Genetic overlap between temporomandibular disorders and primary headaches: A systematic review

Bruxism, temporomandibular disorders, and headache: a narrative review of correlations and causalities

ABSTRACT

The co-occurrence of bruxism, temporomandibular disorders (TMDs), and headache is common in patients. However, there is conflicting evidence regarding whether this association is simply a result of their high prevalence or whether there are indeed causal relationships. This review provides an overview of the current state of research while taking into account the controversies surrounding research methods, particularly in definitions and diagnostic standards. Bruxism-defined as repetitive jaw muscle activity during sleep or wakefulness-is not a painful disorder but may-particularly in co-occurrence with TMD-worsen pre-existing headache. It seems important to differentiate between sleep and awake bruxism because of different impact on pathophysiological processes in different primary headache disorders such as migraine and tension-type headache. Temporomandibular disorder is a heterogenous entity with both myofascial and arthrogenous types of pain in addition to nonpainful disorders. Research suggests a correlation between TMD pain and migraine, as well as between awake bruxism and tension-type headache. However, psychosocial factors may act as confounders in these relationships. Determining causality is challenging because of the limited number of experimental and clinical studies conducted on this topic. The main finding is an apparent lack of consensus on the definition and assessment criteria for bruxism. Treatment wise, it is important to differentiate all 3 conditions because treatment of one condition may have an effect on the other 2 without proving causality. For future research, it is crucial to establish greater consistency and applicability in diagnostic procedures and definitions. In addition, more experimental and clinical studies investigating the question of causality are needed.

Genome-Wide Association Study of Temporomandibular Disorder-Related Pain in Finnish Populations

BACKGROUND

Temporomandibular disorders (TMD) are multifactorial musculoskeletal pain and dysfunctions in temporomandibular joints (TMJs) and masticatory muscles. Genetic factors play a role in TMD-related pain, but only a few genome-wide association studies (GWAS) have been conducted.

OBJECTIVE

The aim of this GWAS was to explore genetic factors associated with painful TMD in Finnish populations.

METHODS

Data from two epidemiological surveys, the Northern Finland Birth Cohort 1966 (NFBC1966) and the Health 2000 Survey in Finland, including altogether 468 cases and 6833 controls, were used. Case definition was based on pain on palpation of masticatory muscles and/or TMJs. GWASs of the whole data and stratified by sex were conducted from both cohorts using additive models, followed by meta-analysis of the two cohorts. Replications of the previously reported TMD risk loci (rs73460075, DMD; rs4794106, SGCA; rs73271865, SP4; rs60249166, RXP2; rs1531554, BAHCCI; rs5862730, OTUD4/SMAD1; rs10092633, SFRP1; rs34612513, SOX14/CLDN18; rs878962, TSPAN9) were also investigated.

RESULTS

Four genome-wide significant loci were found in sex-stratified analysis of NFBC1966, including associations at three loci in males (rs1023114, PRIM2, p = 5 × 10-9; rs4244867, ALG10, p = 3 × 10-8; rs79841648, ADCYAP1, p = 4 × 10-9) and one locus in females (rs148476652, DNER, p = 4 × 10-9). However, the results could not be replicated in the Health 2000 Survey or in the meta-analysis of these two cohorts. The previous TMD GWAS associations did not replicate in our data either.

CONCLUSION

Several TMD pain-associated variants were found in sex-stratified analysis of NFBC1966, suggesting the role of neuroendocrine stress responses and central nervous system. These findings need to be confirmed in future studies.

Investigating the Association between Catechol-O-Methyltransferase Gene Activity and Pain Perception in South African Patients with Different Temporomandibular Disorders Diagnoses

