Factors involved in the etiology of temporomandibular disorders - a literature review

Effectiveness of Ultrasound Therapy, TheraBite Device, Masticatory Muscle Exercises, and Stabilization Splint for the Treatment of Masticatory Myofascial Pain: A Randomized Controlled Trial

BACKGROUND

Myofascial pain syndrome (MPS) is a particular type of temporomandibular joint disorder. Research findings comparing various treatment approaches are scarce and controversial. Therefore, this study aimed to compare the effectiveness of ultrasound therapy, stabilization splint, TheraBite device, and masticatory muscle exercises in reducing pain intensity and improving mandibular mobility in patients with MPS.

METHODS

It was a single-blind, randomized, parallel-group, active-controlled trial that took place between April 2023 and October 2023 at the Department of Fixed Prosthodontics, Damascus University. Patients older than 18 years old with myofascial pain accompanied by limited jaw opening and pain lasting for at least 6 months were included. Eighty patients were randomly assigned into four groups using online randomization software: ultrasound therapy, stabilization splint, TheraBite device, and masticatory muscle exercises. Only outcome assessors were masked to treatment allocation. The exercise regimen was the exercise program for patients with TMD. The following primary outcome measures were considered at the baseline (t0), at the first (t1), second (t2), and fourth (t3) week of treatment, and at the second (t4) and fifth (t5) month of follow-up: pain intensity using the visual analogue scale, maximum interincisal opening, right lateral movement, and left lateral movement measured in millimeters.

RESULTS

The pain level changed from severe to mild at t3 in ultrasound therapy, stabilization splint, and TheraBite device groups. In the masticatory muscle exercises group, it changed to moderate, with a significant difference between ultrasound therapy (p = 0.012) and stabilization splint (p = 0.013) groups. In addition, the mandibular mobility continued to improve at the subsequent follow-up periods (t4 and t5).

CONCLUSIONS

All therapies are equally effective after 5-month follow-up. However, ultrasound therapy and stabilization splints have the benefit of achieving rapid improvement.

TRIAL REGISTRATION

ISRCTN20833186.

Ultrasound-Guided Vs Non-Guided Prolotherapy for Internal Derangement of Temporomandibular Joint. A Randomized Clinical Trial

OBJECTIVES

This randomized clinical trial study aims to compare ultrasound-guided versus non-guided Dextrose 10% injections in patients suffering from internal derangement in the temporomandibular joint (TMJ).

MATERIAL AND METHODS

The study population included 22 patients and 43 TMJs suffering from unilateral or bilateral TMJ painful clicking, magnetic resonance imaging (MRI) proved disc displacement with reduction (DDWR), refractory to or failed conservative treatment. The patients were divided randomly into two groups (non-guided and ultrasound (US)-guided groups). The procedure involved injection of 2 mL solution of a mixture of 0.75 mL 0.9% normal saline solution, 0.3 mL 2% lidocaine and 0.75 mL dextrose 10% using a 25G needle in the joint and 1 mL intramuscular injection to the masseter muscle at the most tender point. The Visual Analogue Score (VAS) was used to compare joint pain intensity over four different periods, beginning with pre-injection, 1-, 2-, and 6-months postinjection.

RESULTS

Twenty-two patients 5 males (n = 5/22, 22.7%) and 17 females (n = 17/22, 77.2%) were included in this study. The mean age was 27.3 ± 7.4 years (30.2 ± 7.0) for the non-guided group and 24.3 ± 6.9 for the US-guided group. The dextrose injection reduced intensity over time in both groups with statistically significant improvement (P value <.05) at 2 and 6 months in both groups. There was no statistically significant difference in VAS assessment between both groups.

CONCLUSION

Intra-articular injection of dextrose 10% for patients with painful clicking and DDWR resulted in reduced pain intensity in both US-guided and non-guided groups with significant symptomatic improvement over time in both groups. US guidance allowed accurate anatomical localization and safe procedure with a single joint puncture.

Risk factors associated with temporomandibular joint disorder: A mendelian randomization analysis

BACKGROUND

Temporomandibular joint disorder (TMD), a prevalent orofacial disorder with complex aetiologies and considerable socioeconomic costs. This underscores the critical importance of developing a comprehensive understanding of the risk factors associated with TMD, as existing research is hindered by deficiencies in establishing causal relationships and the limitations of traditional research methodologies.

OBJECTIVES

This research explores the causal link between certain risk factors and temporomandibular joint disorder (TMD) through Mendelian randomization (MR), providing multidimensional perspectives in addressing this worldwide health issue.

METHODS

Utilizing instrumental variables, we applied advanced statistical methods, including the weighted median, inverse variance weighted (IVW) and MR-Egger, to evaluate the impact of twelve potential risk factors on TMD.

RESULTS

Our results identified a significant positive association of TMD with malocclusion (p < .001), sleeping disorders (p = .006), anxiety (p = .002), major depression (p = .0002), daily cigarettes consumption (p = .029) and autoimmune diseases (p = .039). Conversely, a negative association was observed with educational attainment (p = .003).

CONCLUSION

These findings suggest that malocclusion, sleeping disorders, anxiety, major depression, daily cigarettes consumption and autoimmune diseases, could potentially increase TMD risk while educational attainment might mitigate its increase. No direct causal relationships were established between serum 25-hydroxyvitamin D levels, menopause, frequent alcohol consumption, coffee intake and severely worn dentition and TMD.

Is There a Relationship between Salivary Cortisol and Temporomandibular Disorder: A Systematic Review

BACKGROUND

This systematic review examines and evaluates the relationship between salivary cortisol levels and temporomandibular disorder (TMD) in young adult patients.

METHOD

Six databases-PubMed, Scopus, Web of Science, Google Scholar, ProQuest, and Cochrane Library-were utilized to screen eligible studies. A systematic search was performed based on PECO questions and eligibility criteria. The research question for this review was "Do salivary cortisol levels correlate with TMD in individuals aged 18-40?" The risk of bias for quality assessment was determined by the Cochrane tool. PRISMA guidelines were followed while performing this review.

RESULT

A total of fourteen studies were included in this review. Of these, eleven were observational studies (four cross-sectional and seven case-control), and three were randomized control trials. Eleven of the included studies presented a low to moderate risk in the qualitative synthesis. The total sample size of the included studies was 751 participants. The included studies suggest higher salivary cortisol levels in TMD patients than in healthy individuals.

CONCLUSIONS

The findings of this review indicate higher salivary cortisol levels in adult patients with TMD than in healthy controls. Thus, supportive psychological treatment and clinical modalities should be provided to patients with TMD. Moreover, higher-quality studies with low heterogeneity are required to support this finding.

The relation between persistent foramen tympanicum and degenerative bone alterations in temporomandibular joint region

OBJECTIVES

The aim of this study was to evaluate, using cone-beam computed tomography (CBCT), the relationship of persistent foramen tympanicum (PFT) with degenerative changes in the temporomandibular joint (TMJ) and the presence of pneumatized glenoid fossae and articular eminences.

METHOD

Two experienced oral and maxillofacial radiologists evaluated 510 CBCT scans, from which 94 patients were divided into two groups: G1-patients with PFT and G2-control group. The location of the PFT, presence, or absence of degenerative TMJ changes and morphology were evaluated. Similarly, all images were evaluated for the presence of pneumatized articular eminence and glenoid fossa. The Chi-square test and Fisher's Exact test were used for the categorical variables. A multinomial logistic regression model was performed for subgroup analysis. To assess the estimation-chance occurrence of TMJ alterations the Odds Ratio analysis was used.

RESULTS

Statistically significant results were found for erosion, planning, and subchondral cyst. Regarding TMJ morphology, significant results were found for: round, flat, and others. Moreover, it was possible to observe that patients who had the PFT were approximately 48 times more likely to manifest TMJ alterations and approximately 3 times more likely to manifest articular eminence pneumatization.

CONCLUSION

Since individuals who have FTP have a greater chance of having TMJ and PEA changes, it is important for the dental radiologist to be aware of these signs in CBCT scans for a correct diagnosis.

TRIAL REGISTRATION NUMBER

CAAE: 34328214.3.0000.0104 (11/30/2014).

Effectiveness of a home exercise program when added to a conventional physiotherapy program in patients with temporomandibular disorders: A comparative study

OBJECTIVE

This study aimed to investigate the effect of a home exercise program on pain and quality of life (QoL) in TMD.

METHODS

Twenty patients were included in the study. The Group A received both a home exercise program and a physiotherapy program, while only a physiotherapy program was given to the Group B. Pain was measured using the Visual Analogue Scale (VAS) and QoL using the Short-Form 36 (SF-36).

RESULTS

Pain decreased in both groups (p < 0.05). Among the SF-36 domains, bodily pain, vitality and social functioning scores improved in the Group A, while only the bodily pain parameter improved in the Group B (p < 0.05). On between-group comparison, the positive effect on pain and quality of life was greater in the Group A (p < 0.05).

CONCLUSION

The addition of a home exercise program to the conventional physiotherapy program provided greater improvement in pain and QoL in patients with TMD.

