Abstract
Background. Headaches (HAs) and temporomandibular joint dysfunction (TMD) are common comorbidities, and the presence of one of them in a patient increases the incidence of the other. The relationship between these 2 conditions may involve common pathophysiological processes. Considering the topicality of the problem, it is justified to conduct research in this field. In this study, we assessed HA type and severity in people with TMD.
Objectives. The aim of the study was to conduct qualitative and quantitative assessments of HAs in people with temporomandibular joint (TMJ) disorders.
Materials and methods. The study group consisted of 51 subjects of both sexes with a TMD diagnosed using the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) test. A self-report questionnaire was utilized to self-assess the presence of TMD symptoms, while the standardized Short-Form of the McGill Pain Questionnaire was used to qualitatively and quantitatively assess HAs.
Results. People with TMD were significantly more likely to report HA occurrences (p < 0.001). Pain intensity was statistically significantly higher among individuals with TMD compared to those without TMD symptoms (p < 0.001). Most often, the HA was associated with a pressing pain (r = 0.82) and least often, it was described as cutting (r = 0.30). Neck and shoulder girdle pain (p = 0.059; 82.9%) and clenching and/or grinding of teeth (p = 0.021; 92.7%) were significantly more common among patients who declared HAs than among those without HAs. The results obtained so far may indicate a significant relationship between HA and TMD.
Conclusions. We have described the relationship between the occurrence of HAs and TMD. Headaches are more frequent and more severe in people with TMD.
Key words: pain, temporomandibular joint, headache, dysfunction, craniofacial pain
Background
According to the World Health Organization (WHO) report, temporomandibular joint disorders (TMDs) are the 3rd most common dental disease after tooth decay and periodontal disease.1 Schiffman et al. states that TMD can affect between 5% and 12% of the world population.2 Some studies have shown a higher prevalence of up to 25% and 33–40% in the general population.3, 4, 5
A study by Chisnoiu et al. indicates that 60–70% of the general population have at least 1 sign of TMD, but only 1 in 4 people with TMD symptoms are referred to specialists.6 In the USA, between 40% and 75% of adults have at least 1 sign of TMD.7 In Korea, the percentage of people with TMD is 3.1% of the adult population, among whom 10.5% had more than 1 symptom related to the presence of this dysfunction.8
Patients with TMD symptoms span a wide age range; however, the peak occurrence is between the ages of 20 and 40.9 Temporomandibular joint disorders affect women 1.5–2.5 times more often than men.9
The etiopathology of TMD is multifactorial and under constant investigation by researchers and clinicians. Genetic conditions, factors located inside the oral cavity, and environmental determinants, with a particular emphasis on psycho-emotional factors, are mentioned as etiological factors.10, 11, 12 The most common symptoms of TMD include, among others, temporomandibular joint (TMJ) mobility disorder, pain in the masticatory muscles and/or TMJ, headaches (HAs), and/or cervical spine pain.13, 14
According to the literature, there is a high rate of comorbidities in patients with multiple chronic pain conditions, including fibromyalgia and HAs.15, 16
The International Classification of Headache Disorders (ICHD-3) published by The International Headache Society (HIS) states that within the facial region of the skull, TMD HAs are the second most common symptom after toothache.17
Headaches have been shown to occur more frequently in patients with TMD symptoms (27.4% compared to 15.2%) and can be divided into 2 main types: primary HAs (migraine and tension-type HA (TTH)) and secondary HAs (e.g., pain attributed to TMD, cervicogenic HA).18, 19 Unlike primary HAs, HAs attributed to TMD have a known cause of pain, which is TMD. The underlying condition of TMD needs to be treated in order to reduce HAs attributed to TMD. There is also a strong correlation between cervical HA and TMD, as patients with TMD often report cervical spine dysfunction, and patients with cervical HA often report TMD symptoms.20, 21
Other studies have shown that TMD patients report HAs more frequently (68–85%) than the general population (50%).22, 23, 24 Aggarwal et al. stated that HAs are more common in patients with TMD symptoms (27.4% compared to 15.2%).25 Other studies have reported that approx. 70% of TMD patients complain of HAs.26 In the study by Ballegaard et al., the incidence of TMD and HA was 56.1%.27 Franco et al. examined 226 patients, and according to their study, TMD and HAs coexist more often compared to a control group without TMD (85.5% compared to 45.6%).28 Reiter et al. observed that the HA attributed to TMD in painful TMD may be related to a central sensitization process.29 In contrast, other studies have found that people with TMD are more likely to suffer from a migraine and episodic TTH.30
Also, Magnusson and Carlsson observed that TMD patients, especially women, suffered from migraines more often than the control group.31 The correlation between TMD and HA was also studied by Gonçalves et al., who confirmed a higher frequency of TMD in the migraine and chronic migraine groups than in the control group.32 This relationship may be associated with increased masticatory muscle tone, which generates nociceptive impulses in the central nervous system, increasing the likelihood of a migraine.32 According to previous scientific studies, migraines are associated with the activation and sensitization of the trigeminal vascular system.32 This leads to the release of several pro-inflammatory neuropeptides and neurotransmitters, and causes a cascade of inflammatory tissue responses, including vasodilation, plasma extravasation secondary to capillary leakage, edema, and mast cell degranulation. It is now believed that neurogenic inflammation contributes to the development of a migraine attack.33, 34 Other researchers have also described a link between HAs and TMD.35, 36, 37, 38
Currently, numerous scientific studies are being carried out in search of innovative methods of HA treatment.39, 40, 41, 42 Also, in the context of TMD, there is more and more new scientific evidence confirming the effectiveness of pharmacological treatment as well as splint therapy and physiotherapy.43, 44
Therefore, it can be assumed with great caution that the coexistence of TMD and HAs may suggest a common pathogenesis, causation, or common confounding factor, although this issue is not fully understood and may seem controversial.45 Therefore, further research on this topic seems justified. In this study, the authors set themselves the goal of assessing the nature of the HAs, their frequency and severity in people with diagnosed disorders of the TMJs.
