Development of the human temporomandibular joint.
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A great deal of research has been published on the development of the human temporomandibularjoint (TMJ). However, there is some discordance about its morphological timing. The most controversial aspects concern the moment of the initial organization of the condyle and the squamous part of the temporal bone, the articular disc and capsule and also the cavitation and onset of condylar chondrogenesis. Serial sections of 70 human specimens between weeks 7 and 17 of development were studied by optical microscopy (25 embryos and 45 fetuses). All specimens were obtained from collections of the Institute of Embryology of the Complutense University of Madrid and the Department of Morphological Sciences of the University of Granada. Three phases in the development of the TMJ were identified. The first is the blastematic stage (weeks 7-8 of development), which corresponds with the onset of the organization of the condyle and the articular disc and capsule. During week 8 intramembranous ossification of the temporal squamous bone begins. The second stage is the cavitation stage (weeks 9-11 of development), corresponding to the initial formation of the inferior joint cavity (week 9) and the start condylar chondrogenesis. Week 11 marks the initiation of organization of the superior joint cavity. And the third stage is the maturation stage (after week 12 of development). This work establishes three phases in TMJ development: 1) the blastematic stage (weeks 7-8 of development); 2) the cavitation stage (weeks 9-11 of development); and 3) the maturation stage (after week 12 of development). This study identifies the critical period of TMJ morphogenesis as occurring between weeks 7 and 11 of development. (+info)
Internal derangements of the temporomandibular joint: the role of arthroscopic surgery and arthrocentesis.
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Arthroscopic surgery appears to be a safe, minimally invasive and effective method for treating internal derangements of the temporomandibular joint (TMJ), reducing pain and increasing mandibular range of motion for approximately 80% of patients. Although these results are encouraging, they are largely based on retrospective, uncontrolled and short-term studies. The landmark observation that lysis and lavage in only the upper compartment of the TMJ produce successful clinical results without repositioning the disc has prompted clinicians to question the importance of disc position as a significant factor in the etiology of TMJ pain dysfunction. Although there are prospective, controlled, randomized short-term studies indicating that arthrocentesis and arthroscopic surgery have comparable success rates in the management of acute TMJ closed lock, similar long-term studies are lacking. Until they have been done, the roles of arthroscopic surgery and arthrocentesis in the management of TMJ internal derangements remain unclear. (+info)
The changes in temporomandibular joint disc position and configuration in early orthognathic treatment: a magnetic resonance imaging evaluation.
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This study aimed to examine the effects of chin cup therapy on the temporomandibular joint (TMJ) disc position and configuration with magnetic resonance imaging (MRI). Twenty-five individuals ranging in age from 5 to 11 years were evaluated. The treatment group consisted of 15 subjects (10 females and five males) with prognathic facial structures, while the control group comprised 10 subjects (six females and four males) with an orthognathic facial structure. The magnitude of the chin cup force applied to the mandible was 600 g. Unilateral MRIs of the TMJ were taken in all subjects at the beginning and end of the study. No statistically significant changes in the TMJ disc position and configuration during the treatment and control periods could be seen. The values of the alpha angle measurements were found to be different in the treatment and control groups at the beginning (166.23 +/- 2.15 and 172 +/- 1.97, respectively), and end of the treatment and control periods (160.00 +/- 2.16 and 172.00 +/- 2.68). These findings show that if the chin cup appliance is used at an early age and with appropriate forces, there will be no adverse effect on the TMJ disc position and configuration. (+info)
Functional magnetic resonance imaging of temporomandibular joint disorders.
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Fifty-eight temporomandibular joints (TMJs) from 40 patients with TMJ-related symptoms were examined by means of magnetic resonance scans with modified gradient echo sequences and a special double coil. This technique yielded a good spatial resolution of the intra-articular soft tissues, especially the articular disc and the bone structure of the TMJ. In combination with an incremental jaw opener, the disc-condyle complex was analysed in various closed and open mouth positions, depending on the clinical examination. Open mouth movement with differentiation of disc-condyle rotational and translation movement was demonstrated. Disturbances of TMJ motion showed interrupted condylar translation combined with mandibular deviation during open mouth movement (n = 8/58). Early phases of internal derangement of the TMJ with partial anterior disc displacement with (n = 12/58) or without (n = 2/58) reduction, total anterior disc displacement without reduction (n = 10/58), disc deformation (n = 10/58), disc adhesion (n = 2/58), condylar hypermobility (n = 6/58), condylar displacement (n = 8/58), and late phases of internal derangement of the TMJ with osteoarthrosis (n = 14/58) were clearly identified. Bilateral TMJ disorder was found in 72.5 per cent of the patients. By using motion-adapted, semi-dynamic magnetic resonance imaging (MRI), it is possible to improve the understanding of the complexity of TMJ movements. (+info)
Synovial chondromatosis in the temporomandibular joint complicated by displacement and calcification of the articular disk: report of two cases.
