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[The functional therapy of fractures of the mandibular condyle. Our experience].

This work dealt with clinical experience since 1992, in management by functional therapy of mandibular condyle fractures, of the Institute of Oral and Maxillo-Facial Surgery in the I Policlinico of Naples. In this work from 87 treated patients, only a group of 8 has been considered because it expresses the heterogeneity of all cases about the age, the sex, the kind and the level of fracture and the association with other fracture of the skull. The results obtained show that the functional therapy must be considered the first opinion in the mandibular condylar fractures at least there are specific conditions.

Adolescent↗

Simple bone cyst of the mandibular condyle with severe osteoarthritis: report of a case.

A rare case of simple bone cyst in the mandibular condyle of a 33-year-old woman is reported. The condition was difficult to diagnose because the cyst was accompanied by severe osteoarthritis. T1-weighted magnetic resonance (MR) images revealed a cystic lesion with intermediate signal intensity within the condylar head and an irregular margin with intermediate signal intensity on the superior surface of the condyle. The patient was treated by high condylectomy, discectomy and reconstruction by sagittal split ramus osteotomy. Histopathological examination showed a simple bone cyst in the condylar head and erosion of the anterior articular surface due to degenerative changes.

Adult↗

Destructive lesions of the mandibular condyle following diskectomy with temporary silicone implant.

Dacron-reinforced silicone is widely used as disk-replacement implant material in the temporomandibular joint. A retrospective radiographic analysis was undertaken in a series of thirty-two patients on whom diskectomy had been performed. Twenty patients had received temporary silicone implants, whereas twelve patients had surgery without disk-replacement implants. Six of the patients with implants had destructive lesions of the mandibular condyles at follow-up examinations, but no such lesions were seen in any of the patients who had surgery without implants. Histologic analysis of material removed from one patient who had a second operation showed multiple particles of foreign material surrounded by focally marked inflammatory reaction with foreign body granulomas. The underlying cartilage and bone showed focal resorption and bone destruction. Electron microscopy combined with energy-dispersive x-ray microanalysis showed that the foreign material contained silicone. It was concluded that the radiographically observed destructive lesions of the mandibular condyle may be a sign of a reactive synovitis induced by silicone particles abraded from the silicone implant.

Adult↗

Recurrence of a solitary bone cyst of the mandibular condyle in a bone graft. A case report.

The recurrence of a solitary bone cyst of the mandibular condyle in a costochondral bone graft is reported. A solitary bone cyst of the right condylar head and neck of a 10-year-old boy was treated by total resection and immediate reconstruction with a costochondral bone graft. Two years after the first operation, a recurrence of the solitary bone cyst within the bone graft was noted. An open treatment was performed. A review of the literature on solitary bone cysts and recurrences of solitary bone cysts shows that the case reported is unique. Possible reasons for the recurrence are discussed.

Bone Transplantation↗

A comparative study of the treatment of unilateral fractured and dislocated mandibular condyles in the rabbit.

This study evaluated the results of three methods of managing simulated unilateral dislocated fractured mandibular condyles in the rabbit. The first method consisted of surgical reduction of the fractured condyle to its anatomic position and its subsequent fixation with a titanium plate. The second method differed from the first by completely detaching the condyle, then replacing it as free graft. The third method left the fractured condyle in its dislocated position outside the glenoid fossa. Eighteen rabbits were used, 6 animals for each method. Half the animals in each group were killed at 4 weeks, the other half at 14 weeks postoperatively. Clinical, morphologic, functional, radiologic, and histologic examinations were conducted on all animals. The results indicated that open reduction with internal fixation with no disruption of the blood supply to the condyle provided the most favorable results. While closed reduction without internal fixation gave good functional results, definite reduction in ramus height on the operated site was observed in this group of animals. Animals that had open reduction and internal fixation using the condyle as a free graft did not do as well as the other two groups. Despite good mouth opening and occlusion, more animals showed facial asymmetry and it was more severe. None of the condyles were lost as result of necrosis, but healing took longer when compared with the other group of animals.

