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Results for “Condylar position”

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At least 361 records · Page 20Linked to original sources

PubMed2000

[Position and mobility of the articular disk after surgical management of diacapitular and high condylar dislocation fractures of the temporomandibular joint].

Magnetic resonance imaging (MRI) assessment of traumatized temporomandibular joints (TMJ) usually focuses on disc position, defining regular joint function by normal, excentric or displaced disc position. So far, there are only few reports regarding disc position after open reduction of diacapitular or high condylar fractures of the TMJ with dislocation. The aim of the present study was to evaluate the role of the disc as regards postoperative functional outcome by electronic axiographic recordings of condylar movements and MRI, displacement of the disc and lesions of TMJ soft tissues being frequent in this type of mandibular fractures. A total of 30 subjects with 37 condylar fractures in whom osteosynthesis was performed using a preauricular approach were imaged postoperatively (mean 24 months) with a 1.5-Tesla MRI system to determine, (a) the position of the disc, (b) the range of mobility of the disc and (c) condylar mobility in closed and open mouth position, comparing fractured sides (FS) vs nonfractured sides (NFS). Linear movements between the two jaw positions in the sagittal plane were measured by superimposing transparencies. The results indicate: (1) more than 70% of the discs (FS) were found to be in normal position; there was no disc displacement without reduction. However, these data stood in contrast to severe limitations of the axiographic tracings as presented by almost 30% of the subjects. (2) Significant correlations were found between fixed (alpha = 0.05) or highly immobilized (alpha = 0.01) discs and axiographic limitations, suggesting disc mobility to be a valuable parameter for assessment of the postoperative functional outcome.

Adult↗

PubMed1990

[The development of a device for condylar movement by electro-magnetic field. 1. Outline and characteristics of the device].

It is very important for clinical diagnosis to record and analyze condylar movement in cranio-mandibular disorders. Recently, many devices have been developed for this purpose. These devices can measure precisely condylar movements, but are difficult to manipulate. We have developed a simple device which substitute a palpation of the posterior aspect of the TMJ. We modified the Cardiokymograph which use electro-magnetic field. The characteristics of this device are the use of a frequency-variable crystal-controlled oscillator, and the application of the coil itself which is a part of the oscillator as a probe. We tested many electrical characteristics of this device and assured the effectiveness, that is, sensitivity, directivity, frequency response characteristic, transient response characteristic, and temperature response characteristic. We tried to insert a probe into the external auditory meatus, and record condylar movement as a positional change of the skin. It seems to suggest that our device can record a feature of condylar movement.

Electromagnetic Fields↗

PubMed2005

Mechanical strain leads to condylar growth in adult rats.

Mechanical strain produced by forward mandibular positioning was found to enhance mandibular condylar growth in experimental animals and in patients. This study was designed to identify the changes in number and rate of the proliferating mesenchymal cells in mandibular condyles of adult rats and to correlate these changes to the expression of SOX9 and type II collagen under mechanical strain. Seventy-eight 120-day-old female Sprague-Dawley rats were randomly allotted to six groups, nine animals in each experimental group according to different time points. Cell kinetic studies for expression of PCNA were used to identify number and rate of proliferating mesenchymal cells. Immunostaining of SOX9 and in situ hybridization of Col2a1 gene were carried out. Results showed a significant increase in number of replicating mesenchymal cells and proliferation rate. The expression of SOX9 was enhanced and Col2a1 gene transcript was then activated. The proliferative layer became thicker on experimental day 21. The thickness of chondroblast layer and chondrocyte layer showed significant increase from experimental day 14 to day 30. In conclusion, mechanical strain produced by mandibular advancement in adult rats promotes the proliferation of mesenchymal cells. Under control of transcription factor SOX9, these mesenchymal cells are then committed to enter the chondrogenic route leading to condylar growth.

Animals↗

PubMed2003

Four-dimensional analysis of mandibular movements with optical position measuring and real-time imaging.

Mandibular movement findings have not always been useful in clinical, even though measuring techniques have improved. This is because there is no method to evaluate condylar movement including the position of the temporal bone. In this study, we have attempted to apply 3-dimensional imaging to mandibular movement data, and have developed a 4-demensional analysis system representing mandibular movements. In this system, the mandibular movement can be observed in real-time by using the CT dataset from a volunteer. As a result the relationship between the mandibular movement and the anatomic structures becomes clear.

