Conflict of Interest: Dr. Bigal is an employee of Merck Research Laboratories and owns stock and stock options in Merck.
Headache and Symptoms of Temporomandibular Disorder: An Epidemiological Study
Article first published online: 14 SEP 2009
© 2009 the Authors. Journal compilation © 2009 American Headache Society
Headache: The Journal of Head and Face Pain
Volume 50, Issue 2, pages 231–241, February 2010
How to Cite
Gonçalves, D. A.G., Bigal, M. E., Jales, L. C.F., Camparis, C. M. and Speciali, J. G. (2010), Headache and Symptoms of Temporomandibular Disorder: An Epidemiological Study. Headache: The Journal of Head and Face Pain, 50: 231–241. doi: 10.1111/j.1526-4610.2009.01511.x
- Issue published online: 24 JAN 2010
- Article first published online: 14 SEP 2009
- Accepted for publication July 2, 2009.
- temporomandibular joint;
- primary headaches;
Objectives.— A population-based cross-sectional study was conducted to estimate the prevalence of migraine, episodic tension-type headaches (ETTH), and chronic daily headaches (CDH), as well as the presence of symptoms of temporomandibular disorders (TMD) in the adult population.
Background.— The potential comorbidity of headache syndromes and TMD has been established mostly based on clinic-based studies.
Methods.— A representative sample of 1230 inhabitants (51.5% women) was interviewed by a validated phone survey. TMD symptoms were assessed through 5 questions, as recommended by the American Academy of Orofacial Pain, in an attempt to classify possible TMD. Primary headaches were diagnosed based on the International Classification of Headache Disorders.
Results.— When at least 1 TMD symptom was reported, any headache happened in 56.5% vs 31.9% (P < .0001) in those with no symptoms. For 2 symptoms, figures were 65.1% vs 36.3% (P < .0001); for 3 or more symptoms, the difference was even more pronounced: 72.8% vs 37.9%. (P < .0001). Taking individuals without headache as the reference, the prevalence of at least 1 TMD symptom was increased in ETTH (prevalence ratio = 1.48, 95% confidence interval = 1.20-1.79), migraine (2.10, 1.80-2.47) and CDH (2.41, 1.84-3.17). At least 2 TMD symptoms also happened more frequently in migraine (4.4, 3.0-6.3), CDH (3.4; 1.5-7.6), and ETTH (2.1; 1.3-3.2), relative to individuals with no headaches. Finally, 3 or more TMD symptoms were also more common in migraine (6.2; 3.8-10.2) than in no headaches. Differences were significant for ETTH (2.7 1.5-4.8), and were numerically but not significant for CDH (2.3; 0.66-8.04).
Conclusion.— Temporomandibular disorder symptoms are more common in migraine, ETTH, and CDH relative to individuals without headache. Magnitude of association is higher for migraine. Future studies should clarify the nature of the relationship.
