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

Introduction

Temporomandibular disorders (TMDs) are the most prevalent group and the most common source of chronic pain in the orofacial area.^1,2 They are characterized by pain in the temporomandibular joints (TMJ) and masticatory muscles, noises of the TMJ during mandibular function, and by restriction in jaw movements.^1,3,4 Painful TMDs have been shown to be biopsychosocial and multifactorial disorders; hence, there is not a singular cause that can explain the onset of painful TMDs.⁵ Notwithstanding, the psychological profile, state of pain amplification and general health and global symptoms have been proposed to play an important role in the etiology of painful TMDs,^5–7 which are probably adjusted by gene expression and affected by environmental contributions such as social and demographic factors.⁶

In addition, the most common sociodemographic factor reported by the literature related with TMDs incidence is the gender frequency, which is higher in females than in males, and age prevalence, being greatest among people between 18 and 44 years old.^5,8 However, while other sociodemographic factors disparities like race, social and ethnicity have been associated with clinical pain experiences in many health conditions,^9–11 their role in TMDs is not clear, especially regarding TMDs onset.⁶ In the same way, discrepancies have been described in subgroups with different socioeconomic status. Further, it seems that educational attainment and factors associated with moving to another country are less important predictors, even though could influence TMDs pain.^12,13

Most clinical trials in the field of TMDs use the Research Diagnostic Criteria for TMD (RDC/TMD),¹⁴ or its updated version, the Diagnostic Criteria for TMD (DC/TMD),¹⁵ as a diagnostic tool that also assesses the sociodemographic profile of patients. Intriguingly, even though they assess the sociodemographic profile of the included patients, these data are rarely reported. Both the RDC/TMD and the DC/TMD include questions regarding age, race, sex, marital status, ethnicity, level of schooling and family income, which as explained before, could influence the onset of TMDs.^14,15 Therefore, since the actual knowledge about the role of sociodemographic factors is scant, but merits attention for both scientific and public health reasons, it is important to summarize the current findings to provide a basis to construct TMDs patients sociodemographic profile as well as suggestions for future researches. Taking this into account, the aim of the present scoping review is to report the prevalence of sociodemographic factors in TMDs patients using the RDC/TMD and DC/TMD.

Materials and Methods

Search Strategy and Selection Criteria

During February 2023, a search of the literature was performed using the following Medical Subjects Headings (MeSH) and related terms: [Temporomandibular Joints disorders] OR [Temporomandibular disorders] OR [TMD] AND [sociodemographic factors] OR [sociodemographic] AND [Research Diagnostic Criteria for Temporomandibular Disorders] OR [RDC/TMD] AND [Diagnostic Criteria for Temporomandibular Disorders] OR [DC/TMD] in the National Library of Medicine Medline (PubMed) and Web of Science databases to identify a list of potential papers for inclusion in this scoping review. In addition, search expansion strategies were also used to identify other potentially relevant citations (ie, hands-on search in private libraries and reference lists of the included articles).

The inclusion criteria were limited to: (1) studies written in English published from January 1992 to February 2023, (2) articles on adult populations (if adults and teenagers/children were included in the same study, just adult data was considered for the analysis), (3) clinical trials focused or reporting sociodemographic data in TMD patients, (4) studies using the RDC/TMD and DC/TMD as diagnostic tools. Manuscripts using different diagnostics tools, not reporting the criteria for TMD diagnosis, reporting data on TMD prevalence only in teenagers/children, or unrelated to the review aim and case reports were excluded.

Assessment of Papers

Two of the authors (I.C. and G.D.C.) independently reviewed the titles and abstracts of all articles, and potential articles were obtained in full text for careful read to check the eligibility. In all cases of disagreement between reviewers regarding the potential inclusion of an article or data interpretation, a third author (R.P.) was involved. Then, after final selection and inclusion of articles for the review, another author (M.B.C.S.) performed data extraction based on the Population Exposure Comparison Outcome (PECO) strategy.¹⁶ The population (“P”) was described including the sample size. The exposure (“E”) concerned information on the study design, diagnostic tool used, and TMD diagnoses. The comparison (“C”) included if data for the control group if present depending on the study design. The outcome (“O”) was reported in terms of sociodemographic frequency data.

