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PubMed2006

Pathologic-sonographic correlation in temporomandibular joint pathology.

The accuracy of high-resolution ultrasonography (HR-US) in detecting disk displacement and condylar erosion of the temporomandibular joint (TMJ) was evaluated, using corresponding cryosections as a "gold standard". HR-US of the TMJ was performed with a high frequency 12 MHz transducer on 30 preserved autopsy specimens. Succeeding sonography, the autopsy specimens were deep-frozen and cut in paracoronal planes corresponding to the sonographic images. HR-US diagnoses were compared with cryosectional findings in a blinded fashion. HR-US detected 19 (95%) of 20 instances of condylar erosion and 16 (73%) of 22 instances of disk displacement. There were one false-positive finding for condylar erosion and two false-positive findings for disk displacement. The accuracy of HR-US evaluating condylar erosion and disk displacement rated 93% and 73%, respectively. In conclusion, condylar erosion was reliably assessed by HR-US, but the evaluation of disk position was less accurate.

Aged↗
PubMed1996

Condylar movement and centric relation in patients with internal derangement of the temporomandibular joint.

This study was designed to compare the reproducibility of the condylar translation pathway and the centric relation position in patients with and without internal derangement of the temporomandibular joint. Reproducibility of condylar movement and variability of the axis point of condylar rotation in centric relation was studied in 15 patients with internal derangement of the temporomandibular joint and 15 patients with no history or clinical signs of mandibular dysfunction. Condylar movement and axis point location were recorded with a sagittal recording device at three separate recording sessions. Lead markers were placed on the skin over the axis and orbital points, and lateral cephalometric radiographs were taken at each session. Analysis of cephalometric and axiographic recordings included both linear and angular measurements. Analysis of the condylar movement pathway revealed greater within-subject reproducibility in the control group for both the right and left condyles (p < 0.0005 and p < 0.0003, respectively). The axis point of condylar rotation in centric relation, as shown by cephalometric analysis, had significantly more within-subject variability in the horizontal plane for the control group (p < 0.003). There was no significant difference between groups for within-subject variability of condylar position in the vertical direction. These findings are consistent with the contemporary concept of centric relation that a vertically stable condyle with a disk interposed against the anterior eminence is capable of functional adaptation in the horizontal plane. The results have implications with regard to treatment and rehabilitation of patients with temporomandibular joint internal derangement.

Adaptation, Physiological↗
PubMed1999

[Effects of various condylar operations on its compressive mechanical property and bone density].

OBJECTIVE: To investigate the changes and relationship of condylar mechanical properties and its material character after various condylar operations. METHODS: Condylar compressive mechanical properties and its bone mineral content were analyzed quantitatively by compressive mechanical property measurement technique and dual energy X-ray absorptiometry in 6 and 6 adult dogs undergone either high shaping or reconstruction of condyles respectively, and compared with 12 normals. RESULTS: Condylar elastic--limit load and displacement, its largest load and displacement were the highest in control, but stiffness and bone mineral content were the highest in high-shaping group, all data were the lowest in the reconstruction ones. There was marked and extremely marked linear positive relativity among condylar elastic--limit load, largest load, stiffness and bone density, in which all relative coefficients exceeded 0.862. CONCLUSION: The changes of condylar shape induced by various operations directly influence its compressive mechanical properties and bone mineral content. There is linear positive relativity between condylar compressive mechanical properties and its bone mineral density.

Animals↗
PubMed1985

The control of condylar growth: an experimental evaluation of the role of the lateral pterygoid muscle.

The present study used 21 male albino rats to test the hypothesis that lateral pterygoid traction regulates the growth of the mandibular condyle. The condyles, the rami, and the top of each glenoid fossa were marked with metallic implants, and, following bilateral section of the condylar neck, one lateral pterygoid muscle was extirpated. On the basis of the literal details of Petrovic's cybernetic model, it was assumed that the continued forward growth of the midface and the backward translation of the glenoid fossa would combine to produce a progressive disturbance in the buccal occlusion that would, in turn, generate a reflex contraction of the remaining lateral pterygoid muscle. Initially, however, growth of the isolated condyles would have little impact on the spatial position of the rest of the mandible. As a result, the condyles on the side with the intact lateral pterygoid should grow for a time at a maximal, open-circuit rate, whereas the experimental condyle, deprived of all muscle traction, should show only a minimal "commanded" rate of growth. The serial change in the position of the condylar and ramal implants was assessed cephalometrically for 6 weeks, and between-sides differences were analyzed by randomized block analysis of variance. The presence or absence of the lateral pterygoid muscle had no significant effect on the anteroposterior position of the condylar implants and only a slight, transitory effect on their vertical position. The translation of the ramal implants, however, was greatly affected by the condylotomy. On both control and experimental sides, the mandible collapsed upward and backward until contact between the growing condyle and ramus had been achieved, whereupon a downward and forward pattern of translatory growth was re-established. Although it could not be shown that lateral pterygoid traction per se is a significant factor in the growth of isolated condyles, it was concluded that the condyle is vitally important to the translatory growth of the mandible as a whole. On the basis of these data and the current literature, a simple hypothesis was advanced for the control of condylar growth by the ongoing pattern of functional loading and for the role of this growth in the normal downward and forward displacement of the rest of the mandible.