Animals↗

Osteoarthritis of the temporomandibular joint: a light microscopic and scanning electron microscopic study of the articular cartilage of the mandibular condyle.

The aim of this study was to investigate the organization of collagen fibrils and the histopathologic alterations as well as the morphologic aspects of osteoarthritic articular cartilage of the human mandibular condyle. Nine osteoarthritic condyles, three obtained at necropsy and the other six during surgery, were examined by light microscopy and scanning electron microscopy. Light microscopic observations revealed features of progressive and regressive remodeling and the presence of clefts. Scanning electron microscopic observations showed the presence of thick, coiled fibrils at the joint surface and numerous osmiophilic lipid globules scattered between the collagen fibrils. The collagen fibrils were disordered. It was concluded that collagen fiber network disintegration and fatty degeneration comprise the osteoarthritic changes of the articular cartilage of the human mandibular condyle.

Adult↗

The structure of the mandibular condyle in the monkey (Macaca mulatta).

The articulating surfaces of bones which ossify in mesenchyme, like the mandible, are covered by a layer of dense, fibrous tissue. The purpose of the present study was to examine the structure of the mandibular condyle in the monkey. Young Rhesus monkeys (Macaca mulatta) were perfused with glutaraldehyde-paraformaldehyde. Small pieces of the condyles were dissected out, demineralized in 0.5 M EDTA and processed for light microscopy and electron microscopy. The mandibular condyle was covered by an avascular tissue, extending from the surface to the underlying bone. The tissue could be divided into three zones. The zone facing the articular cavity was about 50 microns wide and consisted of a dense, fibrous tissue. Layers of collagen fibers, 1-4SS microns wide and parallel with the articular surface, but oriented at angles to each other, were seen. Between the collagen fibers fibroblast-like cells were noted. The second zone was also approximately 50 microns wide and rich in cells. The cells were ovoid or flat and had a dark staining cytoplasm with some mitochondria and a well developed rough-surfaced endoplasmic reticulum. The third zone was about 150 microns wide and here the cells were larger and located in lacunae. An increase in the size of cells and lacunae was seen approaching the bone. This zone showed hyaline cartilage undergoing maturation. Closer to the bone, degeneration of the chondrocytes was noted. In the underlying bone, soft tissue with several chondroclasts resorbing the hypertrophic cartilage were seen, alternating with areas where bone formation was occurring, partly on the top of cartilage remnants. The observations confirm that in the growing condyle there is an articular part as well as a growth zone, and that the cells in the cell-rich zone serve as precursors for the hyaline cartilage cells in the growth zone, and possibly as a cell reservoir for the articular part as well.

Animals↗

Osteochondroma of the mandibular condyle. A case report.

A 52-year-old woman presented with pain on the right temporal region, restricted mandibular movement and a gradually developing malocclusion. Osteochondroma of the mandibular condyle was suspected based on diagnostic imaging. Local resection with preservation of the condylar head resulted in complete resolution of symptoms.

Chronic Disease↗

Severe osteoarthrosis after fracture of the mandibular condyle: a clinical and histologic study of seven patients.

The factors that induce complications subsequent to fractures of the mandibular condyle have long been controversial. A clinical and histologic study of seven patients (nine temporomandibular joints [TMJs]) who suffered from severe TMJ problems subsequent to condylar fractures showed that the complications were related to comminution of the condyle, sagittal fracture of the condyle, and subcondylar fracture dislocation. Alterations in these TMJs all involved secondary osteoarthrosis. Additionally, aseptic necrosis, bifid deformity of the condyle (two of the three sagittally fractured condyles), and TMJ ankylosis occurred in these patients. It is suggested that the involved fracture patterns be given more attention by clinicians.

Adult↗

Quantitative analysis of extracellular matrix proteins in hypertrophic layers of the mandibular condyle and temporal bone during human fetal development.