Voice quality in patients with temporomandibular disorders

OBJECTIVES

This study assessed the voice quality in TMD patients compared to healthy individuals using the Dysphonia Severity Index (DSI) and evaluated the correlation between the DSI and TMD severity.

METHODS

Patients who had TMD with Fonseca's anamnestic index were subjected to an examination based on the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). A sample of 35 patients with TMD and 36 healthy subjects were included in the study.

RESULTS

There were significant differences in the DSI score and its components between healthy subjects and TMD patients (p < .001). A significant correlation was found between the DSI scores and TMD severity (Spearman's rho: -0.90, p < .001).

CONCLUSION

Patients with TMD demonstrated lower DSI scores and lower voice quality compared to healthy subjects.

Exploring Temporomandibular Disorders (TMDs) and Occlusion Debate in Dentistry: Biting Into Controversy

Some conditions known as temporomandibular disorders (TMDs) affect surrounding muscles and jaw joints. In dentistry, there has been discussion and research on the connection between TMDs and occlusion, which is how the upper and lower teeth meet. Although some dental experts have proposed a direct link between TMDs and occlusion, the specifics of this relationship are still unclear and have many facets. More particularly, the research facets of "occlusion" remain one of the most contentious subjects in TMDs. This abstract aims to provide an overview of TMDs and occlusion, summarizing the key points from the literature. The etiological factors contributing to the TMDs, including occlusal, psychological, and hormonal factors, are also analyzed. The second part of the article includes the concept of malocclusion, emphasizing its significance in masticatory function and overall health. Anterior open and posterior open bites and the potential influence of occlusal factors on TMDs are elucidated.

Comparison of the efficacy of occlusal splint and botulinum toxin therapies in patients with temporomandibular disorders with sleep bruxism

PURPOSE

This study aims to evaluate the efficacy of occlusal splint and botulinum toxin (BTX) therapies for improving the pain scores and mouth opening in patients with temporomandibular disorders (TMD) with sleep bruxism (SB).

MATERIALS AND METHODS

A retrospective cohort study was conducted based on clinical record reviews of patients with TMD symptoms (e.g., temporomandibular joint [TMJ] pain, masticatory muscle pain, TMJ internal derangements, joint sounds, and limited mouth opening) and SB. The patients were divided into two groups: occlusal splint group and BTX group. Maximum unassisted mouth opening (MMO) and pain score on a visual analogue scale (VAS) before treatment and at 1‑, 3‑, and 6‑month follow-up were analyzed to evaluate the clinical outcomes.

RESULTS

A total of 60 patients (49 women and 11 men, mean age 34.63 ± 11.85 years) were enrolled. Each group had 30 patients. The comparisons of the groups at 1 and 3 months after treatment indicated that the BTX group had higher MMO values (P = 0.013 and 0.034, respectively) and lower VAS scores than the occlusal splint group (P = 0.000 and 0.001, respectively). No difference between the two groups was observed 6 months after treatment (P > 0.05).

CONCLUSIONS

Both occlusal splint and BTX treatment methods were successful in treating TMD with SB. BTX provided patients with rapid relief in the early period; therefore, BTX can be recommended as a primary treatment option in patients with greater pain.

Neurodevelopmental disorders as a risk factor for temporomandibular disorder: evidence from Mendelian randomization studies

Objective: This study aims to clarify the incidence rate of temporomandibular joint disease in patients with mental disorders. Methods: Data extracted from the Psychiatric Genomics Consortium and FinnGen databases employed the Mendelian Randomization (MR) method to assess the associations of three neurodevelopmental disorders (NDDs)-Attention-Deficit/Hyperactivity Disorder (ADHD), Autism Spectrum Disorder (ASD), and Tourette's Disorder (TD)-as exposure factors with Temporomandibular Disorder (TMD). The analysis used a two-sample MR design, employing the Inverse Variance Weighted (IVW) method to evaluate the relationships between these disorders and Temporomandibular Disorder. Sensitivity analysis and heterogeneity assessments were conducted. Potential confounding factors like low birth weight, childhood obesity, and body mass index were controlled for. Results: The study found that ADHD significantly increased the risks for TMD (OR = 1.2342, 95%CI (1.1448-1.3307), p < 0.00001), TMD (including avohilmo) (OR = 1.1244, 95%CI (1.0643-1.1880), p = 0.00003), TMD-related pain (OR = 1.1590, 95%CI (1.0964-1.2252), p < 0.00001), and TMD-related muscular pain associated with fibromyalgia (OR = 1.1815, 95%CI (1.1133-1.2538), p < 0.00001), while other disorders did not show significant causal relationships. Conclusion: This study reveals the elevated risk of various TMD aspects due to ADHD. Furthermore, we discuss the link between low vitamin D levels ADHD and TMD. Future research should address these limitations and delve further into the complex interactions between ADHD, ASD, TD, and TMD.

Platelet-Rich Plasma in the Management of Temporomandibular Joint Pain in Young Adults With Temporomandibular Disorder

BACKGROUND

Temporomandibular disorder (TMD) encompasses a range of conditions affecting the temporomandibular joint (TMJ) and associated structures, with TMJ pain being a prevalent symptom. Conventional management strategies have limitations, which require the exploration of innovative interventions. Platelet-rich plasma (PRP), known for its regenerative properties, presents a potential therapeutic avenue. This study aims to investigate the effectiveness of PRP in reducing the pain associated with mild TMJ in young adults.

METHODOLOGY

Participants (n = 128) aged 18 to 35 years with mild TMD were evenly randomized into PRP treatment and placebo control groups. PRP was prepared using a standardized protocol, and intra-articular injections were administered. Placebo injections mimic PRP. Follow-up evaluations were carried out at four and eight weeks after the intervention.

RESULTS

The study successfully randomized comparable groups, and the PRP treatment group experienced a significant reduction in TMJ pain (visual analog scale [VAS] score: 6.8 ± 1.2 to 2.1 ± 1.0 at eight weeks, P < 0.001). The PRP treatment also increased the largest opening of the mouth (from 38.2 ± 2.5 to 43.5 ± 3.1, P < 0.001) and the number of lateral movements (12.3 ± 1.5 to 14.9 ± 2.0, P < 0.001), while the placebo group had very few changes. Positive patient-reported outcomes on daily activities were observed, with no serious complications reported in either group.

CONCLUSIONS

This study provides evidence supporting the efficacy of PRP in reducing TMJ pain, improving jaw function, and improving quality of life in young adults with mild TMD. The results underscore the potential of PRP as a minimally invasive intervention for TMJ disorders.

Temporomandibular disorder in individuals with spinal cord injuries

OBJECTIVE

This study evaluated Temporomandibular Disorder (TMD) in individuals with Spinal Cord Injuries (SCI) compared to individuals without physical disabilities.

DESIGN

Cross-sectional.

SETTING

International Fair of Technologies in Rehabilitation and Accessibility (REATECH) and School of Dentistry at the University of São Paulo (USP), Brazil.

PARTICIPANTS

In total, 19 patients with SCI and 19 patients without SCI (36.9 ± 11.4 years old) were examined by a calibrated examiner.

METHODS

using the following parameters: cervical spine mobility, palpation of muscle groups of the head and neck, functional manipulation of the lateral and medial pterygoids, and joint palpation (Diagnostic Criteria). The pattern and amplitude of mandibular movements were determined during screening using the Helkimo index.

STATISTICAL ANALYSES

Student's t-test, chi-square, Fisher's exact and Shapiro-Wilk test were used.

RESULTS

The groups did not differ in the presence of noise, pain, temporomandibular joint palpation, locking, dislocation, jaw pain, muscle sensitivity, or in pain, mobility of the cervical spine and functional manipulation. With respect to the jaw mobility index, the groups differed in range of movement (P = 0.020) and maximum right lateral movement (P = 0.007), with the worst values in the SCI group. The groups also differed in relation to lateral flexion in cervical mobility, in which the group without SCI presented better results (P = 0.046).

CONCLUSION

The Spinal Cord Injuries group showed higher levels of TMD in terms of range of movement, lateral flexion, and maximum right lateral movement, than the individuals without physical disabilities, demonstrating a clinical significance between cervical and mandibular disability in this group.

Prevalence of temporomandibular disorders in clear aligner patients using orthodontic intermaxillary elastics assessed with diagnostic criteria for temporomandibular disorders (DC/TMD) axis II evaluation: A cross-sectional study

BACKGROUND

The objective of this investigation is to assess the relationship between the utilisation of orthodontic intermaxillary elastics and temporomandibular disorder (TMD) symptoms in clear aligner patients and to examine the correlation between the elastic usage time with the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD)-Axis II Evaluation Forms.

METHODS

This study was carried out on a total of 40 clear aligner patients using intermaxillary elastics in the experimental group and 30 clear aligner patients who did not use any intermaxillary elastics in the control group. The data were evaluated using the Mann-Whitney U, chi-square, Fisher's exact chi-square, and Fisher Freeman Halton exact chi-square tests.

