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Results for “Condylar position”

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PubMed1998

"Effective condylar growth" and chin position changes in Herbst treatment: a cephalometric roentgenographic long-term study.

In 98 Class II Division 1 malocclusions treated with the Herbst appliance "effective condylar growth" (a summation of condylar remodeling, glenoid fossa remodeling, and condylar position changes within the fossa) and its influence on the position of the chin was analyzed. Lateral head films in habitual occlusion from before and after 0.6 years of Herbst treatment as well as 0.6 years and 3.1 years posttreatment were evaluated. All patients were treated to Class I or overcorrected Class I dental arch relationships. During the treatment period, effective condylar growth was relatively more backward directed and about three times larger than that in untreated subjects with ideal occlusion (Bolton Standards). During the first posttreatment period of 0.6 years, effective condylar growth recovered with respect to both the direction and amount of changes. During the second posttreatment period of 2.5 years, effective condylar growth was "normal." The corresponding chin position changes during the different examination periods were a mirror image of effective condylar growth provided no mandibular autorotation occurred. In cases with anterior mandibular autorotation, relatively more forward and in cases with posterior mandibular autorotation relatively more backward directed chin position changes resulted.

Adolescent↗

PubMed1989

[Alterations in the size, shape and position of the condylar surfaces in the orthopantomograph. In vitro study].

Although the orthopantomograph has some disadvantages comparing with other techniques in the study of the TMJ, is useful sometimes for visualization of extensive osseous changes of the condyles. This study was done in order to study the exact site of the radiographic representation of the condylar surfaces in the orthopantomograph and to evaluate the degree of alteration of their size and shape. In two dry skulls (one edentulous and the other with complete dentition) a lead foil was placed in each one of the five surfaces of the condyles. The orthopantomographs were taken and the site of the radiopaque lead foil was evaluated for the radiographic representation of each surface. Also the degree of the alteration of the size and shape of the condylar surfaces was determined by the calculation of the two dimensions of each surface, in the skull and in the radiograph. The results of this study showed that all five condylar surfaces are contributing for the radiographic image of the condyle and always in an exact position each of them. The greatest distortion of the size and shape is taken place in the upper surface of the condyle and finally that the orthopantomograph cannot give us exact and accurate representation of the shape or the morphology of the condyle.

Humans↗

PubMed1988

A simple method for establishing the position of the condylar segment in sagittal split osteotomy of the mandible.

When a rigid fixation of the mandibular sagittal split osteotomy is performed, the exact position of the condyle has to be maintained. We report a simple method for determining the preoperative position of the proximal segment. The method is fast and does not require additional technical equipment. Preliminary results indicate that a decrease in postoperative temporomandibular joint problems can be achieved by using this method. A follow-up will show whether the method also can decrease the incidence of skeletal relapse.

Bone Plates↗

PubMed2005

[Effect of Fränkel function regulator on the condylar and mandibular positions of patients with class II malocclusion].

OBJECTIVE: To determine the positional changes of condyle and mandible in children treated successfully with Fränkel function regulator. METHODS: 30 Angle's class II patients including 15 boys and 15 girls treated with Fränkel function regulator were selected. Superimposition of the pretreatment and posttreatment lateral cephalograms of all the patients was done on the stable bone structure of the anterior cranial base and mandible. Cartesian coordinate system was used to measure the positional changes of condyle and mandible over time by computer. RESULTS: There was significant inferior displacement of condyle, gonion and pogonion after treatment with reference to stable bone structure of anterior cranial base. Anterior displacement of pogonion in boys was also significant. There was significantly superior and posterior displacement of condyle and posterior displacement of gonion after treatment with reference to stable bone structure of mandible. CONCLUSION: Fränkel function regulator can stimulate condylar growth and do favor to mandibular remolding.

Activator Appliances↗

PubMed1982

[Influence of various positions on the condylar location].

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Dental Articulators↗

PubMed1999

Horizontal condylar angulation and condyle position associated with adolescent TMJ disk status.

