Mandibular dysfunction in adulthood in relation to morphologic malocclusion at adolescence

WITHDRAWN: Orthodontics for treating temporomandibular joint (TMJ) disorders

The Cochrane Oral Health Group withdrew this review as of Issue 1, 2016. The review is out of date and does not meet current Cochrane methodological standards. It will be superseded by a new Cochrane review on Occlusal interventions for managing temporomandibular disorders.

The editorial group responsible for this previously published document have withdrawn it from publication.

Skeletal pattern in subjects with temporomandibular joint disorders

INTRODUCTION

To establish the skeletal pattern in subjects with malocclusions and temporomandibular disorders (TMD); to assess the relationship between craniofacial skeletal structures and TMD in subjects with malocclusions.

MATERIAL AND METHODS

Sixty-four subjects with malocclusions, over 18 years of age, were included in the study. Temporomandibular disorders were clinically assessed according to the Helkimo Anamnestic Index. Subjects underwent a lateral cephalogram. Subjects were grouped according to the sagittal skeletal pattern (ANB angle) into class I, II and III. Parametric Student tests with equal or unequal variations were used (variations were previously tested with Levene test).

RESULTS

Twenty-four patients with TMD (experimental sample); 40 patients without TMD (control group); interincisal angle was higher in class I and II (p < 0.05) experimental subjects; overjet was larger in experimental subjects; midline shift and Wits appraisal were broader in the experimental group in all three classes. In class III subjects, the SNB angle was higher in the experimental group (p = 0.01). Joint noises followed by reduced mandible mobility, muscular pain and temporomandibular joint (TMJ) pain were the most frequent symptoms in subjects with TMD and malocclusions.

CONCLUSIONS

Temporomandibular joint status is an important factor to consider when planning orthodontic treatment in patients with severe malocclusions; midline shift, large overjet and deep overbite have been associated with signs and symptoms of TMD.

Condylar shape in relation to anterior disk displacement in juvenile females

The purpose of the study was to test the hypothesis that condylar shape varies based upon the condition of anterior disk displacement in young adolescent patients with temporomandibular disorder (TMD). The study design consisted of 96 juvenile female patients (aged 9 to 20; 15.1 +/- 2.3 yrs.) with clinical signs and/or symptoms of TMD. Bilateral high-resolution magnetic resonance imaging scans were performed in frontal and horizontal views with the mandible in the closed position. Disk positions were evaluated to classify the patients into three diagnostic groups. The results of the study, using ANOVA and Bonferroni tests, demonstrated significant differences among the groups. The conclusion drawn from the study was that condylar shape and size vary based on anterior disk position in juvenile females with TMD. The study's results suggest that disk displacement results in a smaller condyle.

Orthodontics for treating temporomandibular joint (TMJ) disorders

BACKGROUND

Temporomandibular disorders (TMD) relate to discomfort of the temporomandibular joint (TMJ). The disorder is multifactorial with a degree of psychogenic influence varying throughout an individual's life with phases of symptoms affecting the quality of life. In an attempt to treat this complex group of disorders many treatment modalities have been identified some of which are also considered in other Cochrane reviews. The disorder also has a normal cycle of events appearing to spontaneously improve without treatment.

OBJECTIVES

To establish the effectiveness of orthodontic intervention in reducing symptoms in patients with TMD (compared with any control group receiving no treatment, placebo treatment or reassurance) and to establish if active orthodontic intervention leads to TMD.

SEARCH STRATEGY

The Cochrane Oral Health Group's Trials Register, CENTRAL, MEDLINE and EMBASE were searched. Handsearching of orthodontic journals and other related journals was undertaken in keeping with the Cochrane Collaboration handsearching programme. No language restrictions were applied. Authors of any studies were identified, as were experts offering legal advice, and contacted to identify unpublished trials. Most recent search: 13th April 2010.