RESULTS

The characteristic pain intensity, mastication, mobility, communication, global and PHQ-9 scores of the experimental group were significantly higher than those of the control group (p < .05). The characteristic pain intensity score, interference score and chronic pain grade score of patients using Class III elastics were statistically significantly higher than those of patients using Class II elastics (p < .05). Patients who used elastics for less than 6 months had statistically significantly higher PHQ-9 scores than those who used elastics for more than 6 months (p < .05).

CONCLUSIONS

Orthodontic treatment may affect occlusion, bite force and jaw movement, which may cause or worsen TMD symptoms, and the DC/TMD questionnaires can determine if orthodontic patients acquire TMD by assessing their psychosocial state and pain-related problems.

Sociodemographic Profile: A Forgotten Factor in Temporomandibular Disorders? A Scoping Review

The literature on Temporomandibular Disorders (TMD) incidence commonly reports sociodemographic factors such as gender and age. However, the role and prevalence of other sociodemographic factors in TMD are not well defined. Therefore, this scoping review aimed to report the prevalence of sociodemographic factors in TMD patients. A systematic search was conducted in the PubMed and Web of Science databases to identify clinical trials in adult populations, using the Research Diagnostic Criteria for TMD (RDC/TMD) or the Diagnostic Criteria for TMD (DC/TMD) and reporting sociodemographic data in TMD patients. Twenty-seven studies meeting the criteria were included in this review. The most commonly reported sociodemographic factors assessed in the included studies were age, race, education, job, income, and marital status. TMD prevalence was observed to be higher among younger and divorced individuals among the included studies. However, conflicting results were found for education level, and employment was not considered a risk factor for TMD. Although this review has methodological limitations, it suggests an association between TMD incidence and certain sociodemographic factors; nevertheless, further studies are needed to establish this relationship more conclusively.

Adverse effect of botulinum toxin-A injections on mandibular bone: A systematic review and meta-analysis

INTRODUCTION

Botulinum toxin-A (BTX) is a potent neurotoxin that is emerging in the scope of dental practice for its ability to temporarily paralyse musculature and reduce hyperfunction. This may be desirable in diseases/disorders associated with hyperactive muscles such as the muscles of mastication, most implicated in painful temporomandibular disorders (TMDs). The use of BTX extends beyond its indications with off-label use in TMD's and other conditions, while potential adverse effects remain understudied. BTX is well-established hindlimb paralysis model in animals leading to significant bone loss with underlying mechanisms remaining unclear. The objective of this study is to systematically review the literature for articles investigating changes in mandibular bone following BTX injections and meta-analyse available data on reported bone outcomes.

METHODS

Comprehensive search of Medline, Embase and Web of Science retrieved 934 articles. Following the screening process, 36 articles in animals and humans were included for quantitative synthesis. Articles in human individuals (6) and three different animal species (14) presented mandibular bone outcomes that were included in the meta-analysis.

RESULTS

The masseter and temporalis muscles were frequently injected across all species. In humans, we observe a decrease of about 6% in cortical thickness of mandibular regions following BTX injection with no evident changes in either volume or density of bone structures. In animals, bone loss in the condylar region is significantly high in both cortical and trabecular compartments.

DISCUSSION

Our analysis supports the concept of BTX-induced bone-loss model in animal mandibles. Further, bone loss might be confined to the cortical compartments in humans. Most studies did not address the reality of repeated injections and excessive dosing, which occur due to the reversible action of BTX. More rigorous trials are needed to draw a full picture of potential long-term adverse effects on bone.

Efficacy of Injectable Platelet-Rich Fibrin (I-PRF) in Managing Temporomandibular Joint Pain: A Prospective Clinical Study

BACKGROUND

Temporomandibular joint (TMJ) pain is a common condition that can significantly impact an individual's quality of life. Current treatment options often fall short of providing long-lasting relief. So, this prospective clinical study aimed to investigate the efficacy of injectable platelet-rich fibrin (I-PRF) in mitigating TMJ pain.

METHODS

A total of 68 participants, aged 18-60 years, clinically diagnosed with TMJ pain, were recruited from dental clinics and specialist referrals. Participants were randomly assigned to either the intervention group (I-PRF injections) or the control group (placebo). Primary outcome measures included TMJ pain intensity and jaw function, assessed using the Visual Analog Scale and functional examinations, respectively. Secondary outcomes comprised patient-reported outcomes (PROs) on quality of life and satisfaction. Data were collected at baseline and six, 12, and 24 weeks post intervention.

RESULTS

Baseline characteristics demonstrated successful randomization, with no significant differences in age, gender, or TMJ pain duration between groups. Post intervention, the intervention group exhibited a significant and sustained reduction in TMJ pain intensity compared to controls (p<0.001). Improvements in jaw function were also notable in the intervention group at all follow-up time points (p<0.001). PROs related to quality of life and satisfaction substantially increased in the intervention group compared to controls (p<0.001).

CONCLUSION

I-PRF demonstrated significant efficacy in reducing TMJ pain intensity, improving jaw function, and enhancing PROs. These findings support the consideration of I-PRF as a valuable therapeutic intervention for individuals with TMJ pain.

Association Between Oral Behaviors and Painful Temporomandibular Disorders: A Cross-Sectional Study in the General Population

Background

Studies have reported correlations between various oral behaviors and painful temporomandibular disorders (TMD), yet comprehensive research on the independent effects of each oral behavior within the general population remains sparse.

Objective

This cross-sectional study aimed to investigate the association between painful TMD (PT) and various oral behaviors in general population.

Methods

A questionnaire survey was conducted with participants to collect data encompassing demographic characteristics, eight specific oral behaviors, and the 5 major TMD symptoms(5Ts) checklist. Participants were categorized into PT and non-PT (NPT) groups based on their responses to the 5Ts checklist. Those reporting TMJ/facial pain or headaches were assigned to the PT group, while all other participants constituted the NPT group. Both univariate and multivariate logistic regression analyses were employed to evaluate the association between individual oral behavior and the presence of PT, controlling for demographic confounders including age, sex, systemic diseases, and dental treatments history.

Results

A total of 441 valid questionnaires were received, including 156 males and 285 females. The prevalence of PT was identified to be 33.33%, with 61.00% of participants engaging in one or more types of oral behaviors. Each oral behavior was more frequently reported in the PT group compared to the NPT group. The univariate logistic regression analysis identified positive correlations between all eight oral behaviors and PT. In the multivariate logistic regression analysis, these associations persisted after adjustment for demographic confounders including age, sex, history of systemic diseases and dental treatments (P<0.01). The behaviors most strongly associated with PT were "Hold or jut jaw forward/to the side" (OR:4.478), "Hold, tighten or tense muscles without clench" (OR:3.343) and "Hold jaw in rigid or tense position" (OR:3.209).

Conclusion

The presence of oral behaviors has significant association with PT. Individuals exhibiting multiple oral behaviors are more likely to experience PT. Additional studies are needed to clarify the effects of reducing oral behaviors on pain-related symptoms.

Effects of physical activity levels on characteristic pain in temporomandibular dysfunctions: a cross-sectional study

BACKGROUND

Physical activity is known to influence the symptoms of a variety of pain disorders including fibromyalgia and osteoarthritis although the underlying mechanism is not fully understood. In spite of the high prevalence of temporomandibular disorders (TMD), no previous study has objectively evaluated the relationship between TMD and general physical activity. This study aims to investigate the influence of physical activity on pain and disability from TMD, considering various confounders including sleep, systemic inflammation, psychosocial disturbances, and widespread pain.

METHODS

This observational cross-sectional study is based on consecutive samples of 100 TMD patients (22 with high pain disability and 78 with low pain disability level). Physical activity levels were assessed with actigraph. Level of pain and disability were evaluated using the Graded Chronic Pain Scale. Hematologic examinations including inflammatory biomarkers were assessed and comorbidities were investigated with validated questionnaires. Differences were analyzed according to disability level.

RESULTS

Patients with high disability level spent significantly more time doing both moderate (p = 0.033) and vigorous (p = 0.039) level physical activity. Light physical activity, on the other hand, was associated with low disability but the difference did not reach statistical significance. Time spent in light physical activity was significantly associated with high levels of pain and disability (p = 0.026, β = -0.001) and time spent in vigorous physical activity had significant predictive power (cutoff value 2.5 min per week, AUC 0.643, p = 0.041). Scores of the Jaw Function Limitation Score-20 (p = 0.001), present McGill Pain Score (p = 0.010), and number of people potentially diagnosed with fibromyalgia (p = 0.033) were significantly higher in the high disability group.

CONCLUSIONS

Moderate or vigorous physical activity is associated with worse TMD symptoms while light physical activity may be beneficial. Further research related to the amount and frequency of physical activity is necessary to establish clinical guidelines for TMD.

TRIAL REGISTRATION

clinical trial registration of the Clinical Research Information Service of Republic of Korea (number KCT0007107).

