Signs of temporomandibular disorders in tinnitus patients and in a population-based group of volunteers: results of the Study of Health in Pomerania

The literature has documented a controversial discussion on the possible relationship of otogenous symptoms and craniomandibular dysfunction since the 1920s. Therefore, an investigation was conducted which consisted of two parts: a case study with population-based controls and a cross-sectional study. The aim of the first study was to screen a group of patients suffering from acute or chronic tinnitus for temporomandibular disorders (TMD) in comparison with a population-based group of volunteers without tinnitus. To this end, 30 patients (13 females and 17 males, age 18-71 years) suffering from acute hearing loss associated with tinnitus, isolated acute tinnitus, and chronically transient tinnitus were examined for symptoms of craniomandibular dysfunction. The results were compared with those of clinical functional analysis from 1907 subjects selected representatively and according to age distribution from the epidemiological 'Study of Health in Pomerania' (SHIP); the occurrence of tinnitus was ruled out in these control subjects. Statistical analysis was performed with Chi-square and Mann-Whitney U-tests. Sixty per cent of the tinnitus patients and 36.5% of the control subjects exhibited more than two symptoms of TMD (P = 0.004). Tinnitus patients had significantly more muscle palpation pain (P < 0.001), temporomandibular joint (TMJ) palpation pain (P < 0.001), and pain upon mouth opening (P < 0.001) than the general population group. No statistical differences were found in TMJ sounds, limitation of mandibular movement, or hypermobility of the TMJ. Furthermore, 4228 subjects of the population group examined in the epidemiological study were screened for co-factors of tinnitus with the help of a multivariate logistic regression model which was adjusted for gender, age, and a variety of anamnestic and examined data. Increased odds ratios (OR) were found for tenderness of the masticatory muscles (OR = 1.6 for one to three painful muscles and OR = 2.53 for four or more painful muscles), TMJ tenderness to dorsal cranial compression (OR = 2.99), listlessness (OR = 2.0) and frequent headache (OR = 1.84) A relationship between tinnitus and TMD was established in both examinations. Tinnitus patients seem to suffer especially from myofascial and TMJ pain. A screening for TMD should be included in the diagnostic survey for tinnitus patients.     

Effect of turban use on temporomandibular joint problems

The aim of this study was to evaluate the effects of daily turban wear on temporomandibular joint (TMJ) problems. This cross-sectional study was carried out on 249 female patients. Of these, 119 patients were using turban daily, while 130 patients did not use. Patients were asked questions to ascertain the signs of TMJ problems. Thereafter, the TMJ region was examined clinically. Cross-tabulations and Chi-square statistics were computed in accordance with Bonferroni correction for multiple comparisons. To investigate the association between continuous turban wear and temporomandibular disorder symptoms, logistic regression analysis was performed. Limited mouth opening, deviation, pain on TMJ palpation and mouth opening were not affected with turban usage. However, turban users more frequently demonstrated pain during palpation of the masticatory muscles than non-users (P = 0.001). Duration of the turban usage did not affect clinical examination findings except pain on masticatory muscles during palpation (P = 0.001). Complaint of pain on masticatory muscles are more frequently seen among the turban users.     

Short Communication Motor activity in sleep bruxism with concomitant jaw muscle pain. A retrospective pilot study

In a controlled polysomnographic (PSG) study that we recently performed in our laboratory, we noticed that some patients with a chief complaint of sleep bruxism reported concomitant non-myofascial pain in their masticatory muscles. To study the influence of such pain on the pattern of bruxism motor activity, we re-assessed the 2nd out of 2 consecutive PSG and masseter electromyographic (EMG) recordings of 7 bruxers without pain and 6 bruxers with concomitant jaw muscle pain. Among others, the selection of these patients was based on reports of current jaw muscle pain intensity, using 100-mm visual analogue scales. In our sample of bruxism patients with pain, levels of pain intensity did not differ significantly between bedtime and awakening in the morning. Although there were no significant differences between both subgroups of bruxers in the number of bruxism bursts per episode and the root-mean-squared EMG level per bruxism burst, bruxers with pain had 40% less bruxism episodes per hour of sleep. This suggests that non-myofascial jaw muscle pain decreases the number of initiations of bruxism episodes, but leaves their contents unaffected.     

Type A botulinum toxin in the treatment of chronic facial pain associated with masticatory hyperactivity.

