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Results for “Condylar position”

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PubMed1990

[TMJ lesions. Dysfunction and occlusion. Radiographic study].

A tomographic investigation was performed on 51 randomly selected patients with Rheumatoid Arthritis in order to identify the prevalence of the temporo-mandibular joint involvement and the relationship with the clinical dysfunction and occlusal state. The relation between the condyle and the fossa in intercuspal position and during opening were measured: protrusive condylar path often got reduced. Articular shape and structural changes were also evaluated: only 4% of total joints resulted uninjured. The survey showed a significant incidence of structural as well as functional involvement of the tmj. Instead subjective symptoms and dental support seemed to be relatively independent, to confirm the heterogeneity of factors in masticatory dysfunction.

Adult↗

PubMed1987

Chondroid bone arises from mesenchymal stem cells in organ culture of mandibular condyles.

Mandibular condyles of fetal mice 19 to 20 days in utero comprising clean cartilage and its perichondrium were cultured for up to 14 days, and their capacity to develop osteoid and to mineralize in vitro was examined. After 3 days in culture the cartilage of the mandibular condyle appeared to have lost its inherent structural characteristics, including its various cell layers: chondroprogenitor, chondroblastic, and hypertrophic cells. At that time interval no chondroblasts could be seen; instead, most of the cartilage consisted of hypertrophic chondrocytes. By that time, the surrounding perichondrium, which contains pluripotential mesenchymal stem cells, revealed the first signs of extracellular matrix enclosing type I collagen, bone alkaline phosphatase, osteonection, fibronectin, and bone sialoprotein as demonstrated by immunofluorescent techniques. Electron microscopic examinations of the newly formed matrix revealed foci of mineralization within and along collagen fibers as is normally observed during bone development. The composition of the latter mineral deposits resembled calcium pyrophosphate crystals. Following 14 days in culture larger portions of the condyle revealed signs of osseous matrix, yet the tissue reacted positively for type II collagen. Hence, the condylar cartilage, a genuine representative of secondary-type cartilage, elaborated in vitro a unique type of bone that would be most appropriately defined as chondroid bone. Biochemical assays indicated that the de novo formation of chondroid bone was correlated with changes in alkaline phosphatase activity and 45Ca incorporation. The findings of the present study imply that mesenchymal stem cells that ordinarily differentiate into cartilage possess the capacity to differentiate into osteogenic cells and form chondroid bone.

Animals↗

PubMed1980

Results after mandibular advancement surgery: an analysis of 87 cases.

Clinical results and stability after mandibular advancement surgery were evaluated in a multi-institutional study of 87 individuals. Skeletal and dental stability were evaluated by a computer morphometric technique and clinical results were determined by recall of patients. Analyses of multiple variables were performed to determine factors that contributed to optimum treatment results or relapse, or both, after mandibular advancement. It was found that the mandible can be advanced successfully in all types of mandibular deficiency. Problems primarily related to surgical technique, such as postoperative condylar distraction, were consistently associated with relapse. Position of the proximal segment and the use of skeletal fixation were important in preventing relapse, but the value of suprahyoid myotomies and cervical collars was not proved. Significant postural changes of the head and cervical spine were observed after surgery.

Adult↗

PubMed1994

Patellar resurfacing or retention in total knee arthroplasty. A prospective study of patients with bilateral replacements.

Patellofemoral problems are a common cause of morbidity and reoperation after total knee arthroplasty. We made a prospective study of 52 patients who had bilateral arthroplasty (104 knees) and in whom the patella was resurfaced on one side and not on the other. A movable-bearing prosthesis with an anatomical femoral groove was implanted on both sides by the same surgeon using an otherwise identical technique. The mean follow-up was 5.24 years (2 to 10). In the 30 available patients (60 knees) there was no difference between the two sides in subjective preference, performance on ascending and descending stairs or the incidence of anterior knee pain. Radiographs showed no differences in prosthetic alignment, femoral condylar height, patellar congruency or joint line position. The use of an appropriate prosthetic design and careful surgical technique can provide equivalent results after knee arthroplasty with or without patellar resurfacing. Given the indications and criteria, which we discuss, retention of the patellar surface is an acceptable option.

Adult↗

PubMedDate not supplied

Changes in the rabbit temporomandibular joint associated with posterior displacement of the mandible.

