Research diagnostic criteria for temporomandibular disorders: a systematic review of axis I epidemiologic findings

The contribution of computerized axiography to the functional evaluation of the temporomandibular joint: a case report

The aim of this case report is to give comprehensive information on the clinical use of computerized axiography (CA) in the evaluation of temporomandibular joint (TMJ) mobility in a patient who undergoes orthognatic surgery. A 20-year-old female patient with class III skeletal anomaly and who underwent orthognatic surgery is presented. Pre- and postsurgical CA recordings for the patient are compared in order to evaluate the functional modifications that appear. The CA is a functional investigation of the TMJ and records the border movements of the mandible: protrusion, lateral movements and open/close. The starting point for every movement is the centric relation position. This allows for very high reproducibility of the CA and the data can later become available for comparison of examinations performed at different times. The CA can offer data to programme an articulator or to evaluate the functional evolution of the TMJs after various occlusal interventions (prosthodontic, orthodontic or orthognatic). After comparing the pre- and postsurgical CA recordings, a significant improvement of the TMJ function after the repositioning of the maxilla and mandible through orthognatic surgery was confirmed. In conclusion, our case confirms the results in literature that CA is a reproducible and reliable investigation method in the evaluation of TMJ function in orthognatic surgery patients, that it facilitates the monitoring of the evolution of the functionality of the TMJ ever time and that it allows for comparative evaluation of the two TMJs.

Clinical effects of an avocado-soybean unsaponifiable extract on arthralgia and osteoarthritis of the temporomandibular joint: preliminary study

The aim of the present preliminary study was to investigate the effectiveness of an avocado-soybean unsaponifiable extract (ASU) in patients with arthralgia and osteoarthritis of the temporomandibular joint (TMJ). A randomized, double-blind, placebo-controlled trial was carried out. Fourteen women diagnosed with arthralgia and osteoarthritis of the TMJ using the Research Diagnostic Criteria for Temporomandibular Disorders were included in the statistical analysis. The women were allocated randomly to two groups: ASU group and placebo group. Pain was measured using a visual analogue scale and pressure algometer. Mandibular function was evaluated through measurement of mandibular movements. Quality of life was measured using the Oral Health Impact Profile (OHIP-14). The medication (ASU capsules or placebo capsules) was used for 4 months and the total follow-up was 6 months. Those taking the ASU extract had a decrease in pain symptoms and an improvement in quality of life. Moreover, a significant reduction in the use of rescue medication was found in the ASU group compared to the placebo group. This preliminary study provides strong evidence of the effectiveness of an avocado-soybean unsaponifiable extract in patients with degenerative joint diseases and arthralgia in the TMJ. Further studies with larger samples should be performed.

Comparison of three different options for immediate treatment of painful temporomandibular disorders: a randomized, controlled pilot trial

OBJECTIVE

The purpose of this study was to compare the short-term effectiveness of three different types of immediate, non-pharmacological intervention for alleviation of the painful symptoms of temporomandibular disorders (TMD).

MATERIAL AND METHODS

Thirty-six patients (mean age 41.6 ± 16.7 years, 25 females) diagnosed with non-dysfunctional painful TMD received counselling and subsequently were randomly allocated to three treatment groups: patients in Group A received prefabricated oral splints with water-filled elastic pads (Aqualizer(®)), those in Group B were provided with vacuum-formed co-polyester oral splints and those in Group C were given appointments to receive Michigan-type hard splints. Clinical examination was conducted, at baseline and after 2 weeks, by use of the RDC/TMD. Current pain intensity was determined by evaluation of graded chronic pain status (GCPS) on a numerical rating scale (NRS). Active maximum mouth opening without pain (AMMOP) was also measured. Paired sample t-tests and one-way analysis of variance with a significance level of p ≤ 0.05 were conducted.

RESULTS

After 2 weeks, overall mean current pain was reduced by 41.95% (p < 0.001). Current pain reduction was significant for Group B (66.6%, p < 0.001) but not for Groups A (37.88%, p = 0.56) and C (22.29%, p = 0.26). After 2 weeks, current pain level for Group B was significantly lower than that for Group C (p = 0.041). Overall, there was a statistically significant increase of AMMOP (p = 0.01).

CONCLUSION

All therapeutic options were pain-reducing. The results from this study suggest that cost-effective and time-effective intervention of counselling combined with use of a vacuum-formed splint is a favourable option for initial, short-term treatment of painful TMD.

Evaluation of condylar positions in patients with temporomandibular disorders: A cone-beam computed tomographic study

Purpose

This study was performed to compare the condylar position in patients with temporomandibular joint disorders (TMDs) and a normal group by using cone-beam computed tomography (CBCT).

Materials and Methods

In the TMD group, 25 patients (5 men and 20 women) were randomly selected among the ones suffering from TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD). The control group consisted of 25 patients (8 men and 17 women) with normal temporomandibular joints (TMJs) who were referred to the radiology department in order to undergo CBCT scanning for implant treatment in the posterior maxilla. Linear measurements from the superior, anterior, and posterior joint spaces between the condyle and glenoid fossa were made through defined landmarks in the sagittal view. The inclination of articular eminence was also determined.

Results

The mean anterior joint space was 2.3 mm in the normal group and 2.8 mm in the TMD group, respectively. The results showed that there was a significant correlation between the superior and posterior joint spaces in both the normal and TMD groups, but it was only in the TMD group that the correlation coefficient among the dimensions of anterior and superior spaces was significant. There was a significant correlation between the inclination of articular eminence and the size of the superior and posterior spaces in the normal group.

Conclusion

The average dimension of the anterior joint space was different between the two groups. CBCT could be considered a useful diagnostic imaging modality for TMD patients.

Effect of Toll-Like Receptor 4 on Synovial Injury of Temporomandibular Joint in Rats Caused by Occlusal Interference

Synovitis is an important disease that causes intractable pain in TMJ. Some investigations suggested that the increasing expression of IL-1β secreted by synovial lining cells plays an important role in synovial inflammation and cartilage destruction in TMJ. In our previous research, the results demonstrated that TLR4 is involved in the expression of IL-1β in SFs from TMJ with lipopolysaccharide stimulation. However, the inflammatory response that occurred in synovial membrane is not caused by bacterial infection. In the current study, we investigated whether or not TLR4 participates in the inflammatory responses and the expression of IL-1β in synovial membrane of rats induced by occlusal interference. The results showed that obvious inflammation changes were observed in the synovial membranes and the expression of TLR4 and IL-1β was increased at both mRNA and protein levels in the occlusal interference rats. In addition, the inflammation reactions and the increased expression of IL-1β could be restrained by treatment with TAK-242, a blocker of TLR4 signaling. The results prompted us that the activation of TLR4 may be involved in the inflammatory reactions and increased expression of IL-1β in patients with synovitis and participate in the mechanisms of the initiation and development of synovial injury by regulating the expression of inflammatory mediators like IL-1β in synovial membranes.