Effect of a centric stabilization splint on masticatory muscles in patients with temporomandibular disorders: An electromyographic study

AIM

Occlusal splint treatment is commonly used to treat a variety of temporomandibular disorders (TMDs), with efficacy ranging between 70% and 90%. Centric splints are effective in relieving muscular soreness in individuals with TMD. Electromyography (EMG) quantifies muscle activity and can be used as an accessory diagnostic tool to evaluate the efficiency of the splint on the masticatory complex. Electromyography is used for assessing patients with TMD and observing muscle electromyography. TMD patients have altered electromyographic (EMG) masticatory muscle activity because of its change in electrical activity index or because of the compensatory mechanism for the disorder. Therefore, this study serves to evaluate the efficacy of the centric stabilization splint on TMD using EMG.

SETTINGS AND DESIGN

This cross-sectional study enrolled Ten TMD Patients with TMD, who underwent treatment with centric stabilization splint.

MATERIALS AND METHODS

The study involved ten young adults with TMD aged 18-45 years who were recruited without regard to sex, religion, caste, or socioeconomic background. The participants were randomized to receive a flat-contact upper stabilization splint and pregelled EMG electrodes to assess the immediate impact of centric splints on TMDs. After 3 months of follow-up, muscle activity and muscle symmetrical activity were measured to assess improvement in the symptoms of TMD.

STATISTICAL ANALYSIS USED

The Shapiro-Wilk test was used to assess the normality of the variables' distribution using SPSS 26.0. Symmetrical activity and treatment response were investigated using the Wilcoxon signed-rank test.

RESULTS

It showed an improvement in the temporalis, masseter, and sternocleidomastoid muscles' resting EMG activity. A statistically significant improvement was seen in the EMG activity of the bilateral temporalis, right masseter, right sternocleidomastoid, and left digastric muscles while clenching. The masseter, sternocleidomastoid, and digastric muscles all displayed significantly enhanced symmetrical activity (P < 0.05).

CONCLUSIONS

This research concludes that a centric stabilizing splint assists in relieving TMD symptoms. There was enhanced masticatory muscle activity both at rest and during function. Furthermore, there was an improvement in symmetrical activity of the masticatory muscles, which improved balance and enhanced the effective functioning of the masticatory complex.

Sensory innervation of masseter, temporal and lateral pterygoid muscles in common marmosets

Myogenous temporomandibular disorders is associated with an increased responsiveness of nerves innervating the masseter (MM), temporal (TM), and lateral pterygoid muscles (LPM). This study aimed to examine sensory nerve types innervating MM, TM and LPM of adult non-human primate-common marmosets. Sensory nerves were localized in specific regions of these muscles. Pgp9.5, marker for all nerves, and NFH, a marker for A-fibers, showed that masticatory muscles were primarily innervated with A-fibers. The proportion of C- to A-fibers was highest in LPM, and lowest in MM. All C-fibers (pgp9.5+/NFH-) observed in masticatory muscles were peptidergic (CGRP+) and lacked mrgprD and CHRNA3, a silent nociceptive marker. TrpV1 was register in 17% of LPM nerves. All fibers in masticatory muscles were labeled with GFAP+, a myelin sheath marker. There were substantially more peptidergic A-fibers (CGRP+/NFH+) in TM and LPM compared to MM. MM, TM and LPM NFH+ fibers contained different percentages of trkC+ and parvalbumin+, but not trkB+ fibers. Tyrosine hydroxylase antibodies, which did not label TG, highlighted sympathetic fibers around blood vessels of the masticatory muscles. Overall, masticatory muscle types of marmosets have similarities and differences in innervation patterns.

Causal relationship between psychiatric traits and temporomandibular disorders: a bidirectional two-sample Mendelian randomization study

OBJECTIVES

This study was to investigate the causal relationship between temporomandibular disorders (TMD) and psychiatric disorders by Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

A two-sample bidirectional MR analysis was adopted to systematically explore the causal relationship between TMD and eight psychiatric traits, including anxiety disorder (AD), panic disorder (PD), major depressive disorder (MDD), neuroticism, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar disorder (BIP), and schizophrenia (SCZ). Inverse variance weighted (IVW), weighted median, and MR-Egger regression were used in my study. Furthermore, we also performed three sensitivity analyses to illustrate the reliability of the analysis.

RESULTS

Two psychiatric traits have risk effects on TMD: PD (OR = 1.118, 95% CI: 1.047-1.194, P = 8.161 × 10-4, MDD (OR = 1.961, 95% CI: 1.450-2.653, P = 1.230 × 10-5). Despite not surpassing the strict Bonferroni correction applied (P > 0.00625), we could think that there was a suggestive causal effect of neuroticism and SCZ increasing the risk of TMD. On the reverse MR analysis, we found no significant evidence of causal effects of TMD on these psychiatric traits. Except for heterogeneity in the causal analysis for SCZ on TMD, no heterogeneity and horizontal pleiotropy were detected in the other analyses.

CONCLUSIONS

Our two-sample MR study has provided further evidence of PD and MDD being related to a higher risk of TMD.

CLINICAL RELEVANCE

These findings highlight the importance of closely monitoring mental traits during future TMD treatments to prevent an increased risk of TMD.

Efficacy of the transcutaneous electrostimulation in treatment dysfunctions of the TMJ associated with occlusion distortions

BACKGROUND

The study evaluation of the effectiveness the method of electrostimulation in treatment TMJ associated with occlusion disorders with the use of a patches by the company "Aganyan''.

METHODS

The study included 54 patients with temporomandibular dysfunction syndrome who had previously undergone endodontic dental treatment. In patients temporomandibular disorders (TMD) determined on the basis of Diagnostic criteria for temporomandibular disorders(DC/TMD).All patients had occlusion disorders due to errors after dental filling restoration. To diagnose the TMJ, a CT scan was used. The complex therapy also included therapy and with the use of a patches by the company "Aganyan''. The wearable patch includes a flexible substrate, a binder an adhesive layer, with an electrode foil attached to it. Patients applied one patch behind each TMJ. The patches were applied for eight hours every third day for three months. All the patients were given full-fledged endodontic treatment and restoration of the crown part, taking into account anatomical features.

RESULTS

The dynamics of the complex treatment of patients diagnosed with TMJ dysfunction syndrome showed that after treatment, the clinical symptoms gradually decreased and disappeared at the end of treatment. CT scan a year after treatment showed a normal ratio of TMJ elements. Сomplex treatment was effective in 87% of patients, after 3-5 months gradually decreased pain, noise in the joints, restriction of opening and closing of the mouth disappeared. Patients recovered their chewing functions, psycho-emotional state.

CONCLUSION

The results of the studies revealed a positive effects for the complex treatment dysfunctions syndrome TMJ the using the patches by the company "Aganyan" through electrical stimulation with low intensity.

Myopia & painful muscle form of temporomandibular disorders: connections between vision, masticatory and cervical muscles activity and sensitivity and sleep quality

The main aim of this study is to evaluate the effects of painful muscle form of temporomandibular disorders and myopia on the connections between the visual organ, the bioelectrical activity and sensitivity of the masticatory and cervical muscles, and sleep quality. Subjects were divided into 4 groups (Myopia & TMDs, Myopia (Without TMDs), Emmetropic & TMDs and Emmetropic (Without TMDs)). The study was conducted in the following order of assessment: examination for temporomandibular disorders, assessment of the muscle activity by electromyograph, pressure pain thresholds examination, ophthalmic examination and completion of the Pittsburgh Sleep Quality Index. It was observed that the Myopia & TMDs group had higher muscle tenderness, higher resting and lower functional muscle bioelectrical activity. The visual organ is clinical related to the masticatory and cervical muscles. TMDs and myopia alter masticatory and cervical muscle activity. The thickness of the choroid in people with myopia is related to muscle tenderness. TMDs and myopia impair sleep quality. It is recommended to determine the number of people with refractive error and its magnitude in the sEMG study in order to be able to replicate the research methodology.

The Physical Symptom Scale-8: Psychometric Characteristics of a Short-Form Version of the PHQ-15 and its Use in TMD-Related Assessment and Research

AIMS

To describe the development of the Physical Symptom Scale-8 (PSS-8) and to examine its psychometric properties and use in temporomandibular disorder (TMD)-related assessment and research.

METHODS

An online survey comprising demographic variables, the DC/TMD pain screener (TPS), Short-Form Fonseca Anamnestic Index (SFAI), PSS-8, PHQ-15, and Depression, Anxiety, and Stress Scale-21 (DASS-21) was administered to young adults attending a technical college. The PSS-8 adopted the Somatic Symptom Scale-8 (SSS-8) items but maintained the 3-point response scale and 4-week time frame of the PHQ-15. Internal consistency and reliability of the PSS-8 were determined by its Cronbach α value. Known-groups and concurrent/convergent validity were examined using Mann-Whitney U test and Spearman correlation (α = .05), respectively.

RESULTS

Responses from 400 participants (mean age 18.8 ± 1.5 years; 52.3% women) were evaluated. Pain-related (WPT) and all (WAT) TMDs were present in 8.5% and 17.3% of the sample, respectively. The PSS-8 exhibited good internal consistency (α = 0.82) and sound known-groups validity, with the WPT/WAT groups having significantly higher PSS-8 scores than those without TMDs. Good concurrent and convergent validity were also observed, with moderate to strong correlations with the PHQ-15 (rs = 0.97) and DASS-21 scores (rs = 0.48 to 0.60). Correlations with the TPS and SFAI scores were weaker (rs = 0.28 to 0.34).

