Pain-related Temporomandibular Disorder Research Articles

Sleeping and waking-state oral behaviors in TMD patients: their correlates with jaw functional limitation and psychological distress

ObjectivesThis study investigated oral behaviors in various temporomandibular disorder (TMD) subtypes, assessing their frequency, extent, and associations with both jaw functional status and psychological distress.Materials and methodsAnonymized data from consecutive "initial-visit" TMD patients at a university-affiliated oral medicine clinic were obtained. Alongside demographic information, patients completed various questionnaires including the Diagnostic Criteria for TMD (DC/TMD) Symptom Questionnaire, Oral Behavior Checklist (OBC), Jaw Functional Limitation Scale-20 (JFLS-20), Patient Health Questionnaire-9 (PHQ-9), and General Anxiety Disorder Scale-7 (GAD-7). Patients underwent a protocolized clinical examination and received diagnoses of pain-related (PT), intra-articular (IT), or combined (CT) TMD using the DC/TMD diagnostic algorithms. Data were evaluated with Chi-square/non-parametric tests and logistic regression analyses (α = 0.05).ResultsThe study comprised 700 patients (mean age 37.4 ± 15.7 years), with 12.6%, 15.1%, and 72.3% diagnosed with PT, IT, and CT, respectively. For all TMD subtypes, oral activities during sleep were more prevalent than those during wakefulness. While variations in total/subscale OBC scores were insignificant, substantial differences were observed in global/subscale JFLS (PT, CT > IT), depression (PT, CT > IT), and anxiety (CT > IT) scores. Near-moderate correlations (rs = 0,36–0.39) were discerned between overall/waking-state non-functional oral behaviors and depression/anxiety. Multivariate analysis indicated that the odds of different TMD subtypes were influenced by sex, age, and jaw functional status.ConclusionsFor all TMD patients, sleep-related oral activities were more commonly reported than waking-state activities. Factors such as sex, age, and jaw functional limitation are associated with the likelihood of different TMD subtypes.Statement of clinical relevanceOral behaviors, in themselves, do not predict distinct TMD subtypes, in contrast to factors such as sex, age, and jaw functional status.

How do the mindfulness and sensory-behavioural-emotional aspects influence the painful experience related to temporomandibular disorder?

Chronic pain is persistent or recurrent pain lasting longer than 3 months. The experience of temporomandibular disorder (TMD)-related pain is modulated by emotional and social factors, with mindfulness encapsulating these aspects. To investigate the association between cognitive-behavioural-emotional characteristics, mindfulness and the painful experience in women with chronic pain-related TMD. A cross-sectional study was conducted, including 90 women aged between 18 and 61 years old, diagnosed with chronic pain-related TMD according to the Diagnostic Criteria for Temporomandibular Disorder, considering both temporomandibular joint and muscle pain. Specific instruments were employed to assess cognitive-behavioural-emotional aspects. The Mindful Attention Awareness Scale and the Five Facets of Mindfulness Questionnaire scales evaluated the level and construct of mindfulness. The relationship between variables was analysed using bivariate association tests (.05 > p < .20), followed by multiple regression tests (p < .05). The heightened experience of pain correlated with increasing age, a low level of education, the attribution of the locus of control by chance, and lower levels of mindfulness (p < .05). The heightened experience of pain was negatively influenced by mindfulness levels (p < .05). On the other hand, the painful experience was mainly influenced by facets describing negative formulation, distraction, non-reactivity and non-judgement (p < .05). Demographic, cognitive-behavioural-emotional data and levels of mindfulness and its facets presented different influence weights on the painful experience. These findings provide support for future studies focusing on mindfulness strategies, education and pain management in women with chronic pain-related TMD.

Age distribution of East Asian TMD patients and age-related differences in DC/TMD axis I findings.