Assessment of masticatory performance by means of a color-changeable chewing gum

PURPOSE

Previous research determined the relevance of masticatory performance with regard to nutritional status, cognitive functions, or stress management. In addition, the measurement of masticatory efficiency contributes to the evaluation of therapeutic successes within the stomatognathic system. However, the question remains unanswered as to what extent modern techniques are able to reproduce the subtle differences in masticatory efficiency within various patient groups. The purpose of this review is to provide an extensive summary of the evaluation of masticatory performance by means of a color-changeable chewing gum with regard to its clinical relevance and applicability.

STUDY SELECTION

A general overview describing the various methods available for this task has already been published. This review focuses in depth on the research findings available on the technique of measuring masticatory performance by means of color-changeable chewing gum. Described are the mechanism and the differentiability of the color change and methods to evaluate the color changes. Subsequently, research on masticatory performance is conducted with regard to patient age groups, the impact of general diseases and the effect of prosthetic and surgical treatment.

RESULTS

The studies indicate that color-changeable chewing gum is a valid and reliable method for the evaluation of masticatory function.

CONCLUSION

Apart from other methods, in clinical practice this technique can enhance dental diagnostics as well as the assessment of therapy outcomes.

Prevalence of diagnosed temporomandibular disorders among Saudi Arabian children and adolescents

Background

Studies have indicated that the prevalence of symptoms and signs of temporomandibular disorders (TMD) are rare early in childhood, but become more prevalent in adolescents and adulthood. To our knowledge, no study has investigated the prevalence of TMD-diagnoses in children in the general population. The aim was thus to investigate the prevalence of TMD-diagnoses among children and adolescents in the general population using the Research Diagnostic Criteria for TMD (RDC/TMD).

Methods

The current cross-sectional study consisted of 456 children and adolescents, aged between 10 and 18, randomly enrolled from 10 boy’s- and 10 girl’s- schools in Jeddah. The participants first answered two validated questions about TMD-pain, followed by a clinical examination according to RDC/TMD.

Results

One hundred twenty-four participants (27.2 %) were diagnosed with at least one TMD-diagnosis. Myofascial pain was the most common diagnosis (15 %) followed by disc displacement with reduction, arthralgia, myofascial pain with limited mouth opening and osteoarthrosis. Children diagnosed with myofascial pain more often reported orofacial pain, headache and tooth clenching (p < 0.05), whereas children with arthralgia more often reported orofacial pain and tooth grinding than those without a TMD-diagnosis (p < 0.05). Only 18 % of the subjects in the TMD group had sought a dentist or physician for their pain.

Conclusion

TMD was common among children and adolescents in Saudi Arabia. Self-reported orofacial pain and headache as well as bruxism were associated with a TMD-pain diagnosis and disc displacement. A surprisingly low percentage of children and adolescents sought treatment by a dentist or physician for their pains.

Upregulation of lncRNA HOTAIR contributes to IL-1β-induced MMP overexpression and chondrocytes apoptosis in temporomandibular joint osteoarthritis

Temporomandibular joint osteoarthritis (TMJ OA) is a common and heterogeneous disease that causes painful and progressive joint degeneration, which restricts daily activities, including talking and chewing. Long noncoding RNAs (lncRNAs) are an important class of genes involved in various physiological and pathological functions, including osteoarthritis (OA).The present study aimed to identify the lncRNAs that are important in TMJ OA and their potential functions. Here, we found that HOTAIR was significantly upregulated in the synovial fluid of TMJ OA patients compared with that of normal controls. Increased HOTAIR was similarly observed in the synovial fluid of TMJ OA rabbits as compared to control rabbits. Furthermore, in interleukin-1β (IL-1β)-induced TMJ OA in vitro model (primary rabbit condylar chondrocytes), the expressions of matrix metalloproteinase (MMP)-1, MMP3, MMP9 and HOTAIR were all dramatically increased. Most importantly, knockdown of HOTAIR in IL-1β-induced TMJ OA in vitro model could not only reverse the IL-1β-stimulated expressions of MMP1, MMP3 and MMP9, but also significantly decrease the apoptosis rate induced by IL-1β in primary rabbit condylar chondrocytes. Our data provides new insight into the mechanisms of chondrocytes destruction in TMJ OA.

Open-Mouth Bone Scintigraphy Is Better than Closed-Mouth Bone Scintigraphy in the Diagnosis of Temporomandibular Osteoarthritis

PURPOSE

Closed-mouth bone scintigraphy (CM scan) and closed-mouth single-photon emission computed tomography (CM SPECT) are used for conventional evaluation of osteoarthritis of the temporomandibular joint (TMJ). However, the adequacy of open-mouth bone scintigraphy (OM scan) has not yet been evaluated. Therefore, the purpose of this study was to compare the diagnostic performance of CM scan, CM SPECT, and OM scan.

METHODS

Thirty-six patients with suspicion of an abnormality of the TMJ and who underwent a (99m)Tc-HDP CM scan, CM SPECT, and an OM scan were enrolled. The scans were assessed visually for the presence of positive focal uptake in the TMJ. Osteoarthritis was defined as arthralgia plus crepitus or radiologic signs of arthrosis.

RESULTS

Of 72 TMJs, 21 (29.2 %) were diagnosed with osteoarthritis. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 90.5 %, 49.0 %, 42.2 %, 92.6 % and 61.1 % for the CM scan, 81.0 %, 58.8 %, 44.7 %, 88.2 % and 65.3 % for CM SPECT, and 81.0 %, 82.4 %, 65.4 %, 91.3 % and 81.9 % for the OM scan, respectively. The accuracy of the OM scan was higher than that of CM SPECT and the CM scans (p = 0.004 and p < 0.001, respectively).

