Dental attrition models predicting temporomandibular joint disease or masticatory muscle pain versus asymptomatic controls.

AIMS: To determine whether patients with temporomandibular joint disease or masticatory muscle pain can be usefully differentiated from asymptomatic controls using multifactorial classification tree models of attrition severity and/or rates. METHODS: Measures of attrition severity and rates in patients diagnosed with disc displacement (n = 52), osteoarthrosis (n = 74), or masticatory muscle pain only (n = 43) were compared against those in asymptomatic controls (n = 132). Cross-validated classification tree models were tested for fit with sensitivity, specificity, accuracy and log likelihood accountability. RESULTS: The model for identifying asymptomatic controls only required the three measures of attrition severity (anterior, mediotrusive and laterotrusive posterior) to be differentiated from the patients with a 74.2 +/- 3.8% cross-validation accuracy. This compared with cross-validation accuracies of 69.7 +/- 3.7% for differentiating disc displacement using anterior and laterotrusive attrition severity, 68.7 +/- 3.9% for differentiating disc displacement using anterior and laterotrusive attrition rates, 70.9 +/- 3.3% for differentiating osteoarthrosis using anterior attrition severity and rates, 94.6 +/- 2.1% for differentiating myofascial pain using mediotrusive and laterotrusive attrition severity, and 92.0 +/- 2.1% for differentiating myofascial pain using mediotrusive and anterior attrition rates. The myofascial pain models exceeded the > or =75% sensitivity and > or =90% specificity thresholds recommended for diagnostic tests, and the asymptomatic control model approached these thresholds. CONCLUSION: Multifactorial models using attrition severity and rates may differentiate masticatory muscle pain patients from asymptomatic controls, and have some predictive value for differentiating intracapsular temporomandibular disorder patients as well.

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.

The relationship of depression and stressors to immunological assays: a meta-analytic review.

This is a broad meta-analysis of the relations of both depression and stressors to immunological assays. The number of study samples (greater than 180) and measures (greater than 40) is much more extensive than any so far. Analyses are done by both fixed and random effects. By a fixed-effects analysis, both major depression and naturally occurring acute stressors are associated with (1) an overall leukocytosis, (2) mild reductions in absolute NK-cell counts and relative T-cell proportions, (3) marginal increases in CD4/CD8 ratios, and (4) moderate decreases in T- and NK-cell function. However, the degree of heterogeneity of the studies' results raises questions about their robustness. Therefore, we also did the first random effects analysis to estimate what is likely to appear in future studies. For depression, the analysis showed the immunological correlates included (1) an overall leukocytosis, manifesting as a relative neutrophilia and lymphoenia; (2) increased CD4/CD8 ratios; (3) increased circulating haptoglobin, PGE(2), and IL-6 levels; (4) reduced NK-cell cytotoxicity; and (5) reduced lymphocyte proliferative response to mitogen. For stressors, the random effects analysis showed that future studies are likely to find the following effects: (1) an overall leukocytosis, manifesting as an absolute lymphocytosis; (2) alterations in cytotoxic lymphocyte levels, CD4/CD8 ratios, and natural killer cell cytotoxicity with the direction of change depending on the chronicity of the stressor; (3) a relative reduction of T-cell levels; (3) increased EBV antibody titers; (4) reduced lymphocyte proliferative response and proportion of IL-2r bearing cells following mitogenic stimulation; and (5) increased leukocyte adhesiveness. The random-effects analysis revealed that for both major depression and naturally occurring stressors the following effects are shared: leukocytosis, increased CD4/CD8 ratios, reduced proliferative response to mitogen, and reduced NK cell cytotoxicity. The implications for these findings for disease susceptibility and the pathophysiology of these conditions is discussed.

The Penn Psychoanalytic Treatment Collection: a set of complete and recorded psychoanalyses as a research resource.

