Etiologic theory and the prevention of temporomandibular disorders

Mischievous mandibular third molars camouflaging temporomandibular joint disorders

Objectives

The aim of this study was to observe the relationship between impacted mandibular third molars and development of temporomandibular joint (TMJ) disorders. Knowledge of the factors that have an adverse effect on the TMJ is necessary for proper diagnosis, treatment, and prognosis of TMJ disorders.

Materials and Methods

The study was performed on 80 patients aged between 20 and 60 years with impacted mandibular third molars, over a period of two months. The patients were examined clinically and radiologically to determine the type of impaction and detect the associated TMJ symptoms or disorders.

Results

In the 80 patients, 63.8% (51/80) of TMJ disorders were found in the horizontal group, 46.3% (37/80) in the mesioangular group, 42.5% (34/80) in the distoangular group, and 30.0% (24/80) in the vertical group of impacted mandibular third molars.

Conclusion

The study concluded that type of impacted mandibular third molar is factor in the development of temporomandibular disorders.

A cohort study of factors that influence oral health-related quality of life from age 12 to 18 in Hong Kong

Background

There is a lack of cohort studies on the influence factors of oral health-related quality of life (OHRQoL). This study aimed to follow subjects from age 12 to 18 to analyse the sociodemographic and clinical factors that may influence OHRQoL.

Methods

This cohort study selected a representative sample from Hong Kong. Periodontal status and caries were examined according to WHO criteria. Four orthodontic indices were used to assess malocclusion. Child Perceptions Questionnaires (CPQ_11–14) with 8 items (CPQ_11–14-ISF: 8) and 37 items were used to assess OHRQoL at age 12 and age 15, respectively; Oral Health Impact Profile (OHIP-14) was used to assess OHRQoL at age 18. Wilcoxon signed ranks test and Friedman’s test were used to analyse the age-related change of OHRQoL and malocclusion from age 12 to 18. Generalized estimating equations were used to analyse the influence factors of OHRQoL and to calculate adjusted risk ratio (RR).

Results

Subjects recruited in this study were 589 (305 females, 284 males), 364 (186 females, 178 males) and 300 (165 females, 135 males) at age 12, 15 and 18, respectively. Among them, 331 subjects (172 females, 159 males) were followed from age 12 to 15, and 118 subjects (106 females, 82 males) were followed from age 12 to 18. Subjects had less severe malocclusion at age 12 than at ages 15 and 18 (p = 0.000, measured by Dental Aesthetic Index). Age, periodontal status, and malocclusion had an effect on OHRQoL. When compared with OHRQoL at age 12, worse OHRQoL was observed at age 15 (adjusted RR = 1.06, 95%CI = 1.01–1.12, p = 0.032), but not at age 18 (adjusted RR = 1.01, 95%CI = 0.95–1.08, p = 0.759). Unhealthy periodontal conditions had a negative effect on OHRQoL (adjusted RR = 1.14, 95%CI = 1.04–1.25, p = 0.007). Only severe malocclusions had a negative effect on OHRQoL; a more severe malocclusion was associated with a higher effect on OHRQoL (adjusted RR = 1.09, 95%CI = 1.01–1.18, p = 0.032 for severe malocclusion, and adjusted RR = 1.17, 95%CI = 1.07–1.28, p = 0.001 for very severe malocclusion measured by Dental Aesthetic Index).

Conclusion

Age, periodontal status, and malocclusion had an influence on OHRQoL from age 12 to 18. When clinicians attempt to improve subjects’ OHRQoL, it is necessary to consider these factors.

Comparison of temporomandibular disorders between menopausal and non-menopausal women

Objectives

Hormonal changes during menopause alter a woman's susceptibility to some disorders. Information regarding the prevalence of temporomandibular disorder (TMD) in menopausal women is limited in the literature. In this study, the prevalence and severity of TMDs were compared between menopausal and non-menopausal women.

Materials and Methods

The study included 140 women (69 premenopausal and 71 postmenopausal) 45 to 55 years of age that were examined in Shiraz Dental School, Shiraz in Iran. The Helkimo clinical dysfunction index (Di) was used to evaluate temporomandibular joint (TMJ) dysfunction. The data were analyzed using chi-square and Fisher's exact tests.