The purpose of this investigation was to study the changes in temporomandibular joint tissues, in particular the disc and its attachments, associated with muscle-powered continuous posterior displacement of the mandible for 33 days. After measurement of incisal relationships, food and water consumption, histologic and morphometric analysis, and radiologic data, it was determined that spatial relationships of joint tissues were altered. Mandibular retrusion leads to alteration in disc morphology and induces anterior positioning of the disc relative to the condylar head. Nutritional intake was disrupted by distal displacement crowns placed on the maxillary incisor teeth.

Analysis of Variance↗

PubMed1991

Correction of condylar displacement following intraoral vertical ramus osteotomy.

Fifteen patients who demonstrated condylar sag after intraoral vertical ramus osteotomy for the correction of mandibular prognathism were treated nonsurgically to establish the desired postoperative occlusion. A mean inferior displacement of 3.33 mm and anterior displacement of 2.18 mm were observed tomographically after surgery. Postoperatively, a geometric splint was constructed to compensate for the magnitude of condylar displacement and was used to replace the original splint to hold the distal segment in an overcorrected position. Skeletal fixation was maintained for 5 to 6 weeks. Tomographic evaluation of the temporomandibular joint (TMJ) during maxillomandibular fixation showed a slight superior (1.03 mm) and posterior (0.51 mm) movement of the condyle in the fossa. After release of fixation and removal of splint, a further superior (2.05 mm) and posterior (1.01 mm) repositioning of the condyle was observed. This later movement correlated with the placement of light class III elastic traction to seat the condyles into the glenoid fossae and establish a class I occlusion. Temporomandibular joint tomograms confirmed complete seating of the condyles in the fossa and lateral cephalograms demonstrated a corresponding change in the position of the mandible to the desired postoperative position. This technique has been effective in preventing postoperative malocclusion resulting from condylar sag.

Adolescent↗

PubMed1994

Is it time to pay more attention to disc position?

Most surgical and nonsurgical treatments of painful temporomandibular joint internal derangements are primarily directed toward relief of pain and dysfunction; correction of disc displacement is increasingly of lesser or no concern. However, internal derangements are variably progressive and, in some patients, cause condylar deformity with secondary deficiency of the mandible. If data support the hypothesis that condylar deformity and growth retardation can result from a displaced disc, and, conversely, that a normally positioned disc permits normal growth and maintains condylar mass, a goal of any treatment for reducing disc displacement should include reestablishment of a normal disc/condyle relationship. Functional appliance therapy for the deficient mandible may be most effective in those patients that present with a normal disc/condyle relationship; if a reducing disc is present, such therapy may be most effective only when the appliance advances the condyle to a position beneath the disc.

Facial Pain↗

PubMed1999

Distribution of parathyroid hormone-related protein (PTHrP) and type I parathyroid hormone (PTH) PTHrP receptor in developing mouse mandibular condylar cartilage.

The mandibular condylar cartilage undergoes endochondral bone formation and is an important growth site in the mandible. Parathyroid hormone-related protein (PTHrP) has received attention as a physiological regulator attenuating chondrocytic differentiation and preventing apoptotic cell death. In order to examine the localization of PTHrP and its receptor during fetal development of the condylar cartilage, an immunohistochemical study of PTHrP and the type I PTH/PTHrP receptor was carried out. At day 15 of gestation, the condylar cartilage was evident and some chondrocytes showed positive staining for PTHrP. At day 16, the cartilage was increasing in length and width, and PTHrP was localized in the flattened and hypertrophic cell layers. After day 17, when endochondral bone formation had already started, PTHrP was mainly observed in the flattened cell layer and in a few layers of the hypertrophic chondrocytes. The localization of the type I PTH/PTHrP receptor was similar to that of PTHrP on days 15 and 16, and was broadly distributed at day 18. Apoptotic chondrocytes were scarcely observed on days 15 and 16, and only a few cells were present in the erosion front at day 18. This temporal and spatial localization of PTHrP and the type I PTH/PTHrP receptor suggests that PTHrP is a possible autocrine/ paracrine factor regulating condylar chondrocytic differentiation during development.

Animals↗

PubMed1993

A system for the study of jaw movements.