Objectives
The aim of the study was to conduct qualitative and quantitative assessments of HAs in people with TMJ disorders.
Materials and methods
As described above, HA is a common symptom in people with TMD. The diagnosis of TMD can be difficult, with some controversy regarding the relative importance of clinical and radiological evidence.46 Therefore, it is recommended to use the diagnostic criteria developed by the International Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Consortium Network and the Orofacial Pain Special Interest Group.46, 47, 48, 49
Our pilot study was conducted between April and September 2022 at the Department of Rehabilitation Musculoskeletal System of the Pomeranian Medical University in Szczecin, Poland. The study group consisted of 51 individuals of both sexes (women: n = 45, 85.5%; men: n = 6, 14.5%), aged 18–35 years, with TMD diagnosed using the RDC/TMD (n = 51, 82.3%).
The inclusion criteria were consent to participate in the study and the absence of neurological, autoimmune, hormonal, and degenerative joint diseases. The exclusion criteria were orthodontic, prosthetic and implant treatment, history of head trauma, condition after head and neck surgery, and pregnancy.
A study involved completing an anonymous questionnaire consisting of 2 parts:
1. An original 17-question survey. The first question – personal data – concerned the gender and age of the respondents. The next questions were related to the occurrence of TMJ symptoms (HA, pain in the neck and shoulder girdle, pain in the masticatory muscles, ear pain, pain in the TMJ, clenching/grinding of teeth, excessive or limited mobility of the jaw, acoustic symptoms, and feeling of increased tension in the masticatory muscles);
2. McGill Pain Questionnaire – Short-Form50, 51, 52 – questions related to the quantitative and qualitative pain assessment. The questionnaire contains 15 adjectives, divided into 2 categories: sensory (adjectives 1–11) and affective (adjectives 12–15), each rated on a 4-point scale of pain severity (pain quality: 0 – not at all; 3 – very much). Furthermore, it includes a visual analog scale (ranging from no pain to the worst possible pain) and an index of the severity of the currently experienced pain (0 – no pain, 10 – unbearable pain). The higher the score, the more severe the patient’s pain.
Statistical analyses
The analysis was performed using the IBM SPSS v. 24 software (IBM Corp., Armonk, USA). Tests included the χ2 tests of independence for comparison of response proportions and one-sample Wilcoxon tests for comparison of pain severity to a null value. If the expected value criterion was not met in the contingency tables, Fisher’s exact test and the Fisher–Freeman–Halton test were applied. Due to the observation of distributions deviating from the normal distribution based on the Shapiro–Wilk test as well as skewness and kurtosis indices, analyses were performed using non-parametric statistical methods.53, 54 Variable statistics are presented in Supplementary Table 1. A threshold of α = 0.05 was used as the level of significance.
Results
The χ2 test was used to compare the proportion of patients with HAs to those who reported no pain. Statistically significant differences have been observed (χ2 = 18.84, degrees of freedom (df) = 1, p < 0.001). Patients with TMD had significantly more HAs, which is confirmed by 80% of respondents (Figure 1).
The type of HA was verified using a one-sample Wilcoxon test due to the fact that patients who declared no HAs at the same time declared a HA frequency of 0. Thus, it was decided to compare the 41 people with HAs to the null value (declared by people with no HAs). The results are presented in Table 1.
Pain severity is statistically significantly higher among individuals with TMD compared to the value of 0, which indicates no pain. Furthermore, almost every type of pain was statistically significantly more frequent compared to the null value, with the exception of cutting pain (p = 0.059), where the average score was close to the value indicating no pain. The obtained difference results (compared to the null value) were moderate for rushing, continuous and intermittent pain (r ≥ 0.30), and strong for other types of pain (r ≥ 0.50, Table 1).
Table 2 shows the results of Fisher’s exact test for the 2×2 tables and the Fisher–Freeman–Halton exact test for larger contingency tables on the comparison of TMD and HA symptom prevalence.