Results

Occurrence of TMD was significantly higher in menopausal than non-menopausal women (P<0.001). All the TMD criteria based on Helkimo Di except range of mandibular movement were significantly more common in menopausal women. The range of mandibular movement was not significantly different between menopausal and non-menopausal women (P=0.178).

Conclusion

The results from this study show that TMD can be considered more common and severe in menopausal than non-menopausal women. This finding indicates that, similar to other conditions in menopausal women such as arthritis and osteoporosis, TMD should be taken into consideration by dental and medical professionals.

The factors that influence the oral health-related quality of life in 12-year-old children: baseline study of a longitudinal research

Background

Oral health-related quality of life (OHRQoL) could be affected not only by oral health but also by demographic and ecosocial factors. This research aimed to analyze the sociodemographic and clinical factors that may influence the OHRQoL of 12-year-old children.

Methods

A representative sample was selected from Hong Kong. Periodontal status and caries were examined according to WHO criteria. Four orthodontic indices were used to assess malocclusion. Child Perception Questionnaires (CPQ_11–14-ISF:8 and CPQ_11–14-RSF:8) including four domains, namely oral symptoms (OS), functional limitations (FL), emotional well-being (EWB), and social well-being (SWB), were used to measure OHRQoL. Adjusted OR was calculated by ordinal logistic regression.

Results

Totally 589 eligible subjects (305 females, 284 males) were recruited. Males tended to rank higher in OS domain but lower in EWB domain (adjusted OR = 1.89 and 0.67). Mother’s education was linked more closely with children’s CPQ scores. Higher education levels were associated with better quality of life (adjusted OR = 0.45 and 0.37). Household income showed no effect on CPQ scores. Unhealthy periodontal conditions had a negative effect on EWB and total CPQ (adjusted OR = 1.61 and 1.63). High caries experience only had a negative effect on SWB (adjusted OR = 1.60). Malocclusion affected FL, EWB, SWB and total CPQ: all malocclusion severities affected SWB; only severe malocclusions affected FL, EWB and total CPQ.

Conclusion

Males were more tolerant of oral symptoms than females were. Higher levels of mother’s education led to better OHRQoL of their children. Unhealthy periodontal conditions affected emotional well-being, while high caries experience affected social well-being. All malocclusion severities had an effect on social well-being; severe malocclusion further caused functional limitations, worse emotional well-being, and hence worse OHRQoL.

Prevalence of temporomandibular disorders symptoms in patients with multiple sclerosis

The aim of the present study was to assess the prevalence of symptoms of temporomandibular disorders (TMD) in patients with the relapsing-remitting form of multiple sclerosis (MS), the relationship between TMD and the severity of MS, and the presence of TMD symptoms in the evaluated groups. Sixty individuals were evaluated: 30 patients diagnosed with relapsing-remitting MS and 30 control individuals matched for gender and age range with no neurologic pathology. In order to investigate the TMD symptoms, the questionnaires of the EACD (European Academy of Craniomandibular Disorders) and the RDC/TMD (Research Diagnostic Criteria for Temporomandibular Disorders), both validated for TMD research, were administered. To assess the extent of disability produced by MS, the Expanded Disability Status Scale (EDSS) was used. The prevalence of TMD symptoms in patients with MS was 56.7% versus 16.7% for the control group, with a statistically significant difference between the groups (p=0.0016). No correlation was found between the severity of MS and the prevalence of TMD symptoms (Fisher's test, p=1.0).

Clinical orofacial characteristics associated with risk of first-onset TMD: the OPPERA prospective cohort study

Case-control studies have documented clinical manifestations of chronic temporomandibular disorder (TMD), whereas clinical predictors of TMD development are largely unknown. We evaluated 41 clinical orofacial characteristics thought to predict first-onset TMD in a prospective cohort study of U.S. adults aged 18 to 44 years. During the median 2.8-year follow-up period, 2,737 people completed quarterly screening questionnaires. Those reporting symptoms were examined and 260 people were identified with first-onset TMD. Univariate and multivariable Cox regression models quantified associations between baseline clinical orofacial measures and TMD incidence. Significant predictors from baseline self-report instruments included oral parafunctions, prior facial pain and its life-impact, temporomandibular joint noises and jaw locking, and nonspecific orofacial symptoms. Significant predictors from the baseline clinical examination were pain on jaw opening and pain from palpation of masticatory, neck, and body muscles. Examiner assessments of temporomandibular joint noise and tooth wear facets did not predict incidence. In multivariable analysis, nonspecific orofacial symptoms, pain from jaw opening, and oral parafunctions predicted TMD incidence. The results indicate that only a few orofacial examination findings influenced TMD incidence, and only to a modest degree. More pronounced influences were found for self-reported symptoms, particularly those that appeared to reflect alterations to systems beyond the masticatory tissues.