The pattern of age distribution in East Asian temporomandibular disorder (TMD) patients and age-related differences in DC/TMD diagnostic subtypes/categories were evaluated. TMD patients from two University-based centers in China and South Korea were enrolled. Axis I physical diagnoses were rendered according to DC/TMD. Patients were categorized into six age groups (15-24, 25-34, 35-44, 45-54, 55-64, and 65-84 years; Groups A-F respectively). Youths/young adults (Groups A-C) formed 74.1% of TMD patients. TMJ disc displacements (74.9%), arthralgia (49.2%), and degenerative joint disease [DJD] (36.8%) were the most common TMD subtypes. The majority had combined (54.0%) and chronic (58.5%) TMDs. Youths/young adults and middle-aged/old adults had substantially lower frequencies of merely pain-related (6.2-14.5%) and intra-articular (13.8-16.8%) TMDs correspondingly. "Being female" increased the prospects of pain-related/combined TMDs by 96%/49%, respectively. East Asian TMD patients comprised mostly of youths/young adults who had an alarmingly high prevalence of TMJ DJD.

Obstructive sleep apnea treatment improves temporomandibular disorder pain

PurposeThe existence of a bidirectional relationship between poor sleep and pain intensity has been studied, and good sleep quality has been found to be a key factor underlying pain control. The purpose of this prospective cohort study was to observe if OSA treatment provides a reduction in temporo-mandibular disorder (TMD) pain and headache attributed to TMD in patients with obstructive sleep apnea (OSA) after 18 months of OSA treatment.MethodsA prospective cohort study was conducted on consecutive patients suffering from OSA. Patients underwent polysomnography and TMD examination according to the DC/TMD protocol at baseline and after 18 months. Intensity of TMD pain and headache attributed to TMD were analyzed.ResultsOf 40 patients (31 men, mean age 51.3 ± 10.3 years), 33 underwent OSA treatment. At the follow-up examination after 18 months, significant improvements in the intensity of pain-related TMD and headache attributed to TMD were observed (p < 0.05). Seven patients did not start treatment for OSA or discontinued treatment. These patients did not show any significant difference in intensity of TMD-pain or headache attributed to TMD after 18 months (p > 0.05).ConclusionsSignificant reductions in intensity of pain-related TMD and headache attributed to TMD were observed in patients with OSA after 18 months of OSA treatment onset, while no difference was observed in subjects not undergoing or discontinuing OSA treatment.Trial registrationThe protocol was registered on ClinicalTrials.gov database with number NCT04948541.

Headache diagnoses in patients with orofacial pain at a specialized pain center

Background. Headache and orofacial pain (OFP) are widespread at specialized pain centers. However, reliable data on their prevalence and co-occurrence are lacking, and prevalence of OFP in headache patients seems to be underestimated. The aim of this study was to evaluate the types of headache in patients with OFP and types of OFP in patients with headache.Methods. We enrolled patients presenting with headache and/or OFP. Patients were examined by an experienced headache and pain specialist who questioned the patients about the presence of OFP. Depression was assessed with the Beck Depression Inventory (BDI-II), anxiety – with the Beck Anxiety Inventory (BAI). Bruxism was evaluated based on subject self-report.Results. We recruited 310 patients: 177 (57%) patients with headache, 28 (9%) patients with OFP and 105 (34%) patients presenting with both types of pain. The prevalence of OFP in headache patients was 37.2%. Migraine was the most prevalent type of headache, while painful temporomandibular disorder (TMD) – the most prevalent form of OFP. Patients with PFP presented with a high prevalence of sleep and awake bruxism.Conclusion. Migraine and pain-related TMD are the most prevalent diagnoses in a specialized pain center. OKI and OKI ACT are soluble forms of ketoprofen and reach peak concentration in 15 minutes. This enables faster onset of action compared to conventional NSAIDs and better tolerability. OKI and OKI ACT are recommended in the acute treatment of migraine with comorbid painful TMD.

