Analysis of occlusal variables, dental attrition, and age for distinguishing healthy controls from female patients with intracapsular temporomandibular disorders

The Dahl Concept: past, present and future

The Dahl appliance was described nearly 30 years ago. This removable metal bite platform was used to create inter-occlusal space, in a localised part of the mouth, to facilitate the placement of restorations on worn anterior teeth. The Dahl concept is traditionally associated with the management of worn teeth. However, the same principles can be successfully and safely applied to a variety of clinical situations. This has simplified the management of historically complex problems. The advantages are the preservation of tooth tissue and the long-term benefits that brings. This paper reviews the literature related to the Dahl concept and how the concept has developed. There is a discussion regarding possible future applications and research.

Quantification of the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system

STATEMENT OF PROBLEM

There is no consensus on the association between occlusion and temporomandibular disorders (TMD).

PURPOSE

The purpose of this study was to quantify the relative risk of multiple occlusal variables for muscle disorders of the stomatognathic system.

MATERIAL AND METHODS

Eight occlusal features: retruded contact position (RCP) to maximum intercuspation (MI) slide length, vertical overlap, horizontal overlap, unilateral posterior reverse articulation, anterior open occlusal relationship, incisor dental midline discrepancy, mediotrusive interferences, and laterotrusive interferences, were clinically assessed by the same trained operator. The sample consisted of 81 women with a Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) axis I diagnosis of muscle disorder, for example myofascial pain, with or without limited opening, and 48 healthy women (control group). A stepwise multiple logistic regression was used to identify the significant associations between occlusal features and disease.

RESULTS

A slide from the retruded contact position to maximum intercuspation > or =2 mm and mediotrusive interferences were the only 2 occlusal features significantly associated with the presence of myofascial pain according to the RDC/TMD criterion symptoms. The odds ratio for myofascial pain was 2.57 for a slide from RCP to MI > or =2 mm and 2.45 for mediotrusive interferences. The percentage of the total log likelihood for myofascial pain explained by the significant occlusal factors amounted to 10.8% (Nagelkerke's R2=0.108). The multifactorial model, including the 2 significant occlusal factors, showed an acuracy to predict disease of 66.7% (sensitivity 71.6%; specificity 58.3%).

CONCLUSION

Occlusal features showed a low predictive value to detect muscle disorders of the stomatognathic system. Multifactorial complex pathologies, such as TMD, should be studied using multivariate statistical analyses, as univariate models may overestimate some resulting associations.

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 comparison of disk displacement with and without reduction to normals according to temporomandibular joint hard tissue anatomic relationships

STATEMENT OF PROBLEM

There is disagreement about the predictive value of temporomandibular joint tomographic anatomy in the diagnosis of internal derangements.

PURPOSE

This study aimed to identify multifactorial temporomandibular hard tissue relationships that differentiate disk displacement with reduction and disk displacement without reduction from normals.

MATERIAL AND METHODS

Temporomandibular joint tomograms from females diagnosed with unilateral disk displacement with (n=84) or without (n=78) reduction were compared to 42 asymptomatic normal joints with the use of 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 log likelihood accounted for. The tree model was compared with a multiple logistic regression model and univariate testing.

RESULTS

The disk displacement with reduction tree model consisted of 3 disease and 2 normal pathways with interactions between fossa width to depth ratio, condyle position, and linear posterior joint space. This class was characterized by either a much wider- and shallower-than-average fossa shape and/or by a moderately posterior condyle position when the fossa shape was average to deeper and/or narrower. The logistic regression and univariate models also suggested wider and/or shallower fossae, as well as longer eminence length. The disk displacement without reduction tree model consisted of 2 disease pathways and 1 normal pathway. Interactions characterized this class by either a posterior to very posterior condyle position or by a much deeper than average fossa depth when the condyle position was concentric to anterior. The logistic regression model emphasized greater fossa depth and width versus normals. The tree models conservatively predicted the disease classes: Rescaled Cox and Snell R(2) 37.0%, sensitivity 70.2%, and specificity 90.5% for disk displacement with reduction; R(2) 28.8%, sensitivity 66.7%, and specificity 85.7% for disk displacement without reduction.

CONCLUSION

Within the limitations of this study, hard tissue relationships revealed by central tomogram sections were able to model notable differences between disk displacement with reduction and disk displacement without reduction versus asymptomatic normals when temporomandibular joints were examined as a multifactorial system typified by interactions of fossa width to depth proportions and condyle position. While substantial, the hard tissue predicted only part of the biology. The model could be broadened by additional factors and interactions.

No association between incisal tooth wear and temporomandibular disorders

STATEMENT OF PROBLEM

Incisal tooth wear may be a sign of long-term bruxing behavior. Bruxism is purported to be a risk factor for temporomandibular disorders (TMD).

PURPOSE

The purpose of this clinic-based case-control study was to investigate whether the wear of anterior teeth is associated with TMD.

MATERIAL AND METHODS

Two hundred eight TMD patients and 172 control subjects were selected for participation. After exclusion of subjects with more than 1 missing premolar or molar zone in opposite arches, as well as subjects with missing or severely restored anterior teeth, 154 TMD patients and 120 control subjects were included in the study (age 31.2 +/- 13.4 years; range 13 to 76 years). Anterior tooth wear was assessed on casts with a 0 to 5 scale. A multiple logistic regression analysis, controlling for the effects of age and gender, was performed to investigate the relationship between tooth wear and TMD.

RESULTS

An odds ratio of 0.76 (95% confidence interval: 0.51 to 1.15) indicated that after adjusting for gender and age, the odds in favor of TMD decreased an estimated 24% for each additional unit of the mean tooth wear score. This result was not significant (P=.20).

CONCLUSION

Within the limitations of this study, incisal tooth wear (assessed on dental casts) was not significantly associated with TMD when the influence of age and gender was controlled. Based on these findings, a clinically relevant risk for TMD from incisal tooth wear can be excluded. Hence, the presented evidence does not support the idea that treatment of incisal tooth wear is indicated to prevent TMD.

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.