Alterations in kinematics of temporomandibular joint associated with chronic neck pain

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 Cervical Joint Position Sense and Head Posture in Individuals With Myogenic Temporomandibular Dysfunctions and Identifying Related Factors: A Case-Control Study

BACKGROUND

Temporomandibular dysfunctions (TMDs) have the potential to cause changes in cervical muscle strength, muscle endurance and position sense by changing muscle activation patterns, especially as a result of forward head posture. The effects of TMDs on cervical joint position sense (CJPS) and head posture remain controversial.

OBJECTIVE

The aim of this study was to evaluate the head posture and CJPS of individuals with TMDs and compare them with healthy individuals.

METHODS

This research, which was designed as a case-control study, was concluded with the inclusion of total of 84 participants (42 individuals diagnosed with myogenic TMDs, 42 controls). The assessment of participants included pain severity, neck and jaw functionality and disability, CJPS, head posture and temporomandibular joint (TMJ) range of motion (ROM).

RESULTS

Individuals with TMDs exhibited higher angular deviation in CJPS during flexion and extension (p < 0.001). Additionally, individuals with TMDs demonstrated higher TMJ pain, limitation and dysfunction severity, as well as a more limited TMJ ROM (p < 0.001). Head posture was similar between groups (p > 0.05). There is a significant relationship between VAS-TMJ with VAS-cervical, FAI, NDI, JFLS-8 and TMJ ROM (p < 0.05). Moreover, a significant correlation was observed between NDI with FAI and TMJ ROM (p < 0.05).

CONCLUSION

These results indicate that in addition to higher pain severity, disability and lower jaw ROM, CJPS of individuals with TMDs is also negatively affected. Also, parameters related to disability and functionality of cervical and TMJ were significantly correlated. Further studies are needed to determine the factors contributing to these results.