CONCLUSION

The PSS-8 presented good psychometric properties and performed similarly to the PHQ-15. It holds promise as the "de facto" shortened version of the PHQ-15 for TMDs and related work.

Personality, psychosocial and oral behavioural risk factors for temporomandibular disorder symptoms in Asian young adults

BACKGROUND

The relation between personality, psychosocial factors, somatisation, andoral behaviours as risk factors to temporomandibular disorder symptoms have notbeen well established.

OBJECTIVES

This study examined the association of temporomandibular disorder (TMD) symptoms with personality traits, psychological distress, somatisation and oral behaviours. The psychosocial and oral behavioural risk factors for TMD symptoms were also established in Asian young adults.

METHODS

Participants were recruited from a large private University. Based on the quintessential five TMD symptoms (5Ts) of the DC/TMD, the participants were stratified into those with no (NT), painful (PT), dysfunctional (DT) and mixed (MT) TMD symptoms. Personality traits, psychological distress, somatisation and oral behaviours were evaluated with the Big Five Inventory-10 (BFI-10), Depression, Anxiety, Stress Scales-21 (DASS-21), Patient Health Questionnaire-15 (PHQ-15) and Oral Behaviours Checklist (OBC) accordingly. Data were examined using Kruskal-Wallis/Mann-Whitney U and Chi-squared tests, as well as multivariate logistic regression analysis (α = .05).

RESULTS

Of the 420 young adults (mean age 22.7 ± 1.1 years) evaluated, 41.4% had no TMD symptoms, while 17.4%, 20.0% and 21.2% reported PT, DT and MT, respectively. Though personality traits did not vary notably, participants with MT and PT had significantly higher levels of negative affectivity, anxiety and stress than the NT group. Moreover, those with MT and PT presented significantly greater somatisation and more oral behaviours than the DT and NT groups. Multivariate regression analyses indicated that anxiety, somatisation, sleep-related and waking-state nonfunctional oral activities were associated with painful and/or dysfunctional TMD symptoms.

CONCLUSIONS

Except for sleep-related oral activity, psychosocial and oral behavioural risk factors differed for painful, dysfunctional and mixed TMD symptoms in Asian young adults.

Comparative Analysis of Mandibular and Cervical Mobility in Young Adults with Temporomandibular Joint Disorders: A Case-Control Study

BACKGROUND Temporomandibular joint disorders (TMJD) affect the muscles of the mandible or the temporomandibular joint (TMJ). The objective of this case-control study was to compare mandibular and cervical joint mobility in young adults diagnosed with TMJD to a healthy control group. MATERIAL AND METHODS We enrolled 60 participants aged 18-30 years, split evenly between 30 TMJD patients and 30 healthy controls. We employed a millimeter gauge to measure TMJ mobility and a tape-based tool for assessing the range of cervical mobility. RESULTS Our data revealed that TMJD patients exhibited a significantly reduced range of mobility in both the TMJ and cervical spine compared to controls. Controls demonstrated a greater mean cervical mobility through left and right lateral flexion movements (P<0.01 and P<0.05 respectively), as well as right and left rotations (P<0.05). Additionally, they showed significantly higher mandibular mobility across all tested parameters (P<0.001). Within the TMJD group, we observed a significant correlation between cervical and mandibular mobility (P<0.05). CONCLUSIONS Our findings underline that TMJD patients possess significantly diminished mandibular and cervical mobility, particularly in lateral movements and rotations, compared to those without the disorder. The observed correlation between cervical and mandibular mobility in the TMJD group implies the necessity to consider these interconnected aspects when designing rehabilitation programs, thereby enhancing patient quality of life and impeding further mobility deterioration.

DC/TMD Axis I diagnostic subtypes in TMD patients from Confucian heritage cultures: a stratified reporting framework

OBJECTIVES

This study proposed a conceptual framework for reporting Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I conditions and investigated the prevalence of TMD subtypes/categories in patients from Confucian heritage cultures. Variances in gender, age, and TMD chronicity between Chinese (CN) and Korean (KR) patients were also explored.

MATERIALS AND METHODS

Subjects were recruited from consecutive patients seeking care at two University-based centers in Beijing and Seoul. Eligible patients completed a demographic survey as well as the DC/TMD Symptom Questionnaire and were clinically examined according to the DC/TMD methodology. Axis I diagnoses were subsequently rendered with the DC/TMD algorithms and documented using the stratified reporting framework. Statistical evaluations were performed with chi-square, Mann-Whitney U tests, and logistic regression analysis (α = 0.05).

RESULTS

Data of 2008 TMD patients (mean age 34.8 ± 16.2 years) were appraised. Substantial differences in female-to-male ratio (CN > KR), age (KR > CN), and TMD duration (KR > CN) were observed. Ranked frequencies of the most common Axis I diagnoses were: CN - disc displacements (69.7%) > arthralgia (39.9%) > degenerative joint disease (36.7%); KR - disc displacements (81.0%) > myalgia (60.2%) > arthralgia (56.1%). Concerning TMD categories, notable differences in the prevalence of intra-articular (CN 55.1% > KR 15.4%) and combined (KR 71.8% > CN 33.4%) TMDs were discerned.

CONCLUSIONS

Though culturally similar, the two countries require disparate TMD care planning/prioritization. While TMJ disorders in children/adolescents and young adults should be emphasized in China, the focus in Korea would be on TMD pain in young and middle-aged adults.

CLINICAL RELEVANCE

Besides culture, other variables including socioeconomic, environmental, and psychosocial factors can influence the clinical presentation of TMDs. Chinese and Korean TMD patients exhibited significantly more intra-articular and combined TMDs respectively.

The Impact of Temporomandibular Disorders on Orthodontic Management: A Systematic Review and Meta-Analysis

The literature on the impact of temporomandibular disorders (TMDs) on orthodontic management or vice versa lacks clarity. This study presents a review that aims to evaluate the influence of TMDs on orthodontic management and explore the association between TMDs and various aspects of orthodontic treatment. A systematic search was conducted across multiple databases to identify relevant articles documenting the correlation between TMD incidence and orthodontic treatment to achieve the objectives. The selection process followed predefined criteria, and the selected studies underwent bias assessment using the AXIS tool and Cochrane risk of bias (RoB) tool. Among the articles identified, nine studies were deemed suitable for inclusion in the review. The findings from the subsequent meta-analysis indicated a significant overall effect, suggesting that orthodontic treatment may increase the risk of developing TMD. Furthermore, the analysis revealed that patients with TMD had higher odds of experiencing orthodontic issues than those without TMD. Subgroup analysis further demonstrated that orthodontic treatment could have a negative impact on the psychological well-being of TMD patients, while its effect on TMD incidence was found to be negligible. The results highlight the need for additional research to gain a better understanding of the underlying mechanisms and develop appropriate interventions aimed at minimizing the risk of TMD in patients undergoing orthodontic treatment. Clinicians should be aware of TMD as a potential complication of orthodontic treatment and implement appropriate monitoring strategies.

Comparison of painful temporomandibular disorders, psychological characteristics, sleep quality, and oral health-related quality of life of patients seeking care before and during the Covid-19 pandemic

BACKGROUND

Literature concerning Temporomandibular disorders (TMDs) and the Covid-19 pandemic is limited and disparate findings related to TMD frequencies, psychological distress, and quality of life were presented. This study investigated the prevalence of painful Temporomandibular disorders (TMDs) and compared the psychological, sleep, and oral health-related quality of life profiles of patients seeking TMD care before and during the Covid-19 pandemic.

METHODS

Data were accrued from consecutive adult patients 12 months before (BC; control) and during (DC; case group) the Covid-19 pandemic. The Diagnostic Criteria for TMDs (DC/TMD), Depression, Anxiety, Stress Scales (DASS)-21, Pittsburgh Sleep Quality Index (PSQI), and Oral Health Impact Profile (OHIP)-TMDs were utilized and statistical analysis was performed using Chi-square/non-parametric tests (α = 0.05).

RESULTS

The prevalence of painful TMDs was 50.8% before and 46.3% during the pandemic. Significant differences in PSQI and OHIP component scores were discerned between the BC and DC groups contingent on TMD pain. Total-DASS was moderately correlated to total-PSQI/OHIP (rs = 0.41-0.63).

CONCLUSION

The covid-19 pandemic did not appear to exacerbate psychological distress but affected sleep and increased unease over TMD dysfunction.