Psychosocial profiles and their correlation with physical diagnosis in temporomandibular disorders, a preliminary report

ABSTRACT Objective To assess representative psychosocial features in a group of temporomandibular disorder (TMD) patients from Jordan using Axis II of the Diagnostic Criteria for TMD (DC/TMD) protocol. Methods Ninety-eight TMD patients were examined according to Axis I DC/TMD protocol in addition to assessment of their pain-related disability, psychological distress, and stress reactivity. Results Just under half of the patients (49%) had high intensity of characteristic pain (self-reported TMJ-related pain) and one-third (32%) had high levels of pain-related disability. Furthermore, significant proportions of patients expressed moderate-severe degrees of distress and stress reactivity (41% and 39%, respectively). Significant correlations were identified between the Graded Chronic Pain Scale (GCPS) and each of the pain-related TMD subgroups. Conclusion TMD patients are susceptible to high levels of pain-related psychosocial impairment, and clinicians should be aware of the possible correlations between the physical TMD diagnosis and specific psychosocial features during treatment planning.

심리사회적 손상을 동반한 측두하악장애에 대한 물리치료 효과

The purpose of this study was to investigate the effects of physical therapy intervention on psychosocial aspects and temporomandibular function in patients with temporomandibular disorder (TMD) presenting psychosocial impairment. The subjects of this study were twenty-one patients with TMD diagnosed by Pain-Related TMD and Headache through Diagnostic Criteria for TMD (DC/TMD) and with psychosocial impairment characteristics in the Symptom Check-list 90-Revision (SCL-90-R). DC/TMD AxisII assessment tool was used to characterize psychosocial disability, and maximum comfortable opening (MCO) and neck disability index (NDI) were assessed for improvement in temporomandibular and neck function. This study was pre- and post-test single group trial to evaluate he symptoms. Physical therapy interventions were performed for an hour a day, 3 times a week for 4 weeks. As a result of SCL-90-R, there were significant effects in somatization, interpersonal sensitivity, depression, anxiety, paranoid ideation, and global severity index (p<.05). And the number of subjects with T score of 60 or higher was decreased. DC/TMD AxisII evaluation showed a significant effect on psychosocial aspects (p<.05). Furthermore, MCO and NDI had a significant effect on temporomandibular and neck pains and functional improvement (p<.05). Based on these results, it is suggested that physical therapy will be effective in improving not only the function of the temporomandibular mandible but also the psychosocial characteristics for patients with TMDs with psychosocial impairment.

Potential Role of Obstructive Sleep Apnea on Pain Sensitization and Jaw Function in Temporomandibular Disorder Patients.

BackgroundThe relationships between obstructive sleep apnea (OSA) and diverse types of pain disorders have been reported. However, the interaction between OSA and pain-related temporomandibular disorder (TMD) remains obscure.MethodsA total of 60 adults (male/female, 48/12; mean age, 41.7 ± 13.2 years) with pain-related TMD were enrolled. All participants underwent overnight full-channel polysomnography and had assessment of size and position of the tongue, tonsillar size, height, and weight. Diagnostic Criteria/TMD criteria was applied to diagnose TMD. Myofascial trigger points (TrPs) were bilaterally evaluated in the two masticatory and four cervical muscles including the temporalis, masseter, trapezius, sternocleidomastoid, occipitalis, and splenius capitis muscles. Participants were divided into three groups in accordance with their levels of OSA.ResultsThe significantly higher number of active TrPs were detected in participants with severe OSA. The number of active TrPs in the masticatory muscles significantly interacted with diverse types of apneic and arousal indices.ConclusionThe myofascial pain modulating mechanisms and jaw function could have interactions with nocturnal hypoxia and sleep fragmentation in chronic pain-related TMD patients.