A computer image analysis of immunostained extracellular matrix (ECM) proteins (collagen types I, II, III and V, fibronectin and tenascin) in hypertrophic layers in the mandibular condyle and temporal bone of human fetuses, which ranged in gestational age from 12 to 32 weeks, was performed. The percentage of cells positive for proliferating cell nuclear antigen (PCNA) increased in almost the same manner in each region. The level of PCNA was markedly elevated at 16 weeks. The percentage of PCNA-positive cells was low in temporal bone and in the bone-forming layer of the mandibular condyle at 24 weeks. Specific concentration patterns of proteins in the ECM were found at each stage of development. The extent of accumulation of fibrillar collagen and of fibronectin differed, while those of other proteins in the ECM, such as tenascin, osteocalcin and osteonectin, were similar at the two sites.

Bone Density↗

Assessment of the reliability and validity of panoramic imaging for assessment of mandibular condyle morphology using both MRI and clinical examination as the gold standard.

OBJECTIVES: The purpose of this study was to evaluate both reliability and validity of the assessment of the shape of the mandibular condyle in panoramic images of the TMJ. STUDY DESIGN: Forty subjects were included and were examined according to the Research Diagnostic Criteria for Temporomandibular Disorders. Panoramic radiographs (PRs) and magnetic resonance images (MRIs) were completed for all subjects. Both MRIs and PRs were rated by raters blinded to the clinical diagnosis. Kappa statistics were used to compare the results of the raters of the PRs. Additionally, the specificity and the sensitivity of the PRs were calculated for 2 scenarios: one with MRI and the other with clinical findings as the gold standard. RESULTS: The sensitivity was 0.94 (specificity = 0.45) for the assumption that MRI is the gold standard and 0.86 (specificity = 0.49) for the assumption that the clinical examination is the gold standard. For reliability, the results for kappa ranged from 0.06 to 0.327. CONCLUSION: It can be concluded that PRs are not a reliable method of accurately judging the shape of the mandibular condyle.

Adolescent↗

A stereological study of trabecular architecture in the mandibular condyle of the pig.

The morphology of bony trabeculae can indicate the loading conditions that predominate near joint surfaces. This study reports principal orientation, anisotropy, thickness, separation and density of trabeculae in the mandibular condyle of pigs. Condyles from slaughterhouse pigs were serially sectioned anteroposteriorly (n = 4), mediolaterally (n = 5) or horizontally (n = 4) at 0.8 mm using a diamond saw. Sections were viewed under a stereomicroscope and video-images of four sites per section were digitized. Anteroinferior sites had thicker, more widely spaced trabeculae than other sites, suggesting a concentration of stress. Anisotropy in the frontal plane was greater than in the sagittal or the horizontal planes, indicating a more consistent direction of loading in the frontal plane. Principal orientation in the frontal sections was perpendicular to the occlusal plane and did not differ among the sites. In the sagittal sections, trabeculae in inferior sites were variably oriented, whereas those in superior sites sloped posterosuperiorly, possibly reflecting shearing loads resulting from translational movements. In the horizontal sections, the trabeculae were oriented perpendicular to the frontal plane, suggesting an anteroposterior component of loading. Compared to cancellous bone from other locations, the trabeculae of the mandibular condyle are robust and dense, strongly supporting the notion that the temporomandibular joint is heavily loaded.

Animals↗

The fine structure of the fibrous zone of articular cartilage in the rat mandibular condyle.