PERSPECTIVE

OPPERA's prospective cohort study identifies predictors of first-onset TMD comprising self-reported orofacial symptoms and examination findings. The results suggest a complex pattern of TMD etiology that is influenced by disorders locally, in masticatory tissues, and systemically, in pain-regulatory systems.

Temporomandibular disorders after orthognathic surgery in patients with mandibular prognathism with depression as a risk factor

OBJECTIVE

To examine the prevalence of temporomandibular disorders (TMD) after orthodontic-surgical treatment in patients with mandibular prognathism and analyze psychosocial variables related to TMD.

MATERIALS AND METHODS

The case-control study comprised 40 patients with mandibular prognathism who underwent combined orthodontic-surgical treatment (orthognathic surgery group). Forty-two patients with untreated mandibular prognathism served as a control group. Research diagnostic criteria for temporomandibular disorders was used in order to assess the clinical diagnosis of TMD (Axis I) and to estimate depression, somatization and patient's disability related to chronic pain (Axis II).

RESULTS

The overall prevalence of TMD was not significantly different between the groups. Myofascial pain was significantly higher, while arthralgia, arthritis and arthrosis was significantly lower in the orthognathic group compared with the controls (90.5% vs 50.0%, 0.0% vs 27.8%, respectively) (p < 0.05). Females in orthognathic surgery group showed higher prevalence of TMD (p < 0.05) and myofascial pain (p < 0.01) and increased level of chronic pain (p < 0.05) in comparison with post-operative males. No significant difference in chronic pain, somatization and depression scores was found between investigated groups. With respect to presence of TMD within the groups depression was higher in untreated subjects with dysfunction (p < 0.05).

CONCLUSION

Prevalence of TMD immediately after completion of orthodontic-surgical treatment for mandibular prognathism is similar to frequency of dysfunction in untreated subjects, is significantly higher in females and is most commonly myogenic. Furthermore, females show an increased level of chronic pain post-operatively. Somatization and depression levels do not differ between patients with corrected prognathism and untreated prognathic patients.

Temporomandibular joint disorders in children

A child's difficulty in verbalizing the precise location and nature of facial pain and jaw dysfunction often results in a nondefinitive history, increasing the importance of the dentist's awareness of the early signs and symptoms of temporomandibular joint disorders (TMD). A focused examination of the masticatory musculature, the temporomandibular joints, and associated capsular and ligamentous structures can reveal if a patient's symptoms are TMD in origin. An accurate differential diagnosis enables timely referral to appropriate health care providers and minimizes the use of diagnostic imaging.

Depressive and anxiety symptoms as risk factors for temporomandibular joint pain: a prospective cohort study in the general population

Previous studies have associated depression and temporomandibular joint disorders (TMDs). The temporality, however, remains to be clarified. Most patient studies have selected subjects from treatment facilities, whereas in epidemiological studies a clinical examination has not been performed. In this study the 5-year follow-up data of the population-based Study of Health in Pomerania (SHIP) were analyzed. To estimate the effect of symptoms of depression and those of anxiety on the risk of TMD pain, the Composite International Diagnostic-Screener (CID-S) and a clinical functional examination with palpation of the temporomandibular joint and the masticatory muscles were used. After exclusion of subjects having joint pain at baseline, a sample of 3,006 Caucasian participants with a mean age of 49 years resulted. Of those, 122 participants had signs of TMD joint pain upon palpation. Subjects with symptoms of depression had an increased risk of TMD joint pain upon palpation (rate ratio: 2.1; 95% confidence interval: 1.5-3.0; P < .001). Anxiety symptoms were associated with joint and with muscle pain. The diagnosis, prevention, and therapy of TMD pain should also consider symptoms of depression and those of anxiety, and appropriate therapies if necessary.

PERSPECTIVE

Depressive and anxiety symptoms should be considered as risk factors for TMD pain. Depressive symptoms are specific for joint pain whereas anxiety symptoms are specific for muscle pain, findings that deserve detailed examination. These findings may support decision-making in treating TMD.