CONCLUSIONS

The OM scan was more accurate than the conventional CM scan and even CM SPECT for diagnosing TMJ osteoarthritis.

Prevalence of the different Axis I clinical subtypes in a sample of patients with orofacial pain and temporomandibular disorders in the Andalusian Healthcare Service

Background

The main objective of this paper is to analyze the prevalence of each of the different clinical subtypes of temporomandibular disorders (TMD) in a sample of patients with this pathology. In addition, a second objective was to analyze their distribution according to gender.

Material and Methods

To this end, the results of 1603 patients who went to the Unit of Temporomandibular Disorders in the Córdoba Healthcare District because they suffered from this pathology were analyzed. In order to diagnose them, the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) were applied, analyzing the different Axis I subtypes (myopathy, discopathy and arthropathy) and obtaining the combined Axis I for each patient and the relation of all these variables according to gender. The null-hypothesis test confirmed the lack of connection between the gender variable and the different subtypes in the clinical analysis, and between the former and the combined Axis I of the RDC/TMD.

Results

The prevalence was high for the muscle disorders subtype in general, showing an 88.7% prevalence, while the presence of discopathies or arthropathies was much lower. Among discopathies, the most frequent ones were disc displacements with reduction, with 39.7% and 42.8% for the left and right temporomandibular joints (TMJ), respectively, while the prevalence of arthropathies was 26.3% for the right TMJ and 32.9% for the left TMJ. The bivariate analysis on the connection with gender reveals a p≥ 0.05 value for the muscle and arthralgia subtypes.

Conclusions

The patients seen at the TMD Unit where mostly middle-aged women whose main clinical axis subtype was the muscle disorder subtype. For their part, both discopathies and arthropathies, although present, are much less prevalent.

Key words:RDCTMD, axis I, orofacial pain, temporomandibular disorders, gender.

What rheumatologists should know about orofacial manifestations of autoimmune rheumatic diseases

Orofacial manifestations occur frequently in rheumatic diseases and usually represent early signs of disease or of its activity that are still neglected in clinical practice. Among the autoimmune rheumatic diseases with potential for oral manifestations, rheumatoid arthritis (RA), inflammatory myopathies (IM), systemic sclerosis (SSc), systemic lupus erythematosus (SLE), relapsing polychondritis (RP) and Sjögren's syndrome (SS) can be cited. Signs and symptoms such as oral hyposalivation, xerostomia, temporomandibular joint disorders, lesions of the oral mucosa, periodontal disease, dysphagia, and dysphonia may be the first expression of these rheumatic diseases. This article reviews the main orofacial manifestations of rheumatic diseases that may be of interest to the rheumatologist for diagnosis and monitoring of autoimmune rheumatic diseases.

Comparison of a 32-channel head coil and a 2-channel surface coil for MR imaging of the temporomandibular joint at 3.0 T

OBJECTIVE

To quantitatively and qualitatively compare MRI of the temporomandibular joint (TMJ) using a standard TMJ surface coil and a head coil at 3.0 T.

METHODS

22 asymptomatic volunteers were MR imaged using a 2-channel surface coil (standard TMJ coil) and a 32-channel head coil at 3.0 T (Philips Ingenia; Philips Healthcare, Netherlands). Imaging protocol consisted of an oblique sagittal proton density weighted turbo spin echo sequence (repetition time/echo time, 2700/26 ms). For quantitative assessment, a spherical phantom was imaged using the same sequence including a noise scan and a B1+ scan. Signal-to-noise ratio (SNR) maps and B1+ maps were calculated on a voxelwise basis. For qualitative evaluation, all volunteers underwent MRI of both TMJs with the jaw in the closed position. Two independent blinded readers assessed accuracy of TMJ anatomical representation and overall image quality on a 5-point scale. Quantitative and qualitative measurements were compared between coils using t-tests and Wilcoxon signed-rank test, respectively.

RESULTS

Quantitative analysis showed similar B1+ and significantly higher SNR for the head coil than the TMJ surface coil. Qualitative analysis showed significantly better visibility and delineation of clinically relevant anatomical structures of the TMJ, including the articular disc, bilaminar zone and lateral pterygoid muscle. Furthermore, better overall image quality was observed for the head coil than for the TMJ surface coil.

CONCLUSIONS

A 32-channel head coil is preferable to a standard 2-channel TMJ surface coil when imaging the TMJ at 3.0 T, because it yields higher SNR, thus increasing accuracy of the anatomical representation of the TMJ.

Aspectos clínicos e psicossociais avaliados por critérios de diagnóstico para disfunção temporomandibular

RESUMO Objetivo: analisar a associação entre a classificação de diagnósticos clínicos (dor miofascial, desordem discal e articular) e a graduação de dor crônica, depressão e sintomas físicos não específicos em sujeitos com disfunção temporomandibular. Métodos: foram incluídos 32 pacientes, com média de idade de 28,71±4,66 anos. Como instrumento de avaliação, foi utilizado o Critério de Diagnóstico para Pesquisa das Desordens Temporomandibulares - Eixo I e II. Quanto ao grupo diagnóstico, 88,13% dos indivíduos apresentaram diagnóstico misto, sendo 43,75% dos grupos I e III (distúrbios musculares e articulares) e 34,38% dos grupos I, II e III (distúrbios musculares, articulares e deslocamento de disco). Resultados: de acordo com o eixo II, 96,88% dos participantes foram classificados com dor crônica grau I e II (baixa incapacidade e baixa intensidade; baixa incapacidade e alta intensidade). Graus moderado e grave de depressão foram observados em 84,38% dos participantes. Na avaliação de sintomas físicos não específicos incluindo e excluindo dor, respectivamente, 59,38% apresentaram sintomas severos e 71,88% apresentaram sintomas moderados e severos. Verificou-se relação significante dos diagnósticos clínicos de disfunção temporomandibular com o grau de sintomas físicos não específicos incluindo dor. Conclusão: alguns aspectos clínicos e psicossociais estão associados em pacientes com disfunção temporomandibular, observando uma multiplicidade de diagnósticos clínicos com a presença de uma relação significante entre os diagnósticos clínicos encontrados e a presença de sintomas físicos inespecíficos com dor. Queixa de maior gravidade de sintomas físicos foi encontrada em pacientes com diagnóstico clínico múltiplo.