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Two cases of synovial chondromatosis of the temporomandibular joint (TMJ) are presented, including correlation of CT and MR imaging characteristics with surgical and pathologic findings. The usefulness of CT and MR imaging in the diagnosis of TMJ disorders is discussed. (+info)
Correlation between eminence steepness and condyle disc movements in temporomandibular joints with internal derangements on magnetic resonance imaging.
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A steep articular eminence is reported to be a predisposing factor for the development of disc displacement. The purpose of this study was to evaluate the biomechanics of the temporomandibular joint (TMJ) in internal derangements and, additionally, to investigate whether a relationship exists between the steepness of the articular eminence and disc displacement, with (DDR) and without reduction (DDWR). The material consisted of the sagittal TMJ magnetic resonance images (MRIs) of 39 joints (26 DDR and 13 DDWR). Sagittal and coronal TMJ MRIs were obtained at maximum inter-cuspation and in the maximum mouth-opening position. The steepness of the articular eminence, disc, and condyle rotation, and condyle translation were investigated. A Student's t-test was performed and correlation coefficients calculated. The results revealed an increase in disc rotation in the DDR group and in condyle translation in the DDWR group (P < 0.01). Condyle rotation and the steepness of the articular eminence were similar in both groups. Disc rotation was positively correlated with condyle rotation and negatively correlated with condyle translation in the DDR group (P < 0.05, r = 0.44). Condyle translation was positively correlated with steepness of the articular eminence in the DDWR group (P < 0.01, r = 0.74). There was no correlation between movements of the disc-condyle assembly and the steepness of the articular eminence in the DDR group. Nevertheless, a relationship between condyle translation and the steepness of the articular eminence was found in the DDWR subjects. (+info)
The temporomandibular joint and the disc-condyle relationship after functional orthopaedic treatment: a magnetic resonance imaging study.
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Causative correction of Class II skeletal malocclusions may be achieved through bite jumping by various means. Numerous animal experiments have yielded evidence of remodelled temporomandibular structures after mandibular protrusion. However, the mode and extent of structural and/or topographic changes of the disc-condyle relationship after functional orthopaedic treatment is still unresolved. A problem exists in defining the physiological position of the condyles and disc-condyle relationship, which is tentatively determined by various methods particularly in magnetic resonance tomographic studies. Despite the high resolution provided, the results have to be interpreted with caution, as osseous resorption and apposition cannot be assessed by visual evidence. This investigation examined the impact on the temporomandibular joints (TMJ), i.e. the condylar shape and position, and the disc-condyle relationship, of the bionator plus extra-oral traction in combination with vertical elastics. The underlying reactions were studied by means of magnetic resonance images (MRI) obtained from n = 15 successfully treated patients (mean age 11.6 years). (+info)
Ultrastructure of the human intra-articular disc of the temporomandibular joint.
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The ultrastructural appearance of the human intra-articular disc (IAD) was investigated in three discs that had been surgically removed due to disease from three female patients aged 47, 50, and 54 years of age. Regions of the IAD were selected from central areas that appeared to be least affected by disease. Sections were fixed in 2.5 per cent glutaraldehyde in 0.1 M phosphate buffer, pH 7.3 immediately after surgery. The regions examined showed no obvious signs of inflammation. The cells showed moderate amounts of the intracellular organelles associated with protein synthesis and secretion, and possessed considerable amounts of microfilamentous material, thus resembling those described in other mammals. Despite the large number of cells examined, only one cell showed evidence of a chondrocyte-like morphology in that it possessed an incomplete pericellular zone of microfilamentous material separating the cell membrane from the adjacent collagen bundles of the extracellular matrix (ECM). Thus, on morphological grounds, fibrocartilage was virtually non-existent in the specimens examined. The mean collagen fibril diameter was 43.9 nm and the fibril diameter distribution was not unimodal. Although the majority of fibrils had a relatively small diameter, two of the three specimens possessed many fibrils with diameters of over 100 nm, this being consistent with tissue subjected to tension. The mean area of a fibre bundle occupied by collagen (as opposed to the ground substance) was approximately 56 per cent. (+info)