Ossification in adult rat mandibular condyle-SEM of chondroclasia.
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Animals↗
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Effects of local administration of insulin-like growth factor-I on mandibular condylar growth in rats.
Endochondral bone formation observed at the mandibular condyle is regulated by various growth factors including insulin-like growth factor-I (IGF-I). In this paper, we describe a method for the local administration of IGF-I to the bilateral mandibular articular cavities of 3- and 12-week-old rats, and the effects of IGF-I on endochondral bone formation by histomorphometric techniques. In 3-week-old IGF-I-treated rats, three days after administration, an increase in bone tissue was found in the area of the subchondral cancellous bone layer. In 12-week-old IGF-I-treated rats, three days after administration, an increase in the thickness of the condylar cartilage and a decrease in bone tissue were observed in the area of the subchondral cancellous bone layer. This study revealed that the local administration of IGF-I on mandibular condyle caused different histological changes between growth and maturation periods. These results indicated that the effects of IGF-I on endochondral bone formation in the mandibular condyle were age-dependent.
Age Factors↗
Temporomandibular joint involvement in rheumatoid arthritis: a radiological and clinical study.
Temporomandibular joint (TMJ) involvement in rheumatoid arthritis (RA) is not uncommon. In this study a questionnaire, clinical assessment, and high resolution computerized tomography (HRCT) were used in 15 patients with rheumatoid arthritis to evaluate the diagnostic criteria of TMJ involvement. Symptoms due to TMJ involvement were present in 33.3% of the patients. Frequency of involvement was 40.0% on clinical assessment but 86.6% with HRCT assessment. The most common HRCT findings were decreases in the joint space (33.3%), mandibular subchondral cysts (23.3%), temporal subchondral cysts (23.3%), degeneration (23.3%), shape (13.3%) and height (13.3%) anomalies of the mandibular condyle, condylar head resorption (13.3%), erosion of the mandibular condyle (13.3%), and demineralization (13.3%). All patients with positive clinical findings also had positive HRCT findings. In seven (46.7%) of the patients, there were no symptoms or clinical findings implying TMJ involvement; however, they had positive results on HRCT evaluation. The HRCT findings may be the initial sign of TMJ involvement in patients with rheumatoid arthritis. In conclusion, it is suggested that RA patients with the suspicion of TMJ involvement should undergo HRCT evaluation, because HRCT findings may precede the clinical findings.
Adult↗
SPECT bone scintigraphy in the diagnosis and management of mandibular condylar hyperplasia.
Isotope bone scans have been used for a number of years to assess growth activity in the mandibular condyle in patients who present with facial asymmetry. The aim is to distinguish normal bone growth within the condyle from increased activity that may be the cause of the asymmetry. Previous studies have, however, relied only on planar images. SPECT (single photon emission computed tomography) has been used with quantitative assessments of one mandibular condyle to clivus or lumbar spine, but we have compared one condyle with the other, which is more sensitive and accurate in detecting abnormal activity. A relative percentage uptake of 55% or more in the affected mandibular condyle is considered to be abnormal, and this has been validated by comparison with an age-matched control group. We have used SPECT as an aid to diagnosis and treatment in 18 patients with asymmetrical growth and have constructed a therapeutic algorithm to aid the treatment of these patients.
Adolescent↗
Histochemical evidences on the chronological alterations of the hypertrophic zone of mandibular condylar cartilage.
The hypertrophic chondrocytes lack the ability to proliferate, thus permitting matrix mineralization as well as vascular invasion from the bone in both the mandibular condyle and the epiphyseal cartilage. This study attempted to verify whether the histological appearance of the hypertrophic chondrocytes is in a steady state during postnatal development of the mouse mandibular condyle. Type X collagen immunohistochemistry apparently distinguished the fibrous layer described previously as the "articular zone," "articular layer," and "resting zone" from the hypertrophic zone. Interestingly, the ratio of the type X collagen-positive hypertrophic zone in the entire condyle seemed higher in the early stages but decreased in the later stages. Some apparently compacted cells in the hypertrophic zone showed proliferating cell nuclear antigen (PCNA) immunoreaction, indicating the potential for cell proliferation at the early stages. As the mice matured, in contrast, they further enlarged and assumed typical features of hypertrophic chondrocytes. Apoptotic cells were also discernible in the hypertrophic zone at the early but not later stages. Consistent with morphological configurations of hypertrophic chondrocytes, immunoreactions for alkaline phosphatase, osteopontin, and type I collagen were prominent at the later stage, but not the early stage. Cartilaginous matrices demonstrated scattered patches of mineralization at the early stage, but increased in their volume and connectivity at the later stage. Thus, the spatial and temporal occurrence of these immunoreactions as well as apoptosis likely reflect the prematurity of hypertrophying cells at the early stage, and imply a physiological relevance during the early development of the mandibular condyles.