Low Level Laser Therapy Versus Pharmacotherapy in Improving Myofascial Pain Disorder Syndrome

INTRODUCTION

Temporomandibular disorders (TMD) lead to masticatory muscle pain, jaw movement disability and limitation in mouth opening. Pain is the chief complaint in 90% of the TMD patients which leads to disability and severe socioeconomic costs. The purpose of this study was to evaluate the therapeutic effects of low level laser therapy (LLLT) compared to pharmacotherapy with NSAIDs (naproxen) in myofascial pain disorder syndrome (MPDS).

METHODS

In this randomized controlled clinical trial, 40 MPDS patients were divided into two groups. One group received naproxen 500 mg bid for 3 weeks as treatment modality and also had placebo laser sessions. The other group received active laser (diode 810 nm CW) as treatment and placebo drug. Pain intensity was measured by visual analogue scale (VAS) and maximum painless mouth opening was also measured as a functional index every session and at 2 months follow up. Data was collected and analyzed with SPSS software. Independent t test was used to analyze the data. A P < 0.05 was considered significant.

RESULTS

Low level laser caused significant reduction in pain intensity (P < 0.05) and a significant increase in mouth opening. In naproxen group neither pain intensity nor maximum mouth opening had significant improvement. Pain relief, in subjective VAS was observed in third session in LLLT group, but did not occur in naproxen group. Maximum mouth opening increased significantly in laser group compared to the naproxen group from the eighth session.

CONCLUSION

Treatment with LLLT caused a significant improvement in mouth opening and pain intensity in patients with MPDS. Similar improvement was not observed in naproxen group.

Effects of Massage Therapy and Occlusal Splint Usage on Quality of Life and Pain in Individuals with Sleep Bruxism: A Randomized Controlled Trial

PURPOSE

The aim of the present study was to investigate the effects of massage therapy on the masticatory muscles and occlusal splint usage on quality of life and pain in individuals with sleep bruxism.

METHOD

A randomized, controlled, blinded, clinical trial was conducted involving 78 volunteers aged 18 to 40 years with sleep bruxism. Quality of life and pain assessments were performed.

RESULTS

Significant differences (p < 0.05) were found on the physical functioning, general health state, vitality, role emotional and mental health subscales. A large effect size was found for all treatment protocols with regard to pain. The largest effect was found in the combined treatment group.

CONCLUSIONS

The findings of the present study reveal that the occlusal splint usage alone led to improvements in components of quality of life among individuals with sleep bruxism. Moreover, both treatments (occlusal splint usage and massage therapy on the masticatory muscles) led to a reduction in pain.

Association between estrogen levels and temporomandibular disorders: a systematic literature review

Introduction

To evaluate whether the hypothesis that estrogen levels are associated with temporomandibular disorders (TMD) in humans can be confirmed or contradicted by available literature.

Material and methods

A systematic review based on the content of PubMed, Scopus, and Cochrane Library databases was performed. Studies were identified using a combination of key words ‘temporomandibular disorder’ and ‘estrogen’. Nine studies were included into our review.

Results

The relationship between estrogen levels and TMD was found in seven out of nine reviewed papers. Results from two papers suggest that a high estrogen level is associated with an increased prevalence of TMD. Five additional papers found a relationship between a low estrogen level and an increase in TMD pain. In considering the value of evidence and inconsistencies of results in the reviewed publications, we state that there is weak evidence to support the hypothesis that estrogen levels are associated with TMD.

Conclusions

Results of reviewed studies were divergent and sometimes contradictory. One possible explanation is that estrogen influences TMD pain processing differently than temporomandibular joints (TMJ) structures, as shown in many animal studies. Estrogen may influence TMD pain processing differently than TMJ structures. We suggest consideration of the dual action of estrogen when planning future studies on its association with TMD.

The Prevalence of TMD in Polish Young Adults

PURPOSE

The prevalence of temporomandibular disorders (TMD) in the general Polish population has not yet been thoroughly investigated. The aim of this study was to determine how frequently Polish young adults demonstrated the signs and symptoms of TMD, and how often they were aware of these.

MATERIALS AND METHODS

The study involved 260 volunteers of approximately 18 years of age (and with an F:M ratio of 2.8), who had completed the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) questionnaire in its internationally accepted Polish version. The volunteers were students from three randomly selected high schools in Kraków, Poland. Following the clinical examinations, all participants received none or one or more of the RDC/TMD axis I diagnoses on one or both sides: muscle disorders (group I), disk displacements (group II), arthralgia, osteoarthritis, and osteoarthrosis (group III). Classification on RDC/TMD axis II involved pain-related impairment (Graded Chronic Pain Severity, from 0: no TMD pain in the prior 6 months, to IV: high disability-severely limiting), depression, and somatization levels (normal, moderate, severe).

RESULTS

On the RDC/TMD axis I, 69 (26.5%) of the participants received one or more of the possible diagnoses. Awareness of TMD was present in 20 (7.7%) people from that group, in the form of self-complaints. The difference between females and males was statistically significant (p  = 0.0013). On the RDC/TMD axis II assessment, a diagnosis of pain, depression, or somatization was given in 38 (14.6%) cases from that group.

CONCLUSION

Muscle disorders were most frequently diagnosed in the group of Polish young adults, and the prevalence of the disease did not differ across similar groups of young people.

Quantitative and qualitative comparison of MR imaging of the temporomandibular joint at 1.5 and 3.0 T using an optimized high-resolution protocol

OBJECTIVES

To quantitatively and qualitatively compare MRI of the temporomandibular joint (TMJ) using an optimized high-resolution protocol at 3.0 T and a clinical standard protocol at 1.5 T.

METHODS

A phantom and 12 asymptomatic volunteers were MR imaged using a 2-channel surface coil (standard TMJ coil) at 1.5 and 3.0 T (Philips Achieva and Philips Ingenia, respectively; Philips Healthcare, Best, Netherlands). Imaging protocol consisted of coronal and oblique sagittal proton density-weighted turbo spin echo sequences. For quantitative evaluation, a spherical phantom was imaged. Signal-to-noise ratio (SNR) maps were calculated on a voxelwise basis. For qualitative evaluation, all volunteers underwent MRI of the TMJ with the jaw in closed position. Two readers independently assessed visibility and delineation of anatomical structures of the TMJ and overall image quality on a 5-point Likert scale. Quantitative and qualitative measurements were compared between field strengths.