This paper describes a system to record incisal and condylar movements. It consists of two Charge Coupled Device (CCD) cameras that detect the position of markers fixed to the face, real-time hardware to recognize the markers and software for three-dimensional reconstruction of condylar and mandibular movements. The subject sat upright in front of the cameras and was asked to perform jaw movements. The position of the markers was recorded and the coordinates were fed into the computer and converted to three-dimensional kinematic data by a mathematical algorithm implemented on an AT IBM personal computer. Dedicated software calculated the head movements and the mandibular movements separately and performed a three-dimensional mathematical reconstruction of the movements of the condylar points and the interincisive point, using the geometrical rules of a rigid body. This pilot study describes the pattern from opening, closing, protrusive, and lateral movements as obtained from healthy subjects with good dentition.

Humans↗

PubMed1998

A study of condylar movement by bilateral simultaneous videofluorography.

OBJECTIVES: To analyse the condylar movements of patients with temporomandibular disorders and investigate the mutual interaction between both temporomandibular joints (TMJs) by comparing bilateral simultaneous videofluorography with the disk position on MRI. METHODS: Fifty-two patients who had been diagnosed as having internal derangement in one or both TMJs on the base of the clinical symptoms underwent bilateral simultaneous videofluorography and MRI. The TMJs were classified from the MRI into three categories: superior disk position (SDP), reducing disk displacement (RDD) and nonreducing disk displacement (NDD). Condylar movements of the TMJs were analysed from the videofluorography and correlated with the MR diagnoses. RESULTS: The range of condylar movement of NDD joints was significantly shorter than that of SDP or RDD joints at maximum mouth opening (P < 0.001), but not at maximum protrusion and lateral protrusion. Based on the sagittal condylar path during maximum mouth opening and closing, three patterns of condylar movement were identified: normal, deflected and short. Sixty-nine per cent of the normal pattern were SDP, 55% of the deflected RDD and 77% of the short NDD. The condylar movement of a NDD or RDD joint could influence the range and pattern of movement of the contralateral joint. CONCLUSIONS: Analysis of condylar movement was helpful in assessing the state of the disk because they were closely related. The range and pattern of condylar movement of both TMJs were mutually interrelated. Patients with signs and symptoms of internal derangement should have both sides examined for an accurate and complete diagnosis.

Adolescent↗

PubMed1979

[Therapeutic immediate denture, class II].

Without posterior support and because of dysfunction many people have very loose joints: their condyles are in a most retruded and downward situation. The occlusion cannot be stable in this relationship. The most retruded clinical position should not be used for prosthetic restoration. We must establish a therapeutic centric occlusion more anteriorly without increasing the vertical dimension. The amount of anterior condylar repositioning is determined by viewing the original TMJ tomographs. The position and the orientation of a normal occlusal plane can only be accurately determined by cephalometric analysis. This good occlusal scheme programmes the muscle coordination and maintains the anterior mandibular position.

Activator Appliances↗

PubMed1997

Altered mandibular function and prevention of skeletal asymmetries after unilateral condylectomy in rats.

Unilateral condylar injury is known to be a frequent cause of mandibular asymmetry. Whether this is due to the trauma itself or to the disturbed function that follows the injury is a very important question with ramifications for clinical complications related to facial asymmetries. The aim of this study was to test the hypothesis that mandibular function in a protruded position can compensate for the absence of one condyle and prevent potential growth asymmetries. Forty-eight 4-week-old rats were divided into two experimental and two control groups consisting of 12 animals each, as follows: (A) unilateral condylectomy was performed on the right side and the mandible was left to function normally; (B) after unilateral condylectomy on the right side, the mandible was forced to function in a protruded position; (C) a sham operation was performed in the condylar area of the right side but no appliance was used; and (D) 12 animals were used as controls without any operation or appliance. Mandibular protraction was achieved by means of a specific appliance, acting via rubber bands, pulling the mandible in a straight, forward direction with a force of 25 g for 12 hours per day. The experimental period was 30 days. Dorsoventral radiographs were taken and vital dyes were administered at three time intervals, i.e. on days 1, 15 and 30, for all animals. Cephalometric analysis included 14 measurements. Findings resulting from statistical analysis and comparisons of measurements obtained in the four groups can be summarized as follows: (i) when comparing group A with groups C and D, less growth was found in the right mandibular sides in group A; (ii) when comparing group B and groups C and D, less growth was found in the right mandibular sides in group B; (iii) when comparing groups A and B, more growth was found in the right mandibular sides in group B; (iv) when comparing the right and left mandibular sides in group A, less growth was found in the right side; and (v) when comparing the right and left mandibular sides in group B, no significant growth differences were found. These findings support the hypothesis that altered mandibular function in a protruded position can compensate for the effects of unilateral condylectomy and prevent the appearance of skeletal mandibular asymmetries in growing rats.