Alkaline Phosphatase↗
[The effects of growth hormone on rabbit's mandibular condylar chondrocytes proliferation and secretion in vitro].
OBJECTIVE: To study the effect of growth hormone (GH) on the proliferation and type II collagen secretion of chondrocytes of mandibular condyle in rabbit in vitro. METHODS: Flow cytometry (FCM) and immunohistochemical technique were employed to observe the possible changes. RESULTS: (1) The exogenic GH can enhance the proliferation and synthesis of DNA of the chondrocytes of mandibular condyle in rabbit in vitro. The suitable concentration of GH is 10 microg/ml. The synthesis of DNA reaches the highest level after 12 hours, while the proliferation index (PI) hits the highest after 24 hours. (2) GH (10 microg/ml) can stimulate the secretion of type II collagen of the chondrocytes. CONCLUSION: The exogenic GH can enhance the proliferation, the synthesis of DNA and the secretion of type II collagen of the chondrocytes of mandibular condyle in rabbit in vitro.
Animals↗
[Stereognathograph--optoelectronic device for mandible movement recording].
The authors have presented the structure and potentiality of application of a new optoelectronic device called stereognathograph recording the function of mandibular condyles. The meter circuit of this device is placed on the sick's head and connected with the mandible's teeth by means of a peridental splint. It enables to record mandible's movements and in the view onto the horizontal and pterygoid plane and determine the mandibular condyles' position in relation to the chosen reference point in terms of measurable numerical three-dimensional quantities. Furthermore this device enables to designate the axis of rotation of mandibular condyles as well as to designate Bennet's angle and pterygoid angle precisely for individual setting of the SAM-2 articulator.
Dental Articulators↗
Structure of the TMJ as viewed on the pantomograph.
The value of pantomography for visualizing the forms of the TMJ and the position of the condyle is dependent on placing the TMJ accurately in the zone of sharpness. 1. Oblique projection is best for showing the medial and lateral cortices of the mandibular condyle, TMJ space, and articular surfaces. 2. Profile projection is best for demonstrating the posterior and anterior cortices of the mandibular condyle, condyle-fossa relationship, and the position of the mandibular condyle. 3. Image discrepancies are easily detected when the usual radiographic features of the TMJ are not shown. A TMJ positioned too far in front of the zone of sharpness is shortened and slightly blurred, while the TMJ positioned too far behind the zone is elongated and severely blurred.
Humans↗
[Auditory canal hemorrhage as a symptom of mandibular trauma].
Auditory canal hemorrhage is usually a sign of a basal skull fracture. It is commonly unknown that this sign can also be a symptom of combined fracture of the external auditory canal and the mandibular condyle. In our investigations of patients with maxillofacial injuries we found in 15% of 197 fractures of the mandibular condyle within 3 years this combination. In sequence of these results there is a differential diagnostic need for an exact investigation to clear up these various causes in each case as first step toward an accurate therapy. The mechanism of these fractures, their etiology, and therapy are discussed with special reference to possible complications.20
Diagnosis, Differential↗
Histologic comparison of the costochondral, sternoclavicular, and temporomandibular joints during growth in Macaca mulatta.
The costochondral joint (CCJ) is commonly used to replace defective mandibular condyles in children for the restoration of normal temporomandibular (TMJ) growth and function. However, continued and harmonious growth following rib grafting is the exception rather than the rule. This may be due to the differences in the growth characteristics of the costal cartilage and the condyle. A joint that is similar both developmentally and structurally to the TMJ is the sternoclavicular joint (SCJ). The purpose f this study was to describe histologically the SCJ and CCJ during growth in Macaca mulatta and to compare the histomorphologic features with those of the TMJ. Costochondral and sternoclavicular joints were obtained from infant, juvenile, adolescent, and adult Macaca mulatta. The histologic sections were compared with mandibular condyles of the same ages available in our laboratory. The results indicate that the TMJ and SCJ are very similar morphologically throughout the growth period. The clavicular head contained layers of cartilage typical of the mandibular condyle, i.e., articular, prechondroblastic, chondroblastic, hypertrophic, and endochondral ossification layers, at each age during growth. Like those in the condyle, the hypertrophic cartilage cells were arranged in an apparently random, noncolumnar fashion. The CCJ, however, did not resemble the condyle but appeared to be more similar to the growth plate in a long bone epiphysis during growth. The results of this investigation indicate that the SCJ may be more suitable for mandibular condylar replacement than the CCJ.
Age Factors↗
Conventional radiographic and computed tomographic findings in cases of fracture of the mandibular condylar process.
