The many faces of the genetics contribution to temporomandibular joint disorder

Insights for temporomandibular disorders management: From psychosocial factors to genetics-A case report

AIMS

This case report aimed to discuss the multifactorial etiology and also the management of temporomandibular disorders (TMD) by addressing important associated psychosocial and biological factors, emphasizing the interaction between these factors and a probable genetic predisposition.

METHODS AND RESULTS

A 21-year-old female patient was evaluated according to Research Diagnostic Criteria for TMD and diagnosed with arthralgia, myofascial pain, disc displacement without reduction, and temporomandibular joint (TMJ) degenerative disease. TMJ alterations were confirmed through magnetic resonance imaging and cone-beam computed tomography. Pressure pain threshold of masticatory structures was evaluated using a pressure algometer. Sleep bruxism, poor sleep quality, migraine with aura, mild anxiety, and history of facial trauma were also identified through anamnesis and clinical examination. Following this, genetic analysis was performed to evaluate the presence of single nucleotide polymorphisms (SNPs) already associated with TMD: SNP COMT Val¹⁵⁸ Met (rs4680), MMP1-1607 (rs1799750), and tumor necrosis factor alpha-308 (rs1800629), which were all present. A personalized treatment for TMD management was performed, and it included self-management programs, occlusal appliance therapy, pharmacotherapy, anxiety management, and stress control. An 8-year follow-up demonstrated long-term stabilization of TMJ degenerative disease.

CONCLUSION

Genetic evaluation, added to anamnesis and clinical examination, could be useful for TMD prognosis and management.

The many faces of genetic contributions to temporomandibular joint disorder: An updated review

OBJECTIVES

The aim was to review the literature regarding genetic contributions to temporomandibular joint disorder (TMD) after our 2008 publication.

SETTING AND SAMPLE POPULATION

Literature review.

MATERIAL AND METHODS

PubMed and MEDLINE were used to obtain literature in any language regarding genes and TMD, using the keywords "temporomandibular joint disorder" and "temporomandibular joint dysfunction" for studies published from 2009 to 2017.

RESULTS

In our search, 274 studies were found. We excluded 76 studies from animal models, 22 studies that were in vitro and 120 reports that were not cohort or case-control studies. Of the 274 results, 56 articles were selected for this review. Genes that are suggested to contribute to TMD included the ones related to disc and bone alterations as well as pain sensation.

CONCLUSION

Currently, no evidence of associated genetic variants, which can determine the development of TMD in individuals, could be translated to novel clinical management and public health strategies for patients suffering from TMD.

Specific Central Nervous System Medications Are Associated with Temporomandibular Joint Symptoms

Aims

There is evidence of association between bruxism and the increasingly common central nervous system stimulants prescribed for attention deficit hyperactivity disorder (ADHD), as well as the selective serotonin reuptake inhibitors (SSRIs) often prescribed for depression or anxiety. However, the evidence is not clear on whether these medications inducing bruxism are directly associated with temporomandibular joint disorder (TMD). The aim of this work is to evaluate whether these medications are associated with TMD symptoms.

Methods

Medical history and participant data were obtained for 469 patients from the University of Pittsburgh School of Dental Medicine, Dental Registry and DNA Repository, dating back to 2006. The chi-square test was used to determine any statistically significant associations.

Results

There were no statistically significant associations between ADHD stimulant medications or SSRIs and reported TMD symptoms. However, there were significant differences seen between specific brands of medications and reported TMD symptoms. Individuals prescribed methylphenidate (Concerta) were less likely to report temporomandibular joint discomfort (p = 0.01). Conversely, individuals prescribed citalopram (Celexa) were more likely to report temporomandibular joint discomfort (p = 0.04).

Conclusion

Signs and symptoms of temporomandibular joint dysfunction may be influenced by the use of certain medications prescribed for depression or attention deficit hyperactive disorder.