American Academy of Orofacial Pain
chronic daily headache
difficulty during lateral deviation
difficulty during mouth opening
episodic tension-type headache
masticatory muscle pain
trigeminal nucleus caudalis
Headache is a nearly universal human experience, and may represent the final common expression of a wide variety of assaults upon the human nervous system.1 Headache is the major complaint of primary headache disorders, and is also a symptom that may be attributed to secondary disorders (eg, infections or tumors).2 Among the primary headache disorders, migraine is the best studied. It is a prevalent and disabling condition that affects 35 million individuals in the USA only.3
Temporomandibular disorders (TMDs) is a collective term that embraces a number of clinical problems that involve the masticatory muscles, the temporomandibular joint (TMJ), and the associated structures.4,5 TMDs syndromically represent the consequences of several disorders into the masticatory system. The most common symptom of TMDs is pain, usually located in the masticatory muscles and/or the preauricular area.5 Headache is also a common symptom among individuals with TMD.5,6-12 Although not as well characterized as the prevalence of common headache syndromes, the prevalence of TMD (or symptoms suggestive of TMD) ranges from 21.5% to 51.8%.8,13,14 According to the American Academy of Orofacial Pain (AAOP) Guidelines, epidemiological studies of adult populations suggest that 40% to 75% of individuals have at least 1 sign of joint dysfunction, and nearly 33% have at least 1 symptom of TMD.5
Beyond being prevalent and disabling disorders,15,16 limited evidence also suggests that specific headache disorders (such as migraine) and TMD are comorbid.17-19 Clarifying this topic is of clinical importance. If TMDs are comorbid with headaches in general (not with specific headache disorders), the association may reflect spurious association rather than true comorbidity,20 as headache is 1 diagnostic criterion for TMD.2 If TMDs are associated with several headache disorders (eg, tension-type headache [TTH], migraine, etc), it may be speculated that nonspecific activation of common pathways (eg, trigeminal nucleus caudalis [TNC]) explain the comorbidity, which would be therefore bidirectional (pain in the trigeminal distribution predispose to other forms of facial pain or headache). Differently, if TMDs are comorbid with specific headache syndromes (eg, migraine but not TTH), this would have pathophysiological and therapeutic importance as one (eg, TMD) may contribute to refractoriness to treatment of the second (eg, migraine). Finally, if TMD and headaches are not comorbid, the findings are of interest as well, as headache sufferers are often diagnosed as having “TMD,” or receive dental treatments in an attempt to improve their headaches.
The potential comorbidity of headache disorders and TMD has been established mostly based on clinic-based studies.19 Accordingly, herein we investigate the prevalence of headache syndromes and symptoms of TMD in a general adult population sample. We hypothesized the association is stronger for migraine than for episodic tension-type headache (ETTH). Additionally, as limited evidence also suggests that TMD may be a risk factor for chronic daily headaches (CDH),21 we hypothesized that the association is strongest for CDH. Finally, we postulated that association increases as a function of number of symptoms of TMD dysfunction.
Description of the Sample.— This was a population-based cross-sectional study, conducted to determine the prevalence rates of the most common TMD symptoms and of migraine, ETTH, and CDH in a Brazilian urban population.
We identified a stratified probability sample of 1230 habitants, from an urban area of 484,422 habitants, according to the demographic census.22 These individuals were contacted and invited to participate in a telephone survey. The city is well diversified and provides good demographic representation. Furthermore, according to the census, the vast majority of the households have telephones.22 The strategy used (a representative city) is similar to what has been extensively used in the USA.23 The urban area of the city is geographically divided into 4 different regions, and subdivided into 59 subregions. The entire urban geographic area was sampled.
For sample size calculation, due to the variability of headache and TMD prevalence rates presented in the literature, an average of those rates was considered.5,24-29 Based on the sample size calculations, to be representative and adequately powered, our sample should consist of over 1000 individuals (see data analysis, below). The total sample was proportionally distributed according to the numbers of inhabitants in each subsector. We initially numbered all blocks of each subsector, using detailed city maps; we then randomly chosen blocks in each section, and, for each of them, one of their streets was randomly selected (north, south, east, or west). From each selected street, 3 houses were randomly chosen using the telephone number available at the telephone directory of the city.
For each house, a total of 3 call attempts were made. When none of the houses in a street responded or agreed to participate, the block was considered not to be represented. Nonparticipation was therefore defined as a function of nonparticipating streets.
For each household, we interviewed only 1 individual that filled inclusion criteria. Eligibility criteria were: women and men aged 15 to 65 years old, capable of answering the questions and who agreed to do so. The percentage of women and men was very similar to of the total population of the city, 51.5% and 48.5%, respectively. According to the method described, 1230 individuals agreed to answer the questions.
Questionnaires.— We used a questionnaire with 30 questions, assessing 2 different domains, herein described separately.