Clinical findings and pain symptoms as potential risk factors for chronic TMD: descriptive data and empirically identified domains from the OPPERA case-control study

Clinical characteristics might be associated with temporomandibular disorders (TMD) because they are antecedent risk factors that increase the likelihood of a healthy person developing the condition or because they represent signs or symptoms of either subclinical or overt TMD. In this baseline case-control study of the multisite Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) project, 1,633 controls and 185 cases with chronic, painful TMD completed questionnaires and received clinical examinations. Odds ratios measuring association between each clinical factor and TMD were computed, with adjustment for study-site as well as age, sex, and race/ethnicity. Compared to controls, TMD cases reported more trauma, greater parafunction, more headaches and other pain disorders, more functional limitation in using the jaw, more nonpain symptoms in the facial area, more temporomandibular joint noises and jaw locking, more neural or sensory medical conditions, and worse overall medical status. They also exhibited on examination reduced jaw mobility, more joint noises, and a greater number of painful masticatory, cervical, and body muscles upon palpation. The results indicated that TMD cases differ substantially from controls across almost all variables assessed. Future analyses of follow-up data will determine whether these clinical characteristics predict increased risk for developing first-onset pain-related TMD PERSPECTIVE: Clinical findings from OPPERA's baseline case-control study indicate significant differences between chronic TMD cases and controls with respect to trauma history, parafunction, other pain disorders, health status, and clinical examination data. Future analyses will examine their contribution to TMD onset.

Review of aetiological concepts of temporomandibular pain disorders: towards a biopsychosocial model for integration of physical disorder factors with psychological and psychosocial illness impact factors

Several studies have reported that musculoskeletal disorders of the stomatognathic system, commonly known as temporomandibular disorders (TMD) resemble musculoskeletal disorders and chronic pain disorders in general. There is also general consensus that combined biomedical and biopsychosocial methods best support the assessment and management of the cardinal features of TMD, i.e., pain and dysfunction or physical (peripheral) and psychosocial (central) factors. This overview of the aetiology of TMD will outline conceptualizations of past models and present the current view that patients with TMD should be assessed according to both the physical disorder and the psychosocial illness impact factors. The conceptual theories outlined in this review include biomedical models related to temporomandibular joints, muscles of mastication and occlusal factors, psychological models and the biopsychosocial models. An integrated and multidimensional approach concerning physical and psychosocial factors in temporomandibular pain and dysfunction is presented as an example of how the biopsychosocial model and information processing theory may apply in the conceptualization and management of TMD for various health care professionals.

Inferior or double joint spaces injection versus superior joint space injection for temporomandibular disorders: a systematic review and meta-analysis

PURPOSE

To compare the effect and safety of inferior or double temporomandibular joint spaces drug injection versus superior temporomandibular joint space injection in the treatment of temporomandibular disorders.

MATERIALS AND METHODS

MEDLINE (via Ovid, 1948 to March 2011), CENTRAL (Issue 1, 2011), Embase (1984 to March 2011), CBM (1978 to March 2011), and World Health Organization International Clinical Trials Registry Platform were searched electronically; relevant journals as well as references of included studies were hand-searched for randomized controlled trials comparing effect or safety of inferior or double joint spaces drug injection technique with those of superior space injection technique. Risk of bias assessment with the tool recommended by Cochrane Collaboration, reporting quality assessment with CONSORT and data extraction, were carried out independently by 2 reviewers. Meta-analysis was delivered with RevMan 5.0.23.

RESULTS

Four trials with 349 participants were included. All the included studies had moderate risk of bias. Meta-analysis showed that inferior or double spaces injection technique could significantly increase 2.88 mm more maximal mouth opening (P = .0001) and alleviate pain intensity in the temporomandibular area on average by 9.01 mm visual analog scale scores (P = .0001) compared with superior space injection technique, but could not markedly change synthesized clinical index (P = .05) in the short term; nevertheless, they showed more beneficial maximal mouth opening (P = .002), pain relief (P < .0001), and synthesized clinical variable (P < .0001) in the long term than superior space injection. No serious adverse events were reported.

CONCLUSIONS

Inferior or double temporomandibular joint spaces drug injection technique shows better effect than superior space injection technique, and their safety is affirmative. However, more high-quality studies are still needed to test and verify the evidence.

Masseter muscular weakness affects temporomandibular synovitis induced by jaw opening in growing rats

OBJECTIVE

To evaluate the influence of impaired masseter function during growth on the development of temporomandibular synovitis.