The purpose of this research was to examine the relationship between horizontal condylar angulation and position and joint status in an adolescent population. Submentovertex (SMV) radiographs and MRI (magnetic resonance images) of 95 subjects (56 females and 39 males) between the ages of 10-17 years (mean age 13.3 years) were used for this study. Horizontal condylar angulation as well as A-P and transverse condyle position were determined in relation to a cranial base reference (a line formed between the two foramina spinosa) from SMV images. Joint status variables consisted of disk length and disk displacement measurements taken from medial, central and lateral sagittal MRI slices of each joint. Additional joint status variables were derived through a principal component analysis which was used to calculate a single disk length, disk displacement, and internal derangement variable for each joint. The results were: 1. No significant correlations (p = .05) were found between any of the joint status variables and horizontal condylar angulation; 2. Statistically significant correlations (r = .14 to .22, p = .05) were observed between certain joint status variables (anterior disk displacement in medial and central joint slices, disk displacement variable, and TMJ internal derangement variable) and transverse condyle position; and, 3. Statistically significant correlations (r = -.22 to .25; p = .05) were observed between condylar angulation and both A-P and transverse condyle position.

Adolescent↗

PubMed2000

An in vitro study of the accuracy of a new protocol for planning distraction osteogenesis of the mandible.

PURPOSE: The purpose of this study was to determine the in vitro accuracy of a new protocol for distraction osteogenesis of the mandible that involves a planning process and a surgical technique. MATERIALS AND METHODS: An experimental design was developed to simulate distraction osteogenesis on stereolithographic models of patients with craniofacial deformities. All patients had previously undergone 3-dimensional computerized scans of the craniofacial skeleton. The data from these scans were used to generate stereolithographic models. Before the fabrication of the models, the computed tomography (CT) data were manipulated to add a series of rulers and markers to the models. The 3-dimensional computerized scans were also used as the basis of the planning process. They were imported into an animation software (3D-Studio Max; Discreet, Montreal, Canada), and a virtual distractor was built and installed on the model, and the osteotomies and distraction processes were simulated. Finally, a recipe for sequencing the linear and angular changes of the distractor were calculated. A surgical technique was developed to facilitate the precise installation of the distractor as indicated in the presurgical plan. The transfer of information regarding pin position and orientation from the computer model to the patient was accomplished by creating a surgical template. This template was designed in the computer and fabricated by use of stereolithography. Mock surgery was performed on the stereolithographic models, and the results were compared with those predicted by the computer. The difference between the actual position and the predicted position was recorded. RESULTS: On the X-axis, the difference between the predicted position for the condylar marker and the actual position of the marker on the stereolithographic models was 0.6 +/- 1.1 mm. On the Y-axis, the difference between the predicted position for the condylar marker and the actual position of the marker on the stereolithographic models was -0.9 +/- 2.6. On the Z-axis, the difference between the predicted position for the condylar marker and the actual position of the marker on the stereolithographic models was 0.04 +/- 0.8 mm. There was excellent correlation between the predicted and the actual measurements for the X, Y, and Z axes: 0.98, 0.93, and 0.98, respectively. CONCLUSIONS: The results indicate that the combination of this planning process and surgical technique was very accurate. This in vitro study is the first step in determining the clinical usefulness of this protocol. If the results of this study are validated in clinical practice, this protocol will allow clinicians to improve the clinical outcomes of patients treated with distraction osteogenesis.

Analysis of Variance↗

PubMed2005

[Morphometric analysis of the temporomandibular joint with MRI in 320 joints].