Phenotypic analysis of discordant monozygotic twins for pain-related temporomandibular joint disorder. Case report

Phenotypic analysis of discordant monozygotic twins for pain-related temporomandibular joint disorder. Case report

Role of occlusal factors on probable bruxism and orofacial pain: Data from the 1982 Pelotas birth cohort study

ObjectivesThis study aimed to explore the association between occlusal features and temporomandibular disorder (TMD) pain complaints and probable awake or sleep bruxism MethodsPath analysis was used to estimate direct, indirect and total effects of occlusal features on probable bruxism and pain-related TMD in adults aged 31 years from the 1982 Pelotas Birth Cohort. A total of 539 cohort members had an oral examination in 2013. Occlusal features were assessed through the Dental Aesthetic Index (DAI), orofacial pain complaints through the TMD pain screener and probable bruxism based on self-reports in combination with clinical findings. ResultsMalocclusions were found in 28.8% of the participants, while awake bruxism was reported in 35.2%, sleep bruxism in 15.2%, and pain-related TMD in 52.5% of the sample. Occlusion had no direct effect on either awake bruxism [standardized coefficient (SC) -0.002; p = 0.995] or pain-related TMD (SC -0.06; p = 0.115). Conversely, probable awake bruxism was associated with pain-related TMD (SC 0.35; p < 0.001). Similar results were found when sleep bruxism was set as the mediator of interest, as malocclusion did not directly affect sleep bruxism (SC 0.05; p= 0.220) nor pain-related TMD (SC -0.06; p = 0.167). A direct effect of sleep bruxism on pain-related TMD was observed with an SC of 0.16 (p < 0.001). ConclusionOur findings suggested that malocclusion during adulthood did not directly influence probable awake or sleep bruxism nor TMD pain complaints. Instead, probable awake and sleep bruxism was associated with TMD pain complaints. Clinical significanceMalocclusion did not impact the presence of bruxism nor TMD complaints in adulthood, but awake and sleep bruxism were associated with TMD pain complaints. The significance of malocclusion should be reconsidered in contemporary dentistry and oral rehabilitation.

Number and type of temporomandibular disorder symptoms: their associations with psychological distress and oral health-related quality of life

In this case-control study, we investigated the presence of differing numbers and types of temporomandibular disorder (TMD) symptoms, their association with psychological distress, and their impact on oral health-related quality of life (OHRQoL). We recruited a total of 814 participants with TMD and 147 control subjects. The participants were instructed to complete the Diagnostic Criteria for Temporomandibular Disorders Symptom Questionnaire; the Depression, Anxiety and Stress Scale-21; and the Oral Health Impact Profile-Temporomandibular Disorders. The participants were subsequently categorized by their number and type of TMD symptoms. Data were analyzed with the Kruskal-Wallis/Mann-Whitney U test (α=.05). The mean age of the participants (N=961) was 32.99 ± 13.14 years, and 79.2% were women. Participants with more and all types of TMD symptoms generally exhibited significantly higher levels of psychological distress and worse OHRQoL (P < .001). Those with TMD pain plus temporomandibular joint (TMJ) sounds/dysfunction had significantly greater psychological distress, whereas those with painful symptoms and TMJ dysfunction experienced significantly more impairment in OHRQoL than individuals with only TMJ sounds. Psychological states and OHRQoL are influenced by the number and type of TMD symptoms. Individuals with more and all types of pain-related TMD symptoms with/without intra-articular features had greater psychological distress and OHRQoL impairment.

Editorial: The Co-Occurrence of Diseases

Editorial: The Co-Occurrence of Diseases

Psychological well-being and distress: Their associations with temporomandibular disorder symptoms and interrelationships