MATERIALS AND METHODS

Sixteen 3-week-old male Wistar rats were classified into four groups. The first group served as control; and in the second group, jaw opening was forced for 3 hours when the rats were 9 weeks old. In the third and fourth groups, the masseter muscles were bilaterally resected at 3 weeks of age, and the rats in the fourth group were additionally forced to open their jaw at 9 weeks of age. All rats were sacrificed at 9 weeks. Temporomandibular joint (TMJ) tissue samples were processed for histology, and evaluated for cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) expressions by immunohistochemistry to examine the inflammatory changes in the synovial membrane.

RESULTS

The control group showed noninflammatory changes. In the jaw-opening group, vascular dilation and weak COX-2 immunoreactivity were induced by jaw opening in the synovium. In the masseter-resection group, the masseter-resected rats exhibited moderate synovial changes while in the resection with opening group, the masseter-resected rats revealed more significant inflammatory changes including synovial hyperplasia, dilated vasculature, fibrin deposits, and intense immunoreactivity for COX-2 and iNOS, all caused by jaw opening.

CONCLUSIONS

These results suggest that masseter activity in the growth period is an important factor in the induction of temporomandibular synovitis.

Risk factors for the occurrence and prevention of temporomandibular joint and muscle disorders: lessons from 2 recent studies

INTRODUCTION

Our objectives were to demonstrate how standard epidemiologic measurements can assist in evaluating the risk factors for tempormandibular joint and muscle disorders (TMJMD) and to determine whether prevention is feasible.

METHODS

We reviewed 2 recent studies that examined third-molar extractions and severe mandibular retrognathia as risk factors for TMJMD. Cumulative incidences were available from these studies. By using these values, standard epidemiologic measurements of risk, including population attributable risk (PAR), attributable risk (AR), population attributable risk percent (PAR%), and attributable risk percent (AR%), were calculated. (PAR and AR are reported as the numbers of cases per 10,000 per year.)

RESULTS

In the third-molar extraction study, PAR, AR, PAR%, and AR% were 5, 10, 25%, and 40%; in the severe mandibular retrognathia study, they were 0.5, 17.5, 10%, and 80%, respectively.

CONCLUSIONS

This review supports the current consensus that most risk factors explain only a small portion of TMJMD in the population. However, some factors might explain a significant portion of TMJMD in persons exposed to particular risk factors. This review supports the current consensus that prevention, by screening the population for risk factors and intervening, is probably not justified. Modification of certain risk factors among exposed persons to prevent TMJMD might be warranted. Incidence data and epidemiologic measurements of risk are needed to evaluate the importance of risk factors for the occurrence and prevention of TMJMD, in both the population and exposed persons.

Incidence and prevalence of temporomandibular joint pain and dysfunction. A one-year prospective study of university students

OBJECTIVE

The aims of this study were to investigate the incidence and recovery of temporomandibular joint (TMJ) pain and dysfunction during a 1-year period, and to examine factors associated with TMJ signs and symptoms.

MATERIAL AND METHODS

The study population comprised 371 dental students examined at the start of education, out of which 308 were re-examined after 1 year. Case histories were collected with the aid of a questionnaire. The clinical examination involved TMJ mobility, TMJ pain, TMJ sounds, morphological and functional dental occlusion.

RESULTS

The 1-year incidence of TMJ signs and/or symptoms was 12%, with no statistically significant difference between men and women. Reported TMJ sounds (10%) and clinically registered TMJ pain (8%) reached the highest incidence rates. Approximately a quarter of those who had TMJ signs and/or symptoms at baseline had recovered at follow-up. Subjects with a non-symptomatic TMJ were significantly more often found among men and among those with bilateral contacts in centric relation, a normal transverse inter-maxillary relationship, and a stabile mandibular position in centric occlusion.

CONCLUSION

The 1-year incidence of TMJ pain and/or dysfunction was high among 1st-year university students. The persistence of signs and symptoms during the observation period was related to gender, while incidence and disappearance of symptoms were not. Dental occlusion was not rejected as a possible concurrent factor in relation to TMJ pain and/or dysfunction among university students.

Third-molar extraction as a risk factor for temporomandibular disorder

BACKGROUND

Although third-molar extraction is common in the U.S., there are few reports on the relationship between third-molar extraction and temporomandibular disorder (TMD). The aim of this study was to investigate this potential association.