PURPOSE: To compare several morphometric parameters in MRI with the functional status of the articular disc in a large patient group suffering from internal derangement (ID) of the temporomandibular joint (TMJ). MATERIALS AND METHODS: In a retrospective study, 320 analyzable high resolution MRI examinations of the TMJs obtained in a 1.5 T unit were evaluated in 184 patients with clinically suspected ID. The analysis included the anatomical structures and a number of morphometric parameters previously described in the literature. The parameters were compared with the position of the articular disc. RESULTS: The disc position was categorized as "normal" (NDP, 21.9 %, n = 70), "anterior displacement with reduction on opening" (AMR, 51.6 %, n = 165) and "anterior displacement without reduction on opening" (AOR, 26.6 %, n = 85). With increasing disc displacement, significant configurational changes of the disc were observed. Disc displacement was associated with changes of the condyle consisting of increasing deformity and other degenerative changes. A large tuberculum and marked inclination of the eminence can be seen as predisposition for the development of ID. With increasing severity of the ID, the position of the condyle moved from a centric position of the condylar center to an excentric (dorsal and cranial) position. CONCLUSION: MRI demonstrated that increasing disc displacement is associated with changes of the disc, condyles and condylar position in the fossa.

Cartilage, Articular↗

PubMed2006

[Expression of BMP/Smads in rabbit condylar cartilage during mandibular forward positioning].

OBJECTIVE: To identify the relationship between the expression of BMP/Smads in condylar cartilage and condylar growth modifications in rabbits during mandibular forward positioning. METHODS: Sixty male rabbits with 8 weeks of age were randomly divided into the experimental group (n=36) and control group (n=24). The mandibles of rabbits in the experimental groups were induced to forward position by a functional appliance. The rabbits in the experimental group and control group were sacrificed after 3 days and 1, 2, 4, 8, 12 weeks, respectively. The expression of BMP-2, Smad1/5, 4 and 6 in condylar cartilage was examined by immunohistochemical staining. RESULT: The expression of BMP-2, Smad1/5, 4 and 6 was mainly found in the chondrocytes from the transitional zone and hypertrophic zone, and was also found in the chondrocytes and osteoblasts of the mineralized zone. Compared with those of the age-matched controls, the positive signals for BMP-2, Smad1/5, 4 and 6 in the experimental animals were stronger at early stage (P<0.05), coinciding with the remodeling in condylar cartilage after functional appliance. CONCLUSION: The expression of BMP-2, Smad1/5, 4 and 6 is associated with the adaptive remodeling of the condylar cartilage after functional appliance.

Animals↗

PubMed2005

Forward deviation of the mandibular condyle enhances endochondral ossification of condylar cartilage indicated by increased expression of type X collagen.

OBJECTIVE: Using type X collagen as a marker, this research was designed to examine the alteration of condylar growth in response to mandibular condylar forward positioning. METHODS: One hundred female Sprague-Dawley rats with 5 weeks of age were randomly divided into five experimental and five control groups. In the experimental groups, bite jumping appliances created forward positioning of the condyle. The experimental rats, together with the age-matched controls, were sacrificed on days 3, 7, 14, 21 and 30, respectively. Tissue sections were cut in the sagittal plane through the mandibular condyle and were processed for in situ hybridization and immunostaining of type X collagen and then for quantitative imaging analyses. RESULTS: (1) Both type X collagen mRNA in situ hybridization signals and type X collagen immunostaining were localized within the hypertrophic zone of the condylar cartilage. (2) With condylar forward positioning, the level of type X collagen mRNA signals (8,541 +/- 74 microm(2) at peak) was 300% higher than that in the controls (2,117 +/- 78 microm(2) at peak); type X collagen immunostaining in condylar advancing groups (54,864 +/- 134 microm(2) at peak) was 254% more than that in the controls (15,470 +/- 121 microm(2) at peak). (3) The amount of type X collagen mRNA signals and immunostaining in experimental and control groups reached the highest levels at day 14 and day 21, respectively, indicating that an increase in endochondral ossification occurred 21 days after condylar forward deviation. CONCLUSION: Condylar forward repositioning provokes an enhanced maturation of condylar chondrocytes resulting in increased synthesis of type X collagen, a extracellular protein that attributes to endochondral ossification.

Animals↗

PubMed1990

The influence of joint line position on knee stability after condylar knee arthroplasty.

