Is low back pain a risk/prognostic factor for the development and/or progression of temporomandibular disorders? A systematic review with meta-analysis

Exploring the causal relationship between chronic pain and temporomandibular disorders: A two-sample Mendelian randomization study

OBJECTIVES

This study investigates the causal effects of chronic pain on temporomandibular disorders using two-sample Mendelian randomization analysis.

DESIGN

Two-sample bidirectional Mendelian randomization analysis was adopted to systematically explore the causal relationship between temporomandibular disorders and 7 types of chronic pain, including headache, hip, neck/shoulder, stomach/abdominal, back, knee, and facial chronic pain. Genetic variants from genome-wide association studies data served as instrumental variables. Inverse variance weighted, weighted median, and Mendelian randomization-Egger regression were applied, with sensitivity analyses to ensure robustness. And p < 0.05 indicated statistical significance.

RESULTS

Mendelian randomization analyses revealed a significant causal effect of neck or shoulder pain on the risk of temporomandibular disorders, with an Odds ratio of 6.317 (95 % CI: 1.730-23.062, p = 5.30E-3). Additionally, a reverse causal effect was observed where temporomandibular disorders may increase the risk of back pain, with an Odds ratio of 1.008 (95 % CI: 1.002-1.013, p = 8.40E-03). No significant causal relationships were found between other types of chronic pain (headache, hip pain, stomach or abdominal pain, facial pain, or knee pain) and temporomandibular disorders.

CONCLUSIONS

This study provides compelling evidence for the causal relationships between specific chronic pain conditions (neck or shoulder pain) and the risk of temporomandibular disorders. These insights highlight the importance of an integrated approach to patient care and emphasize the need for further research into the biological mechanisms underlying these relationships to guide the development of targeted preventive and treatment strategies.

Assessment of chronic overlapping pain comorbidities for the management of temporomandibular disorders: Secondary analysis of a randomized clinical trial

BACKGROUND

Chronic painful temporomandibular disorders (TMD) are a functional pain syndrome that embodies a spectrum of clinical manifestations and expresses great complexity through the coexistence of multiple comorbidities.

OBJECTIVE

Evaluate the prevalence of pain comorbidities, explore the correlation between comorbidities, kinesiophobia, catastrophizing, and pain disability at baseline, and determine variables of interest for prediction response to physiotherapy interventions at different follow-up times.

METHODS

This is a secondary analysis of a previously conducted randomized controlled trial (RCT). Outcomes and covariables for this secondary analysis were collected from subjects with chronic TMD (≥3 months), based on the DC/TMD diagnostic criteria, assigned to a multimodal treatment and a second manual therapy control group. The participants underwent follow-up assessment at 7 and 19 weeks. The outcomes (dependent variables) for these analyses were craniofacial pain disability, catastrophizing, and kinesiophobia. However, these outcomes were also used as covariables of interest in addition to comorbidity prevalence and severity at baseline for different analyses. We performed linear regression analyses to determine the association between our outcomes and covariables at baseline and at different follow-ups.

RESULTS

Comorbidity severity explained craniofacial pain disability at baseline, showing a strong correlation (Standardized B: 0.40, p-value: 0.017). Higher comorbidity severity, led to higher craniofacial pain score. Comorbidity severity and baseline catastrophizing predicted a better response to treatment for craniofacial pain improvements at short and long term (R2 .22, p-value : 0.009 and R2 .19, p-value: 0.02 respectively).

CONCLUSION

This study provides insight into the prevention and clinical management of chronic pain related to TMD.

Causal effects of educational attainment on temporomandibular disorders and the mediating pathways: A Mendelian randomization study

BACKGROUND

As one of the most important indicators of socioeconomic status, educational attainment (EA) exhibits a strong association with temporomandibular disorders (TMDs). Despite this link, there is a lack of evidence regarding the causal role of EA in either facilitating or preventing TMDs.

OBJECTIVE

This study aimed to investigate the causal effect of education on TMDs and explore potential mediating pathways.

METHODS

Utilizing summary statistics from genome-wide association studies on years of schooling (N = 766 345) and TMDs (N = 211 023), we conducted Mendelian randomization (MR) to assess the overall effect of education. Additionally, a two-step MR approach was employed to evaluate 30 potential mediators and calculate the mediation proportions in the association. Comprehensive sensitivity analyses were used to verify the robustness, heterogeneity, and pleiotropy.

RESULTS

Univariable MR analyses revealed a causal effect of lower EA on an increased risk of TMDs (OR: 0.53, 95% CI: 0.43-0.66, p < .001). Five out of 30 modifiable factors were identified as causal mediators in the associations of EA with TMDs, including feeling nervous (mediation proportion: 11.6%), feeling tense (10.2%), depression (9.6%), feeling worry (7.6%) and daily smoking (8.9%). Meanwhile, no pleiotropy was detected in the analyses (p > .05).

CONCLUSION

Our findings supported that higher EA has a protective effect on the onset of TMDs, with partial mediation by psychological disorders and daily smoking. Interventions on these factors thus have the potential of substantially reducing the burden of TMDs attributed to low education.