Background: Temporomandibular disorders (TMD) affect a significant portion of the population, with profound psychological, behavioral, and social repercussions. Recent investigations have explored the genetic basis underlying pain perception in individuals with TMD, aiming to elucidate the role of specific genetic factors in modulating the condition. Notably, genetic variations have been implicated in the pathogenesis of TMD, particularly genes involved in pain perception pathways. One of the primary candidates is the Catechol-O-Methyltransferase (COMT) gene, which plays a crucial role in the catecholaminergic system and has been associated with the regulation of nociceptive processes. This study seeks to investigate the correlation between COMT gene activity and pain perception among South African patients diagnosed with varying forms of TMD. Methodology: In this study, a total of 196 participants were enrolled, comprising 97 patients diagnosed with TMD and 99 control participants. The control group was meticulously matched with the TMD group for age, gender, and ethnicity. Data collection involved clinical and radiological investigations, and saliva sampling. The English version of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I was utilized to evaluate all TMD participants, focusing on standard diagnostic measures based on clinical signs and symptoms of TMD, which primarily describe common physical manifestations of the disorder. Genomic DNA was extracted from saliva samples, enabling the analysis of single-nucleotide polymorphisms (SNPs) in the COMT gene, specifically targeting polymorphisms rs165774, rs9332377, rs6269, rs4646310, rs165656, and rs4680. Results: The current study demonstrated a pronounced gender disparity, with 80.41% of the participants being female and 19.59% male, suggesting that women in South Africa either exhibit a higher susceptibility to TMD or are more likely to seek treatment for the condition compared to men. The highest prevalence of TMD was observed in the white population (58.76%). Additionally, over 65% of TMD patients were diagnosed with at least two Axis I diagnoses, a figure that increased to 89% for those diagnosed with three Axis I diagnoses. The findings further indicated significant associations between several single-nucleotide polymorphisms (SNPs) in the Catechol-O-Methyltransferase (COMT) gene-specifically rs165656, rs9332377, rs4646310, rs6269, and rs165774-and both TMD and TMD-related pain. Myofascial pain with referral and myalgia showed a strong association with the COMT SNPs rs9332377 and rs4646310. Furthermore, COMT SNP rs4646310 was also associated with disability related to TMD. Conclusions: This study substantiates the hypothesis that pain is prevalent in a considerable proportion of patients affected by TMD. Furthermore, the findings reveal a significant association between COMT gene activity and pain perception in South African patients diagnosed with TMD.

Impact of Stabilization Splint Therapy on Orthodontic Diagnosis in Patients with Signs and Symptoms of Temporomandibular Disorder

BACKGROUND/OBJECTIVES

The relation between the orthopedic temporomandibular joint (TMJ) instability and temporomandibular disorder (TMD) most commonly remain unrecognized by orthodontists. In this study we aimed to evaluate the dentofacial characteristics and temporomandibular disorder symptomatology of patients with orthopedic instability before and after deprogramming with a stabilization splint.

METHODS

Sixty patients with the signs and symptoms of TMD were assessed using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and underwent stabilization splint therapy to place the condyles in a more stable musculoskeletal position. The extent of condylar displacement was evaluated using the condylar position indicator (CPI). Sixteen angular and linear hard tissue landmarks were traced and compared from lateral cephalograms taken in the maximum intercuspation (MI) position before, and in the centric relation (CR) position after, the splint therapy.

RESULTS

Following the splint therapy, the signs and symptoms of TMD were significantly reduced or completely eliminated in more than 90% of patients. Compared with the values registered before the splint therapy, a significant reduction in the mean values of condylar displacement was observed on both sides of the vertical (p < 0.001), horizontal (p < 0.05), and transverse (p < 0.001) planes of space after the splint therapy. A comparison of pre- and post-splint lateral cephalograms revealed that, following the splint therapy, the mandible moved more posteriorly and rotated in a more clockwise direction.

CONCLUSIONS

In patients with orthopedic instability and the signs and symptoms of TMD, muscle deprogramming with a stabilization splint therapy is highly recommended to improve the health of the temporomandibular joint and masticatory structures and contribute to a more correct orthodontic diagnosis.

Effect of Extracorporeal Shock Wave on IGF-1, TNF-α, and IL-1in Joint Fluid of Patients with Temporomandibular Joint Disorder Syndrome

As a new therapeutic method, extracorporeal shock wave (ESW) has shown remarkable efficacy in the treatment of temporomandibular joint disorder syndrome. Numerous studies have shown that it has the advantages of noninvasiveness, short treatment time, etc. It can effectively relieve pain and improve symptoms such as joint mobility and opening degree. In clinical practice, through accurate diagnosis and positioning of different patients, appropriate treatment parameters such as therapeutic transducer, frequency and pressure can be selected to significantly improve the efficacy. At the same time, follow-up evaluation after treatment, including temporomandibular joint disorder index and visual analogue score, is also helpful to fully understand the rehabilitation of patients. Extracorporeal shock wave therapy (ESWT) brings new hope to patients with temporomandibular joint disorder syndrome and has a broad application prospect.