From a set of seventeen complete and tape-recorded psychoanalyses, a sample of findings is presented: (a) the level of agreement of two clinical judges on the psychological health of these patients is adequate for the late sessions, but not for the early sessions; (b) the amount of change during psychoanalysis appears to be similar to that in the Menninger Foundation Psychotherapy Research Project; (c) psychiatric severity measures from the early sessions can yield a significant level of prediction of the later benefits from psychoanalysis. Finally, further research uses of this collection of psychoanalyses are suggested.

Quantification and validation of predictive values of occlusal variables in temporomandibular disorders using a multifactorial analysis.

STATEMENT OF PROBLEM: A consensus is lacking on the association between occlusal variables and temporomandibular disorders (TMDs). PURPOSE: This study estimated the maximum potential power of occlusal variables to differentiate patients with TMD from asymptomatic normal adult subjects. MATERIAL AND METHODS: The occlusal characteristics in 2 sets of female patients with intracapsular TMD (1993, n = 257, and 1998, n = 124) differentiated into disk displacement and osteoarthrosis subdiagnoses were compared with asymptomatic female controls (n = 51 and 47) with multiple logistic regression analysis. Significant variables and total contribution to the log likelihood were compared with the predictive value of univariate analysis, including sensitivity and specificity. RESULTS: Occlusal factors in the females (1993, 1998) explained no more than 4.8% to 27.1% of the log likelihood. In comparison to the logistic regression analysis, univariate analysis was less predictive of patients with TMD, due to notably lower sensitivity. Patients with disk displacement were mainly characterized by unilateral posterior crossbite and longer RCP-ICP slides. Patients with osteoarthrosis were most consistently characterized by longer RCP-ICP slides and larger overjet, and in part to reduced overbite. Significant relative risk for disease (odds ratio > 2:1) was mainly associated with infrequent, more extreme ranges of occlusion measurements. CONCLUSION: Occlusal factors may be cofactors in the identification of patients with TMD, but their role should not be overstated. Some occlusal variation may be a consequence of rather than a cause for TMD. Single variables have more limited value and it takes sets of adverse variables to model TMD. Combinations of variables appear to be disease specific. Some extreme ranges of occlusion were the domain of patients with TMD, but most patients were within the normal ranges.

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

STATEMENT OF PROBLEM: Confusion about the relationship of occlusion to temporomandibular disorders (TMD) persists. PURPOSE: This study attempted to identify occlusal and attrition factors plus age that would characterize asymptomatic normal female subjects. METHODS AND MATERIAL: A total of 124 female patients with intracapsular TMD were compared with 47 asymptomatic female controls for associations to 9 occlusal factors, 3 attrition severity measures, and age using classification tree, multiple stepwise logistic regression, and univariate analyses. Models were tested for accuracy (sensitivity and specificity) and total contribution to the variance. RESULTS: The classification tree model had 4 terminal nodes that used only anterior attrition and age. "Normals" were mainly characterized by low attrition levels, whereas patients had higher attrition and tended to be younger. The tree model was only moderately useful (sensitivity 63%, specificity 94%) in predicting normals. The logistic regression model incorporated unilateral posterior crossbite and mediotrusive attrition severity in addition to the 2 factors in the tree, but was slightly less accurate than the tree (sensitivity 51%, specificity 90%). When only occlusal factors were considered in the analysis, normals were additionally characterized by a lack of anterior open bite, smaller overjet, and smaller RCP-ICP slides. The log likelihood accounted for was similar for both the tree (pseudo R(2) = 29.38%; mean deviance = 0.95) and the multiple logistic regression (Cox Snell R(2) = 30.3%, mean deviance = 0.84) models. CONCLUSION: The occlusal and attrition factors studied were only moderately useful in differentiating normals from TMD patients.

A multiple stepwise logistic regression analysis of trauma history and 16 other history and dental cofactors in females with temporomandibular disorders.