This cross-sectional study established the relationships between temporomandibular disorder (TMD) symptoms, psychological well-being (PWB), and psychological distress (PD). Additionally, the psychological predictors for various TMD features were determined. TMD symptoms were ascertained with the Diagnostic Criteria for TMDs Symptom Questionnaire in young adults and PWB and PD were assessed with Ryff's Scales of Psychological Well-Being-18 (SPWB-18) and Depression, Anxiety, and Stress Scales-21, respectively. Statistical analyses were conducted using Kruskal Wallis/Mann-Whitney U tests, Spearman's correlation, and multivariate logistic regression (α=.05). Of the 734 participants (mean age=19.35 ± 1.24 years) appraised, 40.7% had no TMD manifestations and 59.3% reported various TMD symptoms (25.2% pain-related, 14.6% intra-articular, and 19.5% combined). Among the 4 symptom groups, significant differences in PWB were perceived for total SPWB and the Environmental Mastery/Self-Acceptance subscales. Significant differences in total Depression, Anxiety, and Stress Scales-21, depression, anxiety, and stress were also noted between the pain-related TMD symptoms/combined TMD symptoms and no TMD symptoms groups. For all groups, the strongest correlation was observed between total SPWB and depression (rs=-0.52 to 0.65). Environmental mastery decreased the likelihood of pain-related and intra-articular TMD symptoms. Conversely, overall PD and anxiety predicted the presence of pain-related and intra-articular/combined TMD symptoms correspondingly.

Subtypes of acute and chronic temporomandibular disorders: Their relation to psychological and sleep impairments.

To determine the differences in psychological states and sleep quality in patients with various temporomandibular disorder (TMD) subtypes, and to ascertain the relationships between TMD duration with psychological and sleep impairments. A total of 830 TMD patients were recruited categorized into pain-related (PT), intra-articular (IT), and combined (CT) TMD groups. Each group was further divided into acute and chronic subtypes. The Depression, Anxiety, and Stress Scales-21 (DASS-21), and Pittsburgh Sleep Quality Index (PSQI) were used to assess emotional states and sleep problems. Although chronic TMDs generally had higher levels of anxiety, depression, stress, and sleep impairments than acute TMDs, significant differences were only observed for the PT group. Ranking of the mean depression, anxiety, and stress scores was as follows: acute TMDs: CT>PT>IT; chronic TMDs: PT>CT>IT. For both acute and chronic TMDs, the ranking of mean PSQI global and component scores was PT≥CT≥IT. Logistic regression analyses indicated that stress (ORs=4.40) and depression (ORs=2.82) increased the risks of chronic pain-related TMDs (p<.05). Chronic pain-related TMDs are associated with high levels of psychological distress and poorer sleep, while chronic intra-articular TMDs are not. Stress and depression increased the probability of chronic pain-related TMDs.

Factors associated with signs of temporomandibular pain: an 11-year-follow-up study on Finnish adults

Background: Pain in the temporomandibular region is a main complaint causing disability and distress among temporomandibular disorders sufferers.Objectives: The aim of the study was, over an 11-year follow-up on Finnish adult population, to investigate the prevalence of clinically assessed pain-related temporomandibular disorder (TMD) signs, i.e. temporomandibular joint (TMJ) and masticatory muscles (MM) pain on palpation, and their association with sociodemographic background and denture status.Methods: The data were based on the nationally representative Finnish Health 2000 and Health 2011 Surveys (BRIF8901). The sample comprised 1210 adults who underwent clinical oral examinations including TMD signs assessment. Statistical evaluations included chi-square tests and logistic regressions.Results: The prevalence of palpatory MM pain decreased from 9.5% at baseline to 4.6% in the follow-up. Cross-sectionally, presence of palpatory MM pain significantly associated with gender (p < .001, p = .002) and educational level (p < .001, p = .001) in both years, and with age (p = .006) and denture status (p = .022) at baseline. The prevalence of palpatory TMJ pain increased from 2.1% at baseline to 3.5% in the follow-up. Presence of palpatory TMJ pain significantly associated with gender in both years (p = .012, p = .032). Female gender, lower education and palpatory MM pain at baseline predicted palpatory MM pain in the follow-up.Conclusion: Palpatory MM pain is relatively prevalent in adults, yet with a favourable prognosis. Women and people with low education are more susceptible groups. Previous experience of palpatory MM pain increases the risk of exhibiting it later in life.