Using a special knee-testing device, ten knees obtained at autopsy were subjected to varus-valgus, anterior-posterior, and flexion-rotation analysis in the intact state and after total knee arthroplasty. The ten knees showed no significant change in stability after knee replacement when the joint line was maintained in its natural position. When the femoral component was repositioned 5 mm proximally and 5 mm anteriorly, a significant increase in laxity occurred during midflexion. When the joint line was shifted 5 mm distal and 5 mm posterior to its anatomic location, significant tightening occurred in midrange of motion. Coupled rotation of the tibia with knee flexion was decreased after surgery in all knees with no specific relationship to joint line position. Coupled rotation with varus-valgus testing, however, remained within the normal range through the first 30 degrees of flexion only when the joint line was restored to its normal anatomic position. Stability in condylar knee arthroplasty is in part dependent on position of the joint line. Surgical techniques that rely on restoring the flexion and extension gap without regard to joint line position may result in alteration of varus-valgus or anterior-posterior displacement in midrange flexion.

Biomechanical Phenomena↗

PubMed2006

[The temporal and spatial expression of CBFalpha1 in rabbit condylar cartilage during forward mandibular positioning].

PURPOSE: To identify the relationship between the expression of Core binding factor alpha1 (Cbfalpha1) in condylar cartilage and condylar growth modifications in growing rabbits following forward positioning mandibles with functional appliance. METHODS: Sixty rabbits with age of 8 weeks were randomly divided into the experimental group (n=36) and control group (n=24). Rabbits in the experimental groups were induced to forward their mandibles by a functional appliance. The animals in the two groups were killed after 3 days and 1, 2, 4, 8 and 12 weeks, respectively. The temporal and spatial expression of Cbfalpha1 in condylar cartilage was examined by immunohistochemical staining and measured with Image Computer Analysis Software. Date was statistically analyzed by Student's t test and one-way ANOVA. RESULTS: The expression of Cbfalpha1 was mainly found in the chondrocytes from the transitive zone and hypertrophic zone, and was also observed in the chondrocytes and osteoblasts of the mineralized zone. Compared with those of the age-matched controls, the positive signals for Cbfalpha1 of each zone in the experimental animals were significantly stronger (P<0.05), and the highest expression of transitive zone, hypertrophic zone and mineralized zone was detected after 4 weeks of treatment (71.00+/-1.52, 50.00+/-0.75, 82.00+/-0.39). CONCLUSION: The pattern of Cbfalpha1 expression is concerned with the adaptive remodeling of the condylar cartilage after functional appliance.

Animals↗

PubMed2001

MRI examination of the TMJ after surgical treatment of condylar fractures.

The position of discs in 20 adult patients whose unilateral condylar fractures were treated by open reduction was investigated by means of magnetic resonance imaging. In four (20%) of the 20 cases, the disc was anteriorly displaced in both the closed mouth and open mouth positions. Three of the four cases had a high condylar neck fracture with dislocation and one had a high condylar neck fracture with displacement. The results of this study showed that repositioning the dislocated condyle did not always lead to anatomical restoration of the joint structures.

Adult↗

PubMed1984

Total condylar knee arthroplasty. Prosthetic component positioning and radiolucent lines.

Prosthetic positioning and overall postoperative alignment were studied in 138 consecutive total knee replacements, using the Insall/Burstein total condylar knee system. Overall alignment was within 7 +/- 5 degrees of valgus in 63 per cent of the knees, while tibial component positioning was within 4 degrees of tilt in any direction in 53 per cent of the knees. A radiolucency index incorporating width and extent of radiolucent zones at the tibia was shown to progress from 3 months to 2 years postoperatively. The radiolucency index 2 years postoperatively was higher with postoperative varus alignment in the rheumatoid arthritis group; a tibial component tilt of more than 4 degrees in any direction increased the radiolucency index in both treatment groups.

Adult↗

PubMed2006

Functional lateral deviation of the mandible and its positional recovery on the rat condylar cartilage during the growth period.