TMD Section.— The questions focusing on TMD symptoms were adapted from the anamnesis proposed by the AAOP5,17 for the survey of TMD symptoms and identification of possible TMD. The questionnaire consisted of 5 questions that individually asked about TMJ sounds and pain, masticatory muscle pain (MMP) or fatigue of the jaw, difficulty during mouth opening (DDMO), or difficulty during lateral deviation (DDLD). For example, the question about TMJ sounds was: “have you ever had any clicking or other sounds in the joint around your ears?” If the answer was positive, the respondent was asked if they had presented the symptom more than once, and if they had presented the symptom in the last month. Only last month data were considered for capturing information on TMD. Questions about other symptoms were similarly constructed. This questionnaire has been validated, and has excellent internal consistency (0.70) in addition to good internal measure constructs.30-32 The questionnaire also has good reproducibility with the 5 questions presenting Kappa (κ) > 0.71.30,33,34 According to the guidelines of the AAOP, a positive answer to at least one of these questions is indicative of possible TMD.5,17 Therefore, herein the individuals that answered yes to at least one of the 5 questions were classified as presenting possible TMD. However, to achieve our aims, we also used figures of individuals presenting at least 2, and 3 or more symptoms. Finally, we separately considered the presence of pain (MMP and TMJ pain) as a surrogate to possible TMD dysfunction.
Headache Section.— The headache module of the questionnaire consisted of 19 questions, assessing the distinguishing features required for headache diagnosis, such as headache characteristics, frequency of pain, nausea, photophobia, phonophobia, duration of the episodes, presence of aura, etc. Further, we also asked about behaviors related to pain, and some aspects of quality of life. The questionnaire not only followed the International Classification of Headache Disorders—Second Edition classification criteria for primary headaches, but also assessed headache frequency and other headache parameters.2 The questionnaire was tested by means of 40 telephone interviews conducted in patients from an outpatient headache clinic (individuals could have any form of headache or be in remission). Diagnoses were compared with those obtained during personal consultation with a specialist. Diagnostic agreement happened in 97.5% of cases. The time for application for both questionnaires was around 10 minutes.
Based on the responses, individuals were categorizing as having: (1) no headaches; (2) migraine; (3) ETTH; (4) CDH;35 and (5) other headaches.
Data Analysis.— We used literature estimates to assume headache prevalence (12% for migraine, 40% for episodic TTH, and 4% for CDH). For TMD, a prevalence rate of 38% suggested by the AAOP was considered.17 Since our original study focusing on testing comorbidity of TMD with headache overall vs no headache, and then with specific headache syndromes, we powered our study based on the prevalence of migraine (12%), which would give us enough power to also use TTH (40%) as a contrast. For CDH, data were exploratory. Confidence interval (CI) of 95% and a sampling error of 3% were fixed. The sample size calculation totaled 1006 individuals to allow detecting a difference in the relative risk of 20% for migraine vs TTH. Assuming an attrition of 20%, the size of the sample was corrected to 1258 individuals.
To characterize the sample, descriptive statistics were performed. The sample was stratified by gender and age for study of the associations with TMD and headache. For comparison of proportions, the chi-squared (χ2) test was performed. Then, the respondents were grouped according to the presence of TMD for study of the association with headache by means of prevalence ratio (PR) test, with 95% of CI. PR is the ratio of the proportion of the persons with disease (eg, prevalence of migraine) over the proportion with the exposure (eg, prevalence of TMD). If the prevalence is the same, the ratio will equal 1.0. If disease prevalence is higher in those with the exposure (placed on top in the ratio), the ratio will be greater than 1.0. If the prevalence is lower in those with the exposure, the ratio will be less than 1.0. If the CI does not incorporate the number 1, then the difference is significant to the 5% level (as we worked with 95% CI).
We separately summarized number of TMD symptoms as a function of headache diagnosis. Using individuals with no headache as the reference, we estimated the odds of having TMD symptoms in different headache groups.
The level of significance adopted was 5%. Statistical analysis was performed with the aid of the spss 15.0 for Windows (SPSS Inc., Chicago, IL, USA).
This study and the phone survey received full approval from a Human Research Committee (School of Medicine, University of Sao Paulo).
