In literature, large-scale studies on the clinical profile of TMD among TMD patients seeking care are rare, especially after the publication of DC/TMD. The present study with 3362 TMD patients in 2021 may help to understand the real clinical profile of TMD currently.
As one kind of common maxillofacial diseases, TMD are most commonly reported in young to middle-aged adults (20 to 50 years of age), with a peak of occurrence between 20 and 40 years of age9,10. A recent meta-analysis of studies using RDC/TMD and DC/TMD estimated that 31% of adults and 11% of children had TMD11. In the present study, among 3362 TMD patients seeking care, the age varied from 7 to 85 years old, with an average age of 29.89 ± 13.73Y. It was startling that the percent of TMD patients aged 16-35Y was as high as 68.6%, and the percent of TMD patients aged below 35Y was 76.1%. In addition, in TMD patients seeking care, the percent of patients aged ≤ 15Y and ≥ 56Y was both only 7.5%. In 2018, Marpaung C et al. reported that the prevalence of pain-related TMD was 21.6% in a large group of Dutch adolescents, aged between 12 and 18 years12. In 2023, Rentsch M et al. reported that the self-reported prevalence of TMD was 18.8% in Swiss children and adolescents aged 7–14 years13. It seems that with the increasing social pressure TMD is becoming a common disease in children and adolescents. However, due to low awareness of TMD or other reasons, the percent of TMD patients aged ≤ 15Y seeking care was relatively low.
In literature, most epidemiological studies showed that predilection of TMD in females is striking. Population-based studies show the prevalence of TMD to be 2 to 5 times higher in women than in men in community samples14. In a review from the New England Journal of Medicine, it has been reported the female-to-male ratio of patients seeking care ranged from 3:1 to as high as 9:19. In 2018, a meta-analysis showed that the odds for presenting TMD were 2.2 times higher in women as compared to men13. In the present study, the female-to-male ratio of TMD patients seeking care was also 2.2:1, which is identical to the previous meta-analysis13. Unlike similar diseases of other joints that also have a greater female predilection but occur postmenopausally14, a large proportion of women with TMD are adolescents and young adults. The reasons for this marked sexual dimorphism and age distribution remain unclear. It is estimated that the differences might be related to hormonal factors (particularly estrogen), cultural and social factors, higher levels of work stress for women, differences in pain sensitivity, as well as health-seeking behaviors15. Additionally, in an OPPERA cohort study of community populations in the United States published in 2013, women were more likely to develop chronic TMD16,17. Several studies have shown that women are approximately three times more likely to have chronic TMD than men7,11,18. Anyway, this sexual dimorphism topic is worthy to be studied further.
It is well known that females tend to seek treatment more frequently and show more signs and symptoms of TMD than males14,19. In most reports, the prevalence of jaw movement limitation symptoms was significantly different between men and women, but the prevalence of TMJ clicking and pain symptoms varied between studies20,21. In a 2010–2017 longitudinal study in Sweden, based on 37,647 individuals surveyed in 2010, the incidence of self-reported jaw catching/locking was higher in women than in men (3.2% vs. 1.5%), and this relationship and magnitude remained similar throughout the study period22. In a study on 502 TMD patients during 2000–2002 in Vienna, females (mean age 40 ± 16 years) showed higher pain intensity, severer muscle tenderness on palpation, and lower degree of mouth opening than males (mean age 41 ± 16 years) 23. In a 2012 comparative study of TMD symptoms in adolescents aged 6–18 years, there was no significant gender difference in symptoms except for more headache and neck pain in late adolescents aged 16–18 years24. A Finnish study reported in 2023 showed that headache was more common among 32-year-old adult subjects in women (odds ratio, 2.4), with no gender differences in prevalence of TMD pain symptoms and TMJ sounds25. In the present study, females (mean age 30.49 ± 13.90 years) were more likely to have limitations in jaw movement than males (mean age 28.56 ± 13.26 years), which is consistent with previous reports. However, no significant difference in self-reported pain intensity and muscle tenderness on palpation was found between male and female TMD patients in the present study. Additionally, in the study in Vienna, females showed peaks of prevalence of TMD in the age group below 25 years and in the group 55–60 years, whereas males had a more even age distribution22. However, in the present study, the percent of TMD patients in different age group was similar in males and females, with highest percent in the 16-35Y age group. The difference may be due to the different era background and different TMD suffering population. Although it is reported that women show more pronounced pain responses to experimentally induced stimuli and also increased pain and reflex responses to glutamate application to jaw muscles than men26,27,28, the real pain in natural TMD process may be different from experimental pain.
In literature, males were usually reported to have higher pain threshold and tolerance than females29. Interestingly, in the present study, the average age of female TMD patients was significantly higher than that of male TMD patients, and female TMD patients had a longer duration of disease before seeking care than males. This might be due to more pain experience in females than males, especially during menstrual period and child birth. Thus, females may do better at coping with pain experience. In addition, East Asian women are relatively under greater social pressure, more involved in family affairs, and less concerned about themselves, so they might come to the clinic later. The longer duration of TMD in women may also contribute to a higher prevalence group in the cross-sectional analysis.
This study was a retrospective analysis, and only a small number of patients underwent MRI assessment for economic reasons, so it was not included in the statistics, which is the limitation of this study. In addition, patients came from a single dental hospital, not multi-center, and there may be some bias in the data.