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Results for “MANDIBULAR CONDYLE”

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PubMed1997

Positional changes in the mandibular condyle and amount of mouth opening after sagittal split ramus osteotomy with rigid or nonrigid osteosynthesis.

PURPOSE: The purpose of this study was to investigate postoperative positional changes in the mandibular condyle and mouth opening in patients undergoing sagittal split ramus osteotomy with either rigid or nonrigid osteosynthesis. PATIENTS AND METHODS: The forty-six patients with mandibular prognathism underwent sagittal split ramus osteotomy for mandibular set back followed by fixation with one of four methods: circumferential wire (n = 11), lag screw technique (n = 10), positional screw technique (n = 10), or miniplates (n = 15). The changes in the condylar position were assessed by measuring the angle of the condylar long axis (the condylar angle) on submentovertex radiographs. Mouth opening was evaluated by measuring the interincisal distance immediately after the release of maxillomandibular fixation and by monitoring the duration of trismus. RESULTS: Regardless of the procedure used the condylar angle increased in most patients after surgery (80 of 92 condyles). Although the amount of increase tended to be higher with rigid osteosynthesis than with nonrigid osteosynthesis, no significant differences were observed among the groups. Mouth opening was not significantly influenced by the type of osteosynthesis, and no patient complained of limitation 1 year after surgery. CONCLUSIONS: Although inward rotation of the condyle frequently occurs after osteosynthesis regardless of the procedure used, the changes in condylar position are within the range of adaptability of the patient.

Adaptation, Physiological↗
PubMed1994

Regional and temporal changes in the synthesis of matrix metalloproteinases and TIMP-1 during development of the rabbit mandibular condyle.

Connective tissues synthesise and secrete a family of matrix metalloproteinases (MMPs; collagenases, gelatinases and stromelysins) capable of degrading all the components of connective tissue matrices at physiological pH. We document the patterns of synthesis and distribution of MMPs and the tissue inhibitor of metalloproteinases-1 (TIMP-1) within the developing rabbit mandibular condyle using immunofluorescence microscopy. MMPs and TIMP-1 were detected both as bright intracellular accumulations within Golgi vesicles and also as diffuse matrix-bound extracellular deposits. Cells in the articular zone, proliferative zone, condylar cartilage and bone of the mandibular ramus were shown to produce all 3 classes of MMPs and TIMP-1 with the exception of stromelysin, which was not synthesised by cells of the bone of spongiosum. Temporal synthesis of MMPs and TIMP-1 within these regions varied during the period 18 d postcoitum to 14 d postnatum. Our results document unique patterns of MMP and TIMP-1 synthesis during embryonic and early postnatal development of condylar cartilage and support the concept that cells synthesise and secrete MMPs and TIMP-1 before undergoing proliferation and hypertrophy. A comparison of these results with data in the rabbit growth plate show many similarities, but some differences exist that probably reflect differences in the modes of growth of the 2 cartilages.

Animals↗
PubMed2005

Architecture and mineralization of developing trabecular bone in the pig mandibular condyle.

Architecture and mineralization are important determinants of trabecular bone quality. To date, no quantitative information is available on changes in trabecular bone architecture and mineralization of newly formed bone during development. Three-dimensional architecture and mineralization of the trabecular bone in the mandibular condyle from six pigs of different developmental ages were investigated with micro-CT. Anteriorly in the condyle, a more advanced state of remodeling was observed than posteriorly, where more active growth takes place. Posteriorly, the bone volume fraction increased with age (r=0.87; P<0.05) by an increase of trabecular thickness (r=0.88; P<0.05), while the number of trabeculae declined (r=-0.86; P<0.05). Anteriorly, despite an increase in trabecular thickness (r=0.97; P<0.001), there was no change in bone volume fraction due to a simultaneous decline in trabecular number (r=-0.84; P<0.05) and increase in trabecular separation (r=0.95; P<0.01). Posteriorly, rods were remodeled into plates as expressed by the structure model index (r=-0.97; P<0.001), whereas anteriorly, a plate-like structure was already present in early stages. The trabecular structure had a clear orientation throughout the developmental process. The global degree of mineralization increased both anteriorly (r=0.86; P<0.05) and posteriorly (r=0.89; P<0.05). We suggest that the degree of mineralization does not depend on the bone volume, but on the thickness of the trabeculae as the mineralized centers of trabeculae were getting larger and more highly mineralized with age compared to their appositional layers. This indicates that besides apposition of new bone material on the surface of trabeculae, the mineralized tissue in their centers still changes and matures.

Animals↗
PubMed1990

Periostomy and growth of the mandibular condyle in the rat.

It has been shown that a release of periosteal tension may augment the growth of a long bone; however, similar experiments in the mandible have produced equivocal results. For further definition of the role of periosteal tension in the growth of the mandibular condyle, 80 young female Sprague-Dawley rats were randomly assigned to four equal groups: (1) sham, (2) condylotomy, (3) narrow periostomy, and (4) wide periostomy. All procedures were performed unilaterally. Lateral cephalograms, transcranial condylar radiographs, and metallic implants made possible the measurement of the actual increment of condylar growth over three post-operative periods: 0 to 14 days, 14 to 28 days, and 0 to 28 days. Analysis of covariance was performed (weight gain as the covariate) and, where overall significance was found, Turkey's HSD test was used for determination of individual group differences. Conservative, circumferential periostomy of the condylar neck as well as condylotomy failed to alter the condylar growth rate, whereas removal of a wide band of periosteum led to a small decrease. These findings suggest that, at least in the rat, periosteal tension plays only a minor role-if any-in the control of condylar/mandibular growth. Furthermore, a subsequent increase or decrease in condylar growth, in experiments that use a condylotomy model, cannot be attributed solely to a disturbance in periosteal integrity caused by the condylotomy.