The simultaneous contribution of 11 occlusal factors, dental attrition severity, orthodontic history, trauma (motor vehicle accident [MVA] and non-MVA), and age in defining two independent large populations of females diagnosed with five mutually exclusive temporomandibular disorders was tested through multiple stepwise logistic regression analysis. Non-MVA trauma was significant in both groups in defining disc displacement (DD) with and without reduction, and osteoarthrosis (OA) (both primary and following DD). Anterior open bite was also a significant factor in defining OA in both groups. Much smaller contributions were also made by missing teeth in one of the populations with OA following DD, and by retruded contact position-intercuspal position slide lengths and overjet in one of the primary OA populations. Motor vehicle accident trauma was significant in defining myofascial pain (MP) in both populations, and laterotrusive attrition mildly defined MP in one population. Only a minority of total variance was explained: 6% to 8% of DD with reduction; 10% to 14% of DD without reduction; 11% to 20% of OA following DD; 17% to 38% of primary OA; and 4% to 10% of MP. Non-MVA trauma was the major defining feature of the temporomandibular joint intracapsular disorders, and MVA trauma explained a very small percentage of the MP patients. Implications are discussed and recommendations are made for future research.

The degree to which dental attrition in modern society is a function of age and of canine contact.

Dental attrition ranked according to a validated severity scale correlated with age as a proxy for functional wear in 148 asymptomatic subjects. Anterior, posterior, mediotrusive, laterotrusive, and total attrition severity was analyzed. The geometric contribution of canine attrition to the variance of posterior attrition was also tested through correlations, and the time span required to record a statistically significant difference in attrition using the scale was determined. Age explained 12.6% of the differences the total attrition scores (P < .001, Spearman's rho), 6.4% of the anterior scores (P < .01), and 20.9% of the laterotrusive scores (P < .0001). Canine wear in subjects aged 20 to 49 years explained between 20% to 34% of the posterior attrition (P < .05 to P < .001), 6% to 36% of the mediotrusive attrition (P < .05 to P < .01), and 20% to 29% of the laterotrusive attrition (P < .05 to P < .001). At least 20 to 30 years was necessary to show significant clinical differences, except that laterotrusive attrition changes could be discriminated in only 10 years for the 20- to 29-year-old group. Notable attrition was already evident in the 20- to 29-year-olds, and accelerated wear rates prior to age 20 years were not maintained in most areas of the dentition. A nonlinear progression with age was observed, thereby inhibiting prediction of subsequent attrition from prior levels. Attrition was concluded to have multifactorial etiology, with age and the geometry of canine guidance having a significant influence, in addition to commonly accepted parafunction.

Occlusion, Orthodontic treatment, and temporomandibular disorders: a review.

A review of the current literature regarding the interaction of morphologic and functional occlusal factors relative to TMD indicates that there is a relatively low association of occlusal factors in characterizing TMD. Skeletal anterior open bite, overjets greater than 6 to 7 mm, retruded cuspal position/intercuspal position slides greater than 4 mm, unilateral lingual crossbite, and five or more missing posterior teeth are the five occlusal features that have been associated with specific diagnostic groups of TMD conditions. The first three factors often are associated with TMJ arthropathies and may be the result of osseous or ligamentous changes within the temporomandibular articulation. With regard to the relationship of orthodontic treatment to TMD, the current literature indicates that orthodontic treatment performed during adolescence generally does not increase or decrease the odds of developing TMD later in life. There is no elevated risk of TMD associated with any particular type of orthodontic mechanics or with extraction protocols. Although a stable occlusion is a reasonable orthodontic treatment goal, not achieving a specific gnathologically ideal occlusion does not result in TMD signs and symptoms. Thus, according to the existing literature, the relationship of TMD to occlusion and orthodontic treatment is minor. Signs and symptoms of TMD occur in healthy individuals and increase with age, particularly during adolescence; thus, TM disorders that originate during various types of dental treatment may not be related to the treatment but may be a naturally occurring phenomenon.

A multiple logistic regression analysis of the risk and relative odds of temporomandibular disorders as a function of common occlusal features.