Alveolar Process↗

PubMed2006

The inter-relationship between mandibular autorotation and maxillary LeFort I impaction osteotomies.

The purposes of the present investigation were to: 1)locate the instantaneous rotation center of mandible autorotation during maxillary surgical impaction; 2) identify the discrepancies between the resultant mandibular position following by maxillary surgical impaction and presurgical predictions, which use the radiographic condylar center as the rotation center for mandibular autorotation; and 3)find the interrelation between the magnitude of maxillary surgical impaction and the sagittal change of mandible. Ten patients underwent maxillary LeFort I impaction without concomitant major mandibular ramus split osteotomies were included. The preoperative (T0) and postoperative (T1) lateral cephalograms were used to evaluate the surgical changes and locate the center of rotation of mandibular autorotation with Reuleaux method. Prediction errors were measured by comparing the predicted (Tp) and postoperative (T1) cephalometric tracings. The magnitude of the maxillary surgical impaction was compared to the positional changes of mandible after mandibular autorotation with correlation and regression analysis. The results demonstrated that the centers of mandibular autorotation located 2.5 mm behind and 19.6 mm below the radiographic condylar center of the mandible in average with large individual variations. By using the radiographic condylar center of the mandible to predict the mandibular autorotation would overestimate the horizontal position of chin by 2 mm and underestimate the vertical position of chin by 1.3 mm following an average of 5 mm surgical maxillary impaction. The magnitude of maxillary impaction was highly and positively correlated to the horizontal displacement of chin position. The rotation centers of mandibular autorotation following by maxillary LeFort I impaction osteotomies might not usually locate at the radiographic condylar center of the mandible also with large individual variations in their positions. Surgeons and orthodontists should be aware of the horizontal and vertical discrepancies of chin positions while planning a two-jaw surgery by using the radiographic center of mandibular condyle as the rotation center in mandibular autorotation.

Adolescent↗

PubMed2000

Measurement of femoral neck anteversion in 3D. Part 1: 3D imaging method.

Femoral neck anteversion is the torsion of the femoral head with reference to the distal femur. Conventional methods that use cross-sectional computed tomography (CT), magnetic resonance or ultrasound images to estimate femoral anteversion have met with several problems owing to the complex, three-dimensional (3D) structure of the femur. These problems include not only the difficulty of defining the direction of the femoral neck axis and condylar line but also the dependency upon patient positioning. In particular, the femoral neck axis, the direction of the femoral head, known as the major source of error, is difficult to determine from either a single or several two-dimensional (2D) cross-sectional images. A new method has been devised for the measurement of femoral anteversion using the 3D imaging technique. 3D reconstructed CT images from the femoral head and trochanter to the distal femur are used to measure the anteversion. It is necessary to remove the soft tissue from the CT images and extract just the bone part. Then, the femoral anteversion is measured from a computer-rendered femur image. The 3D imaging method is compared with both the conventional 2D method and the physical method using 20 dried femurs. For the physical method, which is used as a reference value, a special apparatus is devised. The average difference between the results of the physical method and those of the 2D CT method is 5.33 degrees. The average difference between the results of the physical method and those of the 3D imaging method is 0.45 degrees. Seventy-four patients, who suffer from toe-in-gait disease, are tested to compare the 3D imaging method with the conventional 2D CT method. The average difference between the 2D and 3D methods is 8.6 degrees, and the standard is 7.43 degrees. This method provides a very accurate and reliable measurement of femoral anteversion, as it is virtually equivalent to the direct measurement of bisected dried femur in vitro.

Adolescent↗

PubMed1999

Clinical and magnetic resonance findings in the temporomandibular joints of patients before and after orthognathic surgery.