Results

Overview

The literature search identified 316 articles, of which eight were overlapping articles retrieved in both databases. From the 308 articles screened by title and abstract, 181 were read in full for eligibility. Of these, 151 were excluded for not fulfilling the inclusion criteria, and three were excluded since it was not possible to retrieve the full text. Therefore, a total of 27 manuscripts were included in the review (Figure 1).

Figure 1 Flow diagram of the literature search strategy.

The included articles covered a wide spectrum of populations of different sex, age and ethnic background. The age of the subjects varied from ≥15 years to ≤80 years, and the sample size ranged from 15 to 4289 participants with and without TMD. Regarding the sex distribution, a predominance of females was found (Table 1).

Table 1 Characteristics of the Included Studies

Summary of the Studies

Most of the included studies aimed to investigate the role of sociodemographic characteristics and their association with TMDs. Besides sociodemographic aspects, such as age, race, education, job, income, and marital status, two manuscripts investigated features related to height, weight, and BMI. Further, psychological characteristics and parafunctional habits were investigated in most studies but are not presented in this scoping review since they do not relate to the present aim (Table 2).

Table 2 Summary of the Findings from the Included Studies (PECO)

The environment in which each study was conducted differed substantially from each other. While there were epidemiological studies aiming to access the influence of socioeconomic features, some papers were developed to investigate specific situations, such as patients with Parkinson’s disease, COVID-19 pandemic, headaches, etc. Thus, the results of the 27 papers retrieved differed substantially in most aspects. Nevertheless, it was possible to summarize the findings according to the frequency of reported results (Table 2).

In general, no statistically significant difference was reported by the included studies between men and women regarding sociodemographic factors. The differences found were that women demonstrated higher prevalence of TMDs and pain-related impairments. Only one study reported that men were more likely to have higher pain-related disability than women.³¹

Diagnosed TMDs were higher among younger individuals, while those aged above 50 years showed a lower prevalence. Conversely, the prevalence of non-painful TMDs was also higher in the 20–30 years old individuals, while older individuals were more likely to experience high-impact pain.

As for race, no significant difference was found in most of the evaluated studies, except for one in which Black/African American people were more likely to experience high-impact pain compared to other racial/ethnic categories.³⁴ When it comes to education, two articles reported that higher educational level, could be a risk factor for TMDs, because it may be associated with having more stressful jobs.^18,25 Conversely, three studies demonstrated that a lower level of education, was associated with a higher pain degree.^20,27,35 Further, being employed or not, in general, was not a risk factor for TMDs.

Considering the marital status, no difference was usually found, but when reported it was considered that divorced individuals reported higher intensity pain (p<0.05), followed by married ones.

Discussion

The influence of sociodemographic factors on the development, presentation, and treatment outcomes of chronic painful conditions is widely acknowledged.^43–45 Understanding these factors can inform the creation of tailored prevention programs and personalized treatment methods, ultimately enhancing patient outcomes and improving the quality of life for individuals with TMDs. This scoping review highlights age, gender, marital status, education level, and profession as the most frequently studied sociodemographic factors.

Age was investigated in every study in this review. While TMDs can manifest in any age group, research indicates that the incidence rises during adolescence and young adulthood, peaking between 20 and 40 years of age. This heightened prevalence may be linked to hormonal fluctuations, psychosocial stress, and an increased vulnerability to injury or trauma during this life stage.^8,46–48 With aging, structural changes occur in the joints and surrounding tissues. Wear on joint cartilage, bone remodeling, and tissue degeneration can impact the function and stability of the TMJ, potentially contributing to TMDs such as disc displacement, as noted in Velly et al case–control study.^17,49–51

Similar to age, gender was a focal point across all studies in this review. Extensive evidence highlights gender disparities in the prevalence of TMDs, with women exhibiting a higher prevalence compared to men in diverse populations and geographic regions (Table 1). Women tend to perceive oral health, particularly orofacial pain, more negatively than men.²⁸ This gender bias is influenced by hormonal factors, anatomical variations in the TMJ and muscles, psychosocial factors, and differences in pain reporting and mechanisms.^31,52–54 A comprehensive understanding of gender-specific aspects in TMDs can contribute to the development of personalized treatment strategies and targeted interventions to enhance TMDs management.