SELECTION CRITERIA

All randomised controlled trials (RCTs) including quasi-randomised trials assessing orthodontic treatment for TMD were included. Studies with adults aged equal to or above 18 years old with clinically diagnosed TMD were included. There were no age restrictions for prevention trials provided the follow-up period extended into adulthood. The inclusion criteria required reports to state their diagnostic criteria for TMD at the start of treatment and for participants to exhibit two or more of the signs and/or symptoms. The treatment group included treatment with appliances that could induce stable orthodontic tooth movement. Patients receiving splints for 8 to 12 weeks and studies involving surgical intervention (direct exploration/surgery of the joint and/or orthognathic surgery to correct an abnormality of the underlying skeletal pattern) were excluded. The outcomes were: how well were the symptoms reduced, adverse effects on oral health and quality of life.

DATA COLLECTION AND ANALYSIS

Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted in triplicate and independently by three review authors. As no two studies compared the same treatment strategies (interventions) it was not possible to combine the results of any studies.

MAIN RESULTS

The searches identified 284 records from all databases. Initial screening of the abstracts and titles by all review authors identified 55 articles which related to orthodontic treatment and TMD. The full articles were then retrieved and of these articles only four demonstrated any data that might be of value with respect to TMD and orthodontics. After further analysis of the full texts of the four studies identified, none of the retrieved studies met the inclusion criteria and all were excluded from this review.

AUTHORS' CONCLUSIONS

There are insufficient research data on which to base our clinical practice on the relationship of active orthodontic intervention and TMD. There is an urgent need for high quality randomised controlled trials in this area of orthodontic practice.When considering consent for patients it is essential to reflect the seemingly random development/alleviation of TMD signs and symptoms.

TMD in Relation to Malocclusion and Orthodontic Treatment

OBJECTIVE

The aim of this systematic literature review was to evaluate associations between different malocclusions, orthodontic treatment, and signs and symptoms of temporomandibular disorders (TMD).

MATERIALS AND METHODS

This review was part of a project at the Swedish Council on Technology Assessment in Health Care focusing on malocclusion and orthodontic treatment from a health perspective. As a first step, the literature was searched in the Medline and Cochrane Library databases from 1966 to May 2003. A later update was made in January 2005. Human studies in English or in Scandinavian languages were included.

RESULTS

Associations between certain malocclusions and TMD were found in some studies, whereas the majority of the reviewed articles failed to identify significant and clinically important associations. TMD could not be correlated to any specific type of malocclusion, and there was no support for the belief that orthodontic treatment may cause TMD. Obvious individual variations in signs and symptoms of TMD over time according to some longitudinal studies further emphasized the difficulty in establishing malocclusion as a significant risk factor for TMD. A considerable reduction in signs and symptoms of TMD between the teenage period and young adulthood has been shown in some recent longitudinal studies.

CONCLUSIONS

Associations between specific types of malocclusions and development of significant signs and symptoms of TMD could not be verified. There is still a need for longitudinal studies.

Effects of sagittal split ramus osteotomy on temporomandibular disorders in seventy-two patients

Preoperative and postoperative temporomandibular disorders (TMDs) were observed in 72 patients before surgical-orthodontic treatment and about 2 years after bilateral sagittal split osteotomy. Prevalence and degree of TMD were assessed using the modified clinical dysfunction index of Helkimo. A total of 49 women and 23 men (mean age 32 years) were included in the study. To find out which patients benefit most from the treatment, the sample was classified into subgroups--myogenous, arthrogenous, or both components of TMD. The prevalence of clicking and headache decreased significantly with the treatment, while the incidence of crepitation increased. In general, severity of the dysfunction was greatly reduced. Furthermore, multiple regression analysis showed that patients with excessive overjet and previous occlusal splint therapy benefit most from orthognathic treatment. In addition, patients with signs of mainly myogenous origin got more relief from their dysfunction than patients with mainly arthrogenous components of TMD. The results suggest that in patients with severe maxillomandibular discrepancy surgical-orthodontic therapy is a good choice of treatment for reducing myogenous TMD pain and discomfort.