It is difficult to achieve the correct position of the condyle in the temporal fossa during orthognathic surgery in angle class II patients with disorders of the temporomandibular joint. This led us to examine the TMJ of 25 of our own patients before and shortly after orthognathic operations. We recorded the clinical and magnetic resonance imaging findings of the temporomandibular joint preoperatively and three months postoperatively. The patients had skeletal class II dysgnathia and had been treated with fixed orthodontic appliances for a mean of two years and three months before operation. Operation resulted in a mean reduction of maximal incisor distance of 12 mm. In five of the 25 patients, the pattern of mouth-opening changed. Nine patients had less pain than before surgery, and nine had fewer abnormal joint sounds. The magnetic resonance imaging showed displacement of the articular disc in 38 of the 50 joints preoperatively and in 28 postoperatively. Degenerative joint changes were not improved by operation. Improvement of the disc position was achieved by repositioning of the condylar-disc complex during orthognathic surgery in angle class II patients. Clinical and magnetic resonance imaging findings regarding the temporomandibular joint in class II patients correlated significantly both preoperatively and postoperatively.

Adult↗

PubMed1978

[Geometric-mathematical analysis of errors during transfer to the articulator and their practical consequences. II].

With the aid of a computer faults are examined which result in the occlusal surfaces when several articular parameters are simultaneously wrongly applied in laterotrusion. The calculations which are derived from the geometrical relations of the Dentatus articulator refer to a circular field of 3 mm radius on a molar tooth. Vertical deviations, which are caused by faulty setting up of a preferred articulator size, evidently depend on the angle of the joint on the balancing side and depend on the working side on the sagittal position of the model in relation to the condylar axis and on the length of the condylar axis. In the most unfavourable case, errors of the order of 1.3 mm on the balancing side and of 0.75 mm on the working side were demonstrated. As regards horizontal deviations, all articulator sizes were shown to be independent of one another. The effects of faulty setting up on periodontal strain is presented in a practical example.

Computers↗

PubMed1984

Radionuclide bone scanning in the diagnosis and management of condylar hyperplasia.

Four patients with maxillo-mandibular facial dysharmony and four controls were evaluated by 99Tcm-MDP (methyl diphosphonate) scintiscanning. The scintiscans in all patients with dysharmony showed positive uptake of the tracer indicating the increased degree of activity in the condylar region of the mandible. The significance of this is discussed.

Adolescent↗

PubMed2002

Computer-assisted orthognathic surgery: clinical evaluation of a mandibular condyle repositioning system.

PURPOSE: The purpose of this study was to evaluate a new method for positioning the mandibular condyle during orthognathic surgery based on 3-dimensional optical localization of infrared emitting diodes. PATIENTS AND METHODS: Eleven patients ("empirical group") underwent condylar repositioning using the empirical repositioning method (standard technique) and were considered controls. In 10 patients ("active group"), the computer-assisted system was used to replace the condyle-bearing fragment in its sagittal preoperative position. In these patients, the condylar torque was not controlled. In the third group of 10 patients ("graft group"), the computer-assisted system was used to replace the condyle in all 3 directions. Very often it was necessary in this group to fill the osteotomy gap with a bone graft. The clinical evaluation was based on 4 major criteria: the quality of the postoperative occlusion, the stability of skeletal position on successive cephalometric radiographs, the occurrence of temporomandibular dysfunction (TMD), and the preservation of mandibular motion. Clinical assessment was made at 1, 3, 6, and 12 months follow-up. RESULTS: Forty-five percent of the "empirical group" did not have the expected postoperative occlusion, 5 patients showed evidence of clinical relapse at 1 year, 45% had worsened TMD status, and only 63.37% of mandibular motion had been recovered at 6 months. All the patients in the "active group" had the expected occlusion and only 1 patient exhibited a mild relapse and TMD symptoms; however the average mandibular motion recovery was only 62.65% at 6 months. All the patients in the "graft group" had a good occlusion and no relapse or TMD. Their percentage of mandibular motion recovery was 77.58%. CONCLUSION: The quality of sagittal repositioning is the main factor contributing to a good occlusion and bone stability. Functional results (in particular, recovery of mandibular motion) are more related to limiting condylar torque.

Adolescent↗