Animals↗
PubMed2001

Ectopic third molar in the condylar process: case report.

We describe an ectopic inferior third molar which is positioned in the condylar process and associated with an odontogenic cyst. The ectopic third molar is a quite frequent condition but it become unusual when the tooth is placed in the condylar region. In the reported case the removal of both the tooth and the cyst was recommended to solve the infective and articular symptoms and to prevent worse complications like pathologic fractures due to bone's absorption.

Adult↗
PubMed1992

[Condylar displacement and mandibular bending deformation due to bite force].

The purpose of this study was to investigate the influence of the difference of the biting pivot positions, vertical dimensions and mandibular positions on the condylar displacement during clenching. The condylar displacement was measured by the Pantograph using the point of condyle on the Kinematic Axis as the representative and the Path of the Kinematic Axis (PKA) as the standard for the judgement of the displacement. The bending deformation of the mandible was also measured by a multi-vision and image analyzing system in order to correct its influence on the condylar displacement measured. The results were as follows: 1. The direction and magnitude of the condylar displacement changed with the biting pivot position. The bilateral condyles moved upwards deviating from the PKA when clenching on the bilateral 2nd-molar or the bi-or unilateral canine teeth; Whereas the biting-side condyle moved downwards and the idling condyle either moved upwards deviating from the PKA or backwards along the PKA when clenching on the unilateral 2nd-molar. 2. The displacement of the idling condyle was multi-directional when clenching on the habitual closure whereas it was unidirectional and of a smaller magnitude when clenching on the most retruded closure. 3. When clenching on the unilateral 2nd-molar, the mandible on the non-pivot side had an inward and upward bending deformation and the arch width decreased. It can be inferred that the actual idling condylar displacement was more inward and upward than that measured by the Pantograph.

Adult↗
PubMed1996

Geometric analysis of occlusal plane orientation using simulated ear-rod facebow transfer.

PURPOSE: Ear-rod facebow techniques may position casts high or low between the upper and lower members on the articulator when using orbitale or nasion as anterior reference positions. This study assessed the effect of changing the anterior reference position on simulated mountings utilizing simulated ear-rod facebow. MATERIALS AND METHODS: Tracings from latoral cephalographs made on seven subjects were superimposed with an outline model of a semiadjustable articulator. Three simulated mountings were performed for each subject in which the plane of occlusion was positioned (1) high, (2) midway, and (3) approaching the lower member (low). Maxillary and mandibular occlusal planes representing intercuspal position were determined from the cephalographs and positioned on the articulator model in a simulated centric relation position for each mounting. Condylar guidance was determined from a simulated protrusive position. RESULTS: Analysis of the three mounting positions demonstrated no change in intercuspal position within subjects; however, angles formed between upper member and condylar guidance were 14.9% smaller for the mid-distance mounting, 42.9% smaller for the high mounting, and 13.4% higher for the low mounting positions when compared with a standard Frankfort horizontal plane reference. CONCLUSIONS: The cephalographs showed extreme variability in the position of the ear piece to bony structures of the skull, but this deviation appeared to be compensated by a change in the horizontal condylar guidance relative to mounting. Results also suggest that casts may be mounted in a convenient mid-position for routine articulation.

Cephalometry↗
PubMed2000

Open treatment of condylar process fractures: assessment of adequacy of repositioning and maintenance of stability.

PURPOSE: This study was designed to determine how well fractured condylar processes were reduced and the stability of the internal fixation in a group of patients whose fractures were treated by open reduction. PATIENTS AND METHODS: Sixty-one patients treated by open reduction and internal fixation for unilateral condylar process fractures were studied prospectively using Towne's and panoramic radiographs. The radiographs were made before surgery, and immediately, 6 weeks, and 6 months postoperatively. The images were traced and digitized, and the position of the fractured condylar process was statistically compared with the position of the nonfractured condylar process in both the coronal and sagittal planes. Additionally, 2 observers examined the images and assessed these same 2 factors. RESULTS: After surgery, the difference in position between the fractured and nonfractured sides averaged less than 2 degrees (not significantly different), indicating good reduction of the fractures. However, subsequently, between 10% and 20% of condylar processes had postsurgical changes in position of more than 10 degrees. CONCLUSIONS: This study showed that it is possible to anatomically reduce the fractured condylar process, but changes in position of the condylar fragment may then result from a loss of fixation.