PURPOSE: Chronic hyperactivity of the masticatory muscles is a common functional disorder associated with chronic facial pain and headache. The positive therapeutic effect of botulinum toxin type A on functional disorders and pain symptoms has been known in connection with the treatment of cervical dystonia. The purpose of this report is to assess whether the targeted reduction of masticatory muscular hyperactivity by local injection treatment with botulinum toxin type A can improve facial pain headache symptoms in the event that other treatment methods prove ineffective. Materials and Methods: In an randomized blinded placebo-controlled study, 90 patients (60 verum and 30 placebo) with chronic facial pain were treated with botulinum toxin type A (Botox; Allergan, Ettlingen, Germany) injections into masticatory muscles. RESULTS: Ninety-one percent of patients who received botulinum toxin improved by a significant mean reduction of approximately 3.2 on a visual analog pain scale. By comparison with t test and chi(2) test, there was a significant difference compared with the placebo group (P <.01). CONCLUSIONS: The local injection of botulinum toxin type A constitutes an innovative and adequately efficient treatment method for chronic facial pain associated with hyperactivity of the masticatory muscles. An improvement in the painful symptoms can be expected in up to 90% of patients who do not respond to conservative treatment methods.     

Absence of joint pain identifies high levels of sleep masticatory muscle activity in myofascial temporomandibular disorder

Although the development of reliable diagnostic criteria for temporomandibular disorders (TMDs) has operationalised identification of a subgroup with myofascial pain (mTMD), causal mechanisms remain elusive. This study examines masticatory muscle activity (MMA) in more homogenous research subgroups of mTMD. Data from an existing case‐control study of women were used to subcategorise mTMD cases based on joint pain with palpation to isolate muscle‐only pain (M‐pain) vs muscle and joint pain (MJ‐pain). Differences in laboratory indicators of MMA, specifically research diagnostic criteria for sleep bruxism (SB) and high background EMG activity, and other clinical and sociodemographic indicators were examined between groups. Compared to controls, the MJ‐pain subgroup did not show elevated background EMG or sleep bruxism. In contrast, the M‐pain subgroup showed significantly higher background EMG and a trend towards elevated prevalence of sleep bruxism. These results may explain why it has been difficult for studies of SB in mixed TMD and even mTMD samples to find a consistent positive association, since a positive association may be limited to mTMD without joint pain. The subcategorising of mTMD based on joint pain with palpation (ie M‐pain, MJ‐pain) appears to reveal subgroups with relatively high and low sleep masticatory muscle‐specific activity. Findings need replication in a larger study with updated mTMD diagnostic criteria, but may prove useful for understanding mechanism of pain maintenance in mTMD with and without joint pain.     

Relationship between self‐reported sleep bruxism and pain in patients with temporomandibular disorders

The aim of this study was to evaluate the association between self‐reported sleep bruxism and the age, gender, clinical subtypes of temporomandibular disorders (TMD), pain intensity and grade of chronic pain in patients previously diagnosed with TMD. Thousand two‐hundred and twenty patients of the Andalusian Health Service were examined using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) questionnaire. The inclusion and exclusion criteria were those included in the RDC/TMD criteria. The bruxism diagnosis was drawn from the question, ‘Have you been told, or do you notice that you grind your teeth or clench your jaw while sleeping at night?’ in the anamnestic portion of the questionnaire. A bivariate analysis was conducted, comparing the presence of perceived parafunctional activity with age (over age 60 and under age 60), gender, different subtypes of TMD, pain intensity, grade of chronic pain and presence of self‐perceived locked joints. The overall prevalence of self‐reported sleep bruxism (SB) was 54·51%. A statistically significant association was found between the presence of SB and patients under age 60, women, greater pain intensity, greater pain interference with activities of daily living, and the axis‐I groups affected by both muscular and articular pathology. There is a statistically significant association between self‐reported sleep bruxism and women under age 60 who have painful symptoms of TMD. There is also a positive association between this parafunctional habit and the presence of chronic pain. However, more studies that cover larger samples and differentiate between sleep bruxism and awake bruxism are needed.     