Temporomandibular disorder and cervicalgia: pathophysiology underlying the comorbidity with chronic migraine

To analyze the prevalence of various clinical forms of temporomandibular disorder (TMD) and cervicalgia in episodic (EM) and chronic migraine (CM). Ninety patients with CM and 42 patients with EM as defined by the International Classification of Headache Disorders (ICHD)-3 beta were recruited. TMD and sleep bruxism were diagnosed according to the DC/TMD criteria and the International Classification of Sleep Disorders (ICSD-R), respectively. Myofascial pain was the most prevalent form of TMD in both EM and CM. The prevalence of TMD was higher in CM as compared to EM (60% vs. 21.4%, respectively, p=0.0001). The prevalence of bruxism was comparable across EM and CM (14.3% vs. 28.8%, respectively, p=0.08) and significantly lower than that of TMD in the CM population (28.8% vs. 60%, respectively, p=0.0001). Frequent cervicalgia (≥15 days per month) was reported by 65.5% and 21.4% of CM and EM patients, respectively (p=0.0001); 44.4% of CM patients reported neck pain immediately before or during migraine attacks only, 14.4% during the headache and interictal phases. The higher prevalence of pain-related TMD and cervicalgia in CM population compared to EM and the general population was shown. In CM, myofascial pain and tenderness in the masticatory and neck muscles may be caused by central sensitization (CS) with no link to temporomandibular joint or spinal pathology. Myofascial TMD and neck muscle dysfunction are an integral part of CM pathophysiology underlying headache chronification.

Muscle hardness and masticatory myofascial pain: Assessment and clinical relevance.

The impression of increased muscle hardness in painful muscles is commonly reported in the clinical practice but may be difficult to assess. Therefore, the aim of this review was to present and discuss relevant aspects regarding the assessment of muscle hardness and its association with myofascial temporomandibular disorder (TMD) pain. A non-systematic search for studies of muscle hardness assessment in patients with pain-related TMDs was carried out in PubMed, Cochrane Library, Embase and Google Scholar. Mechanical devices and ultrasound imaging (strain and shear wave elastography) have been consistently used to measure masticatory muscle hardness, although an undisputable reference standard is yet to be determined. Strain elastography has identified greater masseter hardness of the symptomatic side in patients with unilateral myofascial TMD pain when compared to the contralateral side and healthy controls (HC). Likewise, shear wave elastography has shown greater masseter elasticity modulus in patients with myofascial TMD pain when compared to HC, which may be an indication of muscle hardness. Although assessment bias could partly explain these preliminary findings, future randomised controlled trials are encouraged to investigate this relationship. This qualitative review indicates that the muscle hardness of masticatory muscles is still a rather unexplored field of investigation with a good potential to improve the assessment and potentially also the management of myofascial TMD pain. Nonetheless, the current evidence in favour of increased hardness in masticatory muscles in patients with myofascial TMD pain is weak, and the pathophysiological importance and clinical usefulness of such information remain unclear.

Predictors of Long-Term Temporomandibular Disorder Pain Intensity: An 8-Year Cohort Study.