RESULTS

The quantitative analysis showed similar SNR for the high-resolution protocol at 3.0 T compared with the clinical protocol at 1.5 T. The qualitative analysis showed significantly better visibility and delineation of clinically relevant anatomical structures of the TMJ, including the TMJ disc and pterygoid muscle as well as better overall image quality at 3.0 T than at 1.5 T.

CONCLUSIONS

The presented results indicate that expected gains in SNR at 3.0 T can be used to increase the spatial resolution when imaging the TMJ, which translates into increased visibility and delineation of anatomical structures of the TMJ. Therefore, imaging at 3.0 T should be preferred over 1.5 T for imaging the TMJ.

Correlation Between Clinical Findings of Temporomandibular Disorders and MRI Characteristics of Disc Displacement

Objectives : Temporomandibular joint (TMJ) dysfunction is a common condition that is best evaluated with magnetic resonance (MR) imaging. The first step in MR imaging of the TMJ is to evaluate the articular disk, or meniscus, in terms of its morphologic features and its location relative to the condyle in both closed- and open-mouth positions. Disk location is of prime importance because the presence of a displaced disk is a critical sign of TMJ dysfunction. However, disk displacement is also frequently seen in asymptomatic volunteers. It is important for the maxillofacial radiologist to detect early MR imaging signs of dysfunction, thereby avoiding the evolution of this condition to its advanced and irreversible phase which is characterized by osteoarthritic changes such as condylar flattening or osteophytes. Further the MR imaging techniques will allow a better understanding of the sources of TMJ pain and of any discrepancy between imaging findings and patient symptoms. Henceforth, the aim of the study was to evaluate whether MRI findings of various degrees of disk displacement could be correlated with the presence or absence of clinical signs and symptoms of temporomandibular disorders in symptomatic and asymptomatic subjects. Materials and Methods : In this clinical study, 44 patients (88 TMJs) were examined clinically and divided into two groups. Group 1 consisted of 22 patients with clinical signs and symptoms of TMDs either unilaterally or bilaterally and considered as study group. Group 2 consisted of 22 patients with no signs and symptoms of TMDs and considered as control group. MRI was done for both the TMJs of each patient. Displacement of the posterior band of articular disc in relation to the condyle was quantified as anterior disc displacement with reduction (ADDR), anterior disc displacement without reduction (ADDWR), posterior disc displacement (PDD). Results : Disk displacement was found in 18 (81.8%) patients of 22 symptomatic subjects in Group 1 on MRI and 4 (18.1%) were diagnosed normal with no disc displacement. In Group 2, 2 (9.1%) of 22 asymptomatic patients were diagnosed with disc displacement while 20 (90.1%) were normal. Sensitivity and Specificity tests were applied in both the groups to correlate clinical findings of TMD and MRI characterstics of disc displacement and results showed Sensitivity of 90% and Specificity of 83.3%. Conclusion : Disk displacement on MRI correlated well with presence or absence of clinical signs and symptoms of temporomandibular disorders with high Sensitivity and Specificity of 90% and 83.3% respectively.

Early magnetic resonance imaging control after temporomandibular joint arthrocentesis

Temporomandibular joint (TMJ) lysis and lavage arthrocentesis with viscosupplementation are an effective treatment for acute disc displacement (DD) without reduction. Clinical success seems to be related to multiple factors despite the lack of understanding of its mechanisms. The authors present a case report of 17-year-old women with acute open mouth limitation (12 mm), right TMJ pain-8/10 visual analog scale, right deviation when opening her mouth. The clinical and magnetic resonance imaging (MRI) diagnosis was acute DD without reduction of right TMJ. Right TMJ arthrocentesis was purposed to the patient with lysis, lavage, and viscosupplementation of the upper joint space. After 5 days, a new MRI was performed to confirm upper joint space distension and disc position. Clinical improvement was obtained 5 days and 1 month after arthrocentesis. Upper joint space increased 6 mm and the disc remained displaced. We report the first early TMJ MRI image postoperative, with measurable upper joint space.

Botulinum toxin in the treatment of muscle specific Oro-facial pain: a literature review

Facial pain associated with temporomandibular joint (TMJ) and surrounding structures has been a challenge to clinicians as far as diagnosis and management is concerned. Complexity of anatomical structures within a small area, function of teeth and surrounding periodontal ligament, action of muscles, pathologies, lack of diagnostic investigations, all these complicate specific diagnosis of TMJ disorders. Various classifications have been designed and studied to help diagnose and treat TMJ related disorders, of which the simplest one is pain from TMJ proper and surrounding muscles. Many treatment modalities to treat pain arising from muscles around TMJ like splints, mouth restriction exercises, injection of sclerosing agents etc. have been used with various degrees of success. Botulinum toxin has been shown to be effective in the treatment of oro-facial pain due to muscular disorders and the same is discussed in detail in this review literature.

Orthognathic surgery and temporomandibular joint symptoms

The aim of this article is to review temporomandibular joint symptoms as well as the effects of orthognathic surgery(OGS) on temporomandibular joint(TMJ). The causes of temporomandibular joint disease(TMD) are multifactorial, and the symptoms of TMD manifest as a limited range of motion of mandible, pain in masticatory muscles and TMJ, Joint noise (clicking, popping, or crepitus), myofascial pain, and other functional limitations. Treatment must be started based on the proper diagnosis, and almost symptoms could be subsided by reversible options. Minimally invasive options and open arthroplasty are also available following reversible treatment when indicated.

TMD manifesting in a variety of symptoms, also can apply abnormal stress to mandibular condyles and affect its growth pattern of mandible. Thus, adaptive developmental changes on mandibular condyles and post-developmental degenerative changes of mandibular condyles can create alteration on facial skeleton and occlusion. The changes of facial skeleton in DFD patients following OGS have an impact on TMJ, masticatory musculature, and surrounding soft tissues, and the changes of TMJ symptoms. Maxillofacial surgeons must remind that any surgical procedures involving mandibular osteotomy can directly affect TMJ symptoms, thus pre-existing TMJ symptoms and diagnoses should be considered prior to treatment planning and OGS.