Ultrasonographic examination of masticatory muscles in patients with TMJ arthralgia and headache attributed to temporomandibular disorders

This study used ultrasonography to compare the thickness and cross-sectional area of the masticatory muscles in patients with temporomandibular joint arthralgia and investigated the differences according to sex and the co-occurrence of headache attributed to temporomandibular disorders (HATMD). The observational study comprised 100 consecutive patients with TMJ arthralgia (71 females and 29 males; mean age, 40.01 ± 17.67 years) divided into two groups: Group 1, including 86 patients with arthralgia alone (60 females; 41.15 ± 17.65 years); and Group 2, including 14 patients with concurrent arthralgia and HATMD (11 females; 33.00 ± 16.72 years). The diagnosis of TMJ arthralgia was based on the diagnostic criteria for temporomandibular disorders. The parameters of the masticatory muscles examined by ultrasonography were subjected to statistical analysis. The pain area (2.23 ± 1.75 vs. 5.79 ± 2.39, p-value = 0.002) and visual analog scale (VAS) score (3.41 ± 1.82 vs. 5.57 ± 12.14, p-value = 0.002) were significantly higher in Group 2 than in Group 1. Muscle thickness (12.58 ± 4.24 mm) and cross-sectional area (4.46 ± 2.57 cm2) were larger in the masseter muscle than in the other three masticatory muscles (p-value < 0.001). When examining sex-based differences, the thickness and area of the masseter and lower temporalis muscles were significantly larger in males (all p-value < 0.05). The area of the masseter muscle (4.67 ± 2.69 vs. 3.18 ± 0.92, p-value = 0.004) and lower temporalis muscle (3.76 ± 0.95 vs. 3.21 ± 1.02, p-value = 0.049) was significantly smaller in Group 2 than in Group 1. An increase in VAS was significantly negatively correlated with the thickness of the masseter (r =  - 0.268) and lower temporalis (r =  - 0.215), and the cross-sectional area of the masseter (r =  - 0.329) and lower temporalis (r =  - 0.293). The masseter and lower temporalis muscles were significantly thinner in females than in males, and their volumes were smaller in patients with TMJ arthralgia and HATMD than in those with TMJ arthralgia alone. HATMD and decreased masseter and lower temporalis muscle volume were associated with increased pain intensity.

Craniofacial disorders and headaches. A narrative review

OBJECTIVES

Craniofacial- and headache disorders are common co-morbid disorders. The aim of this review is to provide an overview of the research discussing craniofacial pain, especially temporomandibular disorders, and its relationship and impact on headaches, as well as suggestions for diagnostic assessment tools and physical therapeutic management strategies.

METHOD

A narrative structured review was performed. A search was conducted in MEDLINE using terms related to craniofacial pain and headaches. Additionally, papers regarding this topic were also extracted from the authors' personal libraries. Any study design (i.e., RCT, observational studies, systematic review, narrative review) that reported the concepts of interest was included, using Covidence. Results were narratively synthesized and described.

RESULTS

From an epidemiological perspective, craniofacial pain and headaches are strongly related and often co-existing. This may be due to the neuroanatomical connection with the trigeminal cervical complex, or due to shared predisposing factors such as age, gender, and psychosocial factors. Pain drawings, questionnaires, and physical tests can be used to determine the cause of pain, as well as other perpetuating factors in patients with headaches and craniofacial pain. The evidence supports different forms of exercise and a combination of hands-on and hands-off strategies aimed at both the craniofacial pain as well as the headache.

CONCLUSION

Headaches may be caused or aggravated by different disorders in the craniofacial region. Proper use of terminology and classification may help in understanding these complaints. Future research should look into the specific craniofacial areas and how headaches may arise from problems from those regions. (249 words).

Exercise therapy improves pain and mouth opening in temporomandibular disorders: A systematic review with meta-analysis

OBJECTIVE

To analyse the effectiveness of exercise therapy in improving pain and active or passive maximum mouth opening in patients with temporomandibular disorders.

