seldom employed. This procedure induces important articular modifications but the complete extent of ultrastructural changes is still unknown. Twenty-one Wistar rats were submitted to unilateral meniscectomy. Animals were randomly divided into three groups and followed for 15, 35 or 60 days. After killing both meniscectomized and contralateral TMJ specimens were sectioned sagittally and prepared for light and scanning electron microscopy studies. Normal TMJs are characterized by glenoid fossa and condylar process with distinct conjunctive layers in which regularly arranged type 1 collagen fibres predominate. Meniscectomized animals initially exhibit a different tissue covering the eroded articular surface of the condyle with the prevalence of type 3 collagen fibres but type 1 fibres predominate in the late postoperative period. Subchondral cysts are clearly visible. A complex remodelling process of the TMJ after meniscectomy is evident with important ultrastructural modifications that may correlate to unsatisfactory clinical results. The dynamic nature of this process is also observed when specimens from different postoperative periods are compared. Surgeons should always bear in mind these alterations when indicating this procedure.

Avaliação ultra-sonográfica dos distúrbios intra-capsulares têmporo-mandibulares / Ultrasonography evaluation of the temporomandibular joint internal derangements

Com o intuito de avaliar a sensibilidade e a especificidade do exame ultra-sonográfico para a avaliação dos distúrbios da articulação têmporo-mandibular (ATM) estudamos um grupo controle de 10 pacientes hígidos e 38 pacientes com queixas articulares e comparamos os resultados obtidos com a ressonância magnética, padrão ouro para o estudo da ATM. O trabalho evidenciou alta sensibilidade e especificidade para a localização do disco articular com o paciente em repouso, não apresentando bons resultados para a análise de alterações morfológicas condilares e do disco articular, e embora o método ainda apresente limitações, a sua utilização pode vir a ser uma opção útil ao exame de RM / Aiming at evaluating the sensibility and specificity of the ultrasound examination for the study of the disturbances of the temporomandibular joint (TMJ) we have studied a control group of 10 healthy patients and 38 other patients with articular complaints and we have compared the results obtained with the magnetic resonance, gold standard for the study of the TMJ. The work has shown high sensibility and specificity for the location of the articular disk with the patient at rest, not presenting good results for the analysis ofarticular disk and condyle morphologic alterations and, although it still presents some limitation, the method may turn out to be a helpful option to the MR exam...

Morphology and ultrastructure of the temporomandibular joint disc in human fetuses 21 to 28 weeks old

Ultrastructure of human fetuses temporomandibular joint is poorly understood specially by scanning electron microscopy and cryofracture techniques. In this work, the morphology of the temporomandibular joint (TMJ) articular disc and its insertions was examined in 12 human fetuses. Four TMJs were sectioned in the frontal and sagittal planes and five were cryofractured prior to examination using light and scanning electron microscopy. The three remaining TMJs were fixed, embedded in paraffin, sectioned and stained with HE and NMC trichrome. The articular disc inserted into the mandibular head, temporal bone, joint capsule and upper head of the lateral pterygoid muscle. The fibrous architecture of this disc was complex, with longitudinal fibers predominating in the upper and lower regions, and interposed transverse and oblique fibers predominating in the central region.

Immunocytochemical localization of MAPKAPK-2 and Hsp25 in the rat temporomandibular joint.