Sleep bruxism and temporomandibular disorder: Clinical and polysomnographic evaluation

OBJECTIVE: To seek better understanding of chronic musculoskeletal facial pain and its relation to sleep bruxism, by comparing patients with sleep bruxism, with and without temporomandibular disorder. DESIGN: Forty sleep bruxism patients were evaluated according to the Research Diagnostic Criteria for Temporomandibular Disorders: group A-20 patients with myofascial pain, 3 men, 17 women; average age 32.7yr; mean duration of pain 4.37yr; group B-20 without myofascial pain, 5 men, 15 women; average age 30.8yr. Sleep and bruxism were evaluated in one-night polysomnography. RESULTS: There were no statistically significant differences for bruxism and sleep variables of the two groups: number of bursts and bruxism episodes per hour, amplitude and duration of bruxism episodes, sleep efficiency and latency, percentage of non-REM and REM sleep, respiratory events, periodic limb movements, and micro-arousals. CONCLUSIONS: The polysomnographic characteristics of patients with sleep bruxism, with and without orofacial pain, are similar. More studies are necessary to clarify the reasons why some sleep bruxism patients develop chronic myofascial pain, and others do not.     

Clinical, microscopical and biochemical investigation of synovial fluid from temporomandibular joints

Abstract – The aim of this study was to investigate the relationship between pain and tenderness to palpation of the temporomandibular joint (TMJ), radiographic changes of the joint and signs of inflammation in the synovial fluid. Saline was injected into and aspirated from the TMJ of 29 patients with painful and tender TM joints and from five individuals with healthy joints. In another two patients synovial fluid could be aspirated without saline. The aspirated fluid was analyzed for inflammatory cells and for plasma proteins. A clinical examination of the stomatognathic system and a radiographic examination of the TMJ were performed before the aspiration. Besides tenderness to palpation of the TMJ, pain on mandibular movement and tenderness to palpation of the masticatory muscles were common. Erosion of the cortical outline of the joint surfaces was the most common radiographic finding. Inflammatory cells were present in the fluid of three patients but in none of the healthy individuals. Plasma proteins of inflammatory type could be detected in the fluid from seven of the patients. The results show that radiographic, cellular or biochemical signs of inflammation can frequently be found in the TMJ of patients with longstanding pain and tenderness of this joint.     

Influence of masticatory muscle pain on electromyographic activities of cervical muscles in patients with myogenous temporomandibular disorders

The present study tested the hypothesis that the resting electromyographic (EMG) activities of sternocleidomastoid and trapezius muscles of myogenous temporomandibular disorder (TMD) patients would be significantly greater than healthy individuals. Eight masticatory muscle pain patients without disc interference disorders (DID) and 30 patients with DID along with 41 matched control subjects were included in the study. The resting EMG activities of sternocleidomastoid and trapezius muscles were recorded with a portable EMG machine. Pain intensities described over the muscles were recorded with a 100 mm visual analogue scale. The two groups of patients had significantly higher resting activities compared with control subjects. Patients (in both groups) who had pain in sternocleidomastoid and trapezius muscles reported significantly higher resting activities in the respective muscles than patients who were free of pain and the controls. The presence of pain over the examined muscles showed significant association with the myogenous TMDs without DID. The observed association of the cervical muscles with myogenous TMDs is expected to be a result of functional link between masticatory and cervical muscles. The present findings suggest that the myogenous TMDs without DID could be a distinct sub-group that can be a part of broader regional or generalized diseased entity.     

Methadone treatment,bruxism, and temporomandibular disorders among male prisoners

There is little information on bruxism related to illicit drug use. Prolonged drug use may damage the stomatognathic system via oral motor overactivity. The aim of the present study was to compare the rates of bruxism and temporomandibular disorders (TMDs) between prisoners with and without drug‐use disorders, to evaluate the association between methadone treatment and bruxism and to assess the possible relationship between bruxism and pain. The sample included 152 male prisoners, 69 of whom were drug users maintained on methadone. All prisoners were examined by an experienced dentist and completed a questionnaire on their oral habits, with the aim of detecting signs or symptoms of TMD and/or bruxism. Additional data were collected from medical files. The prevalence of sleep bruxism and awake bruxism, but not of TMDs, was significantly higher among drug‐user than non‐drug user prisoners (52.2% vs. 34.9% for sleep bruxism, 59.7% vs. 30.1% for awake bruxism, and 46.3% vs. 25.6% for TMDs, respectively). Participants with awake bruxism were statistically more sensitive to muscle palpation compared with participants with sleep bruxism [rating scores (mean ± SD): 0.32 ± 0.21 vs. 0.19 ± 0.28, respectively]. An association was found between sleep bruxism and awake bruxism. It seems that there is a direct or an indirect association between methadone maintenance treatment and sleep bruxism or awake bruxism in male prisoners.     