The ultrastructure of the articular fibrous zone of the rat mandibular condyle was observed at 3 and 6 weeks of age in order to investigate the histological changes that occur during the establishment of mastication after suckling. We divided the articular fibrous zone into two layers (F1 layer and F2 layer). The F1 layer was composed of fibroblast-like cells, macrophage-like cells, and the matrix which consisted of granular or fibrillar material, loosely arranged small bundles of collagen fibrils with uniform thickness of 30-50 nm, and independent microfibrils. The F1 layer was continuous with the synovial membrane without any distinct boundary in its peripheral area. Mitotic figures could infrequently be observed in the fibroblast-like cells. The cells in the F2 layer closely resembled fibroblasts. The matrix in the F2 layer mostly consisted of densely arranged bundles of collagen fibrils which are not of uniform diameter ranging 40-100 nm. Elastic fibers occurred among the collagen fibrils. The F1 layer which was observed clearly at 3 weeks almost disappeared at 6 weeks of age. It is confirmed that the F1 layer resembling the synovial membrane exists over the condyle up to the weaning period about 3 weeks of age but it degenerates before 6 weeks of age when the masticatory function is established.

Animals↗

Adaptive adjustment of the adolescent porcine mandibular condyle.

The effect of occlusal support during primary dentition on the mandibular condyle remains controversial. We sought to determine whether unilateral loss of occlusal support leads to quantifiable adaptive changes of the condyle. Quantitative analysis of condylar growth and spongy bone volume after unilateral removal of teeth on the left side in adolescent minipigs was examined over a period of 4 months. Serial sagittal sections of the temporomandibular joint were examined using microradiography, fluorescence microscopy, and light microscopy. The condyles on the nonextracted side showed a higher growth rate than those on the extracted side, with a 1.56-fold thicker (p = 0.003) additional vertical bone layer. This factor was greater ventrally than dorsally (p = 0.0311), increasing from dorsomedial (1.33) to ventrolateral (2.38). There was therefore a reciprocal change of the condylar surface curve between the left and right condyles. Increased condylar growth correlated with a lower subchondral spongy bone volume (7.38% difference, p = 0.002). The amount of mineralized bone matrix generated was estimated to be about 1.33-fold higher in the nonextraction side condyles compared with those on the extraction side. Thus, unilateral loss of occlusal support was shown to lead to quantifiable alterations of condylar vertical growth and spongy bone volume in minipigs.

Adaptation, Physiological↗

Influences of ovariectomy and orchiectomy on the remodeling of mandibular condyle in mice.

Ovariectomy (OVX) and orchiectomy (ORX) are well known to increase bone turnover; however, the influences on condylar remodeling are not fully understood. The purpose of this study was to examine histological changes of the mandibular condyles in OVX and ORX mice in comparison to the femora. Eighty 8-week-old mice were used in this study. In each of the experimental and control groups, five mice were sacrificed 2, 4, 8, and 12 weeks after surgery for OVX and ORX. Histological changes of the mandibular condyle were studied in comparison to the femur, which is liable to undergo the influences of OVX and ORX. The number of TRAP-positive cells and the thickness of articular cartilage layer were also quantified. TRAP-positive cells in the condylar head of OVX and ORX mice exhibited the most prominent increase 4 weeks after the surgery and approached the control levels at the later experimental stages. Trabecular bone volume in the condyle of the OVX and ORX mice also decreased, although the rate was less than in the femora. It is shown that influences of OVX on the remodeling of femora appear earlier than those of ORX, whereas OVX and ORX affect the remodeling of condyle during the same growth period. It is also demonstrated that the influences of OVX and ORX are less in the condyle than in the femora. These findings emphasize that the influences of OVX and ORX on bone remodeling are varied by sexual difference and the type of bones.

Acid Phosphatase↗

Computer-assisted mandibular condyle positioning in orthognathic surgery.

PURPOSE: The correct placement of the mandibular condyle in the glenoid fossa during the osteosynthesis after the sagittal ramus osteotomy is often a problem. This article describes a computer-assisted positioning device. METHODS: The procedure is based on the use of a three-dimensional optical localizer to establish the condylar segment position. The operative procedure is only slightly different from the usual. RESULTS: The system is very easy to use, it does not require preoperative data acquisition, and the accuracy obtained is in fractions of a millimeter.

Bone Nails↗