Systematic review of population-based epidemiological studies of oro-facial pain

OBJECTIVES

To conduct a systematic review of epidemiological literature in order to determine the prevalence and associated risk factors of oro-facial pain.

DATA

Population based observational studies (cohorts, cross-sectional and case-control studies) of oro-facial pain, published in the English language, prior to 1999 were included.

SOURCES

Electronic databases (Medline, Embase, Cinahl, BIDS and Health CD) were searched. Reference lists of relevant articles were examined, and the journals "Pain" and "Community Dentistry and Oral Epidemiology" were handsearched for the years 1994-1998.

RESULTS

The results of the search strategy were screened for relevance. A standardised checklist was used to assess the methodological quality of each study by two reviewers before an attempt was made to summarise the results. The median quality score was 70% of the maximum attainable score. Due to methodological issues, it was not possible to pool the data on the prevalence of oro-facial pain. Age, gender and psychological factors were found to be associated with OFP, however there was not enough information on other factors such as local mechanical and co-morbidities to draw any reliable conclusions. None of the factors fully fulfilled criteria for causality.

CONCLUSIONS

There is a need for good quality epidemiological studies of oro-facial pain in the general population. To enable comprehensive examination of the aetiology of oro-facial pain, it is necessary to address a broad range of factors including demography and life-style, local mechanical factors, medical history and psychological factors. Future studies should recruit adequately sized samples for precise determination of the prevalence and detection of important associated factors. Data on potential confounders and effect modifiers should also be collected and adjusted for in the statistical analysis.

Sex differences in mandibular movements during opening and closing

This study evaluated the sex differences in maximum 3-dimensional opening and closing movements. The sample included 29 men (ages, 23-39 years) and 27 women (ages, 23-35 years), who were selected for normal Class I occlusion, temporomandibular function, and skeletal patterns. Condylar (hinge axis) translation and mandibular incisor movements, were recorded with an optoelectric jaw-tracking system; each participant performed 4 maximum opening/closing cycles. The results showed significant (P <.05) sex differences for incisor opening and closing movements, with most of the differences in the vertical component. Male incisor straight-line distances and curvilinear pathways averaged 52.1 mm and 54.8 mm, respectively. Female straight-line distances and curvilinear pathways averaged 46.0 mm and 48.1 mm, respectively. There were significant (P <.05) sex differences for condylar translation, with most of the differences in the anteroposterior component. Male condyles translated 15.4 to 17.6 mm (straight-line distances) and 20.5 to 20.7 mm (curvilinear pathways); female condyles translated 12.4 to 12.7 mm (straight-line distances) and 16.2 to 17.9 mm (curvilinear pathways). Mandibular length accounted for some of the sex difference in interincisal opening and for most of the sex differences in condylar translation. Closing movements showed the same pattern of sex differences as opening movements. Mandibular opening rotation was approximately 4 degrees larger in men than in women. The shapes of the condylar opening and closing pathways also differed significantly between men and women. For both sexes, condylar translation did not correlate with incisor opening or closing movements. It was concluded that (1) significant sex differences exist in incisor opening movements that are independent of mandibular size, (2) sex differences in condylar translation are dependent on mandibular size, (3) incisor opening movements should not be used as an indicator of condylar translation, and (4) sex differences in the shapes of the condylar pathways indicate sex differences in articular eminence morphologic features.

