Relationship of articular soft tissue contour and shape to the underlying eminence and slope profile in young adult temporomandibular joints

Multifactorial modeling of temporomandibular anatomic and orthopedic relationships in normal versus undifferentiated disk displacement joints

STATEMENT OF PROBLEM

There is persistent dispute about the diagnostic value of hard tissue anatomic relationships in predicting temporomandibular joint disorders and normals.

PURPOSE

The goal of this study was identification of multifactorial temporomandibular hard tissue relationships that differentiate asymptomatic normal joints.

MATERIAL AND METHODS

Central section lateral tomograms of 162 female temporomandibular joints with pooled diagnoses of unilateral disk displacement with and without reduction were compared to 42 female asymptomatic normal joints using 14 linear and angular measurements and 8 ratios. A validated classification tree model was tested for accuracy with sensitivity, specificity, goodness of fit, and the amount of the log likelihood accounted for. The tree model was compared with a multiple logistic regression model and univariate testing.

RESULTS

The classification tree model consisted of 3 asymptomatic and 4 disk displacement terminal nodes consisting of interactions of condyle position with measures of fossa size and shape, of which mainly average non-extreme measurements and more frequent concentric ranges typified the asymptomatic joints. The logistic regression and univariate models also incorporated condyle position and size, but the logistic regression accounted for less of the log likelihood than the tree (23.3% vs. 32.6% Rescaled Cox and Snell R(2)). The tree and the logistic regression models were moderately good predictors for distinguishing normals from disk displacement joints (sensitivity 67.9% and 72.2%, specificity 85.7% and 76.2%, respectively). Although the univariate analysis showed that the asymptomatic joints had smaller mean fossa width to fossa depth ratios (P<.0005), shorter mean eminence length (P<.007), and more concentric to anterior mean condyle position (P<.049), overlap in most of the ranges limited the predictive value.

CONCLUSION

Within the limitations of this study, multifactorial analysis revealed that several subsets of asymptomatic temporomandibular joints could be distinguished from joints with disk displacement according to hard tissue measurements taken from central section tomograms. In general, asymptomatic normal joints were typified by interactions of less extreme ranges of fossa size, shape, and condyle position.

Multifactorial analysis of differences in temporomandibular joint hard tissue anatomic relationships between disk displacement with and without reduction in women

STATEMENT OF PROBLEM

Without multifactorial models, it is difficult to resolve whether hard tissue tomographic relationships can distinguish differences between temporomandibular joint (TMJ) internal derangement diagnoses.

PURPOSE

The purpose of this study was to use multifactorial models to examine whether there are hard tissue anatomic and orthopedic characteristics that distinguish temporomandibular joints with disk displacement with reduction from disk displacement without reduction.

MATERIAL AND METHOD

. TMJ tomograms from female patients who had unilateral disk displacement diagnosed with (n = 84) or without (n = 78) reduction were compared with the use of 14 linear and angular measurements and 8 ratios. A representative classification tree model was tested for fit with sensitivity, specificity, accuracy, and likelihood accountability, and the results were compared with a multiple stepwise logistic regression model and univariate analysis.

RESULTS

Disk displacement without reduction joints had longer mean postglenoid fossa heights (P<.0005), greater mean fossa depth (P<.017), and narrower mean absolute superior joint spaces (P<.041) than disk displacement with reduction joints (univariate t test). The classification tree had 4 terminal nodes; to differentiate the joints, it used the eminence radius and the absolute superior joint space to anterior joint space ratio subordinate to the postglenoid process height. The tree model accounted for 31.4% of the likelihood (Rescaled Cox and Snell R(2)) with 73.5% accuracy (sensitivity 82.6% and specificity 65.4%). Disk displacement without reduction joints had either deeper posterior fossa walls or posterior walls of average length combined with a superior-to-anterior joint space ratio of less than 0.83; this suggests a more open-wedge-shaped anterior joint space combined with a less-rounded articular eminence. In contrast, most disk displacement with reduction joints had shorter posterior fossa wall height combined with more equal or larger superior-to-anterior joint spaces. The logistic regression model was less accurate than the classification tree model (sensitivity 60.9%, specificity 66.7%) and accounted for only 9.9% of the likelihood (Rescaled Cox and Snell R(2)) and 63.6% accuracy. The postglenoid process height was the strongest differentiating factor in all models.