Bone Plates↗
PubMedDate not supplied

The temporomandibular joint in rheumatoid arthritis.

The temporomandibular joint (TMJ) was investigated clinically and by orthopantomography in 110 patients with rheumatoid arthritis (RA) and in 73 control subjects. Clinical symptoms in the TMJ were established in 34 per cent of the RA patients and in 18 per cent of the controls. Radiographic abnormalities were found in 60 per cent of the RA patients compared with 15 per cent in the controls. No single radiographic abnormality was characteristic of joint involvement by RA. The most common radiologic features in RA patients were changes in the morphology of the condylar head and articular eminentia, marginal irregularities, reduced mobility, and an anterior position of the condylar head. No abnormalities were encountered in the early stage of the disease, which at least in part could be attributed to the inherent limitations of orthopantomography. The incidence of joint lesions increased with duration of the RA.

Adult↗
PubMed2006

Cephalometric evaluation of condylar and mandibular growth modification: a review.

OBJECTIVE: Based on a wealth of orthodontic archives, this work aims to review the cephalometric analysis systems that can identify the changes in condylar and mandibular position as well as growth direction in response to bite jumping therapy. DESIGN: Numerous cephalometric approaches were screened to testify their feasibility and reliability in accurately depicting the growth modification of the condyle and the mandible. The critical assessment of the working mechanisms of these cephalometric methods was elaborated to help build up the rationale and justification for their clinical use. RESULTS: 1) The changes in condylar and mandibular size, position and growth direction can be identified by using lateral cephalograms with closed-mouth or open-mouth posture. 2) With superimposition methods where the anatomical structures for superimposition registration must be stable and reproducible, the growth modification of the condyle and the mandible between two time-points is qualitatively demonstrated in a diagram if reference lines are not constructed. The growth modification can be quantitatively identified if the reference lines are created. 3) With non-superimposition methods, the size and position of the condyle and the mandible are separately identified for each time-pint by relating them to the stable reference structures. The growth modification between two time-pints is evaluated by comparing the two separate measurements. CONCLUSION: The application of a standardized and well designed cephalometric evaluation system may reduce the bias that attribute to the arbitrariness of the clinical effects of bite jumping functional appliances.

Activator Appliances↗
PubMed2006

The influence of the leaf gauge and anterior jig on jaw muscle electromyography and condylar head displacement: a pilot study.

BACKGROUND: A leaf gauge and an anterior jig may be used to assist the recording of a reproducible jaw position for restorative and prosthodontic treatment. This study investigated possible condylar displacement using an opto-electronic jaw-tracking device and a leaf gauge or anterior jig. The effect of a leaf gauge and anterior jig on jaw muscle electromyography was also examined. METHODS: Five healthy adults without symptoms of temporomandibular disorders were selected. Condylar displacement during clenching were recorded simultaneously with electromyographic activity of superior and inferior heads of the lateral pterygoid, anterior and posterior temporalis, masseter, and suprahyoid muscles. Subjects were trained to bite at maximum and half-maximum bite-force using an anterior jig incorporating a force transducer. RESULTS: No consistent condylar displacement was observed in x, y and z axes between different bite-forces although there was a trend towards superior displacement. Comparison of maximum intercuspal clench and maximum clench on a leaf gauge and an anterior jig produced significant decrease in anterior temporalis activity (p < 0.05), whilst an anterior jig with maximum clench significantly decreased posterior temporalis muscle activity. CONCLUSION: Within the limits of this pilot study, no consistent change in condylar position was identified with these appliances.

Adult↗
PubMed1997

Magnetic resonance imaging of the temporomandibular joint after functional treatment of bilateral condylar fractures in adults.

The position and functioning of discs in ten adult patients, whose bilateral condylar fractures were treated following a nonsurgical protocol, were investigated by means of magnetic resonance imaging. In seven temporomandibular joints (TMJs), where the condylar fragments were situated in the confines of the glenoid fossa, the discs were not displaced and were functioning normally. In 13 TMJs, where the condylar fragments were medially dislocated out of the fossa, the discs were displaced together with the condylar head but moved forward together with the condyle during mouth opening. This relationship between disc and condyle appears to play an important role in the reestablishment of function using nonsurgical treatment in patients with condylar fractures.

Adult↗
PubMed1994

The effect of incisal bite force on condylar seating.

The purpose of this study was to investigate the relationship between different incisal biting forces and condylar seating. Bite force was measured with strain gauges at the incisors in 22 adult subjects. The subjects were positioned with mandibles in retruded centric and with an opening not exceeding the range of hinge axis movement. Condylar movement was measured using standard true hinge axis location procedures. Condylar position was measured with no force, then with bite forces of 4.5 kg, 7.5 kg and a comfortable maximum. Biting force significantly affected condylar movement (p < 0.001). As incisal bite forces increased, so did the amount of condylar seating to an average of 0.49 mm anteriorly and 0.27 mm superiorly using maximum biting force. Therefore, when taking a centric relation record, a technique involving an anterior stop and sufficient biting force should seat the condyles more fully.

