[New methods of fixing fragments in fractures of the mandibular condyle].
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Fracture Fixation↗
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[Mandibular condyle fractures].
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Humans↗
[Surgical treatment of a luxation fracture of the mandibular condyle].
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Adult↗
[Hyperplasia of the mandibular condyle].
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Humans↗
Spatial arrangement of collagen fibrils in the articular cartilage of the mandibular condyle: a light microscopic and scanning electron microscopic study.
To determine the spatial arrangement of collagen fibrils in articular cartilage of the human mandibular condyle, ten healthy condyles obtained at necropsy were examined by light microscopy and scanning electron microscopy (SEM). Observations using light microscopy showed the existence of four different zones. The organization and alignment of the collagen fibrils were different in every zone and varied from layers to bundles of fibrils running parallel, obliquely, or radially to the articular surface. Observations using scanning electron microscopy revealed a thin, surface layer of disorganized small fibrils with a cotton-wool appearance and a well-organized architecture of collagen fibrils in every zone. It was concluded that the organization of collagen fibrils in articular cartilage shows a three-dimensional network with a special system in every zone.
Adult↗
Penetration of the mandibular condyle into the middle cranial fossa: report of a case in a 6-year-old girl.
Reported cases of dislocation of the mandibular condyle into the middle cranial fossa are rare. Treatment of this injury should be individualized and should take in account the age of the patient, growth potential, the degree of glenoid fossa destruction, the risk of ankylosis and the risk of further cranial injury. In children, functional therapy is aimed at helping the restoration of posterior facial height, good occlusal relations and function. Long-term follow-up is mandatory. Surgery may be required later to correct asymmetrical growth or developing ankylosis. This article describes a case of condylar penetration into the middle cranial fossa in a six-year-old child and the treatment performed to minimize consequences on occlusion and facial development.
Accidental Falls↗
Local administration of IGF-I stimulates the growth of mandibular condyle in mature rats.
AIM: To evaluate the effects of local injection of insulin-like growth factor I (IGF-I) on the growth of mandibular condyle in mature rats. MATERIALS AND METHODS: Sixteen 15 week-old male rats were used in this study. In the experimental group, IGF-I at a concentration of 50 microg/ml was injected into articular capsules of the condyle, while rats in the control group were injected with equal volume of physiological saline. These injections were performed three times at 7 day intervals, and all of the rats were killed on the 7th day after the last injection. Tetracycline and calcein were used for vital staining. After death, the condyles were extracted and undecalcified ground sections were prepared for histological and histomorphometric observations. The thickness of the cartilaginous layer of the condyle, the percentage of bone area in the subchondral cancellous bone layer and the amount of endochondral bone growth in the condyle were measured. The significance of the difference in these measurements between IGF-I and control group was evaluated. RESULTS: An increase in the thickness of the cartilaginous layer, and a decrease in the percentage of bone area in the subchondral cancellous bone layer was recognized in IGF-I treated condyle. The amount of endochondral bone growth in the experimental group was greater than that in the control group. CONCLUSION: The local injection of IGF-I into mature condyle seemed to reactivate the process of endochondral bone formation and induced actual bone growth in mature condyle.
Animals↗
Recruitment of osteoclasts in the mandibular condyle of growing osteopetrotic (op/op) mice after a single injection of macrophage colony-stimulating factor.
The purpose was to elucidate histological changes in the mandibular condyle and ramus in growing osteopetrotic (op/op) mice after a single injection of macrophage colony-stimulating factor (M-CSF). M-CSF (5 microg) was injected into 6-, 11-, 26-, 56- and 86-day-old op/op mice, and the mice were killed 4 days after the injection. In normal mice, the condyle was substantially wider than the ramus beneath it, and enlargement and ossification of the condyle occurred after weaning. These changes were not found in the uninjected and injected op/op mice, the condyles of which were occupied by hypertrophic cartilage cells, and the hypertrophic cell layer was thicker and more irregular in the arrangement of epiphyseal cell columns. In spite of the lack of bone resorption in uninjected and injected op/ op mice, ossification of the mandibular ramus occurred, but later than that of normal mouse. The number of tartrate-resistant acid phosphatase-positive cells in the injected op/op and normal mice approached a maximum at 30 days and then gradually decreased up to 90 days of age, although the numbers were substantially different for all ages. The uninjected op/op mice had no visible osteoclasts until 15 days and their number then increased significantly from 60 to 90 days of age. These results were considered due to the difference in biological responses of bony structures to M-CSF injection in the op/op mice. The influences of mechanical stimuli from masticatory functions, which are deficient in op/op mice, might also be responsible for the differences in bony architecture between the op/op and normal mice.
Animals↗
Histomorphometric analysis of cartilage and subchondral bone in mandibular condyles of young human adults at autopsy.