Adult↗

PubMed2003

Computed tomographic study of the posterior condylar angle in arthritic knees: its use in the rotational positioning of the femoral implant of total knee prostheses.

The epicondylar axis is a reliable reference to check the rotation of the femoral implant in total knee prostheses (TKPs). However, during the operation it seems easier to use the posterior condylar axis as a landmark. The angle between these two axes is called the posterior condylar angle (PCA). The aim of this study was to measure the PCA in arthritic knees to assess the reliability of the posterior condylar axis as a reference for the control of the rotation of the femoral implant and to look for correlation with other radiological measurements. This prospective study consisted of 103 arthritic knees (81 varus, 22 valgus) before a TKP had been done in 103 patients (75 women, 28 men). The assessment of the PCA was made by computed tomographic scanning (CT). The HKA, HKS and HKT angles were measured on the pangonogram. The posterior condylar axis was internally rotated with respect to the epicondylar axis. The average value for all the patients was 2.65 degrees degrees with a range from 0 degrees to 7 degrees. The PCA was significantly increased in the valgus knees. There was no correlation between the angles on the pangonogram and the posterior condylar axis. While the preoperative assessment of the PCA by CT scanning is reliable, the results obtained indicate the marked variability in its value. If one wishes to use the posterior condylar axis as a guide for rotation, it is therefore necessary to assess the PCA for each patient using adjustable jigs according to the value obtained. No measurement on standard radiographs allowed an extrapolation of the value of the PCA, and CT scanning seems to be the preferable radiological examination.

Aged↗

PubMed2003

Computed tomographic findings of the fractured mandibular condyle after open reduction.

The purpose of this study was to evaluate the long-term radiological results obtained with open reduction and fixation of unilateral mandibular condyle fractures in 10 patients. CT images taken at the end of the follow-up period (average of 22 months, range 7 to 33 months), were traced and digitized, and the position and morphology of the fractured condylar process was statistically compared with those of the contralateral non-fractured condylar process in the coronal, transverse and sagittal planes. Little difference was observed in the position or morphology of the condylar process in the operated and non-fractured joints. This study shows that it is possible to anatomically reduce fractured condyles, and thereby to avoid postoperative disadvantageous joint changes.

Adult↗

PubMed2006

The effects of age and sex on the expression of aromatase in the rat temporomandibular joint.

AIMS: To investigate the expression of aromatase in temporomandibular joints(TMJs) of male and female rats of different ages. METHODS: The expression of aromatase in terms of protein and mRNA was examined by immunohistochemistry, Western blot, and in situ hybridization in the TMJs of Sprague-Dawley rats. The expression level of aromatase protein was also quantified by the density of aromatase-positive chondrocytes in TMJ condylar cartilage. A tritiated water assay was used to analyze the activity of aromatase in cartilage chondrocytes. RESULTS: Strong aromatase protein and mRNA hybridization signals were detected in hypertrophic and mature chondrocytes in all the cases examined. The density of aromatase-positive chondrocytes was relatively stable at higher levels before 8 weeks of age. The density decreased gradually in females after 8 weeks of age but not in males. CONCLUSION: These results demonstrate that aromatase is expressed intensely in condylar cartilage and suggest that it may play an important role in pathophysiological mechanisms in condylar cartilage.

Age Factors↗

PubMed1999

Morphologic determinants in the etiology of class III malocclusions: a review.