A total of 40 patients with 46 fractures of the mandibular condylar process were examined an average of 47 months after the injury. The conventional radiologic examination consisted of panoramic radiography and lateral transcranial view of the fracture in the mouth-open and mouth-closed positions. Sixteen patients with 21 fractures of the condylar process were examined additionally by computed tomography (CT) because of temporomandibular joint problems in the sagittal and coronal projection. Computed tomography revealed bony changes in the fractured mandibular condyle and its position in the mandibular fossa more exactly than conventional radiographic examinations. Furthermore, the results showed that disturbances in the position and function of the articular disc may be more common than was earlier anticipated, suggesting the more frequent use of CT examinations to evaluate temporomandibular joint changes after condylar process fractures.
Adolescent↗
Collapse of the condylar head of the mandible in children and subsequent ankylosis.
Five cases are reported of children who presented with limitation of jaw movement and had some degree of deformity with shortening of the mandible on the affected side. X-ray examination demonstrated changes in the head and neck of the mandibular condyle. There were varying degress of sclerosis and new bone formation in the area extending from the neck of the condyle into the sigmoid notch. The left side was affected in each case. Parallels are drawn with Perthes' disease, and although the temporo-mandibular joint is not weight-bearing, in both conditions avascular necrosis is likely to be involved. Both have similar X-ray appearances. The fragmentation of the epiphysis in the later stages causes widening and collapse of the head of the femur and the mandibular condyle.
Adolescent↗
Condylar translation and the function of the superficial masseter muscle in the rhesus monkey (M. mulatta).
The relationship between translation of the mandibular condyle during symmetrical mandibular rotation, i.e., symmetrical jaw depression and elevation, and the function of the superficial masseter muscle was examined in light of relative torque and the length-tension relationship for muscle. Lateral cephalograms of live adult rhesus monkeys (Macaca mulatta) were analyzed using two models: (1) Model A, normal symmetrical jaw rotation accompanied by condylar translation; and (2) Model B, mandibular rotation about an axis fixed at the position of the condyles during centric occlusion. The decrease in relative torque and the excursion of the superficial masseter at mouth-open positions are significantly greater in Model B than in Model A. Symmetrical rotation of the jaw about a fixed axis would result in a 35% greater loss of maximum producible tension at maximum gape than rotation associated with condylar translation. These results suggest that condylar translation during mandibular depression and elevation functions to minimize reduction in relative torque and excursion of superficial masseter muscle, thereby maintaining optimal potential for exerting maximum tension during jaw closure.
Animals↗
[Temporomandibular joint and rheumatoid polyarthritis. X-ray computed tomographic aspects].
Direct coronal computed tomography (CT) examination of the temporomandibular joint (TMJ) was performed in 26 patients with rheumatoid arthritis (RA) and 26 control subjects. Changes in condylar shape, erosions and cysts of the mandibular condyle and condylar head resorption were more frequent among the RA group than the control group. Only the erosions and cysts of the mandibular condyle had a significantly higher frequency in the RA group than in the control group (p less than 0.05). Bone changes were bilateral in RA. Coronal view of the CT examination allow a clear visualization of the osseous elements of the TMJ but a control group is absolutely necessary to affirm with certainty the rheumatoid origin of the bone changes. The erosions and cysts of the mandibular condyle and their bilateral nature are the most specific features of RA on TMJ.
Arthritis, Rheumatoid↗
Remodeling of the temporomandibular joint following mandibular distraction osteogenesis in the transverse dimension.