Prevalence of Temporomandibular Joint Disorder Among Dental Students in Chennai

The objective was to understand the prevalence of temporomandibular joint disorder among dental students. The study was conducted in Tagore Dental College, Chennai. The questionnaire study included a total of 371 students from years I to V, under the age group of 18-30, who had a history of temporomandibular joint disorders on the day of the survey. Each student was given a semi-structured study questionnaire related to assessing possible causes, assessment of habits, assessment of subjective symptoms, and evaluation of pain. It was analysed using an anamnestic scale as 0: no symptoms; I: mild symptoms; II: severe symptoms. An independent t-test was used to compare the variables. The significance level set at 0.05 (p < 0.05) showed that the prevalence of Temporomandibular disorders was insignificant in the study population due to various contributing factors.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12663-023-01866-y.

The Role of Supraerupted and Distoverted Maxillary Third Molars in the Treatment of Temporomandibular Disorder: A Randomised Controlled Trial

Objective Temporomandibular disorder (TMD) is a multifactorial disease that is classified into muscular and joint disorders. The etiology of TMD is unknown but it is related to various factors such as bruxism, uncorrected high dental restorations, and occlusal prematurities. This study aims to provide treatment modalities for TMD patients with supraerupted and/or distoverted maxillary third molars that have premature contact with the opposing arch. Methods A total of 430 subjects diagnosed with TMD were included in the study and randomized into study and control groups based on their treatment needs. A detailed case history was taken, and findings of intra and extra oral examination were recorded along with other investigations such as study model analysis, orthopantomogram (OPG), cone-beam computed tomography (CBCT), and MRI. The multiphase treatment included counseling in phase I, extraction in phase II (only for the study group), and oral appliance in the third phase. The final phase involved the restoration of edentulous areas or reduced vertical dimension. Results Extraction of supraerupted and/or distoverted maxillary third molars in the study group during phase II showed a 96% reduction in TMD when compared to the control group who did not undergo extraction. Conclusion TMD is a repetitive motion disorder, and the success of treatment relies on the elimination of causative factors, the type of appliance used, and the establishment of ideal occlusion. This study suggests that the extraction of supraerupted and/or distoverted maxillary third molars is a prerequisite for treating TMD patients.

Role of Dynamic 3 Tesla MRI in the Evaluation of Temporomandibular Joint Dysfunction

INTRODUCTION

The internal derangement of the temporomandibular joint (TMJ) is the most common type of dysfunction. Internal derangement can be divided into anterior and posterior disc displacement. Anterior disc displacement is the most common type, which is further classified into anterior disc displacement with reduction (ADDWR) and without reduction (ADDWoR). Temporomandibular joint dysfunction (TMD) symptoms are pain, reduced mouth opening, and joint sound. The main aim of this study was to correlate the clinical findings and magnetic resonance imaging (MRI) diagnosis of TMD in symptomatic and asymptomatic TMJs.

METHODS

This prospective observational study was conducted in a tertiary care hospital on a 3T Philips Achieva MRI machine with 16-array channel coils after obtaining approval from the institutional ethical committee. A total of 60 TMJs of 30 patients were included in the study. After the clinical examination of each patient, an MRI of both right and left TMJs was done. In patients with unilateral TMD, the asymptomatic side was used as the asymptomatic joint, and the affected side as the symptomatic joint. Asymptomatic patients without any symptoms of TMD were used as controls for bilateral TMD cases. MRI with high-resolution specific serial sections was obtained in both open- and closed-mouth positions. A p-value of <0.05 was considered a statistically significant agreement between clinical and MRI diagnoses of internal derangement.

RESULTS

Out of a total of 30 clinically asymptomatic TMJs, only 23 were normal on MRI. On MRI, 26 TMJs showed ADDWR and 11 showed ADDWoR. The most common shape of the disc was biconcave and the displacement was anterior in symptomatic joints. The most common type of articular eminence shape was sigmoid in ADDWR and flattened in ADDWoR. Agreement between clinical and MRI diagnosis in this study was 87.5% (p < 0.001).

CONCLUSION

 The study concluded substantial agreement between clinical and MRI diagnosis of TMJ internal dysfunction and suggests that the diagnosis of the internal dysfunction can be made clinically but the exact position, shape, and type of disc displacement can be assessed precisely with the help of MRI.

Development and application of a questionnaire to evaluate signs of temporomandibular disorder observed by caregivers of children with autism spectrum disorder

OBJECTIVE

This study aimed to develop and validate a questionnaire to detect signs of temporomandibular disorders (TMD), verifying whether the perception of signs observed by caregivers of non-verbal autistic children are the same as those observed by caregivers of verbal ones.

METHODS

This is a cross-sectional, exploratory and analytical study. The sample consisted of forty individuals with Autism Spectrum Disorders (ASD), thirty non-verbal and ten verbal, besides their respective caregivers. For this, an experimental questionnaire was applied and compared to the European Academy of Orofacial Pain (EAOP) questionnaire, which is already validated and widely used throughout the world. All responses were compared using the chi-square test and the questionnaires were compared with the McNemar test, considering p < .05.

RESULTS

When comparing the number of coincident responses to the questionnaire between caregivers and children, the mean was 8.2 ± 1.61 responses. After performing the binomial test, no statistically significant discrepancy was found between the results of the two tests adopted when the questionnaires were compared (Mc Nemar test, p > .05) CONCLUSION: The development of this questionnaire and its validation serve as a support for health professionals in the TMD area, for the detection of TMD in non-verbal autistic children, providing them and their caregivers, who are faced with several difficulties in their day-by-day, a facilitating instrument.

Relationship between the Mandibular Condyle Position and the Bite Force in the People with Normal Temporomandibular Joint

Statement of the Problem. The mandibular condyle position is important in temporomandibular joint (TMJ) disorders. The bite force is a mechanical force that may affect the condylar position. Purpose. To investigate the relationship between condylar position in the glenoid fossa and maximum bite force in adults with normal temporomandibular joint. Materials and Methods. In this cross-sectional study, 23 subjects (21 females and 2 males; mean age 38.88 $\pm$ 11.7 years) with 41 joints participated. Right and left joints were examined using cone-beam computed tomography. Maximum bite force was measured using the strain gauge transducer in the regions of right molar, left molar, and incisors. Pearson correlation coefficient, paired sample t-test, and binary logistic regression were employed for analysis. Results. The mean maximum bite force was 169.09 ± 87.7 N. The most common position of the condyle was anterior (n = 36) and inferior (n = 31). The mean of mandibular condyle joint spaces for right and left sides were not statistically significant ( $P>0.05$ ). There were no relationships between the condylar positions and the mean maximum bite force ( $P>0.05$ ). Conclusion. The condylar positions in the glenoid fossa are not related to the bite force in the people with normal temporomandibular joint.

Does physical activity level have an impact on long-term treatment response in temporomandibular disorders: protocol for a prospective study

Background

Temporomandibular disorders (TMD) is a disease characterized by pain and dysfunction of the masticatory muscles and temporomandibular joint. Many factors have been found to be related to the disease however, the underlying mechanism is yet to be fully elucidated. Physical activity is widely known to modulate pain intensity in various pain disorders. However, literature suggesting the association between physical activity and signs and symptoms of TMD are limited.

Methods and design

The “Physical Activity in TMD (PAT)” is a prospective study on TMD patients that aims to determine how daily physical activity and sleep duration affect long-term TMD prognosis following conventional treatment. To analyze such effects, objective data on daily physical activity levels will be collected along with clinical indices including mouth opening ranges and masticatory muscle palpation responses from adult Koreans diagnosed with TMD following standardized diagnostic procedures. Well-known comorbidities of TMD will be extensively evaluated based on validated structured questionnaires on sleep quality, fatigue level, widespread pain, psychological status including depression and anxiety, autonomic symptoms, and health-related quality of life. The collected data will be analyzed according to TMD pain severity and physical activity level, and correlations among physical activity indices and long-term TMD prognosis will be investigated.

Discussion

In this longitudinal prospective study of adult Koreans diagnosed with TMD following standardized diagnostic procedures, primary outcomes include physical activity levels and long-term TMD clinical outcomes and secondary outcomes include disability from pain and related comorbidity levels. Results and analysis are ongoing. The results of this study will provide reliable data for future research and establish clinical guidelines that will allow cause-related, patient-tailored personalized medicine for TMD.

Trial registration: Clinical Research Information Service (Registration number: KCT0007107). Registered March 22 2022 https://cris.nih.go.kr/cris/search/detailSearch.do?search_lang=E&focus=reset_12&search_page=M&pageSize=10&page=undefined&seq=21420&status=5&seq_group=21420.

Prevalence of temporomandibular disorders and its association with malocclusion in children: A transversal study

This study investigated the prevalence of temporomandibular disorders (TMDs) in a sample of children and adolescents and evaluated the correlation with occlusal variables. TMD signs and symptoms were recorded in 411 subjects (age range 7-15 years), divided into two groups: 214 subjects treated in Chieti (Italy) CG group and 197 in Murcia (Spain) MG group. Once the Angle dental class was identified, it was recorded if there were signs and symptoms of temporomandibular disorders (TMDs) and occlusal interferences. The percentages of signs and symptoms were compared to determine the differences among the groups for TMDs, bruxism, joint sounds, deviation during the opening, reduced opening/lateral/protrusive movements, malocclusions, and myofascial pain. There is no statistically significant difference between the two groups (χ² = 1.057, p > 0.05). Subjects with Angle Class I (37.37%), deep bite (43.43%), and increased overjet (41.41%) showed a higher prevalence of TMD symptoms.