From 1263 streets sampled, we obtained participation of at least 1 household in 97.4% of them. Our final sample consists of 1230 individuals, 48.5% men and 51.5% women. The demographics are described in Table 1. Reflecting the age distribution of the Brazilian population, the largest age group was the 20 to 45 years olds (51%), followed by 45 to 60 years (25%), 15 to 20 years (14.2%), and 60 to 65 years (9.8%).22 There were no statistically significant differences in the distribution of men and women according to age groups (χ2 = 3.309; P = .346).
|Women (N = 633)||P value/age||Men (N = 597)||P value/age||Overall (N = 1230)||P value/age||P value/gender|
Overall, TMJ sounds were the most prevalent symptom (23.7%), followed by TMJ pain (16.3%), MMP (15.4%), DDMO (9.8%), and DDLD (6.8%). Overall, 1 TMD symptom happened in 39.2% (n = 482) of our sample; 2 symptoms happened in 17.6% (n = 217); 3 or more symptoms happened in 9.2% (n = 113); pain happened in 25.6% (n = 315). From all TMD symptoms, only DDMO varied significantly as a function of age (χ2 = 9.208; P = .027). For all symptoms but TMJ sounds, prevalence was higher in women than in men (P < .05). MMP and TMJ pain were nearly twice as common in women as in men (P < .01) (Table 1).
TMD and Primary Headaches.— As exposed in the methods, we categorized headaches in migraine, ETTH, and CDH. Other headaches were excluded from the analyses. Accordingly, in this section, data were obtained from 1148 individuals. A total of 41.1% of participants had any headache. Migraine was diagnosed in 20.8% of the sample; ETTH in 17.4%, and CDH in 2.9%. As expected, headaches were more common in those from 20 to 45 years old (χ2 = 17.236; P = .045) and in women (χ2 = 118.697; P = .000). Among individuals without headaches, 43.5% were women and 74.3% were men.
Overall, TMD symptoms were more common in all forms of headache than in the no headache group. When at least 1 TMD symptom was reported, any headache happened in 56.5% vs 31.9% (P < .0001) in those with no symptoms. For 2 symptoms, figures were 65.1% vs 36.3% (P < .0001); for 3 or more symptoms, the difference was even more pronounced: 72.8% vs 37.9%. (P < .0001) (Table 2).
|n (%)||n (%)||n (%)||95% CI|
|At least 1 TMD symptom|
|No headaches||187 (27.7)||489 (72.3)||676 (100)||Reference|
|Migraine||139 (58.2)||100 (41.8)||239 (100)||2.10 (1.80-2.47)|
|CDH||22 (66.7)||11 (33.3)||33 (100)||2.41 (1.84-3.17)|
|ETTH||82 (41)||118 (59)||200 (100)||1.48 (1.20-1.79)|
|Total||430 (37.5)||718 (62.5)||1148 (100)|
|At least 2 TMD symptoms|
|No headaches||67 (9.9)||609 (90.1)||676 (100)||Reference|
|Migraine||78 (32.6)||161 (67.4)||239 (100)||4.4 (3.0-6.3)|
|CDH||9 (27.3)||24 (72.7)||33 (100)||3.4 (1.5-7.6)|
|ETTH||38 (19)||162 (81)||200 (100)||2.1 (1.3-3.2)|
|Total||192 (16.7)||956 (83.3)||1148 (100)|
|At least 3 TMD symptoms|
|No headaches||28 (4.1)||648 (95.9)||676 (100)||Reference|
|Migraine||51 (21.3)||188 (78.7)||239 (100)||6.2 (3.8-10.2)|
|CDH||3 (9.1)||30 (90.9)||33 (100)||2.3 (0.66-8.04)|
|ETTH||21 (10.5)||179 (89.5)||200 (100)||2.7 (1.5-4.8)|
|Total||103 (9)||1045 (91)||1148 (100)|
Table 2 also lists the presence of TMD symptoms as a function of headache type. Taking individuals without headache as the reference, the prevalence of at least 1 TMD symptom was increased in ETTH (PR = 1.48, 95% CI = 1.20-1.79), migraine (PR = 2.10, 95% CI = 1.80-2.47), and CDH (PR = 2.41, 95% CI = 1.84-3.17). At least 2 TMD symptoms also happened more frequently in migraine (PR = 4.4, 95% CI = 3.0-6.3), CDH (PR = 3.4; 95% CI = 1.5-7.6), and ETTH (PR = 2.1; 95% CI = 1.3-3.2), relative to individuals with no headaches. Finally, 3 or more TMD symptoms were also more common in migraine (PR = 6.2; 95% CI = 3.8-10.2) than in no headaches. Differences were significant for ETTH (PR = 2.7; 95% CI = 1.5-4.8), and were numerically but not significant for CDH (PR = 2.3; 95% CI = 0.66-8.04) (Table 2).