After demineralization, sagittal sections were made from the lateral, the central and the medial parts of 33 mandibular condyles from people aged 20 to 36 years, and studied for undifferentiated mesenchymal (UM) cells, cartilage and subchondral bone, the thickness of which were measured. Two condyles showed a continuous layer of UM cells extending all over. In 13 condyles, UM cells were absent; 18 condyles showed variability in UM cell occurrence in one or more out of the nine standardized areas. In 14 condyles, non-hypertrophic cartilage was present, 10 condyles showed hypertrophic cartilage and in nine condyles hyperplastic cartilage. Hyperplastic cartilage was associated with minimal numbers of UM cells. In combination with hypertrophic cartilage the UM cell layer appeared less irregular. Of nine condyles with incongruence of the cartilage-bone interface and the articular surface, seven showed hyperplastic cartilage. Six out of these seven were free of bony changes. A negative correlation was found between the presence of UM cells and the condylar-cartilage thickness (p less than 0.05). These results suggest that condylar changes are initiated by alterations in the cartilage and that changes in the bone are secondary.
Adult↗
EMG activities of two heads of the human lateral pterygoid muscle in relation to mandibular condyle movement and biting force.
Electromyographic (EMG) activities of the superior (SUP) and inferior heads (INF) of the lateral pterygoid muscle (LPT) were recorded in humans during voluntary stepwise changes in biting force and jaw position that were adopted to exclude the effects of acceleration and velocity of jaw movements on the muscle activity. The SUP behaved like a jaw-closing muscle and showed characteristic activity in relation to the biting force. It showed a considerable amount of background activity (5-32% of the maximum) even in the intercuspal position without teeth clenching and reached a nearly maximum activity at relatively lower biting-force levels than the jaw-closing muscles during increment of the biting force. Stretch reflexes were found in the SUP, the function of which could be to stabilize the condyle against the biting force that pulls the condyle posteriorly. This notion was verified by examining the biomechanics on the temporomandibular joint. The complex movements of the mandibular condyle in a sagittal plane were decomposed into displacement in the anteroposterior direction (Ac) and angle of rotation (RAc) around a kinesiological specific point on the condyle. In relation to Ac, each head of the LPT showed quite a similar behavior to each other in all types of jaw movements across all subjects. Working ranges of the muscle activities were almost constant (Ac <3 mm for the SUP and Ac >3 mm for the INF). The amount of EMG activity of the SUP changed in inverse proportion to Ac showing a hyperbola-like relation, whereas that of the INF changed rather linearly. The EMG amplitude of the SUP showed a quasilinear inverse relation with RAc in the hinge movement during which the condyle rotated with no movement in the anteroposterior direction. This finding suggests that the SUP controls the angular relationship between the articular disk and the condyle. On the other hand, the position of the disk in relation to the maxilla, not to the condyle, is controlled indirectly by the INF because the disk is attached to the condyle by tendinous ligaments.
Adult↗
Dental abrasion as a factor in remodeling of the mandibular condyle.
Skulls of 100 male and female subjects of various ages and with unimpaired dental arches were examined with respect to the morphological features of the mandibular condyle. A certain number of typical shapes were distinguished. Dental abrasion was also assessed and three parameters were calculated: (1) total abrasion index; (2) working:balancing abrasion ratio, and (3) frontal abrasion index. These data were then related to condylar shape and subject age. The results show that abrasion influences changes in condyle shape due to bone remodeling. The forces applied on this bone segment are distributed over functional areas that vary both in extent and in their different characteristics.
Adult↗
Mechanical properties of cancellous bone in the human mandibular condyle are anisotropic.
The objective of the present study was (1) to test the hypothesis that the elastic and failure properties of the cancellous bone of the mandibular condyle depend on the loading direction, and (2) to relate these properties to bone density parameters. Uniaxial compression tests were performed on cylindrical specimens (n=47) obtained from the condyles of 24 embalmed cadavers. Two loading directions were examined, i.e., a direction coinciding with the predominant orientation of the plate-like trabeculae (axial loading) and a direction perpendicular to the plate-like trabeculae (transverse loading). Archimedes' principle was applied to determine bone density parameters. The cancellous bone was in axial loading 3.4 times stiffer and 2.8 times stronger upon failure than in transverse loading. High coefficients of correlation were found among the various mechanical properties and between them and the apparent density and volume fraction. The anisotropic mechanical properties can possibly be considered as a mechanical adaptation to the loading of the condyle in vivo.
Aged↗
[Effect of human growth hormone on mandibular condyle growth of the rat].