Morphospatial disharmony of the craniomaxillary and mandibular complexes may yield apparent mandibular prognathism, but Class III malocclusions can exist with any number of aberrations of the craniofacial complex. Deficient orthocephalization of the cranial base allied with a smaller anterior cranial base component has been implicated in the etiology of Class III malocclusions. Whereas the more acute cranial base angle may affect the articulation of the condyles resulting in their forward displacement, the reduction in anterior cranial size may affect the position of the maxilla. As well, intrinsic skeletal elements of the maxillary complex may be responsible for maxillary hypoplasia that may exacerbate the anterior crossbite seen in the Class III condition. Conversely, with an orthognathic maxilla, condylar hyperplasia and anterior positioning of the condyles at the temporo-mandibular joint may produce an anterior crossbite. Aside from the skeletal components, soft tissue matrices, particularly labial pressure from the circumoral musculature, may influence the final outcome of craniofacial growth of a child skeletally predisposed to Class III conditions. Indeed, as some Asian ethnic groups demonstrate an increased prevalence of Class III malocclusions, it is likely that the skeletal components and soft tissues matrices are genetically determined. Presumably, the co-morphologies of the craniomaxillary and mandibular complexes are likely dependent upon candidate genes that undergo gene-environmental interactions to yield Class III malocclusions. The identification of such genes is a desirable step in unraveling the complexity of Class III malocclusions. With this knowledge, the clinician may elect an early course of dentofacial orthopedic and orthodontic treatments aimed at preventing the development of Class III malocclusions.

Humans↗

PubMed1991

Tomographic assessment of alterations of the temporomandibular joint after surgical correction of mandibular prognathism.

The aims of this study were to identify absolute condylar displacements and temporal fossa changes and to assess alterations in the condyle-fossa relationships after bilateral vertical ramus osteotomy for correction of mandibular prognathism. Twenty-four patients had linear tomograms taken of their temporomandibular joints within 1 week preoperatively and 6 months postoperatively. To ensure identical orientation of the focusing plane, a custom-made headholder was constructed and the head of the patient was positioned on the x-ray table in a standardized way. All radiographs were traced, and superimposition was made on stable structures, such as the mastoid cells of the temporal bone, the auditory meatus, the zygomatic arch, and the anterior cranial base. The results of the study indicated that, 6 months postsurgery, the only statistically significant change existed in the posterior joint space, which showed an average increase of 0.7 mm (P = .003). All other variables showed that the condylar position within the joint tended to approach its preoperative value. Small resorptive alterations in the glenoid fossa were also noticed.

Adult↗

PubMed2005

Condylar head remodeling following mandibular setback osteotomy for prognathism: a comparative study of different imaging modalities.

PURPOSE: Condylar remodeling, which develops after mandibular setback osteotomy, was evaluated and compared in CT, plain film radiographs, and MR images acquired postoperatively. METHODS: Thirty-nine patients treated with sagittal split ramus osteotomy (SSRO) and 46 patients treated with intraoral vertical ramus osteotomy (IVRO) were studied. Remodeling as seen in the images and the diagnostic agreement between imaging modalities was evaluated. RESULTS: A newly formed bone layer in the posterior part of the condylar head was identified as a sign suggestive of remodeling. This sign was seen predominantly at periods over 6 months postoperatively. IVRO subjects had a higher incidence of remodeling than did the SSRO group. The diagnostic agreement between the 3 imaging modalities was substantial. There was a positive correlation between postoperative condylar displacement and the incidence of remodeling. CONCLUSIONS: The incidence of postoperative condylar head remodeling may be predictable. High-dose postoperative imaging studies to assess the TMJ should be restricted to those cases having a clear need for such studies.

Adolescent↗

PubMed2002

Immunohistochemical localization and distribution of proliferating cell nuclear antigen in the rabbit mandibular condyle following experimental induction of anterior disk displacement.

The purpose of the present study was to identify proliferating cells in control versus experimental condyles two weeks following experimental induction of anterior disk displacement (ADD) in the rabbit craniomandibular joint (CMJ). The right joint of 15 rabbits was exposed surgically and all diskal attachments were severed except for the posterior attachment. The disk was then repositioned anteriorly and sutured to the zygomatic arch. The left joint served as a sham-operated control. Ten additional joints were used as nonoperated controls. Mandibular condyles were excised two weeks following surgery and processed for proliferating cell nuclear antigen (PCNA) immunostaining. In control and sham operated condyles, PCNA was localized in the nuclei of chondroblasts of the reserve cell layer, chondrocytes of the upper hypertrophic layer and bone marrow cells of the subchondral bone. In contrast to control joints, the PCNA positive cells of the experimental joints were located throughout the osteoarthritic condylar cartilage. In addition, the percentage of PCNA positive cells of the osteoarthritic condylar cartilage was statistically significantly higher when compared to the control group, p < 0.05. It was concluded that surgical induction of ADD in the rabbit CMJ leads to an increase in mitosis of chondrocytes, which lead to cell proliferation and subsequent hyperplasia of the condylar cartilage.