The effect of the local anesthesia to the posterior ramus of the mandible in patients with temporomandibular joint problems

Some clinicians in North America use anesthetic injections to differentiate the symptoms such as pain and stiffness in the facial area and neck in patients with TMJ problems. However, the effects and area which is influenced have not been studied. The purpose of this study was to study procedures and changes following administration of local anesthesia to the posterior ramus of the mandible. Twenty four patients with TMJ problems were used in this study. 0.5ml of 2% Lidocaine (epirenamine included) was injected into the most painful site upon palpation. The pain upon palpation test (following Krogh-Poulsen's method) was compared before and after 50 minutes. Results of this experiment were: 1) decrease of pain upon palpation was found not only in the site. In many cases subjective pain in the head and neck area was also reduced. 2) A significant reduction was found in the pain upon palpation test in the neck area. A highly significant reduction was seen in the Sterunoclydmastoid muscle only in the injected side. In the masticatory muscles. Also, reduction of pain upon palpation was seen in both lateral, medial pterygoid and digastric muscles in the injected side. 3) Contra side lateral pterygoid muscle and trapezius muscle also registered decreased pain upon palpation. 4) The mean values for the injected site were 5.7mm (S.D. 5.9) below the earlobe and the mean depth from the skin surface to the bony surface were 16.6 mm (S.D. 2.7mm). 5) The peak of the subjective effect were seen in one group in 20 minute later injection (early type) and in the 2nd group the peak were seen after 40 minutes (slowly type). 6) We did not experienced any paralysis of the facial nerve in this study.     

Clinical signs of craniomandibular disorders in patients with psoriatic arthritis

Abstract – 110 patients with psoriatic arthritis (PA) and 110 individually matched control subjects were examined for clinical signs of craniomandibular (CM) disorders. Patients with PA differed significantly from control patients as regards the range of mandibular movements, tenderness to palpation of the masticatory muscles and TMJs, arid the frequency of TMJ sounds and painful mandibular movements. In the PA-group clinical signs of CM disorders correlated with the duration, extent and severity of PA.     

Malocclusion

Less than ideal interarch occlusal relationships rarely if ever cause significant untoward effects on the masticatory system. Parafunctional habits (such as bruxism and clenching) are responsible for excessive occlusal wear, fractured teeth, tooth mobility, the periodontal lesion of trauma from occlusion, fractured restorations, myofascial pain involving the muscles of mastication, and painful TMJs. Correction of the malocclusion with orthodontic procedures, restorative procedures, or occlusal adjustment by selective grinding will not control the parafunctional habits. Myofascial pain originating from the muscles of mastication is in an overwhelming number of cases a self-limiting problem. Therapy for this problem should not bring about any permanent physical changes to the patient's interarch occlusal relationships.     

The role of dental loss and denture status on clinical signs of temporomandibular disorders

Studies concerning the role of denture status on in temporomandibular disorders (TMD) are scarce. The aim of this study was to evaluate the association of tooth loss and denture status with clinical findings of TMD. The data were obtained from 6316 subjects aged ≥30 years from the Finnish Health 2000 Survey. The associations between clinically assessed TMD findings and number of teeth, wearing of removable dentures, need for denture repair and age of the dentures were analysed by means of chi‐square test and logistic regression. Among women after adjusting for age, having fewer teeth or wearing complete dentures associated with restricted maximum interincisal distance and pain on palpation of the temporomandibular joints (TMJ) and masticatory muscles. After adding education level and depression in the model, the associations between TMJ pain and explanatory variables were weakened. Among men, having a higher number of teeth associated with occurence of TMJ crepitation. Subjective need for repair of dentures and having a denture aged ≥5 years associated with pain on palpation in masticatory muscles among women. Among men, both the objective and subjective need for denture repair and having at least one denture aged ≥5 years or been repaired during the past 5 years associated negatively with the presence of TMJ crepitation. It can be concluded that edentulousness, wearing of complete dentures and poor condition of dentures associate with pain‐related TMD findings among women. Psychosocial factors have a modifying effect on these associations.     