METHODS

The authors enrolled study subjects on their 15th birthdays and followed them continuously for a minimum of five years. The authors ascertained exposure (third-molar extraction) and outcome (TMD) via electronic dental insurance records. A survival analysis design estimated the relative risk of experiencing TMD after third-molar extraction. They considered sex, dental care utilization and other potentially confounding variables in the analyses.

RESULTS

A total of 34,491 subjects met the inclusion criterion. Fifty percent of all subjects had third molars removed by the age of 20 years, and 391 subjects had claims indicating TMD. The adjusted relative risk of experiencing TMD after third-molar extraction was 1.6 (95 percent confidence interval, 1.3 to 2.0). Calculation of the population risk indicated that 23 percent of all TMD cases in this age group might be due to third-molar extraction.

CONCLUSIONS

Third-molar extraction appears to be a risk factor for TMD.

CLINICAL IMPLICATIONS

Dental providers should be aware of the risk of experiencing TMD related to third-molar extraction and take measures to minimize trauma to the joint during extraction.

Subjective reactions to intervention with artificial interferences in subjects with and without a history of temporomandibular disorders

In a previous double-blind randomized controlled study, subjects with a history of temporomandibular disorder (TMD) reacted to artificial interference with more signs of TMD than did subjects with no TMD history. In the present study, we analysed the subjective reactions of these individuals on several symptom scales. Every day during the 2-week follow-up period, the subjects rated the intensity of their symptoms on 9 VAS scales (occlusal discomfort, chewing difficulties, tender teeth, fatigue in the jaws, headache, facial pain, opening difficulty, bruxism, ear symptoms). Subjects with a history of TMD and true interferences reported stronger symptoms than subjects with no TMD history and placebo interferences. The most prominent symptoms were occlusal discomfort and chewing difficulties. The difference in outcome between the groups with and without a TMD history suggests that there are individual differences in vulnerability to occlusal interferences. It is likely that the etiological role of occlusal interferences in TMD has not been correctly addressed in previous studies on artificial interferences.

Occlusion: Reflections on science and clinical reality

The last 50 years have seen progress in emphasizing scientific evidence as a basis for dental practice, including occlusal therapy. Although a proper understanding of the contributory role of occlusion to temporomandibular disorders should not be minimized, the importance of occlusion in other areas of dental education and practice should not be overlooked. The primary objective of this article is to discuss the nature of this problem as it relates to the duality of science and clinical reality in the evidence-based paradigm, information transfer, quality of evidence, clinical trials, and clinical aspects of occlusion. Some suggested solutions for the problem and thoughts on past and future perspectives of occlusion are expressed in context of inquiry.

Contributing factors to chronic myofascial pain: a case-control study

This case-control study was designed to investigate the contributing factors for chronic masticatory myofascial pain (MFP). Eighty-three patients with MFP, selected from the dental clinics of the Jewish General and Montreal General Hospitals, Montreal, Canada, and 100 concurrent controls selected only at the first clinic, participated in this study. The association with MFP was evaluated for bruxism, head-neck trauma, psychological factors (symptom check list 90 revised questionnaire, SCL-90R) and sociodemographic characteristics by using unconditional logistic regression. Clenching-grinding was associated with chronic MFP in multiple models including anxiety (OR=8.48; 95% CI: 2.85; 25.25) and depression (OR=8.13; 95% CI: 2.76; 23.97). This association also remained for MFP, excluding all other temporomandibular disorders (TMD). Clenching-only (OR=2.54; 95% CI: 1.10; 5.87) and trauma (OR=2.10; 95% CI: 1.0; 4.50) were found to be associated with the chronic MFP, when the level of anxiety was adjusted in the model. No significant change was noted when the effects of clenching-only (2.76; 95% CI: 1.20; 6.35) and trauma (OR=2.08; 95% CI: 1.03; 4.40) were adjusted for depression. Clenching-only and clenching-grinding remained related to MFP regardless of patients being informed about these habits. A higher score of anxiety (OR=5.12; 95% CI: 1.36; 19.41) and depression (OR=3.51; 95% CI: 1.07; 11.54) were associated with MFP, as well as other psychological symptoms. In addition, female gender had almost three times the risk of chronic MFP than males when the model was also adjusted for psychological symptoms. Grinding-only, age, household income and education were not related with chronic MFP. Tooth clenching, trauma and female gender may contribute to MFP even when other psychological symptoms are similar between subjects.