Adult↗
PubMed1983

Size and shape of the mandibular condyle in primates.

The relationships between the size of the articular surface of the mandibular condyle and masticatory muscle size, tooth size, diet, and biomechanical variables associated with mastication were studied by taking 12 measurements on skulls of 253 adult female anthropoid primates, including three to ten specimens from each of 32 species. In regressions of condylar length, width, or area against body weight, logarithmic transformations substantially improve the fit of the equations compared with untransformed data. There is a strong relationship between condylar measurements and body weight, with all correlations being .94 or higher. The slopes of the allometric regressions of length, width, and area of the condylar head indicate slight positive allometry with body size. Folivorous primates have smaller condyles than frugivorous primates, and colobines have smaller condyles than cebids, cercopithecines, or hominoids. When colobines are eliminated, the differences between frugivores and folivores are not significant. However, the two species with the relatively largest condyles are Pongo pygmaeus and Cercocebus torquatus, suggesting that there may be a relationship between unusually large condylar dimensions and the ability to crack hard nuts between the teeth. Cranial features having strong positive correlations with condylar dimensions include facial prognathism, maxillary incisor size, maxillary postcanine area, mandibular ramus breadth, and temporal fossa area. These data are interpreted as indicating that relatively large condyles are associated with relatively large masticatory muscles, relatively inefficient mandibular biomechanics, and a large dentition. These relationships support the growing evidence that the temporomandibular joint is a stress-bearing joint in normal function.

Animals↗
PubMed1989

Mandibular condyle morphology in relation to malocclusions in children.

Recent studies show that forces applied to the mandible during treatment with functional appliances and other orthodontic therapies produce changes in the TMJ. Specific malocclusions might also apply forces that can produce changes in the morphology of the TMJ. This study examined 104 orthodontic patients (44 males and 60 females) prior to treatment. The size and location of the condyle was determined on submento-vertex and tomographic films which was related to clinical findings including age, sex, malocclusion type, facial type, TMJ symptoms, tooth eruption sequence, crossbites and midline discrepancies. The medio-lateral width of the condylar head correlated positively with the patients age (p less than 0.001) and sex (p less than 0.001). Also the antero-posterior widths of the condyle were correlated with age (p less than 0.05). The condylar size in males was found to be greater than in females. Midline discrepancy significantly altered the increase in condylar size during growth. Transversel anomalies had a markedly greater influence on condylar growth compared to other characteristics of occlusion. The major change in condylar size during growth occurred in medio-lateral dimension as compared to the antero-posterior. In addition, the medio-lateral width was affected by midline discrepancy but not the antero-posterior width.

Adolescent↗
PubMed1996

Studies of changes in occlusion after the insertion of complete dentures. Part I.

The present study aims to investigate changes in the occlusion of complete dentures after their insertion. A total of 85 edentulous patients were provided with new complete dentures. Their individual hinge axes were determined using mechanical axiography and the upper finished dentures were transferred by facebows to Dentatus articulators. The lower dentures were mounted according to an intraoral central bearing point (CBP) registration and equilibrated in terminal hinge position. An articulator specially modified for measurements in the condylar area was used. The differences between the positions of the condylar balls with CBP registration and those after equilibrating the occlusion were determined. On average, 19 days after insertion, 71 patients took part in a follow-up examination. As in the first session, the terminal hinge position was registered with the CBP method using the apex of the Gothic arch. Thus, the positions of the condylar balls immediately after the new registration could be compared with those in equilibrated intercuspation 3 weeks earlier. The differences were found to be 0.5 +/- 0.4 mm (0-2.9 mm) in the three axes (sagittal, coronal and horizontal). They are thought to result from settling into the denture bearing tissues and also from neuromuscular adjustment of the masticatory system. Compulsory remounting of complete dentures after insertion is therefore recommended.

Adaptation, Physiological↗
PubMed1993

Stability of the osteotomy site following bilateral sagittal split osteotomy: screw fixation v IMF.

In a group of patients with mandibular deficiency with a low to normal mandibular plane angle (mean 20.7 degrees, range 10-28 degrees) and deep bite, the position of the condylar segment relative to the mandibular body, following bilateral sagittal split osteotomy (BSSO) for mandibular advancement was assessed. Ten patients in whom intermaxillary fixation (IMF) was used for a 5-week period were compared to 10 patients where 2 mm diameter Wurzburg positional screws were used as internal fixation. Six patients who were known bruxists and underwent BSSO were also reviewed. No clinically significant changes were seen in any patient group and no significant differences were found in the relationship with time between the condylar and body segments, irrespective of the fixation method used.

Adolescent↗