A multiple logistic regression analysis was used to compute the odds ratios for 11 common occlusal features for asymptomatic controls (n = 147) vs. five temporomandibular disorder groups: Disc Displacement with Reduction (n = 81), Disc Displacement without Reduction (n = 48), Osteoarthrosis with Disc Displacement History (n = 75), Primary Osteoarthrosis (n = 85), and Myalgia Only (n = 124). Features that did not contribute included: retruded contact position (RCP) to intercuspal position (ICP) occlusal slides < or = 2 mm, slide asymmetry, unilateral RCP contacts, deep overbite, minimal overjet, dental midline discrepancies, < or = 4 missing teeth, and maxillo-mandibular first molar relationship or cross-arch asymmetry. Groupings of a minimum of two to at most five occlusal variables contributed to the TMD patient groups. Significant increases in risk occurred selectively with anterior open bite (p < 0.01), unilateral maxillary lingual crossbite (p < 0.05 to p < 0.01), overjets > 6-7 mm (p < 0.05 to p < 0.01), > or > 5-6 missing posterior teeth (p < 0.05 to p < 0.01), and RCP-ICP slides > 2 mm (p < 0.05 to p < 0.01). While the contribution of occlusion to the disease groups was not zero, most of the variation in each disease population was not explained by occlusal parameters. Thus, occlusion cannot be considered the unique or dominant factor in defining TMD populations. Certain features such as anterior open bite in osteoarthrosis patients were considered to be a consequence of rather than etiological factors for the disorder.

The degree to which attrition characterizes differentiated patient groups of temporomandibular disorders.

Dental attrition severity as the cumulative record of parafunctional and functional wear was graded from study cast analysis using established methodology. Attrition severity was compared in anterior, posterior mediotrusive, and posterior laterotrusive segments. Attrition scores in 48 female and 100 male totally asymptomatic controls were compared to 239 female and 31 male patients differentiated into five patient groups of temporomandibular disorders: (1) disc displacement with reduction, (2) disc displacement without reduction, (3) osteoarthrosis with a history of prior derangement, (4) osteoarthrosis without a history of prior derangement, and (5) myalgia only. All the male patients were in the myalgia-only group. Age was controlled in the analysis to control for functional wear. Comparisons between patients and controls were made according to 10-year age intervals. Analysis included ANCOVA confirmed by a Games-Howell post-hoc test, with P < .01 interpreted as a significant difference in the attrition score. Only 1 of 112 ANCOVAs showed a significant difference, with younger men from 20 to 29 years of age in the myalgia-only group having lower mediotrusive attrition than the male controls. It would therefore be difficult if not impossible to differentiate patients from nonpatients based on the severity of dental attrition. Consequently, a major peripheral occlusal etiologic role for attrition in TMD is questioned. Some clinical implications are elaborated.

Overbite and overjet characteristics of refined diagnostic groups of temporomandibular disorder patients.

Overbite and overjet were studied as continuous variables to examine for any relationship to diagnostic groups of temporomandibular disorders (TMD) compared with symptom-free controls. This avoided the bias of arbitrary definitions of normal and abnormal for these occlusal variables and also avoided the masking effect of studying symptoms rather than diagnostic entities. Incisal overbite in primary osteoarthrosis (OA) was shifted toward the minimal and open bite ranges as compared with the controls (p less than 0.02). Open bite occurred in only the two OA classes studied and in a few cases with myalgia only but was absent in the symptom-free controls. Overbite in myalgia was slightly skewed to the lower range. Deep bite was not more common in the myalgia, disk displacement (with or without reduction), or the OA groups. Increased overjet characterized OA groups, especially when there was a history of derangement (p less than 0.004), but did not characterize the other diagnostic groups. Except for open bite, overbite and overjet characteristics as isolated variables did not distinguish TMD patient groups. It is hypothesized that open bite in OA can be the result of joint changes rather than a predisposing occlusal cause.

Trauma history in diagnostic groups of temporomandibular disorders.

