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Results for “Condylar position”

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At least 235 records · Page 13Linked to original sources

PubMed2002

Temporary intraoperative external fixation in mandibular reconstruction.

OBJECTIVES: To describe the use of a temporary intraoperative external fixation device to assist in the optimal bony reconstruction of the mandible in the setting of vascularized bone grafts. STUDY DESIGN: A retrospective review of six patients who underwent composite resection of the mandible and subsequent reconstruction with osteocutaneous free tissue transfer in a tertiary care center. METHODS: Six cases of mandibular reconstruction using an intraoperative external fixation system to assist the positioning of vascularized bone grafts are presented. All patients had composite resection of the mandible and subsequent reconstruction with either a scapula or fibula osteocutaneous flap. Follow-up ranged from 2 to 16 months. RESULTS: Successful reconstruction as defined by acceptable contour, occlusion, and condylar position was achieved in all cases. Complications were limited to a postoperative cerebrovascular accident requiring anticoagulation and subsequent neck hematoma. CONCLUSIONS: Use of intraoperative external fixation maintains the proper alignment of mandibular segments without the use of a bridging reconstruction plate. This technique is particularly valuable with tumors involving the outer cortex of the mandible.

Aged↗

PubMed1997

Discrepancies between centric occlusion and centric relation in orthodontically treated patients.

Condylar position between centric occlusion (CO) and centric relation (CR) was compared for 24 adolescent orthodontic patients at pretreatment, posttreatment, and during the retention phase of orthodontic treatment. Models were mounted using a face-bow transfer and CR interocclusal registrations. Differences in CO-CR were then measured at the condylar level in the x, y, and z dimensions. The data were analyzed statistically to determine the mean CO-CR differences in the sample as well as the magnitude and direction of the CO-CR differences from one time period to the next. Results showed that the mean three-dimensional distance between CO and CR tended to increase from pretreatment to the retention phase for the right and left sides, the left side showing a greater increase. Intraexaminer variability accounted for 20% to 25% of the total variability when all possible sources of variability were considered. Correlation with a second examiner in recording CR was in the range of .61 and .75 for the right and left sides, respectively. Interexaminer variability was found to be similar to the variability associated with the CO-CR discrepancies over time. Consequently, the differences in measurements obtained could be the result of changes in the CO-CR relationship, examiner variability, or a combination of both.

Adolescent↗

PubMed1998

Techniques for achieving three-dimensional positioning of the maxilla applied in conjunction with the Göttingen concept.

Three-dimensional repositioning of the maxilla is possible after Le Fort I osteotomy. However, the preoperatively planned and desired position of the maxillary dental arch often cannot be sufficiently achieved during actual surgery, and deviations in the sagittal and vertical dimensions are common. To reduce these errors, the model-repositioning instrument was developed for model surgery in conjunction with the Göttingen concept for orthodontic-surgical treatment with condylar position control. This instrument allows a controlled three-dimensional positioning of jaw segments with three reference points directly on the teeth. The three-dimensional double-splint method combined with a surgical facebow was developed for a controlled three-dimensional positioning of the maxilla during surgery. This instrument and method were applied during treatment of 20 adult patients, and the position of the maxilla before and after surgery was analyzed. It was found that the planned position of the maxillary dental arch could be transferred from model surgery to actual surgery with an accuracy of +/- 1 mm sagittally and vertically. Thus, the application of the Göttingen concept for three-dimensional positioning of the maxilla results in an improvement of accuracy compared with other methods. Furthermore, use of these procedures is easier and less time-consuming during model and actual surgery than are other procedures.

Adult↗

PubMed2000

Magnetic resonance imaging-based joint space measurements in temporomandibular joints with disk displacements and in controls.