Transverse mandibular distraction osteogenesis involves moving the osteotomized segments of the mandible in either a varus or valgus direction. This maneuver allows for widening of the bigonial distance or for a lateral shift of an asymmetric mandibular midline. During this process, a significant amount of torque is placed on the mandibular condyles, because they act as the pivot point for the mandibular translation. Although standard linear distraction osteogenesis induces transient, reversible changes in the temporomandibular joint, it is not known what effect the varus and valgus stresses of transverse distraction have on the temporomandibular joint. We therefore designed a study to document the temporomandibular joint changes following various degrees of transverse distraction. Bilateral transverse mandibular distraction was performed on 10 adult, female mongrel dogs using an external, multiplanar mandibular distraction device. The distraction protocol was as follows: (1) complete osteotomy at the angle of the mandible, (2) 5-day latency period, (3) distraction rate of 1 mm/day, (4) rhythm of one turn per day, (5) linear activation 16 to 30 mm bilaterally, and (6) 8-week consolidation period. A variety of varus and valgus distraction vectors were applied to the mandible only after 10 mm of initial linear distraction had been achieved. Posteroanterior and lateral cephalograms were performed throughout the entire process. Pre-distraction and post-consolidation computed tomographic scans were also performed. Changes in mandibular conformation, axis of rotation, temporomandibular joint structure, and glenoid fossa changes were directly assessed by evaluating the postmortem craniofacial skeleton. The findings were compared with those of normal, age-matched mongrel dog skulls. Significant remodeling changes were observed in the temporomandibular joints of all animals involved in the study. The mandibular condyles demonstrated varying degrees of flattening and erosion at all contact points with the craniofacial skeleton. In some cases, the condyle became part of the distraction regenerate process and was hypertrophied in all dimensions. The condyles were frequently displaced out of the glenoid fossa, particularly on the side in the direction of varus distraction. When the latter occurred, a new fossa was created on the undersurface of the zygomatic arch. Varying degrees of mandibular rotation in the sagittal plane were also observed, which led to abnormal torquing of the condyles in the coronal plane, depending on whether the axis of rotation occurred primarily around the condyle or around the distraction regenerate zone.In conclusion, transverse mandibular distraction is an effective means of producing a varus or valgus shift in the gonion relative to the midsagittal plane. However, unlike linear or angular mandibular distraction, transverse distraction has a multitude of nontransient effects on the temporomandibular joint. Therefore it must be emphasized that in clinical practice, transverse distraction should be used cautiously. One must also be aware that such a maneuver in distraction can have negative effects on the temporomandibular joint.
Animals↗
Effects of complete separation of condyle on the facial growth of growing rats.
Normal mastication needs condylar support. Mandibular condyle is thought to be one of the factors which control facial growth. To determine which parts of the face are affected by unilateral complete condylotomy including surrounding connected soft tissues, thirty-nine male Wistar rats, 5 weeks of age, were divided into control, sham treated and experimental groups. The control animals received no treatment, where as the left mandibular condyles of the experimental animals were condylotomized. Soft X-rays of the animals of both groups were taken every two weeks, and all were killed six weeks after treatment. Roentgenografically, it was observed in the experimental animals that a functional condyle-like process generated to fill the condylar space of glenoid fossa. This process was smaller than normal condyle of the control anomals. Furthermore, ANOVA revealed significant differences (P less than 0.01) in some facial structures including facial height as well as mandibular length, which were still affected at six weeks after the surgery. The result of the present investigation suggests that unilateral condylotomy induced the production of a functional condyle-like process and caused some facial deformities.
Analysis of Variance↗
Alterations of morphology and microdensity in the condyle after mandibular osteodistraction in the rat.
PURPOSE: In this study, we examined the effects of mandibular distraction osteogenesis on the morphology and the microdensity of the rat condyle. MATERIALS AND METHODS: One hundred twenty-nine rats were allocated to 4 experimental groups (n = 32 or 33). Each received unilateral mandibular ramus osteotomy and distraction device placement. After a 3-day latency, these were distracted once a day for 5 days. The slow distraction group was distracted a total of 1 mm (0.2 mm/d); the moderate group, 2 mm (0.4 mm/d); the rapid group, 3 mm (0.6 mm/d); and the sham group, no distraction (0.0 mm/d). Eight to 9 rats in each group were sacrificed at each of 4 time points after device placement (6, 10, 24, and 38 days). Baseline data were obtained 3 days after osteotomy and device placement without distraction from an additional 10 rats. Radiographs of the hemimandibles were scanned and measured to evaluate changes in condylar size (height, width, and area), angulation, and bone microdensity converted to equivalent bone thickness using a stepwedge. The wet weights of masseter muscle were measured at the time of harvest. RESULTS: 1) Muscle weight gains over time were significantly lower in the treated than the untreated sides throughout the consolidation period (P <.001). 2) Condylar size and angulation on the untreated side increased postoperatively, whereas there was a significant reduction of these parameters (P <.01 to.001) on the treated side at 24 and/or 38 days. 3) Condylar microdensity significantly increased on the untreated side at 24 and 38 days (P <.05 to.01) but not on the treated side. 4) Faster or larger distraction caused more severe size reduction and more upright condylar angulation, prevented an increase in bone microdensity on the treated side, especially during the consolidation periods (P <.05 to.01), and retarded increase in muscle weight, whereas a slower distraction rate showed few negative, and even some positive effects. 5) Correlations in size, angulation, and microdensity between right and left condyles became less significant over time. 6) There were positive correlations between muscle weight and condylar size, angulation, and microdensity. CONCLUSION: An increased rate of mandibular distraction has significant negative effects on condylar morphology and microdensity.
Analysis of Variance↗
Severe congenital hypoplasia of the mandibular condyle-diagnosis and treatment: a report of 2 cases.
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Adult↗