The objective was to examine the effects of a lateral functional shift of the rat mandible and the effects of a shift release on the condylar cartilage during the growth period. Fifty 5-week-old male Wistar rats were initially divided into three groups: shift, recovery, and control. At 5 weeks of age, each animal in the shift and recovery groups received an appliance designed to produce a lateral functional shift of the mandible to the left side. For the recovery group, the appliance was removed after 2 weeks. For the shift group, the appliance was used for 4 weeks. Total cartilage thickness, 5-bromo-2'-deoxyuridine-labeling index, and toluidine blue and tartrate-resistant acid phosphatase-positive cell number in the condylar cartilage at 1, 2, 3, and 4 weeks were compared with those in age-matched controls that had no appliances. In the shift group at 2 weeks, the cartilage thickness and labeling index increased in the central region on the contralateral side, whereas these decreased in the lateral region on the ipsilateral side. However, in the recovery group, 1 to 2 weeks after appliance removal, the cartilage thickness and labeling index in both investigated regions became similar to the control groups. These results emphasize the importance of early treatment to normalize occlusion and create appropriate conditions for normal occlusal development.

Acid Phosphatase↗

PubMed2003

The relationship between retruded contact position and intercuspal position in patients with TMJ osteoarthritis.

This study was conducted to investigate the relationship between posterior mandibular excursion movement and temporomandibular joint osteoarthntis (TMJ OA) in 25 orthodontic patients with Angle Class I and Class II, using a six degrees-of-freedom measuring device and helical computed tomography. There were significant differences found in three-dimensional length, antero-posterior, absolute latero-medial and supero-inferior incisal, and condylar intercuspal position (IP)-retruded contact position (RCP) slides between bilateral, unilateral, and no condylar bone change groups. With respect to the types of condylar bone change, there were significant differences found in three-dimensional length, antero-postenor, and absolute latero-medial condylar IP-RCP slides between flattening, erosion and osteophyte groups. These results suggest that large three-dimensional, not only incisal but also condylar, IP-RCP slides might be related to the uni-/bilaterality and kind of TMJ pathosis, which might make such slides useful as clinical indices of TMJ OA.

Adult↗

PubMed1996

Computer-assisted mandibular condyle positioning in orthognathic surgery.

PURPOSE: The correct placement of the mandibular condyle in the glenoid fossa during the osteosynthesis after the sagittal ramus osteotomy is often a problem. This article describes a computer-assisted positioning device. METHODS: The procedure is based on the use of a three-dimensional optical localizer to establish the condylar segment position. The operative procedure is only slightly different from the usual. RESULTS: The system is very easy to use, it does not require preoperative data acquisition, and the accuracy obtained is in fractions of a millimeter.

Bone Nails↗

PubMed2005

Magnetic resonance imaging of the condylar growth pattern and disk position after chin cup therapy: a preliminary study.

This study was conducted on lateral cephalograms and magnetic resonance images (MRIs) obtained from 20 subjects with Class III malocclusion. Only clinically temporomandibular joint (TMJ) symptom-free subjects were included in this study. In the treatment group, a chin cup with 600 g of force was applied in 13 patients (10 girls and three boys) with a mean age of nine years. The chin cup was applied in a direction from the chin toward the TMJ. The control group consisted of seven patients (six girls and one boy) with a mean age of eight year nine months. Orthodontic treatment was not applied in the control group. Records were taken at the beginning and end of chin cup therapy from all the subjects. Measurements were made on lateral cephalograms and unilateral-left sagittal-oblique TMJ MRIs. Variables obtained at the beginning and end of the study were compared by Student's t-tests and paired t-tests. Relationships between craniofacial and TMJ variables were analyzed by correlation analysis. The mandibular corpus length was increased and condylar head angle was decreased by chin cup therapy. A positive correlation existed between activation of sagittal maxillary and mandibular growth and bending of the condylar head. This study showed that the condylar growth pattern was altered by chin cup. It may be implied that the source of improvement is adaptation of the craniofacial structures to the changes of the condylar growth pattern produced by the chin cup.

Cephalometry↗