Can palpation-induced muscle pain pattern contribute to the differential diagnosis among temporomandibular disorders, primary headaches phenotypes and possible bruxism?

Background

The evaluation of possible differences in the distribution or characteristics of palpation-induced pain in the masticatory muscles could be valuable in terms of diagnostic assessment. The aim of this study was to evaluate the impact of different combinations of anterior temporalis (AT) and masseter palpation-induced pain in the diagnostic of temporomandibular disorder (TMD), primary headaches and bruxism.

Material and Methods

A total of 1200 dental records of orofacial pain adult patients were analyzed. The outcomes were dichotomously classified (presence/absence) as following: a) AT and/or masseter palpation-induced pain; b) myogenous TMD; c) temporomandibular joint (TMJ) arthralgia (arthrogenous TMD); d) migraine; e) tension-type headache (TTH); f) self-reported bruxism. Binomial logistic regression model (α = 5%) was applied to the data considering the palpation-induced muscle pain as the dependent variable.

Results

Mean age (SD) were 35.7 years (13.4) for 635 included dental records (83% females). Myogenous and arthrogenous TMD, migraine, TTH and bruxism were mainly associated with, respectively, masseter palpation-induced pain (p<0.001 - OR=5.77, 95%CI 3.86-8.62), AT or masseter palpation-induced pain (p<0.001 - OR=2.39, 95%CI 1.57-3.63), bilateral AT palpation-induced pain (p<0.001 - OR=2.67, 95%CI 1.64-4.32), masseter and AT palpation-induced pain (p=0.009 - OR=1.62, 95%CI 1.12-2.33) and bilateral masseter palpation-induced pain (p=0.01 - OR=1.74, 95%CI 1.13-2.69).

Conclusions

Palpation-induced pain in the masticatory muscles may play a role in the differential diagnosis among painful TMD, primary headaches and bruxism. Key words:Diagnosis, temporomandibular joint disorders, migraine, tension-type headache, bruxism.     

The association between wear facets,bruxism, and severity of facial pain in patients with temporomandibular disorders

STATEMENT OF PROBLEM: It is unclear whether patients with temporomandibular disorders (TMD) who report high levels of bruxism have more severe signs and symptoms of TMD and more advanced tooth wear than patients with TMD who report lower levels of bruxism. PURPOSE: The purpose of this study was to determine whether there was a significant association between tooth wear, the parafunctional oral habit of bruxism, temporomandibular joint (TMJ) pain, and muscle pain severity in a TMD population. MATERIAL AND METHODS: A total of 84 subjects previously diagnosed with TMD, according to the Research Diagnostic Criteria for TMD (RDC/TMD) and who met 10 specific inclusion/exclusion criteria underwent a thorough multiaxial examination and classification recommended by the National Institute of Dental and Craniofacial Research (NIDCR). Measurement of tooth wear facets by use of a 4-point scale were graded in 10 zones on mandibular casts. One calibrated examiner performed all scoring. Bruxism was assessed in a standardized pretreatment questionnaire and in the dental history and interview (RDC/TMD) to indicate how frequently (0 = never to 3 = very often) subjects performed a list of oral habits, which included bruxism. The Kappa reliability coefficient (range from: -1.0 to 1.0) was used to correct for chance agreement, and was computed for each of the 10 study sites designated for rating. Subjects were also compared for muscle and joint pain. Muscle pain was a summed measure derived from the dental examination findings (range 0 to 20), calculated from the presence or absence of pain induced by palpation of 20 predetermined muscle sites. Similarly, joint pain was a summed measure of the presence or absence of pain in the TMJs induced by palpation of the joints on the outer surface and in the external auditory canal in 5 different positions of the mandible. A Pearson product-moment correlation was used to compute the summed severity of tooth wear and the subjects' age. Analysis of covariance was used to determine whether the number of wear facets was significantly higher in patients with TMD who reported a history of bruxism, compared with patients with TMD who reported no or minimal bruxism, after controlling for the effect of age. Multivariate analysis of variance was used to determine whether the number of painful muscles of mastication and joint sites on standardized examination were significantly higher in patients with TMD with a history of bruxism (alpha=.05). RESULTS: In the population tested, tooth wear was modestly correlated with age (r =.40, P<.001). Of the 84 subjects studied, 11.9% reported no bruxing activity, 32.1% reported some or occasional bruxing activity, and 47.6% had frequent bruxism activity; the remaining 8.4% were eliminated from analysis because they provided inconsistent responses. Bruxism activity was not correlated with muscle pain on palpation and was inversely associated with TMJ pain on palpation. Tooth wear was not significantly correlated with bruxism, TMJ pain, or muscle pain. CONCLUSIONS: In this TMD population, tooth wear factors did not differentiate patients with bruxism from those without. The amount of bruxism activity was not associated with more severe muscle pain and was associated with less pain in the TMJ on palpation.     