OBJECTIVE: Previous studies have discussed a posterior displacement of the condyle as a possible risk factor for the development of disk displacements (DDs) of the temporomandibular joint (TMJ). The objective of this study was to compare the posterior and anterior joint spaces in healthy TMJs with those of patients who present different forms of DDs. STUDY DESIGN: The anterior and posterior joint spaces from 58 patients with unilateral or bilateral DD with reduction (DDR) or without reduction (DDNR) and from 30 healthy volunteers were measured with 3 sagittal magnetic resonance images (MRIs) from each TMJ in the maximum intercuspid position. RESULTS: Measurements of anterior and posterior joint spaces showed a good interexaminer reproducibility (rank correlation coefficients ranging from 0.88 to 0.95). Patients with bilateral DDR demonstrated a significantly more posterior position of the condyle, as compared with controls and patients with bilateral DDNR. DDNR presented a significant reduction of the anterior and the posterior joint spaces, leading to a mean concentric position of the condyle. Patients with unilateral DDR or DDNR demonstrated a greater variability of anterior and posterior joint spaces, compared with patients with a bilaterally identical type of DD. CONCLUSIONS: The data of this MRI-based clinical study indicate that different stages of disk displacements are associated with significant changes of condylar position. The variation of anterior and posterior joint spaces was influenced by the diagnosis of the contralateral joint.

Adolescent↗

PubMed1997

Magnetic resonance changes in the temporomandibular joint in ankylosing spondylitis.

OBJECTIVE: To evaluate temporomandibular joint (TMJ) involvement of patients with severe ankylosing spondylitis (AS) using magnetic resonance imaging (MRI). METHODS: All patients with severe cervical involvement, defined as occiput-wall distance > or = 3 cm and/or < 10 degrees of cervical flexion, from a consecutive cohort of 103 patients with AS were included in the study. Patients completed a questionnaire designed to evaluate symptoms of temporomandibular disorder (TMD). Open and closed mouth sagittal T1 weighted MRI sequences of the right TMJ was performed in all patients. MR images were specifically reviewed for condylar position and morphology, as well as articular disc position and morphology. RESULTS: Eleven patients were identified and included in the study. Temporomandibular symptoms were absent in 4 (37%), a single symptom was present in one (9%), 2 symptoms in one (9%), 3 symptoms in 3 (27%), and 4 symptoms in 2 (18%). Ten of the 11 patients had abnormalities on MR, including condylar alterations such as abnormal shape, erosions, and reduction in translation. Disc alterations were present in 8 patients and osteophytes in 7. Two patients were graded as having mild abnormalities, another 2 as moderate, and the remaining 6 were considered grossly abnormal. In 2 patients there were changes compatible with ankylosis of the right TMJ. CONCLUSION: Although it is uncommon for patients to complain spontaneously about TMD symptoms, involvement of the TMJ in patients with severe AS appears to be frequent and, in some, severe. The effect of TMJ involvement on the overall well being and nutritional status in patients with AS remains to be determined.

Adult↗

PubMed2004

[Stability of osteosyntheses for condylar head fractures in the clinic and biomechanical simulation].

BACKGROUND: Fractures of the condylar head are traditionally managed by closed techniques, despite a considerable rate of dysfunctional problems. PDS pin osteosynthesis (presented by Rasse 1992) via a preauricular approach failed to become established as a standard procedure due to a lack of stability. Alternatively, mini- or microplating, as performed in our patients (101 condylar head fractures between 1993 and 2000), showed high-grade limitations of translatory movements in about 30% due to scarification after loosening of osteosynthesis materials. The aim of this study was to establish an efficient procedure for achieving a functionally stable and atraumatic osteosynthesis. METHODS: For the definition of a suitable procedure, models of the mandible (standardized fractures, types A, B, and C) were osteosynthesized (six samples for each type of fracture and type of screw), each with three PDS pins, 2.0 mm resorbable, 2.0 cortical, 1.7 and 1.2 mm small fragment screws, and exposed to increasing loads in centric (0-20-35 mm opening) and eccentric (35 mm opening) condylar positions. A computerized biomechanical test stand allowed a dynamic simulation of chewing forces (16 hydraulic drives). The resulting fracture gaps were measured without contact by a motion capture system. RESULTS: Within physiological limits, only 1.7 small fragment and 2.0 mm cortical screws were able to bear occlusal loadings up to 200 N (1.2 mm small fragment screws up to 150 N, resorbable 2.0 mm screws up to 100 N, and PDS-pins up to 50 N). In a pullout experiment (condylar spongious bone of young pigs, aged 4-6 months), 1.7 mm small fragment screws showed superior retention. A consecutively developed small fragment screw-system has been applied clinically in 74 condylar head fractures (58 patients). After removal of osteosynthesis material, 41 of 49 TM joints have so far shown complete restitution. CONCLUSIONS: The newly developed osteosynthesis system using a retroauricular approach based on 1.7 mm small fragment screws makes maxillomandibular immobilization unnecessary. The extra-articular position of the screw heads prevents scar-induced articular limitations. Preexisting degenerative alterations of the TMJ soft tissues, however, will affect functional results adversely.

