Plasma Dopamine Level as a Biomarker for Pain in Myofascial Temporomandibular Disorders

Background: Myofascial Temporomandibular Disorders (M-TMD) are characterized by chronic pain and dysfunction of the jaw muscles, often linked to stress and neurochemical imbalances. Dopamine, a neurotransmitter involved in pain modulation, has been proposed as a potential biomarker for M-TMD-related pain. This study aimed to evaluate plasma dopamine levels in M-TMD patients compared to healthy controls and explore its role as a pain biomarker. Objective: The primary objective was to assess plasma dopamine levels in M-TMD patients and correlate them with clinical pain symptoms. Methods: A case-control study was conducted with 50 participants (25 M-TMD patients and 25 age- and sex-matched healthy controls). Blood samples were collected in EDTA tubes, centrifuged at 2000 g for 10 minutes, and plasma was stored at −60°C. Dopamine levels were measured in nM. Clinical data, including age, gender, symptoms, and OPG findings, were recorded. Statistical analysis included mean comparisons (t-test) and subgroup analysis by gender and age. Results: Plasma dopamine levels were significantly higher in M-TMD patients (mean: 5.01 nM) compared to controls (mean: 2.53 nM; p < 0.001). Female M-TMD patients had slightly higher dopamine levels (mean: 5.12 nM) than males (mean: 4.89 nM), though not statistically significant (p = 0.23). Common symptoms in M-TMD patients included bruxism (44%), morning jaw stiffness (40%), and stress-related jaw tension (56%). All patients exhibited mild condylar flattening on OPG, and no significant correlation was found between dopamine levels and age (r = 0.12, p = 0.34). Conclusion: Elevated plasma dopamine levels in M-TMD patients suggest its potential role as a biomarker for pain and stress-related pathophysiology. The findings support further investigation into dopaminergic pathways in M-TMD and personalized treatment strategies targeting neurochemical imbalances.