Fig. 2

The levels of cytokines during microdialysis. Graph showing the levels of cytokines (mean and SEM) during microdialysis in 20 women with temporomandibular disorder myalgia (Patients) and 20 pain-free healthy aged-matched women (Controls). After 140 min (baseline), a 20-minute repetitive tooth-clenching task (140–160 min) was performed followed by one-hour rest (160–220 min). IL-1β (P = 0.0007), IL-6 (P < 0.001), IL-7 (P = 0.012), IL-8 (P < 0.001), IL-13 (P < 0.001), and GM-CSF (P = 0.008) increased with time in the patients, whereas IL-6 (P < 0.001), IL-8 (P < 0.001), and IL-13 (P = 0.042) increased with time in the controls (Friedman test). IL-6 (P < 0.001), IL-8 (P = 0.001), IL-13 (P = 0.035), and TNF (P = 0.042) had increased after clenching (160 min) compared to baseline (140 min) in the patients, and IL-6 (P = 0.004) and IL-8 (P = 0.032) had increased in the controls (Wilcoxon test). There were no significant differences in cytokine levels between patients and controls after clenching (160 min), although there was a trend for IL-8 (Mann-Whitney U-test, P = 0.074). *= significant difference between the groups (P < 0.05)