Absorbable Implants↗

PubMed2004

Temporomandibular joint growth changes in hyperdivergent and hypodivergent Herbst subjects. A long-term roentgenographic cephalometric study.

The aim of this long-term study was to assess the amount and direction of glenoid fossa displacement, condylar growth, and "effective" temporomandibular joint (TMJ) changes (= the sum of glenoid fossa displacement, condylar growth, and condylar position changes in the fossa) in 3 vertical facial-type groups of Class II Division 1 malocclusions treated with the Herbst appliance. A comparison was made between 38 normodivergent (ML/NSL= 26.5 degrees -36.5 degrees), 17 hypodivergent (ML/NSL or= 37 degrees ) subjects. Lateral headfilms from before, after, and 5 years after treatment were scrutinized. Glenoid fossa displacement, condylar growth, and "effective" TMJ changes were analyzed. Treatment changes: in all facial-type groups, the glenoid fossa was displaced anteriorly and inferiorly. No differences existed between the 3 groups. Condylar growth and "effective" TMJ changes were directed posteriorly and superiorly. The changes in posterior direction were more apparent in the hyperdivergent group than in the normodivergent and hypodivergent groups. Posttreatment changes: in all facial-type groups, the fossa was displaced posteriorly. No differences existed between the 3 groups. Condylar growth and "effective" TMJ changes were directed more vertically compared with the treatment changes. The changes in posterior direction were more pronounced in the hyperdivergent group than in the other 2 groups. It was found that the amount and direction of TMJ growth changes (fossa displacement, condylar growth, and "effective" TMJ changes) were only temporarily affected favorably in the sagittal direction by Herbst treatment. Condylar growth and "effective" TMJ changes were directed more posteriorly in hyperdivergent than in hypodivergent Herbst subjects. This was true for both treatment and posttreatment period changes.

Adolescent↗

PubMed1999

[Results of the application of the Goettingen concept for three-dimensional repositioning of the maxilla in orthognathic surgery].

During orthodontic-surgical treatment, a three-dimensional repositioning of the maxilla is needed after Le Fort I osteotomy. The preoperatively planned and desired position of the maxilla could often not be implemented satisfactorily in the surgical procedure. Several authors described deviations of up to 15 mm in the vertical dimension and 5 mm in the sagittal dimension between the planned and the achieved position. In order to avoid this error, the "model-repositioning instrument" for three-dimensionally controlled cast surgery and the "three-dimensional doublesplint method" in combination with a surgical facebow for actual surgery were developed. A group of 20 adult patients with severe dentofacial deformities were treated according to the Goettingen concept for combined orthodontic-surgical treatment with condylar position control with a surgical facebow. For each patient the position of three marked reference points on the maxillary dental arch under pre- and postoperative conditions was evaluated using superimposed tracings of lateral radiographs. These values were compared with the performed movements of the dental maxillary arch during cast surgery. It can be shown that with the new developments the planned position of the maxillary dental arch could be transferred from cast surgery to actual surgery with an accuracy of +/- 1 mm vertically and sagittally.

Adult↗

PubMed2001

[Analysis of mandibular position of patients with angles Class I and Class II, division 1 malocclusion].