Associations between incisor and mandibular condylar movements during maximum mouth opening in humans

This study evaluated the common clinical assumption that condylar translation and mouth opening at the incisor are closely related. The sample studied comprised 27 adult females (23-35 years), selected for normal temporomandibular function, occlusion, and skeletal patterns. Condylar and mandibular central incisor movements (straight-line distances and curvilinear pathways) were recorded in three dimensions (3D) for 20 s with an optoelectric (Optotrak(R)) jaw-tracking system while each participant performed multiple maximum opening cycles. Masticatory analysis and multilevel statistical programs computed the 3D movements of the incisors and condylar hinge axis during opening and closing. The incisor point moved an average straight-line distance of 46.6 mm during opening and 45.9 mm during closing; the lengths of the opening and closing curvilinear pathways were 48.6 and 47.7 mm, respectively. The condyles moved average straight-line distances of 11.9 and 12.2 mm during opening and closing, respectively. The condyles' curvilinear pathways during opening and closing were 14 and 14.6 mm, respectively. Ranges of condylar movement varied widely between individuals. The straight-line distances and curvilinear pathways were highly correlated for the incisors (R=0.98) and the condyles (R=0.98). Neither the straight-line distances nor curvilinear pathways of the incisors were correlated with those of the condyles. Incisor straight-line distances and curvilinear pathways were moderately correlated with mandibular rotation (R(between subjects)=0.82 and R(between repeats)=0.88). During repeated openings, both condylar and incisor excursions increased, but during repeated closings only incisor excursions increased. It is concluded that (1) maximum incisor opening does not provide reliable information about condylar translation and its use as a diagnostic indicator of condylar movement should be limited, (2) healthy individuals may perform normal opening with highly variable amounts of condylar translation, (3) the straight-line distances of the incisor and condyles provide adequate information about the length of the curvilinear pathway, and (4) variation in maximum incisor opening is largely explained by variation in the amount of mandibular rotation.

Masticatory muscle function in patients with spinal muscular atrophy

The purpose of this study was to determine whether spinal muscular atrophy affects masticatory muscle strength and mandibular range of motion. A sample of 15 subjects with spinal muscular atrophy was compared to a sample of age-matched and sex-matched controls. Maximum bite force, masticatory muscle electromyography activity, mandibular ranges of motion and masticatory muscle endurance were evaluated. Results showed that maximum bite forces were one-half as great for the sample with spinal muscular atrophy than for the controls, even though their EMG activity was not significantly different. Slopes of the relationship between electromyography activity and bite force were two to four times steeper for patients with spinal muscular atrophy than controls. Maximum opening and protrusion were reduced to approximately one-half control values. Fatigue times of patients with spinal muscular atrophy were reduced by 30% (17.9 seconds versus 11.1 seconds). We conclude that the masticatory muscles of patients with spinal muscular atrophy are weakened, that their muscles are less efficient, and that they fatigue more quickly than controls. In addition, mandibular movements of these patients take place over a more limited range than unaffected controls.

Occlusal conditions just after the relief of temporomandibular joint clicking

When the signs and symptoms of temporomandibular joint disorders (TMD) are present, the possibility that occlusal position and mandibular movements are changed is considerable. Accordingly, the presence of occlusal interferences may be misjudged. It is therefore reasonable to consider that occlusal conditions should be examined just after the relief of symptoms. A comparison of occlusal condition in 45 patients with eminence clicking with a group of 60 asymptomatic controls was made. An occlusal examination was administered to the patient group just after the relief of clicking using bite plane therapy alone. The number of occlusal teeth in ICP (intercuspal position) for the patient group was significantly lower than for the controls, and the frequency of no contact of canines on the working side in the patient group was higher than that in the control group. This suggested that in order to avoid the recurrence of eminence clicking, efforts should be made to raise the number of contact teeth in ICP and to make canines on the working side come into contact.