Effect of artificial occlusal interferences depends on previous experience of temporomandibular disorders

Studies on artificial interferences in subjects with no temporomandibular (TMD) history have shown adaptation to the interference within a fairly short period of time. The role of occlusal factors in the etiology of TMD has therefore been questioned. The results might have been different, however, if subjects with a prior TMD history had been included in the study groups. To test this assumption in a randomized double-blind clinical set-up, we included healthy women without (n = 26) as well as with (n = 21) an earlier TMD history. Both groups were randomly divided into true and placebo interference groups. Artificial interferences were introduced in the true interference groups and simulated in the placebo groups. The subjects were followed for 2 weeks, after which the interferences were removed. The subjects without a TMD history showed fairly good adaptation to the interferences, but the subjects with a TMD history and true interferences showed a significant increase in clinical signs compared to the other groups. We suggest that the etiological role of occlusal interferences in TMD may not have been correctly addressed in previous studies with artificial interferences and allow no conclusions as regards TMD etiology.

Occlusion and temporomandibular disorders (TMD): still unsolved question?

The rejection of the occlusal hypothesis cannot be justified with the present empirical evidence.

Risk factors for diagnostic subgroups of painful temporomandibular disorders (TMD)

Temporomandibular Disorders (TMD) encompass several entities, which may have differing etiologies. To test this hypothesis, we investigated risk factors for three diagnostic subgroups of painful TMD. Ninety-seven subjects with myofascial pain only, 20 with arthralgia only, 157 with both myofascial pain and arthralgia, and 195 controls without TMD pain met criteria for study eligibility. Investigated risk factors included both physical and psychological variables. Adjusted odds ratios were calculated by multiple logistic regression analyses. Myofascial pain occurring alone was significantly associated with trauma (Odds Ratio [OR] = 2.0), clenching (OR = 4.8), third molar removal (OR = 3.2), somatization (OR = 3.7), and female gender (OR = 4.2). Myofascial pain with arthralgia was significantly associated with trauma (OR = 2.1), clenching (OR = 3.3), third molar removal (OR = 4.0), somatization (OR = 5.1), and female gender (OR = 4.7). No significant associations were found for the small-arthralgia-only group.

The occlusal theory further complicated

This paper reviews the critique presented against the occlusal theory of the temporomandibular disorders (TMD) and presents a new hypothesis. Although no empirical evidence has been found to refute the role of occlusion in the etiology of TMD, we argue that the occlusal theory in its present form is biased in that it is based on the findings in adults and assumes that the causal chain proceeds from structure to function. However, the close developmental relationship between function and structure and the recent changes in the functional environment of the stomatognathic organ indicate that the causal influences take place in both directions. We suggest that the occlusal theory should be reformulated in such a way that it includes mutual interactions between function and structure during growth. We assume that the structural adaptations taking place in the growing child in response to functional stimuli may play an important role in the etiology of TMD. Testing of our hypothesis requires longitudinal studies which focus on both functional and structural development.

The role of occlusal adjustment in the management of temporomandibular disorders

The use of occlusal adjustment as a treatment for temporomandibular disorders has been questioned because of lack of evidence that occlusal factors play an etiologic role; lack of evidence that this irreversible treatment modality has sufficient efficacy, when reversible modalities are available; the self-limiting character of the disorders; and the possibility of adverse effects. However, controlled clinical trials have yielded results that are difficult to explain unless occlusal factors have a causal role in temporomandibular disorders. Controlled clinical trials also suggest an effect for occlusal adjustment on chronic headaches and on chronic neck and shoulder pain in comparison with conventional treatments. Moreover, no adverse effects of properly conducted occlusal adjustments have been reported. In view of the possibility that occlusal factors have a causal role in temporomandibular disorders, research efforts on the role of occlusion should be intensified, and teaching should be revised accordingly.

Quantitative evaluation of the tonic vibration reflex (TVR) in the masseter muscle

PURPOSE

This study evaluated the efficacy of the tonic vibration reflex (TVR) elicited by high-frequency vibration in evaluating masticatory muscle excitability.