CONCLUSION

Hard tissue relationships revealed by central tomogram sections were able to model notable differences between disk displacement with and without reduction joints when examined as contingency-based multifactorial systems.

Morphology of the mandibular fossa and inclination of the articular eminence in patients with internal derangement and in symptom-free volunteers

OBJECTIVE

The purpose of this study was to evaluate temporomandibular joint morphology and to compare possible structural variations in the temporomandibular joint anatomy of symptomatic anterior disk displacement patients with possible structural variations in the temporomandibular joint anatomy of symptom-free volunteers.

STUDY DESIGN

Fifty-six symptomatic patients and 25 symptom-free volunteers were included in this study. All subjects had bilateral high-resolution magnetic resonance imaging scans performed in the sagittal (closed and open) positions. Disk positions were evaluated with these images, and the patients were accordingly classified into 4 diagnostic groups. The angulation between the Frankfort horizontal plane and the posterior slope of the articular eminence, as well as the width and depth of the glenoid fossa and the articular tuberculum, were automatically measured with the aid of a computer.

RESULTS

The Mann-Whitney U test demonstrated significant differences in the angular and linear values obtained in disk displacement with reduction patients in comparison with the values obtained in patients with disk displacement without reduction and in symptom-free volunteers.

CONCLUSION

It is proposed that a steeper posterior slope and higher tuberculum articulaire are predisposing factors for the development of disk displacement with reduction. Flattening of the eminence may progress in time, leading to the onset of disk displacement without reduction.

Evaluation of the slope of the articular eminence and the transverse angle of the glenoid fossa in an Anatolian population

The purpose of this study was to compare a computer-aided method specially programmed for the measurement of the posterior angle of the articular eminence with formerly used methods, to investigate the angulation differences at different depths of slices, and to evaluate correlation with the transverse angulation. Three slices (central, medial, and lateral) at various depths of the glenoid fossa belonging to 64 dry skulls and two measurement methods were used in this study. The angulation of the articular eminence were measured and the transverse angle of each fossa calculated. No statistical difference was found between the articular eminence results of the two methods. According to the results, the one factor ANOVA central slice was found to be statistically steeper than the other two slices (p < 0.05) (central = 60.33 +/- 10.19, medial = 58.26 +/- 8.6, lateral 58.28 +/- 10.1). No correlation was found between the transverse angle of the inclination of the posterior slope angulation. It was concluded that the computer-aided method is more reliable and accurate and is much easier to use when compared to the manual method. An additional important finding of this study is that the inclination of the articular eminence should be evaluated at various depths of the temporomandibular joint.

Thickness of the articular soft tissue of the temporal component in temporomandibular joints with and without disk displacement

OBJECTIVE

The purpose of this investigation was to test the hypothesis that temporomandibular joint disk displacement is associated with significant functional adaptive changes of the articular soft tissue of the articular eminence.

STUDY DESIGN

Thirteen temporomandibular joint autopsy specimens with normal superior disk position and 12 with complete anterior disk displacement were cryosectioned, and sections were stained and photographed. At a magnification of x20 the soft tissue was measured (1) at the inflection point, (2) on the posterior slope, (3) at the apex, and (4) on the anterior slope of the articular eminence.

RESULTS

Displacement of a deformed or nondeformed temporomandibular joint disk without perforation of the posterior disk attachment was associated with significantly increased thickness of the articulating soft tissue at the apex and on the posterior and anterior slopes of the articulating eminence. When disk displacement was associated with a perforation of the posterior disk attachment, the soft tissue was not significantly thicker than in joints with normal superior disk position.

CONCLUSIONS

Increase in articulating soft tissue thickness is interpreted as an adaptive mechanism to maintain the condyle path and withstand excessive loading at interposition of the temporomandibular joint components. When the plasticity of the tissues is surpassed, the adaptation will be thwarted and replaced by tissue breakdown.