OBJECTIVE: To study changes of condyle position and occlusion between centric jaw relation and maximum intercuspation positions. METHODS: The power centric registration advocated by Roth was used to take centric relation bite registration for 50 patients (25 Class I and 25 Class II, Division 1) and diagnostic models were mounted and analysed with Panadent articulator and condyle position indicator. RESULTS: Nearly all patients had CR-MI differences in all three planes of space. 70% of the sagittal displacement was within 2.0 mm and 87% of the transverse displacement was within 1.0 mm. Most of the condyles moved posteriorly and inferiorly. 65% of the initial contacts in CR occured on the most posterior molar on single side. Correlation was found between some variables of condylar displacement and occlusion changes. No significant difference was observed in condylar position and occlusion changes between Class I and Class II, Dvision 1 patients. CONCLUSIONS: The occlusion in centric jaw relation should be analysed before treatment to reveal the disharmony between occlusion and jaw position.

Adolescent↗

PubMed1997

Soft tissue limitations in orthodontics: treatment planning guidelines.

Orthodontists have traditionally viewed structural discrepancies as the major limitation of treatment. In reality, it is the soft tissues that more closely determine therapeutic modifiability. The boundaries of dental compensation for an underlying jaw discrepancy are established by pressures exerted on the teeth by the lips, cheeks, and tongue; limitations of the periodontal attachment; neuromuscular influences on mandibular position; and the contours of the soft tissue facial mask. The ability of the soft tissues to adapt to changes in tooth-jaw relationships are far narrower than the anatomic limits in correcting occlusal relationships. The tolerances for soft tissue adaptation from equilibrium, periodontal, and facial balance standpoints are in the range of 2 to 3 mm for expansion of the mandibular arch and even less for changes in condylar position. Thus, analysis of the soft tissues is the critical step in orthodontic decision making, and this can only be accomplished through physical examination of the patient. Although quantitative measurements cannot be rigorously applied, guidelines for soft tissue assessment, with particular emphasis on facial esthetics, are proposed. From this perspective, a contemporary philosophy of orthodontic practice is offered, with general indications and contraindications for nonextraction, extraction, and surgical treatment.

Adaptation, Physiological↗

PubMed2000

Osseous morphology and spatial relationships of the temporomandibular joint: comparisons of normal and anterior disc positions.

The objective of this study was to determine differences in spatial relationships and osseous morphology between temporomandibular joints with normal and anterior disc positions. Magnetic resonance imaging was employed to determine disc position in 335 temporomandibular joints in 175 subjects (106 female and 69 male) between the ages of 7.27 years and 20.0 years (mean age: 13.08 years). Twelve tomographic variables were measured from preorthodontic tomograms of the same individuals. Tomographic data were cross-referenced with MRI data for those with normal and full anterior disc displacement. Independent sample t-tests revealed significant differences for all measures of joint space, condylar position, and morphology of the articular eminence (P < .05) between joints with normal disc position and with full anterior disc displacement. This study indicated that measures of joint space and eminence morphology might provide diagnostic information for the assessment of joint status in the adolescent population.

Adolescent↗

PubMed1989

Long-term follow-up after occlusal treatment to correct abnormal temporomandibular joint disk position.

Fifteen patients with temporomandibular joint disk displacement in whom a normal condyle-disk relationship could be established were treated with occlusal changes to maintain the disk in a recaptured position. Occlusal changes were achieved by prosthodontics in 11 patients and by orthodontics in four patients. Follow-up after about 3 years showed that joint function was improved, intensity of pain was reduced, and joint and muscle tenderness were less frequent than before treatment. Intermittent locking, use of analgesics, sleep disturbances, and absence from work because of temporomandibular joint symptoms were also less frequent. Radiographic examination performed in 11 patients at follow-up demonstrated anteroinferior condylar position in the majority of the patients, but only minor hard tissue changes. Arthrography showed the disk to be in a correct position relative to the condyle in 82% (9 of 11) of the patients. These results suggest that permanent change of the occlusion with the objective of eliminating abnormal disk position may be effective treatment for disk displacement when conventional methods of treatment have failed to alleviate the symptoms. The extent of dental treatment needed to maintain the disk in a correct position should, however, be considered relative to the severity of the symptoms.