Marital status was investigated in only 14 studies included in this review. Unlike other health conditions, such as coronary diseases, where the impact of marital status is well documented, the consideration of this factor in the realm of TMDs remains limited. Research in coronary diseases shows that a satisfying marital relationship reduces biological, lifestyle, and psychosocial risk factors associated with disease development.⁵⁵ However, in the context of TMDs, only a few studies have explored this variable. The current findings indicate that individuals who are divorced, separated, or widowed exhibit a higher prevalence of TMDs compared to those who are married or single. This association may stem from the psychosocial ramifications of relationship dissolution.^20,37

In general, a patient’s level of education is a significant factor, as higher education tends to correlate with greater self-care and motivation to seek specialized help for addressing pathologies, particularly painful ones.⁵⁶ The current review reveals that studies examining educational levels indicate that individuals with lower academic degrees or fewer years of education may face an elevated risk of developing TMDs and experiencing more severe symptoms. Health behaviors, psychosocial factors, pain perception, and treatment adherence are all potential mediators in the relationship between educational level and TMDs.^19,26,27,35

The link between a patient’s profession and TMDs has been a focal point in research investigating occupational factors and their potential influence on TMDs prevalence, risk factors, and symptomatology. In this review, numerous studies have shed light on the correlation between profession and TMDs. Various occupational factors have been identified as potential risk factors for the development of TMDs, with variations based on the nature of the profession. Specific professions have been highlighted as potentially having a higher prevalence of TMDs or increased risk factors. These include occupations involving prolonged or repetitive use of the masticatory system, such as playing musical instruments or professions requiring extensive speaking or voice use. Furthermore, professions characterized by high levels of stress, such as teaching, computer office work, healthcare, military service, and emergency services, may also exhibit an increased risk of TMDs.^57–61

In this sociodemographic study segment, parallels can be drawn with other chronic painful conditions, revealing striking similarities. For example, both fibromyalgia and chronic migraine conditions tend to disproportionately affect young women with lower levels of education, thus adversely impacting their personal relationships.^62–64 These shared patient profile similarities also indicate that individuals with TMD could potentially benefit from successful treatment strategies like those used for other conditions, and vice versa.

Finally, all results must be interpreted cautiously due to the methodological limitations of the review. While systematic reviews are considered the highest level of scientific evidence, the wide variability in objectives and methodologies of the included studies made it infeasible in this case. Hence, the decision to conduct a scoping review was based on its capacity to map and provide an overview of the research field, allowing for a flexible analysis of the addressed studies. Moving forward, when there are scientific articles with relevant methodology, a systematic review on the subject should also be conducted. Furthermore, we strongly recommend that future clinical studies on individuals with TMDs include data collection on the not commonly reported sociodemographic factors such as education, job, income, and marital status. By doing that it will allow to explore the actual relationship of sociodemographic factors, especially for individuals with painful TMDs. As a final remark, the results of this review aimed to contribute to the understanding of the influence of various sociodemographic factors on TMD occurrence, but were also an attempt to characterize the individuals suffering from TMD. In addition, by characterizing the individuals with TMD regarding their sociodemographic variables, their psychosocial variables and correlate them to TMDs, especially painful TMDs, might provide clinicians with tools and categorizations that will help them setting up individualized treatment plans based on their condition but also based on sociodemographic and psychosocial factors and variables affecting and causing the condition. That would in turn improve treatment outcome and prognosis, while it will reduce individual pain and suffering.

Conclusion

Given the conflicting results of the included studies on TMD individuals sociodemographic profiles, it can be inferred that young women with lower educational levels and without a partner were the most susceptible to experiencing TMD signs and symptoms.