Trauma history was studied for association with disease among six diagnostic subgroups of 230 patients with temporomandibular disorder (TMD) from a private practice setting with (1) disk displacement (DD) with reduction, (2) DD without reduction, (3) osteoarthrosis (OA) with prior derangement history, (4) primary OA, (5) myalgia only, and (6) subluxation only. Except for subluxation (29%), trauma history typified TMD patient groups 1 to 5 (63%, 79%, 44%, 53%, 54%) (p less than 0.001) compared with 13% and 18% of asymptomatic (n = 61) and symptomatic (n = 161) student control subjects, and 11% of general dental patients (n = 150). TMD groups 2 and 3 differed significantly (p less than 0.05). The high prevalence of trauma in the myalgia-only group complicates the concept of myofascial pain-dysfunction syndrome as solely a stress or centrally mediated disorder. DD without reduction (43%) and with reduction (38%) had the highest prevalences of motor vehicle accident trauma, myalgia and OA groups had less, and subluxation-only cases had none. On the other hand, patients with DD without reduction were also the only group to report multiple trauma (29%), suggesting that although specific traumatic events may seem to precipitate clinical symptoms, they may not always have initiated the problem. Trauma may be both an important cumulative and precipitating event in TMDs.

The role of functional occlusal relationships in temporomandibular disorders: a review.

This review highlights the consensus existing in past research on the role of functional occlusal factors in the pathophysiology of temporomandibular disorders (TMD). The functional occlusal relationships considered are balancing and working occlusal contacts, length and symmetry of retruded contact position-intercuspal position (RCP-ICP) slides, occlusal guidance patterns, parafunction, and dental attrition. Controlled studies fail to demonstrate any association between occlusal interferences and TMD signs or symptoms. Temporomandibular joint condylar autorepositioning secondary to intracapsular arthrosis is associated with larger and asymmetric RCP-ICP slides. Other TMD conditions are not associated with any slide length or asymmetries. Occlusal guidance patterns are not associated with TMD symptom provocation or, conversely, health. Parafunction appears to be universal and is not associated with TMD development or symptomatology in healthy individuals. Furthermore, parafunction is not provoked by longstanding, naturally occurring occlusal variations. Dental attrition is not associated with TMD, and any observed increased attrition in osteoarthrosis patients is likely the result of age effects and occlusal alterations secondary to condylar positional changes.

The role of intercuspal occlusal relationships in temporomandibular disorders: a review.

The purpose of this review is to highlight consensus in past research on the role of intercuspal occlusal factors in the pathophysiology of temporomandibular disorders. The occlusal intercuspal relationships considered are skeletal anterior open bite, overbite, overjet, symmetry of contacts in the retruded contact position (RCP), crossbite, and posterior occlusal support. Skeletal anterior open bite, reduced overbite, and increased overjet are associated with osteoarthritic TMJ patients, but lack specificity for defining patient populations per se. There is no evidence that overbite or overjet plays a role in the pathophysiology of nonarthritic disorders. A combination of unilateral RCP with an absence of a clinically apparent RCP-ICP (intercuspal position) slide may encourage TMJ disc displacement, but unilateral RCP per se was not associated with TMJ diagnoses. Crossbite does not seem to provoke TMJ symptoms or disease. Lost molar support may be associated with osteoarthrosis presence and severity, but studies have not yet been distinguished for age effects. Where appropriate, implications for clinical practice are drawn.

Guidelines for the treatment of temporomandibular disorders.

These guidelines include the usual and customary treatment approaches recommended for each of the diagnostic categories described in a previous article on the examination and diagnosis of temporomandibular disorders. The current article describes when it is appropriate to use initial therapy, behavior modification therapy, pharmacotherapy, occlusal appliances, physical therapy, and surgical treatment for temporomandibular disorders. The physical therapy procedures described include various exercises as well as pain-relief techniques such as vapocoolant spray, massage, electrical stimulation of muscles and nerves, ultrasound, and trigger-point injections. Pharmacotherapy using muscle relaxant, nonsteroidal anti-inflammatory, tricyclic antidepressant, and narcotic pain medications are also discussed. Occlusal stabilization and repositioning appliances are reviewed as well. Finally, the broad indications for arthroscopic surgery, open surgery, and steroid injections are described.