Analysis of Variance↗

PubMed1999

Morphometrical examinations of the mandibular ramus for the indication of lag screw osteosynthesis described by Eckelt in mandibular condylar fractures.

For several years, lag screw osteosynthesis as described by ECKELT has been used for the surgical treatment of condylar fractures with predominantly positive results. However anatomical variations occasionally do not permit the use of the lag screw. The aim of the present study was to re-examine the anatomical requirements for using ECKELT's lag screw osteosynthesis. Based on a detailed structural analysis of 140 isolated cadaver rami mandibulae, it can be seen that they principally meet the anatomical requirements for the treatment of mandibular condylar fractures with lag screw osteosynthesis using 2.0 mm diameter screws. Rare, extreme anatomical variants emphasize the need for a stricter preoperative determination of the indications. Using spiral computerized tomography, it is possible to exactly assess preoperatively the existing anatomical situation of the ascending mandibular ramus on the planned frontal plane of the lag screw.

Bone Screws↗

PubMed1982

The interplay between sagittal and vertical growth factors. An implant study of activator treatment.

Changes in sagittal jaw relationship are dependent on an interplay between a series of basal and dentoalveolar changes in both sagittal and vertical planes. The present article uses the implant method to examine and discuss this interrelationship as well as condylar growth and, in addition, comments on the relative value of accepted methods of expressing sagittal jaw relationship. The interplay between vertical and horizontal dentoalveolar, sutural, and condylar changes occurring relative to the occlusal plane in nineteen patients treated by means of activator was studied quantitatively by means of the implant method. Changes in the sagittal jaw relationship were evaluated by means of the change in ANB angle and utilizing the "Witts appraisal" with a modified occlusal plane construction. Change in sagittal jaw relationship was studied by means of a correlation analysis and shown to be largely dependent on the spatial development of the mandible; the latter was positively correlated to vertical condylar development and maxillary horizontal development but negatively correlated to increase in vertical sutural and dentoalveolar parameters. Vertical condylar development was also demonstrated to influence the rotational pattern of mandibular development. The clinical importance of controlling vertical development, sutural as well as dentoalveolar, in the treatment of sagittal discrepancies was stressed through the findings of the present study.

Activator Appliances↗

PubMed1993

Elusive "stuck" disk in the temporomandibular joint: diagnosis with MR imaging.

PURPOSE: To determine the incidence of a "stuck" disk and its importance in the overall scheme of internal derangement. MATERIALS AND METHODS: Magnetic resonance (MR) images of 212 temporomandibular joints (TMJs) in 106 symptomatic patients were obtained and reviewed. Image analysis included assessment of disk position; disk mobility; and degree of condylar translation, with or without disk recapture in joints with displaced disks. RESULTS: Of the 127 joints with disks in a normal position, 94 had mobile disks and 23 had stuck disks. Ten joints revealed no condylar translation, which precluded assessment of disk mobility. Of 85 joints with displaced disks, 67 joints showed mobility, with recapture in 25 and no recapture in 42. Significant correlation existed between disk mobility and degree of condylar translation (P < .001). CONCLUSION: The TMJ disk may be stuck in a normal or displaced position and limits the normal degree of condylar translation, leading to restricted jaw opening. Recognition of a stuck TMJ disk could alter patient care.

Adolescent↗

PubMedDate not supplied

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↗

PubMed2003

[Effects of unilateral mandibular distraction osteogenesis on temporomandibular joint].