Prevalence of Temporomandibular Disorder-Related Pain among Adults Seeking Dental Care: A Cross-Sectional Study

Objectives

Temporomandibular disorders (TMD) are a constellation of painful conditions that affect the craniofacial complex. The etiology and risk factors of these conditions have been extensively studied; however, the data available describing the epidemiology of TMD in the Middle East are scarce. We aimed to estimate the prevalence and risk factors of TMD-related pain in a sample population of dental school clinic patients.

Methods

This observational cross-sectional study used a translated and culturally adapted temporomandibular disorders pain screener, a part of the Diagnostic Criteria/Temporomandibular Disorders (DC/TMD) criteria instrument, and questions related to demographic characteristics and risk factors for TMD. Data were analyzed through chi-square and Mann–Whitney U tests using SPSS.

Results

The sample population included 199 participants (66% female and 34% male). The prevalence of TMD-related pain was 26.8% (n = 42); men and women did not differ statistically in their TMD-related pain. TMD-related pain cases differed significantly on the Center for Epidemiologic Studies Depression Scale (CES-D) and body pain scores compared with noncases.

Conclusion

The prevalence of TMD-related pain in the clinical sample population was high. Hence, the onus is on dental health services to screen and educate patients on TMD conditions regularly.

Determining the existence of the foramen of Huschke in patients with temporomandibular joint disorders using cone beam computed tomography: retrospective cohort study

Background

Foramen of Huschke has been presented as an unusual developmental defect in anteroinferior aspect of external auditory canal. It can be associated with significant otologic complications. The purpose of this study was to determine the association between existence of foramen of Huschke and temporomandibular joint disorders in Cone Beam Computed Tomography (CBCT) images.

Methods

Of an initial sample of 465 patients, we retrospectively evaluated the CBCT images of 118 individuals with clinical signs and symptoms of temporomandibular joint disorders as case group and 256 individuals as control group. The presence, size and localization of foramen of Huschke were assessed in the axial and corrected sagittal images. The sex and age distribution were determined. Fisher’s exact test, T-test and Pearson’s Chi-square were applied to assess the relationship between foramen of Huschke and temporomandibular joint disorders in the case and control groups considering age and sex.

Results

The foramen of Huschke prevalence was slightly higher in patients with temporomandibular joint disorders (3.4%) than patients without temporomandibular joint disorders (0.8%). However, the difference was not statistically significant (P = 0.082). foramen of Huschke was found in five females and one male. There was no significant difference between case and control groups considering the age of patients with foramen of Huschke (P = 0.683). There was no significant difference between the case and control groups, considering the right and left ears in distribution of foramen of Huschke (P = 0.099) (P = 0.183).

Conclusions

Higher prevalence of foramen of Huschke in patients with temporomandibular joint disorders may suggest possible mechanism for temporomandibular joint disorders development that can be affected by presence of foramen of Huschke.

A Randomized Controlled Trial Evaluating the Levels of the Biomarkers hs-CRP, IL-6, and IL-8 in Patients with Temporomandibular Disorder Treated with LLLT, Traditional Conservative Treatment, and a Combination of Both

Temporomandibular disorders (TMDs) are a type of idiopathic orofacial pain. Inflammation, particularly elevated circulating levels of high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and interleukin-8 (IL-8), has been linked to pain symptoms. The purpose of this study was to compare hs-CRP, IL-6, and IL-8 biomarkers and pain intensity with different treatment strategies (LLLT, standard conservative treatment, and combination) for TMD patients. Methods: A total of 32 participants were randomly included in the study and divided into three groups (Group I, Group II, and Group III) referred from the Dental Clinic, School of Dental Science, HUSM. Patients received LLLT (Groups II and III) in five sessions for the duration of 10 days. Patients in Groups I and III received standard conservative TMD treatment (diet and stress counseling, jaw exercises, physical therapy, which was a hot towel application) by the principal investigator. All blood samples for biomarkers were performed before starting treatments and directly after finishing the treatment protocols, where all results were recorded. Results: The result showed a significant difference in the mean IL-8 (p = 0.001) between the three intervention groups (LLLT, standard treatment, and combined treatment). IL-6 showed an increase in the mean of IL-6 levels from baseline to post-treatment with a better mean in the LLLT treatment group without any significant differences. Additionally, there were no significant mean differences found between the groups and in the group for the hs-CRP biomarker. Conclusions: A statistically non-significant difference was found in hs-CRP and IL-6 before and after LLLT, conservative, and combined treatment strategies of TMD. A statistically significant difference was observed in the mean levels of IL-8 between the LLLT intervention group and the combined treatment group. Although there was no statistically significant correlation between pain intensity and biomarkers, a statistically significant difference was found in pain intensity before and after LLLT, conservative, and combined treatment strategies. TMJ degeneration could be exacerbated by elevated IL-8 levels. Thus, this can be an important biomarker to mark or identify the painful condition of TMJ.

Alterations in kinematics of temporomandibular joint associated with chronic neck pain

BACKGROUND

Temporomandibular disorder (TMD) is an umbrella term for pain and dysfunction of the temporomandibular joint (TMJ) and its associated structures. Patients with TMD show changes in TMJ kinematics and masticatory muscle activation. TMD is commonly comorbid with non-specific chronic neck pain (NCNP), which may be one of the risk factors for TMD.

OBJECTIVES

This study aimed to investigate whether patients with NCNP have altered TMJ kinematics and masticatory muscle activity.

METHODS

This was a cross-sectional exploratory study including 19 healthy participants and 20 patients with NCNP but without TMD symptoms. TMJ kinematics was measured during mouth opening and closing, jaw protrusion and jaw lateral deviation. Surface electromyography was used to record the muscle activity of the anterior temporalis, masseter, sternocleidomastoid and upper trapezius while clenching. Furthermore, cervical posture, cervical range of motion (ROM) and pressure-pain threshold of the neck and masticatory muscles were measured.

RESULTS

Compared with the healthy group, the NCNP group showed significantly reduced upper cervical rotation ROM (p = .041) and increased condylar path length (p = .02), condylar translation (opening p = .034, closing p = .011) and mechanical pain sensitivity of the upper trapezius (p = .018). Increased condylar translation was significantly correlated with reduced upper cervical mobility and poor cervical posture (r = -0.322 to -0.397; p = .012-.046).

CONCLUSION

Increased condylar translation and path length in patients with NCNP may indicate poor control of TMJ articular movement, which may result from neck pain or may be a compensation for limited neck mobility. Evaluation of excessive TMJ translation may be considered in patients with NCNP.

Evaluation of Physiotherapy Impact on Neuromuscular Tension in Analog Astronauts at the LunAres Habitat

The evaluation of manual Trigger Point Therapy (TrPt) on mandible abduction range of Analog Astronauts (AA) surviving isolation conditions during consecutive missions at the LunAres Habitat was performed. This physiotherapy method was applied to decrease stress-related neuromuscular tension. Abduction measurements were conducted on the two groups of five AA, who endured severe isolation conditions for 14 days in the limited space of the LunAres Research Station Habitat (Piła, Poland) during missions. The test group consisted of abduction measurements of AA who received TrPt and control group of abduction measurements of AA who did not receive TrPt. All measurements were noted in the TemporoMandibular Joint (TMJ) diagnosis aspect of the integrated dental examination card SZOPPDP©. The ischemic compression was performed on an active localized trigger point-resulting in cessation of pain. Maximum abduction measurements were made with an electronic caliper, and the abduction range was compared. The change of abduction range in AA with TrPt was bigger than in AA without TrPt. A larger increase in abduction range was observed in every case in the group receiving TrPt compared to the control group. TrPt effectively decreases the neuromuscular tension, which results in an increased mandibular abduction range of AA. Observations conducted in LunAres Research Station regarding stress-related neuromuscular tension can help identify effective therapeutic methods for circumstances of social isolation.

Oral health-related quality of life and psychological states of dental students with temporomandibular disorders

PURPOSE/OBJECTIVES

This study investigates the frequency of temporomandibular disorders (TMD) in dental students, and evaluates the association between TMDs, psychological states, and oral health-related quality of life (OHRQoL). The presence of bruxism was also determined.

METHODS

Two hundred ninety-three dental students completed the Symptom Checklist 90-Revised (SCL-90-R) and Oral Health Impact Profile 14 (OHIP-14) questionnaires and underwent a clinical examination according to Diagnostic Criteria for TMDs.

RESULTS

TMDs were detected in 46.4% of the dental students. OHIP-14 scores of students with TMDs were significantly higher than scores for students without TMDs (p < 0.05). Significant differences were observed in all SCL-90-R scores among students with and without TMDs, except for phobic anxiety and additional SCL-90-R subscale scores (p < 0.05). The prevalence of myalgia was significantly higher in clinical students (26.6%) than in preclinical students (15.6%). OHIP-14 scores of clinical students were significantly higher than preclinical students (p < 0.05).