To investigate, in individuals with pain-related temporomandibular disorder (TMD), the association of long-term pain intensity with baseline health-related quality of life (HRQoL) and jaw functional limitation. Of 513 cases with baseline pain-related TMD (masticatory muscle and/or temporomandibular joint [TMJ] pain), 273 were reevaluated after 8 years, and 258 of them had complete baseline data for Jaw Functional Limitation Scale (JFLS) scores and HRQoL measured by the Physical Component Summary (PCS) and Mental Component Summary (MCS) scores of the 12-item Short Form Health Survey and follow-up data for Characteristic Pain Intensity (CPI) from the Graded Chronic Pain Scale. Secondary analyses of existing data quantified the effects of primary (PCS, MCS) and secondary (JFLS) predictors on follow-up CPI by using multivariable linear regression. Sensitivity analyses considered differences between the included participants (n = 258) and those who were not included (n = 255) by using inverse probability weighting. Interactions of baseline predictors with age, sex, and baseline CPI were evaluated using multivariable linear regression. The score for baseline PCS, but not MCS or JFLS, was associated with follow-up CPI (P = .012). One standard deviation (SD = 9.0)-higher baseline PCS score predicted an overall 3.2-point-lower follow-up CPI (95% confidence interval -5.8 to -0.7) after adjusting for age, sex, MCS, JFLS, and baseline CPI scores. However, the effect of PCS score was not uniform: the association between PCS and follow-up CPI scores was statistically significant for participants with baseline CPI ≥ 51.3/100 and clinically significant for participants with baseline CPI ≥ 68.7/100. Adjustment for TMD treatments and sensitivity analyses had negligible effect. In participants with moderate to severe baseline TMD pain intensity, higher baseline physical HRQoL predicted lower TMD pain intensity at 8 years follow-up. PCS score could contribute to a multifactorial long-term TMD pain prediction model.

Orofacial pain - an update on diagnosis and management.

The diagnosis and management of orofacial pain may be challenging due to complex histories, pathophysiology and associated psychosocial co-morbidities such as depression and anxiety. Neuropathic facial pain conditions such as burning mouth syndrome (BMS), persistent idiopathic facial pain (PIFP), atypical odontalgia (AO) and trigeminal neuralgia (TN) require early recognition by primary care clinicians and referral to secondary care. Acute pain-related temporomandibular disorder (TMD) may be managed in the primary care setting, with identification of those at risk of developing chronic TMD receiving an early referral to secondary care. Adopting a biopsychosocial approach, consisting of physical therapies, pharmacotherapy and psychological support can lead to effective management and may limit the negative impact of facial pain upon quality of life and daily functioning.

TEMPOROMANDIBULAR DISORDER IN CHRONIC MIGRAINE

Rationale: For many years, temporomandibular disorder (TMD) has been studied primarily by dentists and maxillofacial surgeons. However, new data is emerging that TMD is comorbid with various types of headache; however this association has not been studied in detail. Aim: To analyze TMD prevalence and clinical structure in patients with migraine. Materials and methods: We assessed 84 patients with chronic migraine (CM) and 42 patients with episodic migraine (EM). TMD was diagnosed according to the Diagnostic Criteria for Temporomandibular Disorders: Clinical Protocol and Assessment Instruments 2014. We also performed subgroup analysis for low-frequency EM (less than 4 headache days per month, LFEM) vs. high-frequency EM and CM (over 10 headache days per month, HFEM + CM). Results: In both groups, myofascial pain was the most prevalent form of TMD. The prevalence of TMD was higher in CM as compared to EM (52.4% vs. 28.6%, correspondingly, р = 0.02). Even more evident differences were observed between LFEM and HFEM + CM (18.2% vs. 51.6%, correspondingly, р &lt; 0.009). The difference was significant for painrelated TMD only. The prevalence of bruxism was comparable across LFEM and HFEM + CM (18% vs. 30.5%, correspondingly, р = 0.3) and significantly lower than TMD prevalence in HFEM + CM (30.5% vs. 51.6%, correspondingly, p = 0.005). The anxiety level in patients with and without TMD was also comparable (8.1 ± 4.1 vs. 8.3 ± 4.7, correspondingly, р = 0.8). Conclusion: CM patients have a high prevalence of pain-related TMD (52.4%). The prevalence of TMD in LFEM is comparable to that in the general population. The presence of bruxism or anxiety cannot be associated with a high TMD prevalence in our patients. In CM, pain in the masticatory muscles may be caused by anti-nociceptive dysfunction, mirroring central sensitization and disrupted descending modulation of pain.