Table 3 lists the prevalence of individual symptoms, as a function of headache diagnosis. Taking no headache group as reference, each TMD symptom was significantly more common in individuals with headaches. For migraine, stronger associations were seen for TMJ pain (PR = 6.0; 95% CI = 4.0-9.0), DDLD (PR = 4.7; 95% CI = 2.7-8.1), and MMP (PR = 4.5; 95% CI = 3.1-6.7). For CDH, associations were seen for DDLD (PR = 3.9; 95% CI = 1.2-12), MMP (PR = 3.9; 95% CI = 1.7-9.0), TMJ Pain (PR = 3.4; 95% CI = 1.4-8.3), and TMJ sounds (PR = 2.5; 95% CI = 1.2-5.3). For ETTH, associations were only seen for TMJ pain (PR = 3.4; 95% CI = 2.1-5.3) and MMP (PR = 2.2; 95% CI = 1.4-3.5).
|n (%)||n (%)||n (%)||95% CI|
|Difficulty during mouth opening|
|No headaches||633 (93.6)||43 (6.4)||676 (100)||Reference|
|Migraine||202 (84.5)||37 (15.5)||239 (100)||2.6 (1.6-4.3)|
|CDH||28 (84.8)||5 (15.2)||33 (100)||2.6 (0.9-7.1)|
|ETTH||180 (90)||20 (10)||200 (100)||1.6 (0.9-2.8)|
|Total||1043 (90.9)||105 (9.1)||1148 (100)|
|Difficulty during lateral deviation|
|No headaches||653 (96.9)||23 (3.4)||676 (100)||Reference|
|Migraine||205 (85.8)||34 (14.2)||239 (100)||4.7 (2.7-8.1)|
|CDH||29 (87.9)||4 (12.1)||33 (100)||3.9 (1.2-12.0)|
|ETTH||187 (93.5)||13 (6.5)||200 (100)||1.9 (0.9-3.9)|
|Total||1074 (93.6)||74 (6.4)||1148 (100)|
|No headaches||553 (81.8)||123 (18.2)||676 (100)||Reference|
|Migraine||159 (66.5)||80 (33.5)||239 (100)||2.2 (1.6-3.1)|
|CDH||21 (63.6)||12 (36.4)||33 (100)||2.5 (1.2-5.3)|
|ETTH||154 (77)||46 (23)||200 (100)||1.3 (0.9-1.9)|
|Total||887 (77.3)||261 (22.7)||1148 (100)|
|No headaches||627 (92.8)||49 (7.2)||676 (100)||Reference|
|Migraine||162 (67.8)||77 (32.2)||239 (100)||6.0 (4.0-9.0)|
|CDH||26 (78.8)||7 (21.2)||33 (100)||3.4 (1.4-8.3)|
|ETTH||158 (79)||42 (21)||200 (100)||3.4 (2.1-5.3)|
|Total||973 (84.8)||175 (15.2)||1148 (100)|
|Masticatory muscle pain|
|No headaches||618 (91.4)||58 (8.6)||676 (100)||Reference|
|Migraine||167 (69.9)||72 (30.1)||239 (100)||4.5 (3.1-6.7)|
|CDH||24 (72.7)||9 (27.3)||33 (100)||3.9 (1.7-9.0)|
|ETTH||165 (82.5)||35 (17.5)||200 (100)||2.2 (1.4-3.5)|
|Total||974 (84.8)||174 (15.2)||1148 (100)|
We also correlated TMD pain symptoms with headache diagnosis (Table 4). As compared with individuals without headache, presence of TMD pain was increased in migraine (PR = 5.3; 95% CI = 3.8-7.4), followed by CDH (PR = 3.9; 95% CI = 1.8-8.1) and ETTH (PR = 2.7; 95% CI = 1.8-3.9).