Lectin from Abelmoschus esculentus reduces zymosan-induced temporomandibular joint inflammatory hypernociception in rats via heme oxygenase-1 pathway integrity and tnf-α and il-1β suppression

Temporomandibular joint (TMJ) disorders show inflammatory components, heavily impacting on quality of life. Abelmoschus esculentus is largely cultivated in Northeastern Brazil for medicinal purposes, having it shown anti-inflammatory activity. We evaluated A. esculentus lectin (AEL) efficacy in reducing zymosan-induced temporomandibular joint inflammatory hypernociception in rats along with the mechanism of action through which it exerts anti-inflammatory activity. Animals were pre-treated with AEL (0.01, 0.1 or 1mg/kg) before zymosan (Zy) injection in the TMJ to determine anti-inflammatory activity. To analyse the possible effect of the hemeoxygenase-1 (HO-1) and the nitric oxide (NO) pathways on AEL efficacy, animals were pre-treated with ZnPP-IX (3mg/kg), a specific HO-1 inhibitor, or aminoguanidine (30mg/kg), a selective iNOS inhibitor, before AEL administration. Von Frey test evaluated inflammatory hypernociception, synovial fluid collection was performed to determine leukocyte counting and myeloperoxidase (MPO) activity 6h after Zy injection, and Evans Blue extravasation determined vascular permeability. TMJ tissue was collected for histopathological analysis (H&E) and immunohistochemistry (TNF-α, IL-1β, HO-1). In addition, TMJ tissue and trigeminal ganglion collection was performed for TNF-α and IL-1β dosage (ELISA). AEL increased inflammatory nociceptive threshold, reduced leukocyte influx along with MPO activity, leukocyte influx into the synovial membrane, and Evans Blue extravasation. It promoted HO-1 overexpression whilst decreased TNF-α and IL-1β expression in the TMJ tissue. AEL reduced TNF-α and IL-1β levels in TMJ tissue and trigeminal ganglion. AEL effects, however, were not observed in the presence of ZnPP-IX. These findings suggest that AEL efficacy depends on TNF-α/IL-1β inhibition and HO-1 pathway integrity.

Extracellular matrix bioscaffolds in tissue remodeling and morphogenesis

During normal morphogenesis the extracellular matrix (ECM) influences cell motility, proliferation, apoptosis, and differentiation. Tissue engineers have attempted to harness the cell signaling potential of ECM to promote the functional reconstruction, if not regeneration, of injured or missing adult tissues that otherwise heal by the formation of scar tissue. ECM bioscaffolds, derived from decellularized tissues, have been used to promote the formation of site appropriate, functional tissues in many clinical applications including skeletal muscle, fibrocartilage, lower urinary tract, and esophageal reconstruction, among others. These scaffolds function by the release or exposure of growth factors and cryptic peptides, modulation of the immune response, and recruitment of progenitor cells. Herein, we describe this process of ECM induced constructive remodeling and examine similarities to normal tissue morphogenesis.

Gene Mutations Associated with Temporomandibular Joint Disorders: A Systematic Review

Background

The temporomandibular joint (TMJ) is a bilateral synovial joint between the mandible and the temporal bone of the skull. TMJ disorders (TMDs) are a set of complicated and poorly understood clinical conditions, in which TMDs are associated with a number of symptoms including pain and limited jaw movement. The increasing scientific evidence suggests that genetic factors play a significant role in the pathology of TMDs. However, the underlying mechanism of TMDs remains largely unknown.

Objective

The study aimed to determine the associated genes to TMDs in humans and animals.

Methods

The literature search was conducted through databases including Medline (Ovid), EMBASE (Ovid), and PubMed (NLM) by using scientific terms for TMDs and genetics in March 2015. Additional studies were identified by searching bibliographies of highly relevant articles and Scopus (Elsevier).

Results

Our systematic analyses identified 31 articles through literature searches. A total of 112 genes were identified to be significantly and specifically associated with TMDs.

Conclusion

Our systematic review provides a list of accurate genes associated with TMDs and suggests a genetic contribution to the pathology of TMDs.