OBJECTIVE: To study the effects of unilateral mandibular distraction osteogenesis(MDO) on the temporomandibular joint(TMJ). METHODS: Ten rhesus monkeys were used to perform right MDO. After 5 days, latency period, the distractor was initiated at the rate of 0.5 mmx2/day, totally 15 days. When MDO completed, and 2,4,6,and 12 weeks after MDO, X-ray films of bilateral TMJ were taken and one group of animals was sacrificed. Bilateral TMJ were obtained and paraffin slices were made HE and immunohistochemistry stains of TGF-beta1 were done on the slices. RESULTS: After MDO, the monkeys' mandible midline obviously deflected to the left side. The front teeth had open bite and reverse bite. The right molars were severely open bite and the left molars were reverse bite. From the X-ray film, we can see that the right condylar process moved backward and upward in the acetabulum, while the left condylar process moved forward and downward. On the slices, both sides of the TMJ showed different degrees of degeneration and proliferation, but the changes on the right side were more severe and obvious than the left side, and had involved all the cartilage's layers and the bone tissues under the cartilage. In some animals, there even appeared cartilage erosion and light histological changes of acetabulum. During the consolidation period, the open bite gradually closed, and the condylar process gradually moved to normal position. Twelve weeks after MDO, the open bite at the right side disappeared, but the front teeth open bite and reverse bite still existed. The right condylar process still lay a little backward and had some degree of degeneration. The left TMJ had the normal position and histology except for cartilage hypertrophy layer thickness. At different times during consolidation period, the positive stains of TGF-beta1 in condylar process on both sides were all more obvious than that of the control group. CONCLUSION: MDO can cause TMJ position change and light histological degeneration, but these changes can gradually rehabilitate in the future. TGF-beta1 may play a role in the reconstructive process of TMJ degeneration.

Animals↗

PubMed2000

Cranial nerve VII region of the traumatized facial skeleton: optimizing fracture repair with the endoscope.

OBJECTIVE: Cranial nerve VII (CN VII) is anatomically positioned adjacent to the condylar neck of the mandible and arch of the midface. Fracture treatment of this region of the facial skeleton remains controversial because of difficult surgical access. Conservative management rarely achieves anatomic fracture repair and can result in irreversible structural deformity and dysfunction. Traditional operative methods require access through very visible facial incisions and risk injury to the facial nerve. We report endoscopic methods of facial fracture repair in the region of CN VII that achieve excellent fracture reduction and stabilization, with minimal risk of facial nerve injury by using hidden incisions. METHODS: A consecutive series of 65 endoscopically assisted facial fracture repairs were analyzed. Endoscopic repairs of the condylar neck (n = 40) of the mandible were performed through an intraoral incision. Endoscopic arch repairs (n = 25) of the midface were performed through a preauricular incision. Outcomes were evaluated by postoperative fracture reduction on radiographs, occlusion, interincisal jaw opening, and facial nerve function. RESULTS: Thirty-seven of 40 condylar neck mandible fractures went on to anatomic bone union, whereas 3 of 40 had either incomplete fracture reduction or re-fracture through the plate. There was one temporary palsy of CN VII that completely resolved spontaneously. Jaw opening exceeded 40 mm by the 8th postoperative week. Computed tomographic images demonstrated anatomic arch repair in all 25 endoscopically repaired cases. Six of seven endoscopically repaired Le Fort III facial fractures went on to restoration of their premorbid occlusion. One of seven had an excellent restoration of the occlusal interface but a cant to the occlusal plane. Two of seven had improved but incomplete restoration of the malar prominence and enopthalmos ipsilateral to the side of endoscopic arch repair. Eight of 25 endoscopic arch repairs developed temporary paralysis of the frontal branch of CN VII that recovered completely by the 10th postoperative week. CONCLUSION: We have developed novel endoscopically assisted techniques to facilitate repair of facial fractures in the region of CN VII. These techniques have been successfully applied to accurately restore the facial skeleton to its preinjury anatomic position in the region of CN VII with minimal risk of facial paralysis by using limited and well-hidden incisions.

Adolescent↗

PubMed1983

Retrieval analysis of total knee prostheses: a method and its application to 48 total condylar prostheses.

A technique for the classification and quantification of damage in retrieved total knee prostheses is presented and applied to the examination of 48 removed total condylar-type knee replacements. The technique involves inspection of all metallic and polyethylene components for evidence of gross deformation, fracture, and damage to articulating surfaces. A grading system was developed to quantitate surface damage on polyethylene components. Results of the examinations are combined with patient variables (weight, activity level, radiographic findings, time of implantation, and results of histology performed on surrounding tissue) to determine correlations between clinical variables and the mechanical damage experienced by the prostheses. For the 48 total condylar-type prostheses, significant positive correlations were found for the surface damage correlated with the patient's weight and the time the prosthesis was implanted.

Biomechanical Phenomena↗