CONCLUSIONS

In dental students, there was a high frequency of TMDs and bruxism. OHRQoL was poorer in clinical students. Levels of anxiety, depression, and somatization were not different in clinical and preclinical students. SCL-90-R scores are higher in students with TMDs except for phobic anxiety and additional SCL-90-R subscale scores.

Temporomandibular joints disorders (TMDs) prevalence and their relation to anxiety in dental students

Background: Temporomandibular joint disorders (TMDs) are very common disorders affecting the population and causing pain. Researchers have reported a high prevalence of TMDs among university students due to increased distress. The aims of this study were to determine the frequency of TMDs in Umm al-Qura University (UQU) dental students using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD), and to examine the relationship between anxiety, bruxism, and TMDs among those students. Methods: The DC/TMD pain screener questionnaire was completed by dental students. Students who reported TMD pain or had at least one positive TMD symptom were invited to the dental clinic for a full TMJ evaluation. History of bruxism was documented and an ultra-brief tool for detecting anxiety and depression (Patient Health Questionnaire-4 PHQ) was completed by all students. Results: A total of 240 students responded to the TMD pain screener in which 119 reported at least one TMJ symptom. Only 93 dental students presented to clinical examination in which 64.5% (n=60) of them had temporomandibular joint disorders. Disc displacement with reduction and local myalgia (38.7% & 32.25%, respectively) were the most frequent diagnosis. A total of 29% (n=27) of students had more than one diagnosis. Overall, 41 participants (44.09%) reported a positive response to the anxiety scale and (n=38) 40% of participants reported parafunctional habits. Both the history of bruxism and anxiety were significantly related to TMDs (P=0.0002) and also significantly higher in women of higher academic years (P≤0.01). Conclusions: This study found a high prevalence of TMDs among UQU dental students. Disc displacement with reduction was the most prevalent disorder. Bruxism and anxiety were associated with painful TMDs.

Prevalence of New-Onset Otological Symptoms in Patients with Temporomandibular Disorders

The aim of this retrospective study was to evaluate the prevalence of new-onset otological symptoms and the possible associations between tinnitus and oral parafunctional habits among patients with temporomandibular disorders (TMD) who attended a Craniofacial Pain Outpatient and a Dentistry Clinic. The medical reports and charts of patients who experienced TMD between 1 February 2016 and 31 December 2017 were reviewed, in order to evaluate the prevalence of new-onset aural fullness, vertigo and tinnitus. Tinnitus was also analyzed in more detail to evaluate possible associations with parafunctional habits. A total of 400 patients (301 females, 99 males) met the inclusion criteria, with a median age of 39.6 ± 15.6 years. Overall, new-onset otological symptoms were reported by 304 (76%) subjects with TMD. Among otological symptoms, aural fullness was the most common (n = 133, 33.3%), followed by tinnitus (n = 92, 23%) and vertigo (n = 79, 19.8%). No significant correlations were found between tinnitus and bruxism (p = 0.28), clenching (p = 0.11), nail-biting (p = 0.96), sleeping prone (p = 0.27), chewing gum (p = 0.99) and talking for a long time (p = 0.42). The present study suggests that all patients with TMD should be investigated for new-onset otological symptoms, regardless of oral parafunctional habits. Early diagnosis would allow to plan personalized and appropriate therapeutic and rehabilitative pathways, minimizing the negative impact due to TMD.

Craniofacial Morphology of Orthodontic Patients with and without Temporomandibular Disorders: A Cross-Sectional Study

Purpose

We aimed to explore the relationship between temporomandibular disorders (TMDs) and craniofacial morphology in orthodontic patients.

Methods

Altogether, 262 orthodontic patients were included and divided into two groups according to their Fonseca Anamnestic Index (FAI) scores: a no-TMD group (control group, FAI < 20) and a TMD group (FAI ≥ 20). Cephalometric parameters including cranial, maxillary, mandibular, and dental parameters were traced on cephalograms. Craniofacial morphology was compared between TMD and control groups, followed by subgroup analyses based on TMD severity, gender, age, and temporomandibular joint (TMJ) symptoms.

Results

The prevalence of TMDs was 52.7% among included patients (138/262). The mean age of TMD patients was higher than that of the control group. No significant difference in gender distribution between the groups was observed. The most commonly reported FAI items were misaligned teeth, neck pain, and emotional tension. The Frankfort-mandibular plane angle (FMA) was larger in the TMD patients than in the control group, whereas no significant differences in other parameters were observed. Subgroup analysis based on TMD severity revealed that FMA and anterior facial height of moderate/severe TMD patients were significantly larger than those of mild or no-TMD patients. Among male patients, the anterior cranial base length was smaller, and the anterior facial height was larger in the TMD group. Among female patients, no significant differences in craniofacial morphology between the groups were observed. In juvenile patients, overjet and overbite were smaller in the TMD group. In adult patients, SNA, ANB, FMA, and gonial angle were larger in the TMD group. Within the TMD group, patients with TMJ pain or noises exhibited characteristic craniofacial features compared to patients without these symptoms.

Conclusions

Orthodontic patients with TMDs have specific craniofacial morphology, suggesting a relationship between TMDs and particular craniofacial features in orthodontic patients.

Association between temporomandibular disorders and anxiety: A systematic review

Temporomandibular Joint Dysfunction (TMD) is an umbrella term that includes musculoskeletal and neuromuscular conditions affecting the temporomandibular joint. The present systematic review aimed to verify whether there is a specific association between TMD and anxiety. The searches were carried out in electronic databases, including PubMed, Scopus, Web of Science, and LILACS, without restrictions on publication date and language. The acronym PECO was used, whose participants (P) were humans exposed to TMD (E), compared to participants without TMD (C) and the presence of anxiety as an outcome (O). After the search retrieval, the duplicates were removed, and the articles were evaluated by title and abstract, following our inclusion and exclusion criteria; then, the papers were read and thoroughly assessed. After selection, the methodological quality was performed using the Newcastle-Ottawa Scale (NOS) for observational studies. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool was used to assess the level of evidence. A total of 710 studies were found, and 33 articles were considered eligible and were included for the qualitative synthesis and the level of evidence assessment. The studies confirmed the association between anxiety and DTM, although there was a low certainty of evidence among the selected studies. Most articles showed a low risk of bias. Although the limitations of this systematic review, it suggested a significant association between anxiety and TMD, as well as highlights possible directions for future research.

A novel rat model of temporomandibular disorder with improved face and construct validities

AIMS

Temporomandibular disorders are a cluster of orofacial conditions that are characterized by pain in the temporomandibular joint (TMJ) and surrounding muscles/tissues. Animal models of painful temporomandibular dysfunction (TMD) are valuable tools to investigate the mechanisms responsible for symptomatic temporomandibular joint and associated structures disorders. We tested the hypothesis that a predisposing and a precipitating factor are required to produce painful TMD in rats, using the ratgnawmeter, a device that determines temporomandibular pain based on the time taken for the rat to chew through two obstacles.

MATERIALS AND METHODS

Increased time in the ratgnawmeter correlated with nociceptive behaviors produced by TMJ injection of formalin (2.5%), confirming chewing time as an index of painful TMD. Rats exposed only to predisposing factors, carrageenan-induced TMJ inflammation or sustained inhibition of the catechol-O-methyltransferase (COMT) enzyme by OR-486, showed no changes in chewing time. However, when combined with a precipitating event, i.e., exaggerated mouth opening produced by daily 1-h jaw extension for 7 consecutive days, robust function impairment was produced.

KEY FINDINGS

These results validate the ratgnawmeter as an efficient method to evaluate functional TMD pain by evaluating chewing time, and this protocol as a model with face and construct validities to investigate symptomatic TMD mechanisms.

SIGNIFICANCE

This study suggests that a predisposition factor must be present in order for an insult to the temporomandibular system to produce painful dysfunction. The need for a combined contribution of these factors might explain why not all patients experiencing traumatic events, such as exaggerated mouth opening, develop TMDs.

Association between Temporomandibular Joint Disorder and Weight Changes: A Longitudinal Follow-Up Study Using a National Health Screening Cohort

This study aimed to investigate BMI changes following a temporomandibular joint disorder (TMJD) diagnosis. The Korean National Health Insurance Service-Health Screening Cohort from 2002 to 2015 was used. In Study I, 1808 patients with TMJD (TMJD I) were matched with 7232 participants in comparison group I. The change in BMI was compared between the TMJD I and comparison I groups for 1 year. In study II, 1621 patients with TMJD (TMJD II) were matched with 6484 participants in comparison group II participants. The change in BMI was compared between the TMJD II and comparison II groups for 2 years. In Study I, the BMI change was not associated with TMJD. In Study II, the BMI change was associated with TMJD in the interaction of the linear mixed model (p = 0.003). The estimated value (EV) of the linear mixed model was −0.082. The interaction was significant in women < 60 years old, women ≥ 60 years old, and the obese I category. TMJD was not associated with BMI changes after 1–2 years in the overall population. In women and obese patients, TMJD was associated with a decrease in BMI after 2 years.