The prevalence of cardinal TMJ dysfunction symptoms and its relationship to occlusal factors in Japanese female adolescents

Cross-sectional data were obtained from 1182 Japanese high school girls of 12 and 15 years old. The data were analysed for the prevalence of specific occlusal features and the prevalence of cardinal Temporomandibular Joint Dysfunction (TMJD) symptoms in different occlusion groups. The associations between occlusal features and TMJD symptoms were analysed by the Z-analysis. The results were as follows: the prevalence of TMJD symptoms (total) was about 23% in both age groups examined. Noise had the highest prevalence of the specific TMJD symptoms in both age groups (16% and 11%). With age and for different occlusion groups, there was a significant increase in deviation on opening (P < 0.001) and a decrease in pain and noise (P < 0.05). No significant associations were found between the occurrence of TMJD symptoms (total) and occlusal features in all the examined occlusion groups. With respect to specific TMJD symptoms, however, the investigation of the different groups revealed a significant association (P < 0.05) of intra-arch occlusal (crowding) features with the occurrence of deviation on opening and with the occurrence of the combined TMJD symptoms which include deviation on opening. This indicates that crowding may be an important sign for predisposing TMJD. For the other single disorder symptoms (except pain), we did not find a significant relationship (P < 0.05) with aspects of occlusion, which may confirm a multifactorial TMJD problem wherein occlusal features can have a contribution to TMJD.

[Maxillofacial functions and dysfunctions. 1. Their clinical significance in orthodontics]

Predicting the course of treatment for the individual case on the basis of traditional, morphological diagnostic records only, is at best uncertain. Current literature and clinical observations indicate that genetics and the individual's potential of adapting oro-facial functions to morphological changes play a crucial role. The problem of predictability obviously is multifactorial, and should be studied accordingly. In part 1 of this study, based on conventional documentation of two treated cases, the inadequacy of traditional diagnostic documentation limited to morphology and the subsequent uncertainty of predictions based thereon are demonstrated and discussed.

Mandibular elevator muscles: physiology, action, and effect of dental occlusion

In spite of differences in embryologic origin, central nervous organization, and muscle fiber distribution, the physiology and action of mandibular elevator muscles are comparable to those of skeletal muscles of the limbs, back, and shoulder. They also share the same age-, sex-, and activity-related variations of muscular strength. With respect to pathogenesis, the type of muscular performance associated with the development of fatigue, discomfort, and pain in mandibular elevators seems to be influenced by the dental occlusion. Clinical research comparing the extent of occlusal contact in patients and controls as well as epidemiologic studies have shown reduced occlusal support to be a risk factor in the development of craniomandibular disorders. In healthy subjects with full natural dentition, occlusal support in the intercuspal position generally amounts to 12-14 pairs of contacting teeth, with predominance of contact on first and second molars. The extent of occlusal contact clearly affects electric muscle activity, bite force, jaw movements, and masticatory efficiency. Neurophysiologic evidence of receptor activity and reflex interaction with the basic motor programs of craniomandibular muscles tends to indicate that the peripheral occlusal control of the elevator muscles is provided by feedback from periodontal pressoreceptors. With stable intercuspal support, especially from posterior teeth, elevator muscles are activated strongly during biting and chewing with a high degree of force and masticatory efficiency, and with relatively short contractions, allowing for pauses. These variables of muscle contraction seem, in general, to strengthen the muscles and prevent discomfort. Therefore, occlusal stability keeps the muscles fit, and enables the masticatory system to meet its functional demands.

Craniomandibular disorders and masticatory muscle function

The heading craniomandibular disorders covers a wide range of abnormal and pathologic conditions accompanied by orofacial pain and impaired mandibular function, the masticatory muscles and the temporomandibular joints being the structures most frequently involved. Prevalences of severe craniomandibular disorders accompanied by headache and facial pain urgently in need of treatment are 1-2% in children, about 5% in adolescents, and 5-15% in adults, with higher values in women than in men. With respect to physiology and ergonomics, masticatory muscles are comparable to other human skeletal muscles, e.g. of shoulder, neck and lower back. Therefore these muscles share pathogenesis, symptoms and signs of muscular disorders caused by prolonged, low-level static contractions or intermittent isometric contractions at higher levels. Since the same elements of performance in the masticatory muscles are influenced by occlusal factors, they link the development of muscular fatigue, discomfort and pain to the dental occlusion. Furthermore, changes of the occlusal surfaces, e.g. due to dental treatment, may influence the performance of the masticatory muscles, and consequently interfere with local muscular function.

