Comparison of Salivary Cortisol Levels among Patients with Temporomandibular Disorder with and without Depression and Healthy Controls: A Cross-sectional Study

Introduction: Temporomandibular Disorders (TMDs) are musculoskeletal conditions often linked to psychological stress. Cortisol, a key stress biomarker, may play a role in the pathophysiology of TMD. The present study compares salivary cortisol levels in young adults with TMD, with and without depression, and in healthy controls to explore the psychological and physiological interplay in these conditions. Identifying distinct cortisol patterns across these groups could aid in understanding the role of stress-related endocrine function in TMD. Aim: To test salivary cortisol levels in young adults diagnosed with TMD, both with and without depression, and to compare these results with an age-matched control group without TMD and depression. Materials and Methods: The present cross-sectional observational study was conducted at Vishnu Dental College, Bhimavaram, between January and May 2024. The present study included individuals aged 18-28 years of both genders who experienced pain in the Temporomandibular Joint (TMJ) region for a minimum of three months, in accordance with the Research Diagnostic Criteria for TMD (RDC/TMD). A total of 45 patients were divided into three groups: TMD with depression (n=15), TMD without depression (n=15), and a control group (n=15). Patients were evaluated for TMD based on the RDC/ TMD criteria. Psychological status was assessed using the RDC/TMD Axis 2 self-report for all participants, including those with TMD and the control group without TMD. Post awakening salivary samples were collected between 7 and 8 a.m., and salivary cortisol levels were measured using an Enzyme-Linked Immunosorbent Assay (ELISA) kit. Data analysis was performed using a paired t-test, and Pearson correlation was used to examine the relationship between morning and evening cortisol levels. An Analysis of Variance (ANOVA) test was conducted to compare cortisol levels across groups, with a p-value <0.001 considered significant. Results: A strong, significant correlation was found between morning and evening salivary cortisol levels in all groups (TMD with depression: r=0.99; TMD without depression: r=0.989; controls: r=0.725; p<0.001). Morning cortisol was highest in TMD patients with depression (55.7 ng/mL), followed by those without depression (19.63 ng/mL) and controls (12.66 ng/mL). Evening levels followed a similar pattern. Females showed significantly higher cortisol levels than males, especially in the TMD without depression and control groups (p<0.001). In TMD with depression, females had higher levels, though this was not statistically significant. Conclusion: Assessing salivary cortisol levels may provide insight into psychological factors that contribute to the development of TMD. Salivary cortisol could serve as a valuable indicator in detecting psychological elements potentially linked to TMDs.