One series of our research has shown an intense expression of immunoreaction for heat shock protein 25 (Hsp25) in various cellular elements in the rat temporomandibular joint (TMJ). This protein is the major substrate of mitogen-activated protein kinase-activated protein kinase-2 (MAPKAPK-2), which mediates an intracellular stress-activated signaling pathway to stimulate cytosolic actin reorganization under various stresses. The present study was undertaken to examine the localization of MAPKAPK-2 in the rat TMJ by immunocytochemical techniques. Furthermore, confocal microscopy with double staining was employed to demonstrate the colocalization of MAPKAPK-2 and Hsp25. Immunocytochemistry for MAPKAPK-2 showed an intense immunoreaction in the cytoplasm of the synovial lining cells, the endothelial cells, and the fibroblasts in the synovial membrane of the rat TMJ. Double immunostaining under a confocal microscope succeeded in demonstrating the colocalization of MAPKAPK-2 and Hsp25 immunoreactions in the cytoplasm of fibroblastic type B synoviocytes in the TMJ. On the other hand, the macrophage-like type A-cells expressed MAPKAPK-2 immunoreactions but lacked Hsp25 immunoreactivity. The cells in the articular disk and the chondrocytes in the maturative and hypertrophic layer of the mandibular cartilage also showed intense immunoreactions for MAPKAPK-2 and Hsp25. In addition to cytoplasmic localization, MAPKAPK-2 immunoreactions were found in the nucleus of some synovial lining cells, cells in the articular disk, and chondrocytes. Current observations imply the presence of the phosphorylation of Hsp25 via activated MAPKAPK-2 in the cytoplasm. MAPKAPK-2 and Hsp25 possibly participate in the induction of cytoskeletal changes to the various cellular elements in rat TMJ under normal conditions.

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

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

The microanatomy of the rhesus monkey temporomandibular joint.

PURPOSE: The objective of this study was to describe and compare the histology of the rhesus monkey temporomandibular joint (TMJ) with that of the human joint. MATERIALS AND METHODS: Seventeen rhesus monkeys (Macaca mulatta) with an age range from 4 to 11 years were used. Both TMJs of the first animal and the left TMJs of the remaining 16 animals were used for this study. The joint specimens were sectioned sagittally and processed for light and electron microscopic studies. RESULTS: The rhesus monkey TMJ consists of the condylar, glenoid fossa, and articular disc components. The histology of these components is described at the light and electron microscopic level. CONCLUSIONS: The monkey TMJ was found to be anatomically similar to the human joint. It was concluded that the rhesus monkey is one of the most suitable animal models for studies involving the TMJ.

Morphology of the lateral ligament in the human temporomandibular joint.

The morphology of the lateral ligament of the human temporomandibular joint is of two types: ligamentous and without distinct structure. Under the scanning electron microscope, a sheath-like structure that contained bundles of collagen was mainly found in the posterior region of the lateral ligament. Analysis of macromolecular components revealed that type III collagen was mainly present on the collagenous framework of the sheath-like structure. Type I collagen, laminin, and tenascin were found in the framework of the sheath-like structure. Supported collagenous bundles and the distribution of macromolecular components might be related to the stability of the temporomandibular joint. The sheath-like structure and other components of the lateral ligaments store energy and protect the capsule from stress and tension during movements of the jaw.

Endoarticular loose bodies and calcifications of the disk of the temporomandibular joint: morphological features and chemical composition.

We studied articular disks and endoarticular loose bodies taken from patients suffering from different types of temporomandibular joint (TMJ) pathology. The scanning electron microscopy (SEM) analysis of the disks and the endoarticular loose bodies was followed by a chemical-compositional analysis using an energy dispersive spectrometer (EDS) and by characterization of the crystalline phases by X-ray powder diffraction (XRD). The articular disks were composed of a central radiopaque area lacking any evident structural features, surrounded by compact bundles of collagen fibers. EDS and XRD analyses showed that endodiscal radio-opaque areas were hydroxyapatite. By SEM, we observed a fibrous network only in circumscribed areas of the endoarticular loose bodies. The chemical-compositional analysis showed that the loose bodies were composed of calcite (CaCO3). The results of this investigation, along with the clinical history of the patients, allow us to formulate some hypotheses regarding the etiopathogenesis of these structural anomalies. The endodiscal calcifications could be the result of a chronic inflammatory process that produces displastic alterations of the articular disk. Moreover, an acute inflammatory process with modifications in the mechanisms of the synovial fluid turnover seems to be the event that leads to the formation of endoarticular loose bodies.