Temporomandibular joint effusion and its relationship with perceived disability assessed using musculoskeletal ultrasound and a patient-reported disability index

The relationship between effusion of the temporomandibular joint (TMJ) and patient-reported disability is poorly researched. This pilot study explored the link between TMJ inflammation as measured by ultrasound and patient disability assessed by the Steigerwald Maher TMD Disability Index (SMTDI). The study design used a prospective correlational approach involving a sample with TMJ dysfunction (TMD). Twenty-four patients were recruited from the European School of Osteopathy and a Kent dental practice. Participants completed the SMTDI to determine the level of TMD (symptomatic score >20). A SonoSite SLA "Hockey Stick" [13-6 MHz] musculo-skeletal transducer was placed over the TMJ in a transverse direction and effusion was calculated indirectly by measuring capsular width. An upper left quadrant protocol was used throughout. A regression analysis was run with participants' gender, age and capsular width as predictor variables modelled against reported SMTDI. Larger capsular widths were found to be significant predictors of SMTDI scores (r = 0.803, p < 0.0001). The patient profile matched with the previous studies and the TMD sufferer population, indicating external validity. Results suggest that the SMTDI could be integrated into practice life as a quick, accessible and easy tool to monitor patients' progress and assess levels of inflammation, without the need for repetitive imaging. The study design proved reproducible and a larger scale study is indicated.

Impact of dentists' years since graduation on management of temporomandibular disorders

OBJECTIVES

The aims were to assess the impact of the number of years since dentists' graduation on appraisement of diagnostic needs and utilization of treatment options for temporomandibular disorders (TMD) and to investigate whether increased knowledge in TMD is sufficiently considered in today's dentist's undergraduate curricula and, therefore, represented in more evidence-based TMD management in dentists with less years since graduation.

MATERIAL AND METHODS

A questionnaire regarding knowledge and management of TMD was developed and was subsequently applied in a random sample of 400 dentists in a region in Northern Germany.

RESULTS

Of the 222 dentists (response rate 55.6 %), participating in the study, the frequency of TMD treatment need in the general population was estimated at 21.5 %, with lower values in dentists with more years passed since graduation. Measures regarding utilization of standardized examination forms, perceptions of insufficient specialization, and referrals of patients to TMD specialists indicated a lower quality and certainty in TMD management in participants with less time since graduation. While the provision of splints was a well-established treatment option in initial TMD management of all participants, additional TMD treatment options were mentioned less often, with lower proportions of participants making use of these options within the first decade since graduation.

CONCLUSIONS

Evidence-based TMD management is not fully represented in dental practitioners in Germany. This might be due to an insufficient consideration of TMD management in the dentist's undergraduate curricula.

CLINICAL RELEVANCE

Effective interventions to increase dentists' knowledge and to change dentists' practices in TMD management are required.

Validation of the chinese version of the oral health impact profile for TMDs (OHIP- TMDs-C)

OBJECTIVES

The aim of this study was to evaluate the reliability and validity of the the Chinese version of the Oral Health Impact Profile for TMDs (OHIP-TMDs-C).

STUDY DESIGN

The OHIP-TMDs was initially translated and cross-culturally adapted to Chinese following international guidelines; then subsequently validated for the psychometric characteristics of reliability and validity. In total, 156 participants with temporomandibular disorders (TMDs) were recruited to complete the questionnaire. The reliability of the OHIP-TMDs-C was evaluated using internal consistency and test-retest methods. The validity of the OHIP-TMDs-C was analysed by construct validity and convergent validity. Construct validity was determined based on factor analysis, and convergent validity by analyzing the correlation between OHIP-TMDs-C subscale scores and the global rating of oral health question.

RESULTS

Cronbach's alpha value (internal reliability) for the total OHIP-TMDs-C score was 0.917 and the intraclass correlation coefficient (ICC) value (test-retest reliability) was 0.899. Construct validity was determined by factor analysis, extracting five factors, accounting for 78.6% of the variance. All items had factor loadings above 0.40. In terms of convergent validity, the OHIP-TMDs-C subscale was significant correlated to the global oral health rating.

CONCLUSIONS

The results suggest that the OHIP-TMDs-C has good reliability and validity and thus may be used as a valuable instrument for patients with TMDs in China.

Oestrogen receptor beta mediates decreased occlusal loading induced inhibition of chondrocyte maturation in female mice

OBJECTIVE

Temporomandibular joint (TMJ) disorders predominantly afflict women, suggesting that estrogen may play a role in the disease process. Defects in mechanical loading-induced TMJ remodelling are believed to be a major etiological factor in TMJ degenerative disease. Previously, we found that, decreased occlusal loading caused a significant decrease in early chondrocyte maturation markers (Sox9 and Col 2) in female, but not male, C57BL/6 wild type mice (1). The goal of this study was to examine the role of Estrogen Receptor (ER) beta in mediating these effects.

DESIGN

21-day-old male (n = 24) and female (n = 25) ER beta KO mice were exposed to decreased occlusal loading (soft diet administration and incisor trimming) for 4 weeks. At 49 days of age the mice were sacrificed. Proliferation, gene expression, Col 2 immunohistochemistry and micro-CT analysis were performed on the mandibular condyles.

RESULTS

Decreased occlusal loading triggered similar effects in male and female ER beta KO mice; specifically, significant decreases in Col 10 expression, subchondral total volume, bone volume, and trabecular number.

CONCLUSION

Decreased occlusal loading induced inhibition of chondrocyte maturation markers (Sox9 and Col 2) did not occur in female ER beta deficient mice.

Women with more severe degrees of temporomandibular disorder exhibit an increase in temperature over the temporomandibular joint

Aim

The purpose of the present study was to correlate the degree of temporomandibular disorder (TMD) severity and skin temperatures over the temporomandibular joint (TMJ) and masseter and anterior temporalis muscles.

Materials and methods

This blind cross-sectional study involved 60 women aged 18–40 years. The volunteers were allocated to groups based on Fonseca anamnestic index (FAI) score: no TMD, mild TMD, moderate TMD, and severe TMD (n = 15 each). All volunteers underwent infrared thermography for the determination of skin temperatures over the TMJ, masseter and anterior temporalis muscles. The Shapiro–Wilk test was used to determine the normality of the data. The Kruskal–Wallis test, followed by Dunn’s test, was used for comparisons among groups according to TMD severity. Spearman’s correlation coefficients were calculated to determine the strength of associations among variables.

Results

Weak, positive, significant associations were found between FAI score and skin temperatures over the left TMJ (rs = 0.195, p = 0.009) and right TMJ (rs = 0.238, p = 0.001). Temperatures over the right and left TMJ were significantly higher in groups with more severe TMD (p < 0.05).