Update on the genetics of the fibromyalgia syndrome

Fibromyalgia syndrome (FMS), a condition characterized by chronic widespread pain and tenderness, is a complex condition considered to represent a paradigm of centralized pain. FMS has demonstrated a clear familial aggregation, and hence it is considered to have a genetic background. Multiple candidate-gene studies have been conducted in this field, focusing on target genes that play a role in the transmission and processing of pain. While many of these have focused in the past on markers related to neurotransmitter systems such as catecholamines (catechol-O-methyltransferase (COMT)) and serotonin, novel target genes have recently emerged. In addition, genome-wide sequencing scanning (genome-wide association study (GWAS)) is increasingly being harnessed for the study of chronic pain, including FMS. Micro RNAs are another novel field of research related to posttranscriptional inhibition of gene expression, which are currently regarding the pathogenesis of FMS.

Impact of trismus on health-related quality of life and mental health

BACKGROUND

Trismus is a common symptom often related to the treatment for head and neck cancer and to temporomandibular disorders. The purpose of the present study was to measure the impact of trismus on health-related quality of life (HRQOL) and mental health in patients with head and neck cancer and temporomandibular disorder.

METHODS

We used the criteria for trismus of maximum interincisal opening (MIO) ≤35 mm and the study subjects responded to the following instruments: the Gothenburg Trismus Questionnaire (GTQ), the Short-Form 36 Health Survey (SF-36), and the Hospital Anxiety and Depression Scale (HADS). The study also comprised an age-matched and sex-matched control group without trismus.

RESULTS

Patients with trismus reported significantly more dysfunction in all GTQ domains and more facial pain compared to the control group. The patients with head and neck cancer and trismus scored significantly lower on all SF-36 domains except general health compared to the control group, and the patients with temporomandibular disorder with trismus scored significantly lower in 3 of the 8 domains in SF-36. According to the HADS, a greater proportion of patients with head and neck cancer with trismus displayed more depression compared to the control group.

CONCLUSION

The results showed that trismus is associated with a significant impact on HRQOL and that patients with trismus should be approached in a holistic way with respect for the underlying cause, treating not only the physical aspects of trismus but also addressing the patients' mental health.

Risk factors for temporomandibular disorder: binary logistic regression analysis

Objectives: To analyze the influence of socioeconomic and demographic factors (gender, economic class, age and marital status) on the occurrence of temporomandibular disorder. Study Design: One hundred individuals from urban areas in the city of Recife (Brazil) registered at Family Health Units was examined using Axis I of the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) which addresses myofascial pain and joint problems (disc displacement, arthralgia, osteoarthritis and oesteoarthrosis). The Brazilian Economic Classification Criteria (CCEB) was used for the collection of socioeconomic and demographic data. Then, it was categorized as Class A (high social class), Classes B/C (middle class) and Classes D/E (very poor social class). The results were analyzed using Pearson’s chi-square test for proportions, Fisher’s exact test, nonparametric Mann-Whitney test and Binary logistic regression analysis. Results: None of the participants belonged to Class A, 72% belonged to Classes B/C and 28% belonged to Classes D/E. The multivariate analysis revealed that participants from Classes D/E had a 4.35-fold greater chance of exhibiting myofascial pain and 11.3-fold greater chance of exhibiting joint problems. Conclusions: Poverty is a important condition to exhibit myofascial pain and joint problems.

Key words:Temporomandibular joint disorders, risk factors, prevalence.