Differences in need for orthodontic treatment between Native Americans and the general population based on DAI scores

Clinical impressions by Indian Health Service (IHS) dentists of a greater frequency of severe dental malrelations among Native Americans than in the general US population have never been objectively confirmed. This study uses the DAI as the standard to determine whether there is a greater prevalence of severe malocclusions among Native Americans. Four hundred eighty-five Native American students in grades 7-12 from two remote sites--Pine Ridge, SD, and Many Farms, AZ--and one nonremote site--Lapwai, ID--were scored for the DAI. The mean scores from each reservation, as well as the mean score from the three reservations combined, were significantly higher, indicating poorer aesthetics, than the mean DAI score from a large sample of the general US population. These data confirm the clinical impressions of IHS dentists that Native Americans residing on reservations have significantly poorer dental aesthetics than the aesthetics found in the general US population; therefore, Native Americans have greater needs for orthodontic treatment.

Etiologic theory and the prevention of temporomandibular disorders

Over the last 75 years, a variety of etiologic factors has been suggested as the cause of pain and dysfunction in the temporomandibular system. The earliest and still-popular etiologic theory proposed that temporomandibular disorders are induced by abnormal structure, usually described as a malocclusion of the teeth or jaws. The fact that this theory was based on mechanical concepts, ignored biologic diversity, and had limited factual experimental evidence to support it as well as extensive evidence in opposition did not seem to matter to its proponents. In the late 1960's and early 1970's, the structural occlusal model for TM Disorders was challenged and has yielded ground to a more multifactorial model of TMD causation. Other etiologic factors for TM disorders--such as anatomical susceptibility of TM tissues to trauma, polyarthritic diseases, joint laxity, repetitive parafunctional behaviors, and stress-related muscle dysfunction--need to be recognized and quantified. Unfortunately, many practicing dentists demonstrate a very poor understanding of and often fail to recognize these etiologic factors as agents that produce TM disorders. This failure is largely due to the fact that the dental profession has spent the last 90 years dealing with a variety of misconceptions about the etiology of temporomandibular disorders. In the 1990's, one of the more formidable challenges we face is acquiring the ability to segregate and define validly the specific TM Disorder of concern and then correctly identify and measure the specific etiologic factors that produce it. Until these problems are solved, it is unlikely that we will be able to prevent disease of the TM apparatus.

Eminence-posterior occlusal plane angle in patients with temporomandibular disorders

The causes of temporomandibular disorder are not clearly understood. The controversy regarding the role of the features, either dental or skeletal, still exists after nearly a half century of debate. The present study demonstrates an interesting correlation, expressed as an angular value, between the posterior surface of the articular eminence and the posterior occlusal plane. The group with dysfunction had a mean value significantly lower (133 +/- 4) than the group without symptoms (144 +/- 5). In light of this data, it is suggested to interpret a small eminence-posterior occlusal plane as an anatomical predisposing pattern for dysfunction.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The growth in the dental literature continues to escalate, as evidenced by the publication of at least 326 new books in 1988 and 1989 and more than 20 new journals in 1989. There still appears to be undue emphasis on quantity instead of quality of research. This proliferation in the literature poses ever increasing difficulties to this Committee in filtering out the articles that are of particular interest to the members of the Academy and identifying those that are most likely to have a major impact on dental practice and service. The subjects covered include periodontics, caries and preventive dentistry, craniomandibular disorders, occlusion, pulp biology, ceramics, and restorative dental materials.

A dynamic model of etiology in temporomandibular disorders

A dynamic model is proposed to depict the etiology of temporomandibular disorders. A balance is described between destructive factors in the masticatory system that result in dysfunction, and adaptive factors that tend to return it homeostatically to normal. Five factors that cause or potentiate muscle hyperfunction are included on one side of the model with five other factors that affect the ability of the system to adapt on the other side. Relationships among the etiologic factors are discussed, and literature support for each is cited.