Estudio descriptivo macro-microscopico y radiografico del condilo mandibular, articulacion costocondral extremo esternal de la clavicula y metatarsiano en humanos / Morphologic and radiographic characteristics of the mandibular condyle, the sternal end of the clavicle, the costochondral junction and the metatarsal bone in humans

Se realizó un estudio en 12 especímenes de autopsia de humanos adultos, 6 hombres y 6 mujeres, de los cuales se tomó un cóndilo mandibular, el extremo esternal de la clavícula, la unión costocondral de la quinta costilla y el cuarto metatarsiano. Se realizó una descripción de las características tanto macro como microscópicas y una descripción de las características radiográficas de cada una de las articulaciones. Se observó que el metatarsiano es el que tiene mayor similitud con el cóndilo mandibular desde el punto de vista macroscópico y radiográfico, pero el extremo esternal de la clavícula es más parecido al cóndilo mandibular desde el punto de vista histológico

Experimental temporomandibular joint disc perforation in the rabbit: a gross morphologic, biochemical, and ultrastructural analysis.

This study evaluates the progression of osteoarthritis (OA) in the adult New Zealand white rabbit temporomandibular joint following unilateral disc perforation. Thirty-seven animals were divided into five groups: control (n = 8), 6-week sham (n = 5), and experimental 6-, 12-, and 24-weeks (n = 8 each). Quantitative data was examined with two-way analysis of variance, and followed by Scheffe pair-wise comparisons. Transmission electron microscopy, acid phosphatase [AcP] activity, uronic acid content, and gross morphologic analysis indicated that disc perforation induced remodeling activity and degenerative changes in the condylar cartilage and bone as early as 6 weeks postoperatively. AcP activity of homogenized cartilage samples was significantly increased in experimental joints versus the side that did not undergo surgery at 6 and 12 weeks (P < .05). Uronic acid content was significantly greater in experimental joints versus the side that did not undergo surgery at 6 weeks (P < .05). Heightened cellular activity was present in the deep zone of osteoarthritic fibrocartilage of the 6- and 12-week experimental groups. Degenerating chondrocytes appeared to contain greater proportions of intracytoplasmic filaments and lysosome-like bodies. Disc perforation provided the impetus for degenerative or remodeling changes in the condylar cartilage of experimental joints, and is consistent with secondary OA. These dynamic events were most significant in the deep zone of articular fibrocartilage.

Morfologia da articulaçäo temporomandibular e sua relaçäo com a oclusäo dental / The morphologic of the temporomandibular joint and their relationship with dental occlusion

A articulaçäo temporomandibular humana foi estudada quanto ao seu aspecto macro e microscópico, em vinte e dois espécimes "post mortem" com a finalidade de descrever a morfologia e as relaçöes de seus componentes articulares. Os componentes ósseos mandibulares (processo condilar) e temporal (fossa mandibular) foram analisados em uma amostra de trinta crânios secos, cuja morfologia foi correlacionada às características oclusais. A imagem radiográfica das articulaçöes temporomadibulares de cinquenta e dois indivíduos, obtida nas tomadas transcranianas laterais oblíquas, foi pesquisada quanto à aparência radiográfica dos seus componentes articulares, e correlacionada com as características oclusais. Muitos aspectos anatômicos dessa articulaçäo foram confirmados, e alguns detalhes que permaneciam indefinidos na literatura foram esclarecidos, por meio de avaliaçäo microscópica dos espécimes. Näo foi possível demonstrar correlaçäo definida entre oclusäo dental e morfologia articular, utilizando-se a amostra de crânios secos ou a de indivíduos vivos

Light and electron microscopic evaluation of Proplast II TMJ disc implants.

Proplast II disc implants (Vitek Inc, Houston) were used in nine patients (14 joints) who underwent discectomy of the temporomandibular joint (TMJ). These patients subsequently underwent removal of the implants from 10 to 28 months postplacement due to pain and occlusal changes or radiographic changes in the joints. Light and electron microscopic evaluations were performed on the retrieved implants and surrounding tissue. Evidence of gross deterioration manifested by fracture of the implant was present in 10 of the 14 implants, and microscopic evidence of deterioration was present in all implants. Foreign-body giant cell reaction in surrounding tissues and microfragmentation of the implant were evident in all joints.