Adolescent↗

PubMed1994

Reproducibility of the centric relation bite registration technique.

Many orthodontists today are using diagnostic casts mounted in centric relation (CR) because they can reveal a completely different malocclusion than what is seen in maximum intercuspation (MI). The CR to MI slide can be measured at the condyles using a semi-adjustable articulator and a condylar position indicator device (CPI). However, before planning treatment from casts mounted in CR, the reliability of the method must be established. Therefore, the purposes of this investigation were: i) to determine the reproducibility, measured with the CPI, of the two-piece wax CR bite registration technique as described by Roth; ii) to determine the direction of the centric slide; iii) to determine differences in overjet measured from CR and MI and; iv) to evaluate the location of the initial tooth contacts in CR. The condylar displacements for 39 subjects were measured in vertical and horizontal components from mounted models. A CR bite registration was taken five times (approximately every five days) and used to remount the lower cast and record the data five times. Since there was not a significant difference between the five CPI readings (p > .05), the Roth CR bite registration is highly reproducible. The condyle moved inferiorly with a small distal component from CR to MI. A statistically significant difference (p < .001) was found in the overjet measurements between CR and MI. Thirty six out of 39 subjects had an initial tooth contact in CR on the most posterior tooth.

Adult↗

PubMed1979

Centric relation. Its effect on occluso-muscle harmony.

The most common cause of pain in the region of the temporomandibular joint is occluso-muscle imbalance. This results most often from disharmony between the articulation of the teeth and the centric relation of the condyles. Muscle tenderness of palpation indicates that muscle is involved. An examination must then be done to determine the cause of the muscle tenderness. Before the condyle-occlusion relationship can be evaluated, an accurate centric relation must be determined and verified. The condyles are in centric relation when they are in the most superior position possible in the fossae. From that apex of force position, the condyle can travel neither forward nor backward without moving downward. This position can be located with careful bilateral manipulation and then verified if it can resist firm pressure with no tension or tenderness. Until this correct centric relation is located and verified, it is not possible to properly evaluate the occlusal relationship to the temporomandibular joints. If the occlusion is harmonized to a centric related condyle that can resist firm pressure with pressure with no discomfort, there will be no reason for the muscles to protect either the teeth or the joints. If an occlusion is adjusted to a malrelated condylar position, the occluso-muscle imbalance will be perpetuated and often intensified. Centric relation is the starting point of occlusal contact. Incline interferences in excusive movements must also be eliminated and the occlusion must be harmonized to the envelope of function for each patient. If centric relation is not properly located, occlusal interferences will remain regardless of what procedures are used to record or adjust excursive movements.

Dental Occlusion↗

PubMed2002

Tomographic assessment of temporomandibular joint osseous articular surface contour and spatial relationships associated with disc displacement and disc length.

The objective of this retrospective study was to determine whether associations exist between osseous temporomandibular joint (TMJ) characteristics and TMJ internal derangement (disc position and deformation) in an adolescent population. Magnetic resonance imaging (MRI) was used to quantitatively determine disc position and length in 335 TMJs in 175 subjects (106 female and 69 male) between the ages of 7.27 and 20.0 years (mean age, 13.08 years). Nine tomographic variables were measured from pretreatment tomograms. Tomographic data were cross-referenced with MRI data. Male and female samples were evaluated separately. Stepwise linear regression identified associations between disc displacement and reduced superior joint space, increased posterior joint space, increased anterior joint space, and reduced articular eminence convexity (male R(2) value, 0.41; female R(2) value, 0.38). Associations between reduced disc length and condylar position and eminence flattening were weaker (male R(2) value, 0.16; female R(2) value, 0.32). This study demonstrates that TMJ internal derangement is associated with functional osseous adaptation within the joint.

Adaptation, Physiological↗

PubMed1999

The effects of sustained incisal clenching on the temporomandibular joint space.