单侧后牙缺失对咀嚼肌肌电图的影响

目的:观察单侧后牙缺失对咀嚼肌肌电图的影响,从而探讨单侧后牙缺失在颞下颌关节(temporomandibular joint, TMJ)发病中的作用。方法:对40例单侧上颌后牙缺失患者组成的缺牙组和40例牙列完整的自愿者组成的对照组,进行肌电图检查。结果:缺牙组无论是松弛状态或紧咬时咀嚼肌的电位明显高于对照组(P<0.05),并且缺牙组紧咬时同名肌不对称性活动增加(P<0.05),其中对照组的咬肌肌电活动的对称性明显高于缺牙组(P<0.01),以上变化缺牙侧较非缺牙侧显著(P<0.05)。结论:单侧后牙缺失可以对咀嚼肌肌电图造成影响,可能是颞下颌关节疾病的发病原因之一。     

Bruxism: well known, but difficult to fathom

Tooth clenching or grinding may cause serious problems for patients and dentists. Symptoms occur at the level of the teeth (wear), the periodontium and the musculoskeletal system. In the past, the definition of bruxism often was vague and controversial, and also a clinical diagnosis appeared to be difficult. More recently research in the sleep laboratory, using a combination of electromyography video- and sound recording, made it possible to distinguish between bruxism and other oral behaviour. The association between pain and dysfunction of the masticatory system with bruxism is still unclear.     

Is there a relationship between head posture and craniomandibular pain?

An often-suggested factor in the aetiology of craniomandibular disorders (CMD) is an anteroposition of the head. However, the results of clinical studies to the relationship between CMD and head posture are contradictory. Therefore, the first aim of this study was to determine differences in head posture between well-defined CMD pain patients with or without a painful cervical spine disorder and healthy controls. The second aim was to determine differences in head posture between myogenous and arthrogenous CMD pain patients and controls. Two hundred and fifty persons entered the study. From each person, a standardized oral history was taken and blind physical examinations of the masticatory system and of the neck were performed. The participants were only included into one of the subgroups when the presence or absence of their symptoms was confirmed by the results of the physical examination. Head posture was quantified using lateral photographs and a lateral radiograph of the head and the cervical spine. After correction for age and gender effects, no difference in head posture was found between any of the patient and non-patient groups (P > 0.27). Therefore, this study does not support the suggestion that painful craniomandibular disorders, with or without a painful cervical spine disorder, are related to head posture.     

To what extent is bruxism associated with musculoskeletal signs and symptoms? A systematic review

The aim of the present systematic review was to answer the overall research question: “To what extent is bruxism associated with musculoskeletal signs and symptoms?”. The review was performed in accordance with the PRISMA guidelines. A PubMed search of articles published until 23 November 2017 was conducted. The search string included both MeSH terms and text words. Results were presented in categories according to study design, study population (eg, adults, children), bruxism sub‐type (awake, sleep), assessment methods for bruxism and musculoskeletal symptoms (self‐report, validated test) and type of outcome (pain, non‐painful musculoskeletal symptoms). It could be concluded that bruxism is to some extent associated with musculoskeletal symptoms, even though the evidence is conflicting and seems to be dependent on many factors, such as age, whether the bruxism occurs during sleep or wakefulness, and also the quality of the diagnostic methodology regarding bruxism and musculoskeletal signs and symptoms. The literature does not support a direct linear causal relationship between bruxism and such symptoms, but points more in the direction of a multifaceted relationship dependent on the presence of other risk factors. Pain is by far the most commonly assessed symptom, whereas non‐painful musculoskeletal symptoms have generally not been systematically evaluated. In the light of recent findings indicating that non‐painful symptoms may precede TMD pain, it is suggested to increase the scientific focus on non‐painful musculoskeletal symptoms in future studies. Also, future studies should use validated methods for case definition and outcome assessments.