The purpose of the present work was to study the effects of human growth hormone (GH) to the growth of mandibular condyle after hypophysectomy in the growing rats. Ninety female rats of the Wistar SLC strain weighing approximately 60 grams fed on a commercial laboratory chow were divided into three groups of 30 animals each. Except one group (normal control) they were hypophysectomized at 3 weeks after birth, and 10 of the operated groups respectively received intraperitoneally the growth hormone (GH group) in a single dose of 160 mIU per 100 g weight. The remaining one operated group was untreated control (hypophysectomized group). The animals were sacrificed 2 weeks after injection and the heads were fixed in 10% formalin solution for 5 days. Half sides of the heads were decalcified, and the other halves were not decalcified. The blocks were the embedded in paraffin and Big-GMA, and the widest point of the processes were cut in sections, stained with hematoxylin-eosin and Villanueva-Goldner Stein. The results were as follows: 1. Body Weight All of the animals averaged 60 grams initially. At the end of the experiment, the control group averaged 190 grams and the body weight was markedly increased. The hypophysectomized group averaged 63 grams. As compared with the control, this group did not show much increase in the body weight. However, the GH group averaged 110 grams and began to gain weight, but the body weight did not reach to the level of the control. 2. Histopathological Findings 1) In the normal control, the head of the condylar process was large, the articular zone was thick, the cartilage plate wide, and the cells were large in size and number and arranged regularly. Bone tissue adjacent to the erosion zone consisted of fine complicated trabeculae which were joined each other. The osteoblasts and osteoclasts were large in size and number and appeared very active. 2) In the hypophysectomized group, the head of the process was small showing atrophy, and the articular zone was similar to the control. The embryonic zone was thin and cells were small and spindle form in shape as compared with the control. The hypertrophic zone showed extensive atrophy. The cell decreased in size and number and were arranged irregularly.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Bifid mandibular condyle.
Two cases of unilateral bifid mandibular condylar head are reported. A review of the literature showed that only four cases had been reported as occurring in living patients, although another twenty-two cases have been reported in dried skull or cadaver material. A brief discussion of the possible etiology is given.
Adult↗
Costochondral reconstruction of mandibular condyles in nongrowing primates.
The aim of this study was to develop a reproducible model in nongrowing animals to document morphological and histological changes after costochondral reconstruction of the mandibular condyle. Seven adult monkeys underwent a unilateral condylectomy followed by costochondral reconstruction. Dimensional changes of the thorax and reconstructed ramus-condyle unit were documented by in situ and radiographic analysis. Morphological and histological analysis were completed after removal at 4 (n = 2), 8 (n = 2), and 12 months (n = 3). In situ measurements demonstrated no dimensional changes of the thorax, but the reconstructed ramus-condyle unit decreased in height an average of 3.2 +/- 1.4 mm. The original graft remained unchanged morphologically, but new bone and cartilage progressively encompassed it, creating a form similar to the native condyle. Histologically, the transplanted cartilage remained unchanged. However, the articulating surface progressively took the appearance of the native condyle. Results of this study indicated that, in nongrowing animals, the reconstructed ramus-condyle unit decreases in height slightly but remodels to a size and shape morphologically and histologically similar to the native condyle.
Animals↗
Alteration of the horizontal mandibular condyle size associated with temporomandibular joint internal derangement in adult females.
OBJECTIVES: The purpose of this retrospective study was to analyse the relationship between horizontal size of the mandibular condyle and internal derangement (ID) of the temporomandibular joint (TMJ). METHODS: One hundred and thirty-nine joints in 88 women aged over 18 years were included in this study. The horizontal condylar size was measured in the antero-posterior and medio-lateral (ML) dimensions using axial magnetic resonance (MR) images. Radiological findings of ID were also assessed from MR imaging. RESULTS: The condyles in the joints with permanent disk displacement were smaller than those in joints without displacement in both dimensions (Fisher's protected least significant difference, P<0.05). There were statistically significant correlations between horizontal condylar size in the ML dimension and both disk morphology and radiological stage of ID (Spearman's correlation coefficient by rank, P<0.05). CONCLUSIONS: The results of this study suggest a possible relationship between horizontal condylar size and disk displacement. It is also suggested that the condyle becomes smaller in the ML dimension with advancement of ID.
Adult↗
[The use of titanium plates and endoprostheses for the mandibular condyles in reconstructive surgery of the mandible].
Potentialities of titanium plates and endoprostheses of the condyle processes in replacement of the postoperative defects of mandibular bone tissue are discussed. A recently developed Russian kit of titanium plates and instruments and specificities of plasty to repair bone defects using this kit are described. The results of surgical repair in 5 patients subjected to resection of the mandible with exarticulation for tumors or osteomyelitis aftereffects were good: the oval of the face and mandibular function were repaired.
Adult↗
Intracranial dislocation of the mandibular condyle: report of two cases and review of the literature.
Fractures of the mandibular condylar process are common and account for up to 40% of all mandibular fractures. Penetration of the condylar head into the middle cranial fossa is, however, rare. We have found reports of only 43 cases since 1834. The diagnosis of intracranial condylar dislocation is difficult, there are usually no particular symptoms or neurological signs. As a result, detailed radiological studies are necessary. In the absence of clear radiographic images of the condylar structures, computed tomography (CT) is essential to locate the fragments and to investigate and monitor intracranial lesions. This paper describes the diagnostic and surgical procedures used in two cases of condylar dislocation and discusses them with reference to previous cases. The use of a titanium screw, which was positioned intracranially in the first case, has not, to our knowledge, been described previously.
Bone Plates↗