DATA SOURCES

PubMed Medline, Web of Science, Scopus, CINAHL Complete and Physiotherapy Evidence Database, until April 2022, in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

REVIEW METHODS

We included randomized controlled trials evaluating the effect of exercise therapy on pain and on active and passive maximum mouth opening in patients with temporomandibular disorders. Effect size was calculated using Cohen's standardized mean difference (SMD) and their 95% confidence interval (95% CI) in a random-effects model.

RESULTS

A total of 16 studies with 812 participants were included. Exercise therapy is effective in reducing pain (SMD: -0.58; 95% CI: -1.01 to -0.12) and increasing the pain pressure threshold (SMD: 0.45; 95% CI: 0.14-0.76), active and passive maximum mouth opening (SMD: 0.43; 95% CI: 0.14-0.71 and SMD: 0.4; 95% CI: 0.06-0.75, respectively). Subgroup analyses showed more effect of exercise therapy more splints versus splints on pain (SMD: -0.5; 95% CI: -0.73 to -0.26), active and passive maximum mouth opening (SMD: 1.14; 95% CI: 0.22-2.07 and SMD: 0.56; 95% CI: 0.06-1.06, respectively). On pain pressure threshold, exercise therapy was better than physiotherapy approach (manual therapy and electrotherapy) (SMD: 0.48; 95% CI: 0.09-0.87).

CONCLUSIONS

Therapeutic exercise is an effective therapy to reduce pain and increase pain pressure threshold and active and passive maximum mouth opening in patients with temporomandibular disorders.

Headache and orofacial pain: A traffic-light prognosis-based management approach for the musculoskeletal practice

Introduction

Headache (HA) is one of the most prevalent disabling conditions worldwide and is classified as either primary or secondary. Orofacial pain (OFP) is a frequent pain perceived in the face and/or the oral cavity and is generally distinct from a headache, according to anatomical definitions. Based on the up-to-date classification of the International Headache Society, out of more than 300 specific types of HA only two are directly attributed to the musculoskeletal system: The cervicogenic HA and HA attributed to temporomandibular disorders. Because patients with HA and/or OFP frequently seek help in the musculoskeletal practice, a clear and tailored prognosis-based classification system is required to achieve better clinical outcomes.

Purpose

The aim of perspective article is to suggest a practical traffic-light prognosis-based classification system to improve the management of patients with HA and/or OFP in the musculoskeletal practice. This classification system is based on the best available scientific knowledge based on the unique set-up and clinical reasoning process of musculoskeletal practitioners.

Implications

Implementation of this traffic-light classification system will improve clinical outcomes by helping practitioners invest their time in treating patients with significant involvement of the musculoskeletal system in their clinical presentation and avoid treating patients that are not likely to respond to a musculoskeletal based intervention. Furthermore, this framework incorporates medical screening for dangerous medical conditions, and profiling the psychosocial aspects of each patient; thus follows the biopsychosocial rehabilitation paradigm.

Psychological and Behavioral Factors Involved in Temporomandibular Myalgia and Migraine: Common but Differentiated Profiles

BACKGROUND

Many studies have revealed high comorbidity and a clear association between temporomandibular disorders (TMD) and migraine. Furthermore, evidence points out that common psychological and behavioral factors might be related to the observed TMD and migraine association. However, this association and the underlying psychological factors are poorly understood.

OBJECTIVE

The main goal of this study was to describe the psychological and behavioral factors involved in TMD myalgia and migraine.

METHODS

A sample of 142 participants were recruited to form 4 groups: migraine patients (ICHD-III criteria), painful-TMD patients (Myalgia DC/TMD criteria), patients suffering from both pathologies according to the same criteria, and control patients. After a dental and neurological examination, the patients filled several psychological questionnaires validated for the Spanish population to assess anxiety (STAI), depression (DEP), stress coping (CRI), and somatic, anxiety, and depression symptoms (BSI-18).

RESULTS

The TMD myalgia patients, in general, showed a state of elevated anxiety, somatization, and reduced coping strategies, while the patients with migraine presented greater anxiety symptoms, depression (dysthymia trait and state), and somatization.