OBJECTIVE: To determine the effect of sustained incisal clenching on the width of the temporomandibular joint space. METHODS: Nine normal subjects clenched on an anterior appliance for 10 min at 49 N. Sagittal tomograms were obtained during comfortable closure in the intercuspal position (ICP) (ICP-Before), comfortable closure on bite force transducer without clenching (BFT-Before), start of clenching (BFT-0), end of 5 min clenching (BFT-5), end of 10 min clenching (BFT-10), comfortable closure on the bite force transducer immediately after clenching (BFT-After) and comfortable closure in ICP after clenching (ICP-After). Joint space dimensions were automatically measured by a computerized image analysis system. RESULTS: The minimum joint space dimension was significantly reduced at BFT-5 (P = 0.0381), BFT-10 (P = 0.0019) and BFT-After (P = 0.0053) in relation to BFT-Before. The condylar position was also significantly shifted upward at BFT-0 (P = 0.0422), BFT-5 (P = 0.0005), BFT-10 (P = 0.0001), and BFT-After (P = 0.0004) in relation to BFT-Before. CONCLUSION: Sustained incisal clenching at 49 N causes significant anterior joint space reduction. We believe this is due to marked compression of the articular cartilage and disc.

Adult↗

PubMed2003

Amount and direction of temporomandibular joint growth changes in Herbst treatment: a cephalometric long-term investigation.

UNLABELLED: The amount and direction of condylar growth, glenoid fossa displacement, and "effective" temporomandibular joint (TMJ) changes (a summation of condylar growth, glenoid fossa displacement, and condylar position changes within the fossa) were analyzed in 35 Class II, Division 1 malocclusions (23 boys and 12 girls) treated with the Herbst appliance. Lateral head films in habitual occlusion and with the mouth wide open from before (T1) and after 7.5 months of Herbst treatment (T2) as well as 7.5 months (T3) and three years (T4) after treatment were evaluated. As a control group, a sample of 12 untreated male Class II Division I malocclusions was used during a 7.5-month time period corresponding to the treatment period (T2-T1) of the Herbst cases. The results revealed that during the treatment period (T2-T1) condylar growth was directed posteriorly about twice the amount as in the control subjects, and the fossa was displaced in an anterior inferior direction. The effective TMJ changes showed a pattern similar to condylar growth but were more pronounced. During the first posttreatment period (T3-T2), all TMJ changes reverted. The glenoid fossa was displaced backward; the amount of condylar growth and effective TMJ changes was reduced, and the changes were more superiorly directed. During the second posttreatment period (T4-T3), all TMJ changes were considered physiological. CONCLUSION: During Herbst treatment, the amount and direction of TMJ changes (condylar growth, fossa displacement, and effective TMJ changes) were only temporarily affected favorably by Herbst treatment.

Adolescent↗

PubMed2006

Relationship between tooth contacts in the retruded contact position and mandibular positioning during retrusion.

We conducted a series of studies with the purpose to investigate the locations of tooth contacts in the retruded contact position (RCP) and to discuss their significance in the stomatognathic system. In the present study, the relationship between the locations of RCP contacts and mandibular positioning during retrusion was examined. Thirty dentists and clinical residents were selected as subjects. One specialist in prosthetic dentistry examined each subject for the location of the RCP contacts. The mandibular positioning during retrusion was measured using a mandibular movement analysis system with six degrees of freedom. Originally programmed software was developed. Five reference points were selected: the central lower incisor (point I), the first molars on both sides (points RM and LM) and the condyles on both sides (points RC and LC). Tooth contact was observed most frequently at the second molar, followed by the first premolar. Points I, RM and LM all moved in an inferior-posterior direction, whereas points RC and LC moved in various directions ranging from superior-posterior to inferior-posterior. When the subjects were divided into two groups according to the most anterior tooth of occlusion in the RCP, the condylar positioning tended to be more superior in the group with molar contact than that with premolar contact. These results suggest that the locations of RCP contacts could be an important factor in jaw guidance during retrusion.

Adult↗