When analyzing the results, it was found that neck and shoulder girdle pain, masticatory muscle pain, ear pain, and TMJ hypermobility, as well as limited mandibular mobility, a feeling of tension in the masticatory muscles, and acoustic complaints, were not differentiated by the perception of a HA. However, TMJ joint blocking was significantly less common among individuals with HAs (68.3%) compared to the group without HAs. In addition, clenching and/or grinding of teeth occurred significantly more frequently among patients with HAs (92.7%, Table 2) compared to the controls.
Discussion
The study performed the quantitative and qualitative assessment of HAs in people with TMD, and did not examine the basis of their occurrence. Patients with TMD declared the presence of HAs significantly more often, which was confirmed by 80% of the respondents. The obtained difference results (compared to the null value) were moderate for continuous (r = 0.49), intermittent (r = 0.46), rushing (r = 0.41), and cutting (r = 0. 30) pain, and were strong for pressing (r = 0.82), persistent (r = 0.66), pickling (r = 0.62), momentary (r = 0.60), dimmed (r = 0.59), blunt (r = 0.51), and breaking pain (r = 0.51).
According to the literature, patients diagnosed with TTH more often described the type of HA they experience as pressing.55, 56 Therefore, at the initial stage of the conducted research, it could have been assumed with great caution that the oppressive type of pain reported by patients with TMD would indicate the presence of TTH, which should be taken into account in future research.
Previous epidemiological studies have shown an association between TMD pain and TTH.55 Clinically, pain associated with TMD and TTH share a combination of distinct head and face signs and symptoms, i.e., tenderness of the masticatory muscles for TMD and pericranial muscle tenderness for TTH in the active phase of both conditions.57 Other clinical intersections between TMD and TTH include the age of subjects in terms of peak incidence, pain severity, pharmacotherapy, and even non-pharmacological treatment.58, 59, 60 A recent study also showed a high prevalence of active myofascial trigger points in TTH patients.61 This finding may support the hypothesis that peripheral muscle mechanisms are involved in the pathophysiology of TTH.
Current research indicates an important role of central sensitization in the pathogenesis of chronic TTH.62 Continuous episodes of pain involving the pericranial muscles (such as the temporalis muscle) can hypersensitize the central nervous system, activating higher brain centers, which can lead to chronic TTH transformation.63 Despite some clinical similarities and overlaps, both TMD HAs and primary TTH HAs are distinct entities.
Other studies have reported that TMD symptoms are more common in individuals with primary HAs compared to those without HAs.64 This relationship is bidirectional, and several studies have shown that most TMD patients report HAs.65 One prospective study claimed that the presence of TMD predicted future HAs.66 In addition, the onset of TMD was followed by an increased incidence of HAs.67 Several randomized controlled trials have shown a beneficial effect of treating the masticatory muscles for HAs.68, 69
The conducted research shows that pain in the masticatory muscles, ear pain, TMJ pain and hypermobility, as well as limited TMJ mobility, the feeling of masticatory muscle tension, and acoustic complaints are not differentiated by the sensation of a HA presence. Pain in the neck and shoulder girdle (82.9%, p = 0.059) as well as clenching and/or grinding of teeth (92.7%, p = 0.021) are significantly more common among patients with both TMD and HAs, which has been confirmed by previous studies. On the other hand, blocking TMJ occurred less frequently in people with HAs than in those without pain. Studies by other authors showed a significant relationship between HAs, TMJ pain and acoustic symptoms. However, in the study by Melo et al., masticatory muscle pain and TMJ pain were found to be more common in patients with HAs. In addition, TMD seems to be more severe in patients with HAs.70 Temporomandibular joint dysfunction is more common in people with HAs than in the pain-free group.71
Limitations
Our preliminary research has some limitations. The main limitation is the small research group, the lack of a neurological examination of patients with HAs, and the lack of additional imaging diagnostics of the TMJs, which should be taken into account when continuing these studies in the future. Further research is needed on the correct diagnosis and causative treatment of patients suffering from HAs resulting from TMD. Patients with suspected primary or secondary HAs due to TMD should be referred to a dental practitioner to ensure effective causative treatment.
Conclusions
According to the conducted pilot studies, HAs are a serious health problem in people with TMD. At the initial stage of the research, it was assumed that TMD patients were more likely to experience a tension HA. Subsequently, it was observed that people with HAs were more likely to have pain in the neck and shoulder girdle, as well as parafunctions such as clenching and/or teeth grinding. In contrast, TMJ blocking occurred significantly less frequently. Therefore, while continuing the research, it is necessary to differentiate TMJ diseases into those of joint and muscle origin. According to research, the treatment of patients with TMD and HAs may require close interdisciplinary cooperation between specialties (dentistry and neurology). Vigilance should be exercised in the differentiation of these 2 disease entities during their treatment.
Supplementary data
The supplementary materials are available at https://doi.org/10.5281/zenodo.8272638. The package contains the following files:
Supplementary Table 1. Descriptive statistics of indicators of tested variables.