Conclusion

FAI score was associated with skin temperature over the TMJ, as determined by infrared thermography, in this sample. Women with more severe TMD demonstrated a bilateral increase in skin temperature.

Local application of Aqua Titan improves symptoms of temporomandibular joint muscle disorder: a preliminary study

Aqua Titan (AT), comprising microscopic titanium particles dispersed in water, has been reported to have beneficial effects on muscle tissue. This study investigated the effects of local application of AT on symptoms in patients with muscle disorders of the temporomandibular joint (TMJ) compared to patients with joint disorders of the TMJ. Sixteen patients with unilateral masseter muscle pain during motion (muscle disorder group) and six patients with unilateral TMJ pain during motion (joint disorder group) applied an AT-permeated patch over the painful area every night for 2 weeks. Symptoms were evaluated clinically at the initial visit and 1 and 2 weeks later. Clinical symptoms in the joint disorder group showed no tendency towards improvement after 2 weeks. In contrast, mouth opening range with/without pain, visual analogue scale (VAS) scores for pain during mouth opening and eating, and activities of daily living (ADL) scores in the muscle disorder group were improved significantly after 2 weeks. Multiple comparison tests in the muscle disorder group showed significant improvements in the VAS for eating and ADL score after 1 week. These results suggest that the AT patch has a potential supplementary role in the treatment of patients with muscle disorders of the TMJ.

Temporomandibular disorders: evaluation and management

Temporomandibular disorders remain a common cause of visits to primary care physicians, internists, pediatricians, and emergency departments. Advances in the clinical diagnosis, radiographic imaging, and classification of these disorders have improved long-term management. There are several types of disorders of the masticatory muscles and the temporomandibular joint as well as associated structures and each may have a complex cause, clinical course, and response to therapy. Host susceptibility plays a role at several stages of these disorders. Future research offers greater possibility in defining this heterogeneous group of disorders and providing more focused and effective treatment strategies.

Temporomandibular Disorders in a Sample Population of the Brazilian Northeast

Temporomandibular disorder (TMD) is a common condition. This study is part of a research group and it investigated the prevalence of TMD and myofascial pain and its association with gender, age and socioeconomic class. The sample comprised 100 subjects, aged 15 to 70, users of the Family Health Units' services, in the city of Recife, PE, Brazil. The TMD degree was evaluated using the Research Diagnostic Criteria for TMD and socioeconomic class by the Economic Classification Criteria Brazil. Categorical variables were analyzed by chi-square test for proportions and Fisher's exact test for 2x2 tables, and binary logistic analysis to track the relationship between the independent and dependent variables. According to the results, 42% of the subjects had TMD and 14% myofascial pain. No statistically significant association could be found between TMD and gender or socioeconomic class, but it was found to have statistically significant association with age, and myofascial pain was associated with socioeconomic class. Considering that the results of the present study should be confirmed by further studies and the fact that this was a pilot study, the prevalence must be analyzed with caution.

Could different TMJ disc positions observed in MRI cause different sounds? Analysis on a group of subjects with ADD with reduction: a pilot study

AIMS

Magnetic resonance imaging (MRI) is the method of choice for examining soft-tissue pathology of the temporomandibular joint (TMJ). MRI shows a high spatial resolution with accuracy for the identification of internal derangement. Tasaki developed a classification system for disc displacement in the TMJ, identifying eight different types of disc displacements in addition to the superior disc position. This study aims to test the ability of electrosonography (ESG) in discriminating different kinds of disc displacement according to the disc position criteria proposed, comparing the ESG results with those obtained by MRI.

METHODOLOGY

Twenty-seven patients were selected from an initial group of 50 patients with articular disc displacement, selected by means of clinical examinations, according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and who had both MRI and ESG studies performed. For each patient and for each peak in ESG, both in the opening and closing movements, three different parts of the sound were analyzed. The frequency (Hz) and the mean amplitude (μV) of the sounds were calculated in the three analyzed windows. Afterwards, gathering the data for the Tasaki's classes and dividing opening and closing sounds, the number of peaks was calculated, as well as average and standard deviations for both the Hz and µV.

RESULTS

The peak frequency shows significant differences between different disc positions during the first and second third of the opening phase and during the first third of the closing phase. The peak amplitude shows significant differences between different disc positions during all of the opening and closing phases.

CONCLUSIONS

Although limited by sample size, the present study shows the presence of different sounds with different Hzs and μVs associated with different disc positions that were recorded with ESG.

Delayed gadolinium-enhanced MRI of the fibrocartilage disc of the temporomandibular joint--a feasibility study

OBJECTIVE

To 1) test the feasibility of delayed Gadolinium-Enhanced Magnetic Resonance Imaging of Cartilage (dGEMRIC) at 3 T in the temporomandibular joint (TMJ) and 2) to determine the optimal delay for measurements of the TMJ disc after i.v. contrast agent (CA) administration.

DESIGN

MRI of the right and left TMJ of six asymptomatic volunteers was performed at 3 T using a dedicated coil. 2D inversion recovery (2D-IR) sequences were performed at 4 time points covering 120 minutes and 3D gradient-echo (3D GRE) dual flip-angle sequences were performed at 14 time points covering 130 minutes after the administration of 0.2 mmol/kg of Gd-diethylenetriamine pentaacetic acid ion (Gd-DTPA)(2-), i.e., 0.4 mL of Magnevist™ per kg body weight. Pair-wise tests were used to assess differences between pre-and post-contrast T1 values.

RESULTS

2D-IR sequences showed a statistically significant drop (p<0.001) in T1 values after i.v. CA administration. The T1 drop of 50% was reached 60 minutes after bolus injection in the TMJ disc. The 3D GRE dual flip-angle sequences confirmed these results and show plateau of T1 after 60 minutes.

CONCLUSIONS

T1(Gd) maps calculated from dGEMRIC data allow in vivo assessment of the fibrocartilage disc of the TMJ. The recommended measurement time for dGEMRIC in the TMJ after i.v. CA administration is from 60 to 120 minutes.