CONCLUSIONS

According to the data of the present study, situational anxiety (transient emotional state), together with the lack of coping strategies, could be more associated with TMD myalgia, while anxiety, as a more stable and long-lasting emotional state, together with depression, might be more related to migraine. Further longitudinal studies are needed to unravel whether these differentiated profiles are a consequence or possible risk factors for migraine and TMD.

Oral splints in the management of nociceptive pain and migraines: A scoping review

Temporomandibular disorders (TMDs) are characterized by numerous pain manifestations. Their treatment often involves the use of an oral splint. Recent research has found a relationship between migraines, nociceptive pain and TMDs. The aim of the present study was to perform a scoping review of studies in order to evaluate the effectiveness of the various types of oral splint in the treatment of migraine or nociceptive pain. Publications were retrieved from seven databases (PubMed, Web of Science, EMBASE, Scopus, ProQuest, SpringerLink and Ovid). Out of the 15 included publications, three studies were before and after studies, with no control group, whereas the other twelve studies were clinical trials, among which two publications were crossover studies. A clear, single distinction of pain was difficult to describe. Therefore, numerous publications focused on a combination of various types of pains, including myofascial, temporomandibular joint, headaches and migraine-like symptoms, all of which mimicked TMD pain. Overall, six studies used the stabilization splint (SS), three explored the comparison between the SS and the nociceptive trigeminal inhibition splint (NTIS) and two the NTIS. The majority of publications reported a positive outcome of splint therapy. Regarding the type of oral splint usage, the most commonly used one was the SS, followed by the NTIS. The definition and assessment of pain were heterogenous in the identified articles. The findings of the current study showed that occlusal splints may help with pain management, and that effective treatment of TMD-related pain at an early stage can enhance the quality of life of patients.

An Unusual Case of Temporomandibular Joint Disorder Resembling Migraine

This article presents the case of a 32-year-old woman with two distinct temporomandibular joint pathologies: right temporomandibular joint arthralgia, headache, disc displacement with reduction and intermittent locking, and limited opening, whereas the left temporomandibular joint was showing arthralgia and subluxation. A neurologist was regularly consulted and treated the patient for migraine. A detailed clinical assessment was used in the therapeutic approach. Cone beam computed tomography (CBCT) was used in the paraclinical assessment to evaluate the temporomandibular joint (TMJ); CBCT imaging revealed condylar bone changes that were not correlated with the clinical symptoms. To alleviate TMJ symptoms, the treatment plan included anti-inflammatory drugs, physiotherapy and an occlusal splint with lateral guiding ramps. After three months of anti-inflammatory medication, physiotherapy and splint wear, an improvement in the migraine symptoms and enhanced life quality was reported. The variation in pathology between the right and left joints and the extended history of temporomandibular disorder onset with no definitive diagnosis or therapy make this case unique.

The Effect of Individual Nursing on Anxiety and Depression in Patients with Temporomandibular Disorders

Objective

This study aimed to explore the effects of individualized nursing in patients with temporomandibular disorders (TMD).

Methods

From June 2019 to April 2021, 80 patients with TMD were admitted to the First Affiliated Hospital of Wenzhou Medical University. Among them, 40 patients (control group, CG) received routine nursing and 40 patients (experimental group, EG) received individualized nursing. Functional exercise compliance, pain score, maximum mouth opening, nursing satisfaction questionnaire, self-rating anxiety scale, and self-rating depression scale were investigated.

Results

From June 2019 to April 2021, 81 patients with TMD were admitted to the First Affiliated Hospital of Wenzhou Medical University. Among them, 40 patients (control group) received routine care and 41 patients (experimental group) received individual care. There were no significant differences in mouth opening and pain score between the two groups before surgery (P > 0.05), but there were significant differences in mouth opening and pain score between the two groups 3 weeks after surgery. Patients' anxiety and depression were assessed by the SAS and SDS scores. Before nursing, the control group and experimental group (P < 0.05) had no significant difference. After nursing, the score of both groups decreased (P < 0.05). However, the score was lower in the experimental group, compared to the control group (P < 0.01).

Conclusion

In summary, individualized nursing can improve patients' physical condition and reduce negative emotions and complications. In light of this, the study needs further verification by a large sample randomized controlled trial.