Analysis of Variance↗
PubMed2006

Reconstruction of mandibular condyle by transport distraction osteogenesis: Experimental study in rhesus monkey.

PURPOSE: This study investigated histomorphologic changes in the newly formed condyle reconstructed by transport distraction osteogenesis through a nonhuman primate model. MATERIALS AND METHODS: Six adult rhesus monkeys were used in this study. Bilateral condyles and articular discs were extirpated, and the technique of transport distraction osteogenesis was carried out to reconstruct the condyles. X-ray and 3-dimensional (3D) computed tomography (CT) scanning films were taken at various intervals. Two monkeys were killed respectively at 4, 12, and 24 weeks after completion of distraction; the transport segments and the distracted calluses were harvested and processed for histologic examination. The original condyles removed at surgery served as normal control. RESULTS: Open bite was seen in all animals postoperatively and diminished at the end of distraction. Bone regeneration was perfect in the distraction gap between the transport disc and the pre-existing mandible. The bony transport disc gradually remodeled to a neocondyle that was similar to the original condyle in the appearances and structures. The head of neocondyle was covered with a fibrous cap, which might play the role of an articular disc. CONCLUSION: A neocondyle with functional shape can be created by transport distraction osteogenesis. This suggests that this technique is an alternative method for reconstruction of the mandibular condyle.

Animals↗
PubMed2005

The effect of bone loss on rod-like and plate-like trabeculae in the cancellous bone of the mandibular condyle.

Bone loss may affect the structure of cancellous bone. But its effect on trabeculae with different characteristics, like rods and plates, is not accurately known. This study analyzes the effect of bone loss on individual rod-like and plate-like trabeculae. 94 specimens were obtained from mandibular condyles from both dentate and edentate humans and scanned with a micro-CT scanner. The bone volume fraction (BV/TV) of these specimens ranged from 7% to 30%. Next, the rod-like and plate-like trabeculae were identified with an especially developed algorithm. Plate volume fraction (PV/TV), rod volume fraction (RV/TV), plate thickness, rod thickness, number of plates, and number of rods were determined. In individual specimens, the thickness of the rods ranged from 40 mum to 180 mum, while the thickness of the plates ranged from 40 mum to 300 mum. In every specimen, the thickness of the plates was larger than the thickness of the rods. Statistical analysis revealed that PV/TV was proportional (r = 0.98, P < 0.001) and RV/TV inversely proportional (r = -0.45, P < 0.001) to BV/TV. Also the thickness of the plates correlated with BV/TV (r = 0.62, P < 0.001), while the thickness of the rods (mean = 90 mum, SD = 7 mum) remained constant (r = -0.09, P = 0.378). A four-fold reduction of the bone volume fraction was accompanied by a three-fold reduction of the number of plates and a 40% reduction of their thickness, but also by a three-fold increase in the number of rods and RV/TV. It was concluded that the effect of bone loss on plate-like trabeculae was opposite to its effect on rod-like trabeculae. Remarkably, the thickness of the rods (90 mum) was independent of the bone volume fraction. This suggests that there is a minimal thickness for trabeculae.

Aged↗
PubMed1994

Effects of physicochemical factors on the growth of mandibular condyles in vitro.

Cartilage growth and remodeling are known to be influenced by the biochemical and mechanical environment of the tissue. Previous investigators have shown that chemical factors that are relevant to mechanical loading, such as osmotic pressure and pH, induce changes in cartilage metabolism in vitro. Using a neonatal rat mandibular condyle culture system, the objectives of the work reported here were to determine (1) how the growth is influenced by osmotically applied mechanical loads; and (2) whether changes in intratissue osmotic pressure or pH cause metabolic changes in the cartilage which are then reflected by altered growth behavior. High molecular weight (MW) uncharged macromolecules polyvinylpyrrolidone (PVP) and Ficoll (presumed unable to penetrate the tissue matrix) were used to examine the effect of osmotic loading on tissue growth; concentrations corresponding to osmotic pressures of up to 100 kPa resulted in a dose-dependent depression in growth and matrix accumulation. Raffinose (which can penetrate the matrix but not the cells) had no significant effect on growth for osmotic pressures of up to 87 kPa, suggesting that compression-induced changes in intratissue osmotic pressure are unlikely to provide a signal by which cells sense and respond to mechanical compression. By contrast, changes in medium pH resulted in dose-dependent changes in growth behavior. Specifically, slight alkalinity (acidity) greatly enhanced (diminished) growth and matrix accumulation; the sensitivity to pH suggests that intratissue pH could provide a mechanism for cells to sense local glycosaminoglycan concentration and mechanical compression.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Osteosynthesis using a screwed plate in fractures of the mandibular condyle].

The surgical treatment of sub-condylar fractures allows rapid reestablishment of the bite, temporo-mandibular joint function and facial appearance. A pre-auricular approach is used involving dissection of the facial nerve and its upper branch. Surgical reduction is performed under direct vision. Fixation is via a plate with 4 screws. The condylar fragment needs to be large enough to accept at least two screws and hence this needs to be confirmed preoperatively by CT scan examination. In the adult we feel that fixation is indicated for low displaced sub-condylar fractures. We do not feel that surgery is indicated for recent trauma in children.

Adult↗