The chronicity of myogenous temporomandibular disorder changes the skin temperature over the anterior temporalis muscle

The aim of the present study was to investigate the correlation between the chronicity of myogenous temporomandibular disorder (TMD) and skin temperature over the masseter and anterior temporalis muscles. A blind, cross-sectional study was carried out involving 30 women with myogenous TMD, aged 18-40 years (mean of 23.60 ± 5.12 years). The volunteers were recruited from the university community. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) was used for the diagnosis of TMD and the determination of chronicity. The volunteers were also submitted to infrared thermography to measure absolute skin temperature over the masseter and anterior temporalis muscles and determine their temperature asymmetries. A significant association was found between duration of TMD and temperature asymmetry of the anterior temporalis muscle (rs = 0.224, p = 0.034). The present findings demonstrate that chronicity of myogenous TMD changes the skin temperature over the anterior temporalis muscle.

TMJ Disc Displacement without Reduction Management: A Systematic Review

Various interventions have been used for the management of patients with temporomandibular joint (TMJ) disc displacement without reduction (DDwoR), but their clinical effectiveness remains unclear. This systematic review investigated the effects of these interventions and is reported in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Electronic and manual searches up to November 1, 2013, were conducted for English-language, peer-reviewed, publications of randomized clinical trials comparing any form of conservative or surgical interventions for patients with clinical and/or radiologic diagnosis of acute or chronic DDwoR. Two primary outcomes (TMJ pain intensity and maximum mouth opening) and a number of secondary outcomes were examined. Two reviewers performed data extraction and risk of bias assessment. Data collection and analysis were performed according to Cochrane recommendations. Twenty studies involving 1,305 patients were included. Data analysis involved 21 comparisons between a variety of interventions, either between interventions, or between intervention and placebo or no intervention. Meta-analysis on homogenous groups was conducted in 4 comparisons. In most comparisons made, there were no statistically significant differences between interventions relative to primary outcomes at short- or long-term follow-up (p > .05). In a separate analysis, however, the majority of reviewed interventions reported significantly improved primary outcome measures from their baseline levels over time (p < .05). Evidence levels, however, are currently insufficient for definitive conclusions, because the included studies were too heterogeneous and at an unclear to high risk of bias. In view of the comparable therapeutic effects, paucity of high-quality evidence, and the greater risks and costs associated with more complex interventions, patients with symptomatic DDwoR should be initially treated by the simplest and least invasive intervention.

Use of orthopedic manual physical therapy to manage chronic orofacial pain and tension-type headache in an adolescent

Temporomandibular dysfunction (TMD) is frequently associated with multiple headache types. While the efficacy of orthopedic manual physical therapy (OMPT) intervention for TMD with/without headache symptoms has been investigated, it has received less attention than other musculoskeletal conditions. This case describes the OMPT treatment and outcome of a 14 year-old female with a 2-year history of facial pain surrounding the right temporomandibular joint (TMJ), and bilateral occipital and temporal tension-type headaches (TTHs). Intervention included manual mobilization of the TMJ and surrounding cervical/facial soft tissue structures, postural re-education, and patient/family education on prevention, self-treatment, and postural adaptations. Outcomes included pain free and maximal mouth opening (MMO), pressure pain threshold (PPT) over the masseter muscle belly, fear avoidance beliefs questionnaire-physical activity subscale (FABQ-PA), jaw pain and function questionnaire (JPFQ), visual analog pain scale (VAS) for facial pain, and headache frequency, duration, and intensity on a VAS. Results included increased pain free and MMO by 22 mm, improved PPT bilaterally by 403.05 kPa on the affected, and 360.88 kPa on the unaffected side, and decreased reported headache frequency, duration, and intensity. Score decreases of 5 points on VAS with MMO, 8 points on FABQ-PA, and 5 points on JPFQ were also noted. Further research is warranted to investigate the effects of OMPT on pain processing and functional outcomes in patients with TMD and headache.

Temporomandibular disorders. Part 1: anatomy and examination/diagnosis

Temporomandibular disorders (TMD) are a heterogeneous group of diagnoses affecting the temporomandibular joint (TMJ) and surrounding tissues. A variety of methods for evaluating and managing TMD have been proposed within the physical therapy profession but these sources are not peer-reviewed and lack updates from scientific literature. The dental profession has provided peer-reviewed sources that lack thoroughness with respect to the neuromusculoskeletal techniques utilized by physical therapists. The subsequent void creates the need for a thorough, research informed, and peer-reviewed source regarding TMD evaluation and management for physical therapists. This paper is the first part in a two-part series that seeks to fill the current void by providing a brief but comprehensive outline for clinicians seeking to provide services for patients with TMD. Part one focuses on anatomy and pathology, arthro- and osteokinematics, epidemiology, history taking, and physical examination as they relate to TMD. An appreciation of the anatomical and mechanical features associated with the TMJ can serve as a foundation for understanding a patient's clinical presentation. Performance of a thorough patient history and clinical examination can guide the clinician toward an improved diagnostic process.

Correlations between mandibular asymmetries and temporomandibular disorders (TMD)

INTRODUCTION

Mandibular asymmetries are the fulcrum of many debates among modern orthodontists and maxillofacial surgeons. The interest is even greater when facial asymmetries are correlated to the development of TMJ symptoms and temporomandibular disorders (TMD).

OBJECTIVE

The aim of this study is to investigate how mandibular asymmetries constitute etiological or predisposing factors for the development of temporomandibular disorders (TMD). We considered patients with mandibular asymmetries associated with TMD. Using orthodontic or surgical-orthodontic treatment, patients experienced correction of their TMJ symptoms. Thus, mandibular asymmetries represent a major risk factor for the development of TMD.

MATERIAL AND METHODS

We studied a sample of 16 subjects aged between 14 and 36-years-old (11 females and 5 males) with mandibular asymmetries (81% structural asymmetry, 19% functional asymmetry). These subjects presented skeletal and dental malocclusions combined with several temporomandibular disorders, mostly due to muscle tension. In 100% of cases, patients received orthodontic treatment. We compared pre- and post-treatment postero-anterior (PA) cephalometric analyses in order to evaluate asymmetry resolution.

RESULTS

Comparison of measurements from pre- and post-therapy PA cephalograms showed resolution of mandibular asymmetries after treatment. The treatment resolved mandibular asymmetries and completely eliminated temporomandibular symptoms.

CONCLUSIONS

Orthodontic treatment of patients presenting mandibular asymmetry enables correction of all TMJ symptoms and TMD. Mandibular symmetries can therefore be considered to constitute etiological or predisposing factors for the development of TMD.