Guidelines for the examination and diagnosis of temporomandibular disorders.

These guidelines propose performance criteria for the history and examination of patients with temporomandibular (TM) disorders. Pertinent diagnostic subcategories are identified, and the comprehensive history and review of systems are described. The examination procedures include documentation of temporomandibular and craniocervical range of motion, TM joint sounds, and the recording of muscle and joint tenderness. The TM disorders addressed include muscle problems such as myalgia, protective splinting or trismus, spasm, myositis, dyskinesia, muscle contracture, hypertrophy, and bruxism. Temporomandibular joint disorders addressed include disk-condyle incoordination, restricted condyle translation, open condyle dislocation, arthralgia, osteoarthritis, polyarthritis, and traumatic joint injury. Disorders of mandibular mobility such as ankylosis, adhesions, fibrosis, skeletal obstruction, and hypermobility are also described. Finally, disorders of maxillomandibular growth, including masticatory muscle hypertrophy, atrophy, neoplasia, maxillomandibular hypoplasia, condylar agenesis, maxillomandibular hyperplasia, and condyle hypertrophy are described.

Association of occlusal variables among refined TM patient diagnostic groups.

One hundred ninety-six TMJ patients differentiated into five diagnostic groups (disk displacement with reduction [n = 40], disk displacement without reduction [n = 14], TMJ osteoarthrosis with a history of past locking [n = 32], TMJ osteoarthrosis without a history of past locking [n = 30], myalgia only [n = 80]) were compared with 222 nonpatient controls for specific occlusal variables. The patient groups could not be differentiated according to the absence of RCP-ICP slide per se, crossbite, or symmetry of RCP contacts. Among males with reducing disk displacement, Class I was less common and Class II division 1 was more common than in controls. Asymmetric RCP-ICP slides and a combination of unilateral RCP contact and no clinically visible RCP-ICP slide were more prevalent in women with reducing disk displacement. Large RCP-ICP slides, asymmetric slides, and anterior open bite were associated with osteoarthrosis, but this study could not state if these associations were etiologic or secondary. Totally asymptomatic controls were characterized by a lack of anterior open bite, small symmetric RCP-ICP slides (greater than 0 less than 1 mm), and bilateral occlusal contact in RCP. By comparing a control group to well-defined patient diagnostic groups rather than according to symptoms, selective occlusal variables appear more closely associated with some TMJ disorders than indicated in past studies with less specific populations.

The prevalence of dental attrition and its association with factors of age, gender, occlusion, and TMJ symptomatology.

Dental attrition severity in 222 young adults was assessed from dental casts as the sum of the most severe facet in each arch segment. The attrition scores were compared by age, gender, bruxism awareness, prior bite adjustment, orthodontic class, maxillomandibular relationship, and temporomandibular dysfunction symptoms. Awareness of bruxism was not associated with the wear scores and should not be used to define bruxist groups. Attrition scores did not differ significantly between age groups, indicating that notable attrition, when present, often occurs early. Men had higher attrition scores than women (p less than 0.01), despite fewer signs and symptoms. Dental attrition was not associated with the presence or absence of TMJ clicking, TMJ tenderness, or masticatory muscle tenderness. Class II division 2 males had laterotrusive attrition scores lower than those of Class III (p less than 0.05). Class III females had lower incisor attrition scores than did other Angle Classes (p less than 0.05). Discernible dental attrition in a non-patient population was not associated with signs and symptoms of temporomandibular disorders, nor with the occlusal factors studied. These results are compatible with the findings in other studies that point to bruxism as a centrally induced phenomenon common to all people and unrelated to local factors.