|TMD pain||TMD pain-free||Total||Prevalence ratio|
|n (%)||n (%)||n (%)||95% CI|
|No headaches||96 (14.2)||580 (85.8)||676 (100)||Reference|
|Migraine||112 (46.9)||127 (53.1)||239 (100)||5.3 (3.8-7.4)|
|CDH||13 (39.4)||20 (60.6)||33 (100)||3.9 (1.8-8.1)|
|ETTH||62 (31)||138 (69)||200 (100)||2.7 (1.8-3.9)|
|Total||283 (24.7)||865 (75.3)||1148 (100)|
Headaches are among the most common complaint in individuals with TMD.5,7 Furthermore, both headaches and TMD are highly prevalent conditions in the population. Because of the relative scarcity of population-based information about the potential comorbidity between both conditions, our study is justified. Our most important findings are: (1) symptoms of TMD (in different sets of combinations) are more prevalent in individuals with headache than in individuals without headache. Although this may reflect some circularity in reasoning (headache is per se a symptom of TMD), the results are reinforced by different rates of symptoms in different headache syndromes (see below), as well as by the positive association of nonpainful symptoms; (2) all headache syndromes are more common in individuals with possible TMD than in individuals without TMD symptoms.
It is difficult to compare the presence of possible TMD and of headache syndromes found in our study with others because of differences in samples, criteria, and methods used for collecting the information. According to the AAOP,17 a precise diagnosis of TMD requires anamnesis, oral exam, and psychological evaluation of the individual. This approach is expensive and often unfeasible for population surveys. Accordingly, published results vary enormously. In a review of 18 epidemiological studies, prevalence of TMD in adults ranges from 16% to 59%.36 In studies that used similar methodology to ours, the prevalence rates range from 30% to 47%.13,37,38 In our study, rates were 39.2% (at least 1 TMD symptom reported), 17.6% (at least 2 TMD symptoms reported), and 9.2% (3 or more TMD symptoms reported). Considering presence of pain symptoms associated with TMD as a surrogate for possible TMD diagnose, the prevalence rate was 25.6%.
Our findings for headache are also aligned with the literature, and for figures from Brazil.26 Additionally, the prevalence found by us for migraine is very similar to what has been reported in a representative population-based study.26,39,40 Our study is justified on several grounds. First, we applied standard criteria that used the current classification for headache diagnosis.2 We collected data about TMD and headache syndromes at the same sample, with balanced women and men ratios. Additionally, our sample size was large enough and representative of an urban population by demographics. Representative studies assessing the comorbidity of headache syndromes and TMD are scarce. Finally, as biological predisposition (reflecting racial differences) and external exposures may vary in different places, our study adds to the global literature on the theme.
Although TMD symptoms were more common in all headache syndromes, the magnitude of the effect varied. Overall, it was stronger for migraine than for CDH, and it was positive but lowest in ETTH. Our results find support in the literature.19,41 Indeed, migraine and CDH showed strong association with TMD presence. Nonetheless, one of our hypotheses was proven wrong. We expected to see higher degrees of association with CDH rather than with migraine. However, as CDH reflects a syndrome that includes both chronic migraine and chronic tension-type headache (CTTH), it may be that high relative frequency of CTTH may have contributed to attenuate the findings for CDH. Future studies should assign specific diagnosis for CDH subtypes.