Extracellular matrix as an inductive scaffold for functional tissue reconstruction

The extracellular matrix (ECM) is a meshwork of both structural and functional proteins assembled in unique tissue-specific architectures. The ECM both provides the mechanical framework for each tissue and organ and is a substrate for cell signaling. The ECM is highly dynamic, and cells both receive signals from the ECM and contribute to its content and organization. This process of "dynamic reciprocity" is key to tissue development and for homeostasis. Based upon these important functions, ECM-based materials have been used in a wide variety of tissue engineering and regenerative medicine approaches to tissue reconstruction. It has been demonstrated that ECM-based materials, when appropriately prepared, can act as inductive templates for constructive remodeling. Specifically, such materials act as templates for the induction of de novo functional, site-appropriate, tissue formation. Herein, the diverse structural and functional roles of the ECM are reviewed to provide a rationale for the use of ECM scaffolds in regenerative medicine. Translational examples of ECM scaffolds in regenerative are provided, and the potential mechanisms by which ECM scaffolds elicit constructive remodeling are discussed. A better understanding of the ability of ECM scaffold materials to define the microenvironment of the injury site will lead to improved clinical outcomes associated with their use.

Pain and temporomandibular disorders: a pharmaco-gender dilemma

Gender is the biggest risk factor in the development of temporomandibular disorders (TMD) and orofacial pain. Gender differences in pain thresholds, temporal summation, pain expectations, and somatic awareness exist in patients with chronic TMD or orofacial pain. There are gender differences in pharmacokenetics and pharmacodynamics of medications used to treat pain. A better understanding of the mechanisms that contribute to the increased incidence and persistence of chronic pain in females is needed. Future research will elucidate the sex effects on factors that protect against developing pain or prevent debilitating pain. Gender-based treatments for TMD and orofacial pain treatment will evolve from the translational research stimulated by this knowledge.

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.

Development and validation of the Gothenburg Trismus Questionnaire (GTQ)

OBJECTIVES

To develop and validate a comprehensive, self-administered questionnaire for patients with limited ability to open the mouth, trismus.

MATERIALS AND METHODS

We derived the Gothenburg Trismus Questionnaire (GTQ) from empirical evidence in the medical literature and interviews with medical experts as well as patients. The draft version was tested in a pilot study (n=18). Patients with a maximal incisal opening (MIO) of ⩽35mm were included. The study comprised patients with benign jaw-related conditions (n=51), patients treated for head and neck (H&N) cancer (n=78) and an age- and gender-matched control group without trismus (n=129).

RESULTS

The GTQ instrument was well accepted by the patients, with satisfactory compliance and low rates of missing items. After item reduction, due to items not being conceptually relevant and/or low factor loadings, the GTQ demonstrated high internal consistency (Cronbach's alpha 0.72-0.90), good construct validity and known-group validity.

CONCLUSION

We developed a trismus-specific self-administered questionnaire, the GTQ, that showed good psychometric properties. We suggest this questionnaire, that has clear clinical relevance, to be adopted and used in clinical practice and in research, acting as a screening tool as well as an endpoint in intervention and jaw physiotherapy/rehabilitation studies.

Extracellular matrix as an inductive template for temporomandibular joint meniscus reconstruction: a pilot study

PURPOSE

A device consisting of powdered porcine urinary bladder extracellular matrix (UBM-ECM) encapsulated within sheets of the same material was investigated as a scaffold for temporomandibular joint (TMJ) meniscus reconstruction.

MATERIALS AND METHODS

Five dogs underwent unilateral resection of the native meniscus and replacement with a UBM-ECM device. Necropsies were performed at 3, 4, 8, 12, and 24 weeks. Two additional dogs underwent bilateral resection of the meniscus with replacement with a UBM-ECM device on 1 side, leaving the contralateral side empty as a control. Necropsies were performed at 24 weeks for bilaterally treated animals.