SUBJECTS AND METHODS

The experiment was performed on 16 male adult volunteers, 20 to 45 years of age, without spontaneous pain or tenderness in the masticatory muscles. The subjects were seated in a chair in a fixed head position with the mouth kept open with a bite block. TVR was elicited by vibratory stimulation applied to the mandible (approximately 15 m/s2, 160 Hz). An electromyogram (EMG) was recorded bilaterally from the masseter muscles and analyzed quantitatively using an arbitrary index (TVR index) calculated from the response. Bite force was measured during clenching using a pressure-sensitive foil.

RESULTS

Wide variations in the TVR index (maximum, 22.7%; minimum, 0.9%, average, 7.7%) were observed among individuals. The mean index for five subjects with a clenching habit was significantly higher than that for 11 subjects without a history of clenching. Tolperisone HCl (100 mg taken orally), a gamma-drive depressant, was found to reduce the response for 2 hours. There was a negative correlation (r = -.504, P < .05) between bite force and TVR index when the values on both sides were compared.

CONCLUSIONS

The TVR may be of use in evaluating masseter muscle excitability.

The concepts prevalence, need for treatment, and prevention of temporomandibular disorders: a suggestion for terminology

The concepts active and passive treatment need and active and passive prevention need are suggested, to systematize some concepts used in discussions about temporomandibular disorders (TMD), to separate the treatment need figures from the prevalence figures, and to understand the great variation among TMD prevalence studies. On the basis of a summary of recently published papers and on a clinical 2-year follow-up study of 411 subjects, the suggestions seem to provide a reasonably good fit with clinical experience and earlier epidemiologic studies of TMD.

Etiology of temporomandibular disorders

This article discusses the subject of causation (etiology) as it has been applied to the field of temporomandibular disorders (TMD). These disorders have been the focus of considerable disagreement about what constitutes proper diagnosis and treatment, and it is clear that the main basis for these controversies has been conflicting views about the etiology of the various disorders. Many earlier theories emphasized dental morphological factors of malocclusion, occlusal dysharmony, and bad mandibular alignment as being primarily responsible for the development of TMD symptoms. Certain versions of these dental/skeletal concepts have long been a part of the belief system of the orthodontic specialty, leading to some special orthodontic protocols for managing TM disorders. Today, it is generally agreed that the etiology of TM disorders includes a multifactorial combination of physical and psychosocial factors, with some of them being either poorly understood or difficult to assess. In most cases, there are no special occlusal or orthodontic factors to be considered, and therefore occlusion-changing procedures are not generally required for successful treatment. This means that contemporary orthodontists must face the same challenge as all their other dental colleagues: to learn about modern concepts of diagnosis and treatment for all types of orofacial pain patients, and then to use currently recommended protocols for pain management and musculoskeletal therapy for those patients who have temporomandibular disorders.

Chronic illness of the temporomandibular joints as experienced by support-group members

PURPOSE

For temporomandibular disorders, the clinical situation is one of considerable etiologic, diagnostic, and therapeutic uncertainty. Using interview data, this report describes this condition and the search for care from the perspective of sufferers who are support-group members.

PARTICIPANTS AND METHODS

Thirty-two individuals participated; all were members of a support group for individuals with long-term problems attributed to the temporomandibular joints and/or the surrounding masticatory muscles. Using a structured, open-ended interview format, this study investigated how individuals understand and give meaning to their symptoms, their patterns of care seeking, and the consequences of the illness on their lives. The participants also completed several structured questionnaires.

RESULTS

For these support-group members, symptoms extended beyond the jaw and surrounding area, with extensive musculoskeletal involvement and resulting dysfunctions that have far-reaching consequences for the sufferers' lives. Primary care physicians are often consulted, especially early in the illness history. They also provide ongoing care and are asked for guidance when patients seek specialized treatment. A striking aspect of the findings from the interviews is the complex and costly pattern of health care seeking. This extended search for effective treatment is examined with reference to culturally based understanding, shared by patients and clinicians, about the nature of illness.

Prevention Revisited— Summary of Scientific Symposium

A symposium, "Prevention Revisited", was held in September of 1990 in Rochester, New York, as part of the 75th Anniversary celebration of the Eastman Dental Center. The symposium covered a broad range of topics, including risk assessment for oral diseases, the diagnosis and classification of periodontal diseases, caries prevention, fluorides, dental materials, TMJ disorders, and the geriatric patient. Each topic was approached from the perspective of prevention: past accomplishments, present status, and future directions. A format of major presentations, reactor papers, and discussion was used.