It is well established that neurons in the TNC integrate nociceptive input from intracranial as well as extracranial tissues and receive supraspinal facilitatory as well as inhibitory inputs. They sum all these inputs and projects the net results to the thalamus and onto the cortex.42 Further, the presence of proinflammatory factors at the TMJ could contribute to the TNC activation. High levels of prostaglandin E2,43 cytokines such as interleukin 1b (IL-1β),44,45 IL-6,46 and tumor necrosis factor-α47 have been detected in synovial fluid of inflamed joints and demonstrated a strong correlation with pain. Also, calcitonin gene-related peptide, substance P, and serotonin have been detected in the TMJ.48-50 Accordingly, it can be hypothesized that nociceptive inputs provenient from masticatory muscle or TMJ could lead to that mentioned activation. Alternatively, headache syndromes, by activating the TNC, may decrease the threshold for other forms of pain, including TMD pain. Because we found association with nonpainful symptoms as well, this later hypothesis can only incompletely explain our findings.41,51
Our study relied on a questionnaire to assess TMD. Although some of the questions assess signs rather than symptoms (eg, clicks), what we obtained was the self-report and therefore we refer to symptoms and signs collectively as symptoms. Nonetheless, we emphasize that this questionnaire was developed from a 10-item questionnaire.30 In the process of developing a shorter questionnaire, although we found that all of the original questions had good reliability, eliminating any of the 5 questions used by us significantly decreased the reliability of the instrument. Accordingly, herein we opted not to separately analyze questions assessing symptoms from questions assessing signs.
Cautions are required when interpreting our results. First, we did not assess TMD, but presence of any of the TMD symptoms that raise the clinical suspicion of TMD; therefore, what we identified are individuals with possible TMD. It can be argued that our diagnostic criteria is too loose. Indeed, when assessing the prevalence of 2 or more TMD symptoms, the proportion of individuals endorsing criteria falls from 39.2% to 17.6% and 9.2%. If the criteria for possible TMD were presence of TMD pain, the prevalence was 25.6%.30 Nonetheless, the scope of our study was to investigate whether TMD symptoms were more common in individuals with headache than in the control population. Even using different combination of TMD symptoms, the PR to migraine remain higher if compared with individual free of TMD symptoms. When TMD pain was considered, the PR for all type of headache was higher. Second, our study used a questionnaire to assess headaches following standard criteria. The questionnaire is very similar to the headache section of classical studies conducted in the USA, where it has been demonstrated to have very high sensitivity (over 97% and specificity [93%]).2 Nonetheless, the questionnaire has not been totally validated in Portuguese. However, our pilot testing conducted in 40 individuals showed similar agreement to the USA values. Even though, clinic-based studies assessing TMD and headaches should be conducted, validating our tools against gold standards. This is of particular importance, since that, at least for TMD, it has been demonstrated that clinical screening only (without examination) tends to overestimate the severity of pain.52 Third, causation cannot be inferred by our design. Furthermore, the sample was selected by using the telephone directory. In none of the suburbs, irrespective of the socio-economic level they presented, did we have difficulty in finding at least 1 residence with a telephone in each section of the street selected. However, one must point out that the results refer to a population that had fixed telephones in their residences. Finally, although we computed the nonrespondent “streets,” we do not have figures for nonrespondent households.
Temporomandibular disorder symptoms are more common in migraine, ETTH, and CDH relative to individuals without headache. Magnitude of association is higher for migraine. Future studies should clarify the nature of the relationship.
STATEMENT OF AUTHORSHIP
- (a) Conception and DesignDaniela A.G. Gonçalves; Luciana C.F. Jales; José G. Speciali
- (b) Acquisition of DataDaniela A.G. Gonçalves; Luciana C.F. Jales
- (c) Analysis and Interpretation of DataDaniela A.G. Gonçalves; Marcelo E. Bigal; Cinara M. Camparis
- (a) Drafting the ManuscriptMarcelo E. Bigal; Cinara M. Camparis
- (b) Revising It for Intellectual ContentMarcelo E. Bigal; José G. Speciali
- (a) Final Approval of the Completed ManuscriptJosé G. Speciali
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- 52The challenge of measuring the efficacy of treatment of chronic trigeminal myofascial Pain. In: StohlerCS. CarlsonDS, ed. Biological and Psychological Aspects of Orofacial Pain. Ann Arbor, MI: Needham Press; 1994:113-132., .