RESULTS

Macroscopically, the UBM-ECM implants were remodeled rapidly and were indistinguishable from newly deposited host tissue at all time points. Microscopically, remodeling was characterized by a dense infiltration of predominantly CD68(+) mononuclear cells and smooth muscle actin-positive fibroblast-like cells at early time points changing with time to a sparse population of smooth muscle actin-negative spindle-shaped cells resembling those of the native fibrocartilaginous TMJ meniscus. Furthermore, the remodeling process showed deposition of predominantly type I collagen, the density and organization of which resembled those of the native meniscus by the 24-week time point. Ingrowth of calsequestrin-positive skeletal muscle tissue was also observed at the periphery of the remodeled UBM-ECM device and was similar to that found at the attachment site of the native meniscus to the surrounding soft tissues. Histologic results were identical for samples excised from both unilaterally and bilaterally treated animals. No adverse changes in the articulating surfaces of the condyle or fossa were observed in UBM-ECM-implanted joints. In the bilaterally treated animals, the unimplanted control side was characterized by degeneration and pitting of the articulating surfaces of both the condyle and the fossa, with disorganized bands of fibrous connective tissue observed within the joint space.

CONCLUSION

Results of this study suggest that the UBM-ECM device provides an effective interpositional material while serving as an inductive template for reconstruction of the TMJ meniscus.

Temporomandibular disorders in German and Chinese adolescents

OBJECTIVE

The etiology of temporomandibular disorders (TMD) remains unclear. The aim of this study was, by comparing the prevalence of TMD between adolescents of different ethnic origin, to examine whether certain genetic factors may play a role in causing TMD.

SUBJECTS AND METHODS

We assessed the prevalence of TMD according to the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) in 1,058 subjects (561 German, 497 Chinese) aged 13 to 18 years from two general population samples.

RESULTS

In total, the prevalence of RDC/TMD diagnoses was 13.9% (N = 147). The difference between German (13.0%, N = 73) and Chinese adolescents (14.9%, N = 74) was not statistically significant. After controlling for the effects of age, gender and orthodontic treatment using multivariable logistic regression analyses, the prevalence of RDC/TMD group II diagnoses (disc displacement) was lower in China than Germany (odds ratio [OR] = 0.5, 95% confidence interval [CI]: 0.3-0.8), whereas the prevalence of RDC/TMD pain diagnoses (group I, III) was higher in China (OR = 3.3, 95%-CI: 1.7-6.5).

CONCLUSIONS

Our study reveals obvious differences in the prevalence of TMD between adolescents of different ethnic origins (Asians and Europeans). These differences cannot be attributed to cultural differences alone, which implies the involvement of genetic factors in the etiology of TMD.

Chronic pain disorders and headache chronification

It is estimated that nearly half of the global adult population suffers from an active headache disorder, most of whom experience attacks on an episodic basis. The transition from episodic to chronic headache is a poorly understood process. Epidemiological findings demonstrating comorbidity and common risk factors suggest that headache progression or prognosis may be related to the presence of other chronic pain disorders. This review highlights findings from population-based studies on headache and other pain disorders and how they relate to each other, with a focus on understanding headache chronification. We also consider the limitations and methodological challenges in understanding how two different chronic pain disorders may be related.

Current evidence for a modulation of low back pain by human genetic variants

The manifestation of chronic back pain depends on structural, psychosocial, occupational and genetic influences. Heritability estimates for back pain range from 30% to 45%. Genetic influences are caused by genes affecting intervertebral disc degeneration or the immune response and genes involved in pain perception, signalling and psychological processing. This inter-individual variability which is partly due to genetic differences would require an individualized pain management to prevent the transition from acute to chronic back pain or improve the outcome. The genetic profile may help to define patients at high risk for chronic pain. We summarize genetic factors that (i) impact on intervertebral disc stability, namely Collagen IX, COL9A3, COL11A1, COL11A2, COL1A1, aggrecan (AGAN), cartilage intermediate layer protein, vitamin D receptor, metalloproteinsase-3 (MMP3), MMP9, and thrombospondin-2, (ii) modify inflammation, namely interleukin-1 (IL-1) locus genes and IL-6 and (iii) and pain signalling namely guanine triphosphate (GTP) cyclohydrolase 1, catechol-O-methyltransferase, mu opioid receptor (OPMR1), melanocortin 1 receptor (MC1R), transient receptor potential channel A1 and fatty acid amide hydrolase and analgesic drug metabolism (cytochrome P450 [CYP]2D6, CYP2C9).